ITB Graduate School Conference

Prediction of Thermodynamic Simulation of Ash Behavior in Biomass Co-Firing: Eichhornia crassipes, Calliandra calothyrsus, and Gliricidia sepium in Pulverized Coal Boilers Using FactSage

2025-05-30T14:59:48+08:00

This study investigates the ash behavior of three alternative biomass source Eichhornia crassipes, Calliandra calothyrsus, and Gliricidia sepium for co-firing with low-rank (LRC) and medium-rank coal (MRC) using thermodynamic simulations FactSage. Ash fusion temperature (AFT) analysis and ash melt-fraction curves were employed to evaluate slagging and fouling tendencies under oxidizing conditions. Results indicate that Gliricidia sepium significantly enhances AFT and provides a stable melting interval in both LRC and MRC blends, particularly due to its high CaO content. Eichhornia crassipes showed favorable AFT performance despite its high ash content, while Calliandra calothyrsus posed higher slagging risks due to elevated K₂O concentrations and lower fusion temperatures. The integration of AFT values with melt-fraction trends revealed that MRC blends generally exhibited wider melting intervals and smoother transitions, which support better ash flow control. These findings highlight the importance of chemical composition balance and ash thermal behavior in selecting suitable biomass for stable and efficient co-firing operations.

Evaluation of Performance Salak Geothermal Power Plant #1 based on Exergy Analysis

2025-06-03T11:42:04+08:00

This study presents an exergy analysis of the Mount Salak Geothermal Power Plant Unit #1 to evaluate its thermodynamic performance and identify inefficiencies. Exergy analysis is employed to assess operational efficiency by considering both energy quantity and quality. Real operational data and CycleTempo simulation software were used to analyze key components, including the turbine, condenser, and gas removal system. Results indicate that the overall exergy efficiency of the system is 66.88%, with the highest exergy losses occurring in the turbine (13.76%) and condenser (10.01%). Two scenarios were simulated to improve performance: (1) adjusting turbine inlet pressure to 7.02 bara and (2) optimizing condenser pressure to 0.10 bara. These adjustments resulted in an increase in overall exergy efficiency to 68.81% and improved power output. The study emphasizes the importance of maintaining optimal operational parameters and addressing component inefficiencies to enhance power generation and extend the plant's operational life. It also highlights the value of exergy analysis as a tool for identifying potential improvements, offering valuable insights for operators seeking to optimize efficiency, reduce energy losses, and ensure the long-term sustainability of geothermal power plants.

Alternative Direct Use of Geothermal Energy in Atadei

2025-05-23T17:29:27+08:00

The development of geothermal energy in the Atadei 2 x 5 MW geothermal working area cannot be separated from social problems, namely the opposition of the local population in Lembata Regency. This is due to a lack of knowledge about the benefits of geothermal energy. To overcome this, direct use of geothermal energy can be a solution, so that the surrounding community can feel the benefits of geothermal development. One of the direct uses of geothermal energy is the use of a cascade system. The Atadei geothermal field has the potential for direct use of geothermal for the needs of the surrounding community. The results of this research are expected to provide an alternative to solve the problems that exist in the Atadei geothermal working area, so that the development of the Atadei 2 x 5 MW geothermal power plant can proceed smoothly.

Techno-Economic Evaluation of The Implementation of BECCS (Bioenergy with Carbon Capture & Storage) at Anggrek Coal-Fired Power Plants in The Northern Sulawesi Electricity System

2025-06-01T11:54:44+08:00

This study investigates the techno-economic feasibility of integrating Bioenergy with Carbon Capture and Storage (BECCS) into PLN-owned coal-fired power plants in North Sulawesi, Indonesia, with a specific focus on the Anggrek CFPP. A combination of biomass co-firing using rice husk and wood chip at varying blending ratios (5%, 10%, 20%, and 30%) and post-combustion CO₂ capture using a blended MDEA–PZ amine solvent was simulated using Aspen Plus and Aspen HYSYS. The integration of BECCS reduced CO₂ emissions significantly, achieving net-negative emissions of −153 kgmole/h and −219 kgmole/h for 30% co-firing with rice husk and wood chip, respectively. However, the net plant output decreased to around 15.52–15.64 MW due to energy penalties from CCS operations. Economic analysis revealed that all BECCS scenarios resulted in Levelized Electricity Generation Costs (LEGC) between Rp 5,529.44 and Rp 5,646.22/kWh, far exceeding the regional Levelized Cost of Electricity (LCOE) of Rp 2,264/kWh. Key financial indicators NPV, IRR, and B/C ratio were unfavorable under current market conditions. Sensitivity analysis showed that carbon pricing levels above USD 170/tonCO₂ would be necessary to achieve economic viability, with the 5% wood chip co-firing scenario offering the most cost-effective configuration. While BECCS presents strong potential for deep decarbonization and negative emissions, its implementation in Indonesia’s coal fleet requires substantial policy support, including carbon pricing, subsidies, or regulatory incentives to overcome its current economic limitations.

Harnessing the Indonesia’s Banda Sea Thermal Resources Through Comprehensive OTEC Potential Study

2025-05-19T16:05:24+08:00

The Banda Sea, located in Indonesia's equatorial region, exhibits significant potential for Ocean Thermal Energy Conversion (OTEC) due to its deep-water layers and consistent surface temperatures. This study evaluates the OTEC feasibility in the Banda Sea by analyzing monthly and seasonal sea surface temperature (SST) data from 2015, obtained from Copernicus ERA5 reanalysis. Spatial and vertical temperature profiles were processed using Ocean Data View (ODV) to identify mixed-layer, thermocline, and deep-layer characteristics. Results indicate an average temperature gradient (ΔT) of 22.7°C between the surface (29–30°C) and 600–700 m depth (5–7°C), meeting the minimum ΔT requirement (20°C) for OTEC. The Carnot efficiency (η) reached 77%, surpassing the 70% benchmark for viable OTEC systems. However, long-term time-series analysis data from 2005 -2017 revealed intermittent periods where ΔT fell below 20°C, likely due to seasonal upwelling, El Niño-Southern Oscillation (ENSO) events, or anomalous ocean mixing. Those are posing reliability challenges for continuous power generation. While the Banda Sea’s thermal resources are promising, operational intermittency suggests the need for hybrid energy systems to ensure grid stability. This study provides critical insights for OTEC deployment in tropical regions, balancing renewable energy potential with technical constraints.

Techno-Economic Analysis of CCS Implementation for Decarbonization at the Tidore Coal-Fired Power Plant

2025-05-24T17:16:56+08:00

This study presents a techno-economic analysis of Carbon Capture and Storage (CCS) implementation at the Tidore Coal-Fired Power Plant (PLTU Tidore) using post-combustion technology with amine-based solvents. Two solvent formulations—30% monoethanolamine (MEA) with 10% piperazine (PZ) and 30% methyldiethanolamine (MDEA) with 10% PZ—were evaluated through process simulation in Aspen Plus to assess their technical performance and economic feasibility. The MDEA + PZ system demonstrated lower regeneration energy requirements (4.261 MJ/kg CO₂) compared to MEA + PZ (4.315 MJ/kg CO₂), with comparable CO₂ product purity of 99%. Despite MEA's higher absorption reactivity, MDEA showed superior energy efficiency and operational stability. Economic analysis revealed that the CCS investment cost reached IDR 139.17 billion, with annual O&M costs of IDR 65.74 billion. Under a carbon pricing scheme of USD 100/ton CO₂ and LCOE of IDR 2,486/kWh, the project achieved financial viability with a Net Present Value (NPV) of IDR 31 billion, Internal Rate of Return (IRR) of 9.79%, Benefit-Cost Ratio (B/C) of 1.00, and a payback period of 8 years. Additionally, scenario analysis demonstrated that increasing carbon pricing significantly lowers the required LCOE for breakeven, enhancing the attractiveness of CCS.

Coal Processing Modeling for Hydrogen Production

2025-05-30T16:57:24+08:00

This study develops a simulation model for processing low-quality coal using ASPEN Plus software with an entrained flow gasification method, focusing on dry versus wet feeding systems. Entrained flow gasification is selected due to its capability to convert coal into synthetic gas (syngas) at high temperatures and pressures. The resulting syngas can be further purified to produce hydrogen, a clean and sustainable energy source. The simulation analysis key operational parameters—including temperature, pressure, and air-to-coal ratio—while comparing the performance of dry and wet feeders. These comparisons aim to assess the impact of each feeding method on gasification efficiency and hydrogen yield. The goal is to identify optimal conditions for maximizing hydrogen production from low-quality coal. Results from this study are expected to offer insights into the relative advantages of dry and wet feeding techniques in coal gasification. Furthermore, the findings will support efforts to design and operate more efficient gasification systems, helping to reduce dependence on conventional fossil fuels and contributing to global carbon emission reduction initiatives. Overall, this research contributes to the advancement of cleaner coal utilization technologies and the broader development of sustainable hydrogen energy systems.

Land Use Change Analysis on Sediment Yield in the Cisokan Watershed Using SWAT+: Implications for the Operation of the Upper Cisokan Pumped Storage Hydropower Plant

2025-05-30T12:17:53+08:00

The Cisokan watershed plays a crucial role in supporting the sustainability of the Upper Cisokan Pumped Storage Hydropower Plant (UCPS). This study analyzes the impact of land cover change on sediment yield in the Cisokan Watershed during the 2013–2023 period using the high-resolution SWAT+ model. The model was calibrated with monthly observed streamflow data, resulting in a Nash-Sutcliffe Efficiency (NSE) of 0.80 (2013) and 0.65 (2023), indicating good model performance. Land cover data were obtained from the Indonesian Ministry of Environment (KLH), while climate data were sourced from MSWEP and ERA5. Using a zero-threshold HRU approach, the model generated 2,823 spatial units. The simulation results indicate an increase in total sediment yield of approximately 24.3%, with the highest concentrations in Sub-watersheds 1 and 3. These findings provide a scientific basis for spatially targeted land conservation planning to ensure the long-term sustainability of UCPS operations.

A Study on the Utilization of Biomass in Co-firing at the Nagan Raya 1 and 2 Coal-Fired Power Plants

2025-06-03T12:08:08+08:00

Global climate change and greenhouse gas (GHG) emissions, primarily from coal-fired power plants (PLTUs), pose significant threats to environmental sustainability. Biomass co-firing presents a viable solution to reduce CO₂ emissions and support renewable energy integration. However, Indonesia's cofiring implementation remains low, with only about 5% biomass substitution, hindered by technical and supply chain limitations. This study analyzes the technical feasibility and environmental impact of co-firing palm kernel shells and wood chips at PLTU Nagan Raya Units 1 and 2 using Aspen Plus v14 simulation software. Co-firing ratios ranged from 10% to 50%, and evaluations were based on proximate and ultimate analysis data. The findings reveal that a 10% co-firing ratio with palm kernel shells is the most effective, significantly reducing SOₓ and NOₓ emissions while maintaining power efficiency. In contrast, wood chips are recommended at a maximum of 5% due to supply limitations. An optimal blend ratio of 3:2 (palm kernel shell to wood chip) at 10% total biomass offers a practical compromise. This strategy is deemed viable to support sustainable energy transition in the Nagan Raya region and contributes to national decarbonization goals.

Reliability Analysis as A Maintenance Optimization Strategy at PT PLN Indonesia Power Unit PLTP Gunung Salak

2025-06-04T11:42:23+08:00

The Gunung Salak Geothermal Power Plant (GPP), which has been operating for 30 years until now, has experienced several failures that tend to increase from time to time. Failure of power plant equipment and the length of repair time will result in the loss of production. Based on equipment failure data from GPP, there is an indication of ineffectiveness in the implementation of maintenance activities that have been carried out. Maintenance strategies can be determined from reliability analysis and failure prediction. Reliability analysis is expected to maintain power plant equipment from the risk of failure which causes force outage. This study applies a statistical model based on the Weibull-2 Distribution Parameter Method to determine the reliability of the model and failure prediction in power plant equipment. From the equipment failure data obtained, the Mean Time Between Failure (MTBF) value will then be determined. The results of the calculations that have been carried out, the Mean Time Between Failure (MTBF) values obtained for each piece of equipment are as follows: Turbine 20,156 hours; Cooling Tower 23,781 hours; Condenser 17,685 hours. The interval maintenance outage calculated by reliability analysis showed that turbine equipment, cooling tower, and condenser suggested to be overhaul every 2 years to reduce possibilities of failure.

Development of a New Connection Material Distribution Model Based on Integrated Transportation and Storage Cost at PT PLN (Persero)

2025-05-30T16:53:37+08:00

PT PLN (Persero), the national electricity service provider in Indonesia, employs a tiered distribution system to support its New Connection program, involving the movement of materials from suppliers to UP3 (Unit Pelaksana Pelayanan Pelanggan), and subsequently to ULP (Unit Pelayanan Pelanggan). This study proposes a mathematical model utilizing binary and integer decision variables to optimize material allocation and delivery frequency, with the objective of minimizing both transportation and storage costs. A numerical experiment is conducted to evaluate the effectiveness of the model under actual demand conditions. The results demonstrate that the model can generate an efficient and cost-effective material distribution plan.

The Techno-Economic Study on Green Hydrogen Production at the Pelangai Hulu Micro-Hydro Power Plant, Pesisir Selatan - West Sumatera

2025-05-30T14:54:36+08:00

This techno-economic study evaluates the feasibility of integrating the Pelangai Hulu micro-hydropower plant (MHPP) with an alkaline electrolyser (AE) for green hydrogen production in West Sumatra. Aspen HYSYS simulations calibrated with operational data from the Priok Combined-Cycle Plant showed an 18% deviation primarily caused by assumptions in system efficiency, simplified electrolyser modeling, and limitations in the calibration methodology. The MHPP operates at an average capacity factor of 71 % and supplies approximately 3.7 GWh year⁻¹ of surplus electricity, enabling uninterrupted AE operation. AE technology is selected for its TRL-9 maturity, a lifetime of 60–120 k operating hours, and the lowest stack cost (≈ USD 270 kW⁻¹). Scaling up the simulation results to 500 kW equivalent to 13 modules of TITAN™ HMXT-100 module is projected to yield 47 045 kg H₂ year⁻¹. Three electricity-supply scenarios were applied for simulations, utilizing internal excess power at full load reduces the levelized cost of hydrogen (LCOH) to IDR 153.405 kg⁻¹, roughly 30 % below the grid-electricity case. Under this optimum scenario, the financial indicators are compelling: a 39 % internal rate of return, a 2.4-year payback period, and a positive net present value of IDR 15.3 billion over ten years. Sensitivity analysis (±20 % electricity tariff) confirms business-case robustness, indicating that MHPP–AE integration is technically viable, economically attractive, and scalable for wider deployment in Indonesia.

Simulation of Filter Cake Co-firing Characteristics in Circulating Fluidized Bed Coal Fired Power Plant

2025-05-19T16:10:41+08:00

A study on co-firing using coal and filter cake biomass was conducted on a circulating fluidized bed boiler power plant varying the co-firing biomass ratio from 0 to 50%. The mixing of coal fuel and filter cake biomass in the model is carried out before entering the mill. After the model iteration shows convergence, the output simulation is validated by comparing the simulation output value with the design and actual parameter values. The evaluation is carried out by comparing the simulation results of baseline conditions with co-firing conditions on the parameters of performance, power output, equipment condition, energy consumption itself, and the impact on emission products. The addition of 1% of the co-firing ratio using rice husks showed a decrease in boiler efficiency (HHV) by 1.3%. Net plant heat rate and SFC increased by 5% and 0.2171%. Furthermore, co-firing using filter cake also reduces SO2 emission by 1.642 ppmv@6% O2, dry.

Numerical Simulation of the Atadei Geothermal Field: An Integrated Model Based on Updated Data

2025-06-01T22:21:07+08:00

Atadei geothermal system in southeastern Lembata remains unexploited due to insufficient subsurface constraints. This study formulates a calibrated three-dimensional reservoir model to address existing geological ambiguity and enable spatial delineation of productive zones. Multi-disciplinary inputs—comprising thermal logs, alteration mineralogy, resistivity cross-sections, and stratigraphic data—were synthesized and dynamically matched using VOLSUNG under natural-state conditions. The computational domain, exceeding 50 km², integrates deep convective boundaries, fault-aligned flow discontinuities, and phase transition indicators derived from synthetic wells. The simulation attained thermal convergence at log dt ≥ 11, reflecting hydrodynamic stabilization. Thermodynamic profiling indicates reservoir initiation at ~500 m depth, capped by a 600–1100 m thick low-permeability unit, with localized two-phase behavior observed at sub-vertical conduits. Peak reservoir temperatures exceed 240 °C, with steam saturation ranging from 0.2–0.65. Atypical vapor intrusion at shallow depth in ATS-4 indicates vertical migration through breached seal zones. The refined model reveals heterogeneity in phase distribution and offers a predictive basis for optimized well deployment.

Analysis of the Earthquake Load Effects on the Cooling Tower Structure of the Ulumbu Geothermal Power Plant Using the Pushover Method

2025-06-10T02:14:55+08:00

Earthquake loads pose a critical threat to the structural integrity of infrastructure in geothermal power plants, particularly cooling towers, which are essential for thermal regulation. This study aims to evaluate the seismic performance of the cooling tower structure at the Ulumbu Geothermal Power Plant through a nonlinear static pushover analysis. The analysis was performed using structural modeling software and applied the ATC-40 guidelines to assess performance levels under lateral seismic loads. The capacity spectrum method was utilized to transform the pushover curve into an equivalent single degree of freedom (SDOF) system, allowing the identification of the performance point. Results indicate a proportional relationship between base shear and displacement, with the structure capable of resisting a maximum lateral load of 730.383 kN. According to ATC-40 criteria, the structure meets the Immediate Occupancy (IO) performance level, demonstrating sufficient seismic resilience and indicating that the cooling tower remains safe and operational following a moderate earthquake. This research contributes to the understanding of seismic vulnerability in geothermal infrastructure and supports improved structural design and risk mitigation strategies.

Techno-Economic Assessment of Fuel Cell as Backup Power for Power Plant Black Start: An Alternative to Diesel Generator

2025-05-30T15:00:53+08:00

Blackout is a condition that is highly undesirable for employees and consumers of PT. PLN (Persero) as an electricity producer because it has both economic and psychological impacts on affected electricity users. Blackout itself can occur both internally and externally (grid). Therefore, a reliable backup power system is needed to support the restoration of electricity blackouts so that it can be used again by consumers. Diesel generators are generally used as backup power in several power plants during black start. Several obstacles often occur when only relying on diesel generators as backup power during the black start process, thus disrupting the electricity recovery process as a system. Fuel cell are presented as an alternative to replace diesel generators as backup power. The use of hydrogen fuel cells supports the energy transition towards a low-carbon economy and reduces global carbon emissions. This study models the Black Start Diesel Generator (BSDG) and hydrogen fuel cell using a process simulator to see the feasibility of fuel cells in replacing the role of BSDG. The study results show that the fuel cell is able to replace the BSDG function as backup power for black start needs in power plants. The right type of fuel cell to replace BSDG is Proton Exchange Membrane Fuel Cell (PEMFC). The amount of hydrogen needed in the feed model using pure oxygen is less than when using air feed. The Levelized Cost of Electricity (LCOE) of the PEMFC system with hydrogen and oxygen combination is $54.01/kWh. Meanwhile for the PEMFC system with hydrogen and air combination the LCOE value is $54.11/kWh. Green hydrogen used in PEMFC is considered carbon emission free while BSDG produces 2428.9 kg/h CO2 eq to produce 1700 kW of power.

FEASIBILITY STUDY ANALYSIS OF BIOMASS-BASED CO-FIRING ENERGY AT PANGKALAN SUSU POWER PLANT

2025-05-19T17:02:23+08:00

This study examines the implementation of biomass co-firing with a mixing ratio ranging from 3% to 45% as an alternative to reduce dependency on coal. The research evaluates feasibility from technical, environmental, and economic perspectives. Technically, the heat produced from co-firing is comparable to that generated from pure coal combustion. The analysis was conducted using daily operational data, including coal consumption, electric load, furnace temperature, and Specific Fuel Consumption (SFC) measurements. The results show that adding rice husk up to 45% does not compromise the operational stability of the power plant. Coal consumption decreased as the percentage of rice husk increased, without sacrificing electrical output, which remained stable between 126–139 MW. Furnace temperature also remained stable, with the 45% blend exhibiting higher stability compared to other blends. Although SFC slightly increased with rice husk blends, overall system efficiency remained well-maintained. This is attributed to the rice husk’s easy combustibility and cleaner emissions, despite its lower calorific value compared to coal. Environmentally, the application of co-firing resulted in greenhouse gas (GHG) emissions that remained below the established limits. Economically, at a 5% co-firing scenario, annual savings amounted to IDR 6,251,729,419, and reached a peak of IDR 27,702,681,170 per year at 45% co-firing, indicating financial feasibility. The co-firing process was modeled using ASPEN PLUS software and validated with experimental data, showing highly consistent results. A higher biomass-to-air ratio led to lower temperatures but improved efficiency. Higher combustion temperatures contributed to increased levels of NO, CO₂, and SO₂. The study recommends further research on coal-fired power plants with capacities over 2 × 200 MW, utilizing biomass blends exceeding 50% and alternative types of biomass beyond rice husks, to optimize and expand the application of biomass co-firing technology.

Numerical Modeling Of A High-Temperature Geothermal System In A Volcanic Complex: Case Study From The Kepahiang Field, Indonesia

2025-06-03T11:43:06+08:00

The Kepahiang Geothermal Working Area, located in Bengkulu Province, Indonesia, is a high-elevation, high-enthalpy geothermal system characterized by fumaroles, solfataras, and steaming grounds around Mount Kaba and Sempiang. This study aims to update the conceptual model using integrated geoscience data and numerical simulation. Three main reservoirs were identified: Kaba (up to 370°C), Sempiang (240–300°C), and Grojogan Sewu (200–250°C), overlain by a cap rock ranging from 500 to 1,500 meters thick. A numerical model using VOLSUNG software was developed, covering the natural-state conditions and calibrated with data from the KPH-01 temperature gradient well (452 m depth) and geothermometer surface manifestations. The model results align well with field observations, indicating upflow zones near Sempiang and lateral outflows toward Grojogan Sewu. However, further validation using deep exploration wells is necessary to confirm reservoir geometry and productivity. The study concludes that Kepahiang hosts a promising liquid-dominated geothermal system with structurally controlled fluid flow. It is recommended to drill at least three exploration wells in key upflow zones, particularly around Sempiang to support production planning

Techno-Economic Analysis of Hybrid Photovoltaic–Diesel system and PV Expansion on Karanrang Island

2025-05-22T11:58:25+08:00

As an island nation, Indonesia faces many challenges transitioning from fossil fuels to renewable energy, especially in remote areas that rely on diesel power generatio. This study evaluates the techno-economic performance of a hybrid solar–diesel system with potential PV expansion for Karanrang Island, South Sulawesi, Indonesia. The research utilizes software tools such as HOMER Pro and PVSyst to model existing generation systems, simulate hybrid configurations with battery energy storage (BESS), and analyze economic viability. Results from the simulation show that a hybrid configuration integrating solar PV, diesel generator, and battery storage significantly boosts the renewable fraction to 55.8%, achieving the lowest net present cost (NPC) of USD 3.12 million and levelized cost of energy (LCOE) of USD 0.236/kWh. Expanding the existing solar PV capacity from 200 kWp to 326 kWp, combined with installing a 1,000-kWh battery energy storage system, is expected to ensure a continuous 24-hour electricity supply on Karanrang Island.

Development of Vendor Selection Criteria and Its Relationship using Delphi Method, Best Worst Method (BWM) and Structural Equation Modeling-Partial Least Squares (SEM-PLS) in PT PLN (Persero) UPT Durikosambi

2025-05-30T16:59:31+08:00

An accurate vendor selection process is a critical factor in ensuring the successful execution of construction projects and asset maintenance within PT PLN UPT Durikosambi. This study aims to develop a more objective vendor selection framework using a Multi-Criteria Decision Making (MCDM) approach combined with statistical validation. The research process includes a preliminary study, development of conceptual and operational models, data collection, and analysis and interpretation. Criteria and subcriteria were identified based on existing conditions and relevant literature, then validated through the Delphi method to achieve expert consensus. The weighting of criteria was determined using the Best-Worst Method (BWM), recognized for its high consistency and efficiency in comparisons. The relationships among criteria were further analyzed using the Structural Equation Modeling-Partial Least Squares (SEM-PLS) approach to identify significant influences among variables. The findings of this research are expected to provide a strategic and adaptive foundation for decision-making in the procurement of construction services within PLN units or similar public infrastructure agencies.

Techno-Economic Feasibility Study of CCUS Implementation and Biomass Co-Firing System for Teluk Balikpapan Coal-Fired Power Plant (CFPP)

2025-05-24T17:11:12+08:00

This research aims to evaluate the technical and economic feasibility of implementing Carbon Capture, Utilization, and Storage (CCUS) technology as well as biomass co-firing systems at the Teluk Balikpapan 2×110 MW Steam Power Plant (PLTU). CO₂ capture simulations were performed using a post-combustion approach with amine solvents, comparing the efficiency between MEA/PZ and MDEA/PZ mixtures. The simulation results show that the MEA/PZ solvent achieved a CO₂ capture efficiency of up to 92.4%, with a lower regeneration energy requirement compared to MDEA/PZ. Co-firing with biomass (wood bark and palm kernel) affects the flue gas characteristics, increasing the energy consumption of the CO₂ capture system, but still results in a CO₂ purity of 99.2%. The economic analysis indicates that this CCS project is financially viable with an IRR of 10.02%, an LCOE of IDR 2,400.51 /kWh, and an investment payback period of 6.96 years. These findings confirm that integrating CCUS and biomass co-firing in an existing power plant can serve as a sustainable energy transition strategy to reduce carbon emissions in Indonesia.

Optimal Coal Supplier Selection for Sawdust Co-Firing in Power Plants Using Thermodynamic Simulation and Multi-Objective Optimization

2025-06-05T11:00:58+08:00

Indonesia’s pursuit of a low-carbon energy transition prioritizes biomass co-firing in coal-fired power plants (CFPPs) as a pragmatic strategy. At Paiton CFPP, a 5% sawdust co-firing ratio is employed without necessitating boiler modifications. However, coal procurement involves multiple suppliers with variable fuel characteristics, complicating the evaluation of performance under co-firing conditions. This study introduces a systematic framework to identify the optimal coal supplier by assessing blended fuel based on higher heating value (HHV), specific fuel consumption (SFC), and CO₂ emissions. Calorific values are sourced from Certificate of Sampling and Analysis (COSA), emissions are estimated via combustion stoichiometry based on the Intergovernmental Panel on Climate Change (IPCC) methodology, and SFC is calculated using thermodynamic simulation in Cycle-Tempo. A multi-objective optimization is performed using the Weighted Sum Method (WSM) to integrate and rank supplier performance. Findings reveal that Supplier S13 offers the highest HHV, lowest SFC, and relatively low emissions, indicating its superior suitability. The proposed method provides a robust and reproducible decision-making tool to support environmentally optimized coal procurement in co-fired CFPPs.

Optimization of Energy Efficiency Based on Woodchip and Palm Kernel Shell Blending Ratio at PLTBm Deli Serdang

2025-05-30T17:21:33+08:00

This study investigates the impact of biomass fuel blend ratios specifically woodchips and palm kernel shells (PKS) on the energy efficiency and operational reliability of the Deli Serdang Biomass Power Plant (PLTBm). Through analysis of operational data from June to October 2024, the plant's total energy output reached 16,827,157 kWh, with the highest efficiency recorded in August at 449 kWh per ton of biomass. The study expands beyond energy output to evaluate technical performance parameters including Specific Biomass Consumption (1.65–1.85 kg/kWh), Net Plant Heat Rate (4,490–4,780 kcal/kWh), and fuel characteristics such as moisture content and its effect on Lower Heating Value (LHV), which declined from 2,950 kcal/kg to 2,350 kcal/kg as moisture increased from 15% to 35%. Reliability assessments revealed 316 hours of outages over five months, concentrated in periods of increased PKS usage and operational strain. These findings suggest that a fuel blending strategy prioritizing woodchips with moderate PKS supplementation offers the best balance between energy efficiency, combustion stability, and operational consistency. This research contributes practical insights for optimizing biomass power plant performance in tropical and supply-variable environments.

Energy Performance Analysis and Operational Efficiency Improvement of Steam Power Plant: Energy Audit Case Study

2025-05-30T17:06:22+08:00

This study aims to analyze and provide recommendations for increasing energy efficiency at the Labuhan Angin Steam Power Plant (PLTU) by considering technical, economic, and environmental aspects. The Labuhan Angin PLTU, with a capacity of 2×115 MW, uses Circulating Fluidized Bed (CFB) boiler technology that operates the Rankine cycle with high-pressure steam. The method used is a case study with a quantitative and qualitative approach, examining operational data and the thermodynamic system of the power plant during August–December 2024. Quantitative analysis includes measuring cycle efficiency and energy distribution using Aspen HYSYS software, while qualitative analysis assesses operational and technical factors that affect power plant performance. The results of the study show that the thermal efficiency of the PLTU reaches around 22.02%, with steam pressure as the main variable that greatly influences efficiency improvement; the higher the steam pressure, the power plant efficiency increases to more than 23.5%. The study also identified that the efficiency of the boiler, turbine, and air heating system are crucial factors in improving performance, as well as the need for routine maintenance and the use of alternative fuels such as biomass. The application of the regenerative cycle has been proven to reduce boiler energy consumption by up to 22% and heat loss through the condenser by up to 25%, thereby significantly increasing efficiency. These findings provide the basis for technical recommendations for optimizing the operation of the Labuhan Angin PLTU to achieve higher energy efficiency while reducing environmental impacts.

Heuristic Algorithm for Controlled Fresh Produces Inventory Model with Cross-perishable Effects

2025-06-17T14:20:16+08:00

Agricultural business doers perform storing products for agricultural products distribution. Some will store various products in the same storage area. Agricultural products, especially the fresh ones, still carry out biochemical and physiological activities. This study aims to develop an inventory model for fresh produces by considering the effects of cross-perishability to minimize total inventory costs. The model formulation refers to the cross-perishability inventory control approach developed and is adjusted to be more applicable in the context of storing various fresh produces simultaneously. The model is solved using a heuristic algorithm designed to determine the optimal combination of decision variables. The main contribution of this study is the development of a heuristic algorithm based on cross-deterioration formulation that can be applied in fresh product warehouse management practices. By determining the quantity of products ordered, the ordering time, and the preservation efforts, the inventory costs are as minimum as possible, because fresh produces can be stored for a long time and the shortage does not occur so that it is able to fulfill the demands.

Spatial Planning for Transmission Line Routing using Multi-Criteria Decision Analysis

2025-05-30T17:16:02+08:00

Through the Electricity Supply Business Plan (RUPTL) 2021–2023, PT PLN (Persero) outlined plans for the development of transmission systems across Indonesia, projecting an expansion of 76,662 MVA in substation capacity and 47,723 kilometres of transmission lines by 2030. Transmission infrastructure development is further detailed for each major island system in the country. In particular, the transmission network in Sulawesi remains divided into two systems: Southern Sulawesi (SULBAGSEL) and Northern Sulawesi (SULBAGUT). The RUPTL document also highlights several strategic projects in the Sulawesi transmission system, including the 150 kV Tambu–Bangkir Transmission Line. Following an instruction from the Directorate General of Electricity to accelerate the Commercial Operation Date (COD) for the Tambu–Bangkir segment to 2024, the project timeline has been adjusted accordingly and designated as a priority assignment. Current transmission line construction planning still relies on manual methods, which have several weaknesses, including route inefficiency, potential cost overruns, challenges in accessing planning locations, and low planning accuracy that often does not reflect actual field conditions. This approach also inadequately considers disaster factors and the aspects of environmental, social, and corporate governance. This research aims to develop a more effective and efficient method for transmission line planning that reduces cost overruns while improving accessibility and planning accuracy. Additionally, this study will explore ways to incorporate land use, road access, disaster factors, and environmental, social, and corporate governance considerations. Spatial modeling using the Multi-Criteria Decision Analysis (MCDA) method can offer a more comprehensive approach, making transmission line planning more optimal and sustainable.

Greenhouse Heating Using Geothermal Brine: A Case Study from Dieng

2025-06-03T11:40:18+08:00

This study examines the feasibility of utilizing geothermal brine from the Dieng Geothermal Field to support greenhouse heating for highland potato cultivation. A thermodynamic simulation was conducted to estimate the heat load, mass flow, and heat exchanger requirements for a 70 m² greenhouse. Results indicate that a brine flow rate of 0.073 kg/s and a secondary fluid flow of 0.056 kg/s are sufficient to maintain internal temperatures of 18–21°C. The system requires only 0.26 m² of heat exchanger surface area, making it compact and scalable. The use of low-grade geothermal heat enhances the overall thermal efficiency of the plant and reduces dependency on fossil fuels. The proposed system offers agronomic benefits, including improved tuber quality and yield (estimated 15–25%) during cold seasons. Environmental advantages include reduced emissions and optimized energy use. Challenges such as silica scaling and initial investment are acknowledged, with recommendations for mitigation. This research highlights a sustainable pathway for integrating geothermal resources into protected agriculture, especially in highland regions.

Development of a Warehouse Management System for Reusable Materials in Power Plant Maintenance, Repair, and Overhaul Activities

2025-05-20T00:38:32+08:00

Ineffective management of reusable material warehousing at the Indralaya power generation unit has caused inefficiencies in material service time, primarily due to ineffective systems for receiving, storing, and issuing materials. These deficiencies have resulted in delays in the power plant's Maintenance, Repair, and Overhaul (MRO) processes. This study aims to develop an efficient and systematic Warehouse Management System (WMS) for managing reusable materials used in MRO activities, with the objective of improving warehouse operational efficiency and reducing material service lead time. The research methodology involved field observations, literature review, data collection, material classification, and service time analysis using Bizagi Modeler. The findings indicate that the development of a WMS—supported by redesigned business processes, improved warehouse layout, structured recording systems, and process digitalization—significantly enhances the efficiency of receiving, storage, and dispatch activities. These improvements contribute to faster material distribution and reduce search time, ultimately shortening the overall warehouse service time.

Simulation Study of Power Generation from Masaro Incinerator in Babakan Village, Cirebon using the Organic Rankine Cycle System

2025-05-30T16:46:56+08:00

The electricity sector is a crucial element in supporting the economic sustainability of a country. Additionally, the challenge of electrifying 3T (terluar, tertinggal, terdepan) regions (the underdeveloped, frontier, and outermost areas) is a significant concern, as Indonesia is an archipelagic country. One potential energy source that can be utilized as an alternative for electricity generation is the technology used for waste-to-energy conversion. Waste processing, such as the MASARO incineration system in Babakan Village, Cirebon, produces heat energy that, in principle, can be used to generate electricity. Given the small-scale combustion capacity of MASARO, the integration of an Organic Rankine Cycle (ORC) system is considered highly suitable for this application. The ORC system, which efficiently converts medium-temperature heat sources into electricity using organic fluids, is modeled and simulated using Aspen HYSYS ver.14. The simulation process, using Aspen HYSYS v.14 software, can demonstrate the potential power output. It is known that, based on the existing operational conditions of the Masaro incinerator, output potentials of 3–7 kW with thermal efficiency up to 27,4% for a combustion capacity of 10 tons per day, such systems could provide sustainable, off-grid power using locally generated waste.

Kinetic Modeling of Lignite Devolatilization: Comparative Perspectives of DAEM and Iso-conversional Methods

2025-05-19T15:46:54+08:00

DAEM and iso-conversional methods are reviewed for kinetically modeling lignite devolatilization, a critical initial stage in coal utilization that profoundly impacts energy efficiency and emissions. Lignite presents unique challenges due to its high volatile content () and complex multi-stage decomposition reactions. DAEM addresses this by assuming devolatilization as a series of parallel, first-order reactions with a continuous distribution of activation energies, mostly Gaussian or Weibull; multi-Gaussian DAEM extensions further enhance accuracy for intricate decomposition profiles. Conversely, iso-conversional methods like Friedman, FWO, and KAS estimate effective activation energies () at various conversions, offering a robust way to analyze kinetic data from multiple heating rates. Comparative analyses indicate that multi-Gaussian DAEM more effectively captures the staged devolatilization of lignite, with reported for low-rank coal ranging from 142 to and significantly improved sum of squared error (SSE) ratios (e.g., ). While iso-conversional methods are computationally efficient and provide consistent profiles (), DAEM yields more complete kinetic parameters. Both require quality TGA data and primarily describe chemical kinetics, often neglecting physical transport limitations pertinent to reactor design. Future research focuses on refining these models and integrating them with broader system simulations.

Thermodynamic Assessment of Oxy-Fuel Retrofit with Flue Gas Recycle in a Subcritical Coal Power Plant

2025-05-19T23:28:10+08:00

Achieving net zero emissions targets requires deep decarbonization of coal-fired power plants, particularly in countries like Indonesia where coal remains dominant in the electricity mix. As early plant retirement poses risks to energy security, retrofit solutions such as oxy-fuel combustion offer a transitional pathway. This study investigates the thermal feasibility of oxy-fuel combustion with wet flue gas recycle applied to a subcritical pulverized coal plant, using Suralaya Unit 8 (625 MW) as a reference case. A steady-state Aspen Plus model is developed to compare air-fired and oxy-fuel scenarios, with oxygen mass flow fixed and the flue gas recycle tuned to match flue gas heat capacity. Results show that the oxy-fuel case maintains equivalent gross output (560.95 MW) and boiler efficiency (83.21%) while exhibiting higher adiabatic flame (1,652.8°C) and furnace exit temperatures (1,283.4°C), increasing slagging risk. The flue gas outlet temperature rises sharply to 389.7°C due to air preheater bypass, underscoring the need for flue gas cooling or heat recovery systems to protect downstream units. Gas composition analysis reveals significant enrichment in CO₂ (46.1%) and H₂O, along with lower volumetric flow and density, which may allow repurposing of air-side fans and partially offset the ASU energy penalty (~82.6 MW).

Optimizing Financial Feasibility and Resource Utilization in Binary Geothermal Systems: A Case Study from the Dieng Geothermal Field, Indonesia

2025-05-30T16:55:30+08:00

This study evaluates the technical and financial feasibility of developing a binary geothermal power plant by utilizing residual brine from the Dieng geothermal field in Central Java, Indonesia. As one of the most geologically complex and active regions in Southeast Asia, the Dieng field represents significant untapped potential for secondary energy through binary cycle technology. By using data from reservoir simulation, brine chemistry analysis, and economic modeling, the study examines multiple development configurations across several scenarios. Technically, the study finds that several wells will have sufficient brine temperature and sustainability for the project, although there is a risk of silica content, which poses a scaling problem. Finally, the base scenario of the financial project is not viable under the current tariffs of USD 6.23 cents/kWh but becomes attractive when paired with optimized tariffs and resource integration from Dieng Unit-2. The findings support the pathway for enhanced geothermal utilization in Indonesia, emphasizing the importance of flexible development strategies, regulatory alignment, and technological optimization to ensure long-term project viability.

Co-firing of Wood Waste Biopellet with Coal in Coal-Fired Power Plants (CFPP): Evaluating Combustion Efficiency and Carbon Emission Reductions to Support the Sustainable Development Goals (SDGs)

2025-06-05T10:54:39+08:00

Coal-fired power plants (CFPP) remain the dominant source of electricity generation in Indonesia, but they contribute significantly to greenhouse gas emissions. This study investigates the potential of co-firing wood waste biopellets as a partial substitute for coal to enhance combustion efficiency and reduce emissions. Thermochemical simulations were conducted using Aspen Plus v14 at a fixed fuel flow rate of 100 kg/h and 20% excess air, with biopellet ratios ranging from 0% to 25% by mass. Results show a decline in flue gas temperature (FGT) from 840°C to 645°C and a reduction in mass fractions of CO₂ (from 0.5908 to 0.5086), CO (from 0.0089 to 0.0051), NOₓ (from 0.0447 to 0.0256), and SO₂ (from 0.0013 to 0.0009). Meanwhile, H₂O and O₂ mass fractions increased to 0.1928 and 0.2671, respectively. Combustion efficiency improved significantly, from 84.7% to 90.9%. These findings indicate that co-firing biopellets not only lowers pollutant emissions but also enhances thermal performance. This approach offers a promising strategy for reducing the carbon footprint of coal-based power generation and contributes to the achievement of Sustainable Development Goals (SDG) 7 and 13.

The Impact of El Niño on the incoming flow rate of the Saguling Hydroelectric Power Plant (PLTA) for Operational Sustainability

2025-05-19T15:57:09+08:00

This study investigates the impact of El Niño on the inflow dynamics of the Saguling Hydroelectric Power Plant (PLTA), located in West Java, Indonesia. Using 39 years of hydrometeorological data (1986–2024), including rainfall, reservoir inflow, and Oceanic Niño Index (ONI), the research identifies the climatic influence of El Niño–Southern Oscillation (ENSO) events on water availability and power generation sustainability. Results show a significant inverse correlation between ONI and both rainfall (r = –0.41) and inflow (r = –0.45), with El Niño years experiencing a 50–60% reduction in water inputs during dry months. La Niña events, in contrast, enhance inflow and precipitation, thereby supporting reservoir operations. Wavelet transform analysis reveals dominant periodicities in the 2–4 year range, consistent with ENSO cycles. These findings highlight the vulnerability of hydropower generation to climate variability and underscore the importance of adaptive reservoir management strategies based on ENSO projections. The study contributes to strategic planning in energy and water sectors, emphasizing the integration of climate forecasts in maintaining operational continuity of hydropower infrastructure.

A Validation of the Analytical Hierarchy Process (AHP) for Ranking Geothermal Potential for Next PLNs Project: An Academic Expert Perspective

2025-05-19T23:30:46+08:00

The study evaluates the geothermal potential of Indonesia using the Analytical Hierarchy Process (AHP). AHP was employed to rank geothermal sites for development, considering criteria such as resource potential, infrastructure readiness, economic feasibility, and socio - cultural impacts. Academic expert judgment, while inherently subjective, is incorporated to provide structured comparisons among multiple geothermal fields. This study highlights the application of AHP in providing transparent, objective rankings for geothermal site prioritization, which is essential for strategic planning in Indonesia’s energy transition. The results suggest that economic feasibility and resource potential are key drivers in geothermal field selection, particularly for the Ulumbu and Tulehu fields that owned by PT PLN (Persero). These findings have direct implications for future geothermal investments and policy decisions in Indonesia. The study highlights the potential of AHP method in guiding policy and investment decisions for geothermal energy development PLN’s geothermal fields for further study.

A Study on Renewable Energy Certificates as Enabling Instruments for Geothermal Energy Advancement

2025-06-13T07:42:06+08:00

Indonesia, home to the world’s second-largest geothermal reserves, holds strategic potential to accelerate the clean energy transition through expanded geothermal development. This paper examines the role of Renewable Energy Certificates (RECs) as a market-based instrument to support this agenda. Despite the introduction of geothermal RECs in Indonesia’s voluntary market, their sales performance remains lower than those of hydropower and solar sources. Through a multi-phase analysis—encompassing sales trends, international price benchmarking, techno-economic simulations, and market strategy formulation—this study identifies key barriers and opportunities for improving geothermal REC utilization. Benchmarking indicates that REC prices in Indonesia are among the lowest in Asia, with limited financial impact on geothermal project economics at current levels. However, techno-economic modeling reveals that rising REC prices could significantly enhance project bankability. The study proposes a set of targeted marketing strategies, including RE100 corporate engagement, premium product positioning, and integration with ESG policy frameworks. These strategies aim to ensure full recognition and monetization of geothermal electricity via REC markets. The findings offer actionable insights for PT PLN (Persero) and stakeholders to optimize REC deployment and strengthen geothermal’s role in Indonesia’s renewable energy mix.

Optimization of Excess Air and Flue Gas Temperature for Enhanced Efficiency in Circulating Fluidized Boiler Power Plant

2025-05-30T16:45:49+08:00

Enhancing the thermal efficiency of circulating fluidized bed (CFB) boilers is critical for reducing fuel consumption and mitigating emissions in coal-fired power generation. This study presents a practical and data-driven optimization strategy for a 100 MW CFB boiler unit in South Sulawesi, Indonesia, which focuses on regulating excess air and flue gas exit temperature. Using mass and energy balance calculations combined with sensitivity analysis, combustion efficiency curves were developed for two coal types with differing calorific values. The analysis supports a recommendation to reduce excess air from 43.5% to 31% to improve boiler performance and by reducing the flue gas temperature from 134.5 °C to 131 °C, yielding a 0.74% increase in boiler efficiency. Under these optimized conditions, the system demonstrated a measurable fuel saving of 350 ton of coal per month, savings equivalent to IDR 2.44 billion per year. Emission estimates based on stoichiometric combustion and ultimate analysis further indicated a potential reduction of 732.9 tons of CO₂/month. These findings underscore that optimizing excess air represents a cost-effective and operationally viable approach to improving CFB boiler performance, with direct applicability to utility-scale installations in similar contexts.

Conceptual Model of Integrated Spare Parts Inventory Management and Maintenance Scheduling at PT PLN Indonesia Power

2025-06-05T11:06:51+08:00

PT PLN Indonesia Power is facing issues of delays and stockouts of bearing spare parts, which negatively affect the power plant maintenance schedule. This study aims to develop a conceptual model that integrates spare parts inventory management and preventive maintenance scheduling to address these problems. The research is conducted by enhancing the existing model, which applies an inventory policy with fixed (static) stock review intervals and preventive maintenance schedules. This study proposes to make the preventive maintenance schedule a decision variable. Additionally, the developed model specifically integrates the cost of lost electricity production (lost kWh) due to spare parts stockouts as part of the operational costs to be optimized.

Analysis of Geothermal Direct Use in Agriculture and the Social Economic Effects on Local Communities

2025-05-28T12:26:14+08:00

The direct use of geothermal energy offers a promising solution to diverse energy requirements. However, the focus on utilizing geothermal direct use is less explored in Indonesia. The vast geothermal potential suggests more exploration for direct applications, especially in the agricultural industry. This study analyzes the performance of geothermal direct use utilization at two locations: PLTP Wayang Windu (coffee drying) and PLTP Lahendong (drying agricultural products and palm sugar production), with the socioeconomic effect on local communities in the geothermal work area based on literature review. In Wayang Windu, 147°C brine is processed through a closed heat exchanger system, producing 32.65 kW of energy to dry 1,000 kg of coffee for 12.5 hours. In Lahendong, heat waste is used to make a 12-ton/day palm sugar. Heating efficiency for Paddy drying of the dryer is 82.50%, and total drying efficiency reached 51.10%. This direct use of utilization has the potential to reduce carbon emissions from the production process that still uses fossil fuels or wood. Local communities welcomed the direct use of geothermal technology for drying agricultural products. It is also essential to ensure the regulatory and policy landscape surrounding the geothermal work area is safe and sustainable for public.

Intregated Combine flue Gas CCS System on Subcritical Coal-Fired Power Plant

2025-06-05T11:02:02+08:00

Indonesia faces a major challenge in aligning its power sector with the national goal of achieving Net Zero Emissions (NZE) by 2060. The country’s continued reliance on coal for base load electricity due to its low cost and domestic abundance presents a significant barrier to decarbonization. As global energy systems shift toward low-carbon sources, transitional technologies such as Post-Combustion Carbon Capture (PCC) are essential to reduce emissions while maintaining energy reliability. This study evaluates the technical and economic feasibility of applying PCC technology at a subcritical Coal-Fired Power Plant (CFPP) by integrating flue gas from two 315 MW units. Each unit emits flue gas containing approximately 14.3% CO₂, with a capture target of 90%. The research uses literature review, case studies, and Aspen HYSYS V12 simulation to model the PCC system and estimate both capital (CAPEX) and operational (OPEX) costs. Results show that integrating two units into a single PCC system reduces CAPEX by 8.5% compared to separate systems. Additionally, the Levelized Cost of Electricity (LCOE) drops from 103.6–105.2 USD/MWh in individual configurations to 88.6 USD/MWh in the integrated scenario, indicating better economic performance for large-scale CCS deployment.

Characteristics Analysis of Sludge from a Leachate Treatment Plant for Sustainable Construction Material

2025-05-30T16:35:16+08:00

Rapid population growth and increasingly complex community activities have a direct impact on the increase in waste. For this reason, a Final Disposal Site (FDS) is needed. The increase in waste volume at the LTP generates leachate containing organic and inorganic pollutants, as well as heavy metals. To mitigate environmental impacts, the leachate is treated through a Leachate Treatment Plant (LTP), which produces sludge as one of the residues from the treatment process. This sludge has the potential to become hazardous waste if not managed properly. This study aims to analyze the physical and chemical characteristics of the sludge produced by the LTP, as well as evaluate its potential for utilization. The results show that the sludge has a fineness modulus of 2.32, which falls within the range for fine aggregates according to ASTM C33. But, metal oxide content does not meet the criteria for pozzolanic material. Therefore, LTP sludge is not suitable as a cement substitute. However, it has potential as a partial substitute for sand in most structural concrete materials and requires cement as a binder. Sludge can reducing environmental pollution.

Technical Study on The Design of Tangkuban Perahu Geothermal Power Plant

2025-06-01T22:18:22+08:00

The Tangkuban Parahu Geothermal Working Area (WKP) possesses significant geothermal energy potential with high-temperature (high enthalpy) reservoir characteristics estimated at 240–270°C. This potential makes WKP Tangkuban Parahu one of the most promising areas for geothermal power plant development in Indonesia. This study aims to evaluate geothermal resource potential, design an optimal geothermal power generation system, and estimate the overall project development costs.

The analysis integrates geological, geochemical, and geophysical survey data from previous exploration studies. For power generation design, thermodynamic modeling was conducted using Excel with Coolprop extension, considering technologies single flash. This technology were selected for their advantages in utilizing geothermal resources with relatively high efficiency. This research is mainly focused on recalculation of Single Flash Cycle from Tangkuban Perahu Pre-FS Document that were conducted by PT.PLN and PT. New Quest

Based on Monte Carlo simulation results, the electrical power potential of WKP Tangkuban Parahu is estimated at 22 MW (P90) to 67 MW (P10), with a median value of 43 MW (P50).

The findings of this study are expected to serve as an important reference in designing an efficient and sustainable geothermal power plant at Mount Tangkuban Parahu WKP and support PT PLN in achieving its national renewable energy mix targets.

A Conceptual Framework for the Selection of Biomass Alternatives for Coal Co-firing using Multi-Criteria Decision Making (MCDM) Approach

2025-05-30T17:03:55+08:00

The increasing demand for sustainable energy and the need to reduce carbon emissions have driven the implementation of biomass co-firing in coal-fired power plants. Selecting appropriate biomass alternatives for co-firing is a complex decision involving multiple technical, economic, environmental, social, and regulatory considerations. This study aims to develop a conceptual framework for selecting biomass alternatives for co-firing in coal power plants. The framework integrates Analytic Hierarchy Process (AHP) and Structural Equation Modeling-Partial Least Squares (SEM-PLS) to identify and prioritize key selection criteria. The model consists of five main criteria technical, economic, environmental, social, and policy/regulation with a total of 14 validated sub-criteria. The dependent variable, Selection of Biomass Alternative, is measured by four biomass types: Rice Husk, Wood Pellet, Palm Kernel Shell, and Sawdust. The proposed framework provides a comprehensive tool to support decision-making and ensure the sustainable implementation of biomass co-firing.

Feasibility and Efficiency Assessment of Solar PV Systems for Electrification improvement in Tunda Island: A Renewable Energy Approach

2025-06-04T09:26:38+08:00

This study evaluates the technical and financial feasibility of a photovoltaic (PV) hybrid system to enhance power access on the remote Tunda Island in Banten Province, Indonesia. The performance of PV modules was simulated using PVsyst software, while HOMER Pro software was used to optimize the generation operation plan, focusing on minimizing the levelized cost of energy (LCOE). Four system configurations were simulated and compared: 100% diesel, diesel with PV, PV and battery energy storage system (BESS), and a hybrid system combining PV, diesel, and BESS. The results show that the hybrid PV + Diesel + BESS system performs best, generating 785 MWh per year with only 6.6% excess energy, a performance ratio of 76.9%, and an LCOE of USD 0.212/kWh. Compared to the diesel-only baseline, fuel consumption is reduced by over 85%, and the Net Present Cost (NPC) is decreased by USD 1,069,283 This configuration ensures 24-hour energy supply reliability, significantly reduces lowers operating costs. The findings highlight that hybrid renewable energy systems are a technically feasible and economically viable solution for sustainable electrification of remote island communities, contributing to national renewable energy goals.

Techno-Economic and Life Cycle Evaluation of Low Carbon Ammonia Co-Firing Implementation in Coal-Fired Power Plants

2025-05-23T15:58:33+08:00

This study assesses the techno-economic feasibility and environmental impact of ammonia co-firing in coal-fired power plants (CFPPs) in Indonesia. Using Aspen Plus simulation on a 660 MWe subcritical boiler, various blending ratios of low carbon ammonia (0–50%) were evaluated. The results show that increasing the ammonia co-firing ratio reduces direct CO₂ emission intensity from 0.90 to approximately 0.45 ton CO₂/MWh. Emissions of SOx and NOx also decrease due to reduced coal consumption and the reaction of unburned ammonia with NO through a selective non-catalytic reduction (SNCR) mechanism. The Levelized Cost of Electricity (LCoE) increases with higher ammonia content. At a 50% ratio, LCoE reaches 146 USD/MWh (grey), 156 USD/MWh (blue), and 252 USD/MWh (green), compared to a baseline of 49 USD/MWh. Life Cycle Assessment (LCA) shows that grey ammonia increases Global Warming Potential (GWP) by 4.83%. while green ammonia reduces GWP by 49.9% compared to 100% coal combustion. Emissions also vary by delivery distance; supply from Gresik results in 0.17% lower emissions than from Bontang. Ammonia co-firing offers a viable low-carbon transition strategy for Indonesia’s coal-dominated power sector, particularly with blue or green ammonia. Its success depends on fuel selection, supply chain efficiency, and comprehensive life cycle-based policy support.

System Dynamics for Policy Simulation of FABA (Fly Ash and Bottom Ash) Waste Utilization

2025-05-20T00:11:03+08:00

Fly Ash and Bottom Ash (FABA) are by-products of coal combustion in power plants that pose environmental risks if not properly utilized. This study develops a System Dynamics model to evaluate policy scenarios for FABA utilization at the Nagan Raya coal-fired power plant, which produces an average of 2,295 tons of FABA per month. The model is based on historical data from 2016 to 2024 and simulates policy interventions for the 2025–2030 period, including biomass co-firing, public awareness campaigns, and subsidies for industrial users.

The simulation results for 2030 show that the combined policy scenario successfully reduces stored FABA from 98,352 tons to 37,011 tons and increases FABA utilization from 1,050 tons/month to 1,850 tons/month. CO₂ emission reductions also increase significantly, from 1,570 tons/month to 10,220 tons/month. The policy requires industrial subsidies of IDR 130 million/month and socialization costs of IDR 30 million/month. This study demonstrates that simulation-based waste policy modeling can effectively support the transition strategy toward achieving Indonesia’s Net Zero Emission 2060 target.

Simulation of Co-firing Calliandra Sawdust and Coal at CFPP Alor Using Thermoflow v.32 Software

2025-05-30T16:48:28+08:00

The Indonesian government is actively promoting biomass co-firing as a transition strategy to reduce carbon emissions in coal fired power plants (CFPPs). This study investigates the performance of co-firing Calliandra sawdust biomass with coal in the CFPP Alor using Thermoflow v.32 software. Simulations were conducted with co-firing ratios of 0%, 5%, 50% (optimal), 70%, and 100% to evaluate the impacts on net power output, CO₂ emissions, fuel flow, and auxiliary power consumption. The results show that increasing the biomass ratio significantly reduces the CO₂ emission intensity from 1.454 kg/kWh at 0% co-firing to 0.771 kg/kWh at 50%, and to zero at 100%. However, these emission benefits come at the expense of increased fuel flow and internal power consumption due to the lower heating value of biomass. The optimal co-firing ratio is set at 50%, achieving a balance between environmental benefits and operational efficiency, with a net power output of 3,079 MW and moderate auxiliary load. The study concludes that biomass co-firing using Calliandra is technically feasible without modifying existing equipment and can substantially support decarbonization goals, provided that the fuel supply and handling systems are well managed.

Implementation Analysis of Emission Reduction System for SO₂, NO₂, and Hg Emission Reduction Equipment in Coal-Fired Power Plants

2025-05-19T15:45:20+08:00

Coal-Fired Power-Plants (CFPP) have four main emission parameters: SO₂, NO₂, particulate matter, and Hg. Currently, many existing CFPP have yet to install emission reduction equipment for SO₂, NO₂, and Hg emission. This study aims to evaluate the technical and economic impacts of implementing emission reduction equipment in existing CFPP with capacities between 50 and 1000 MW. This study is conducted using SteamPro–Thermoflow, a well-known software in the thermal power plant industry for heat and mass balance analysis. The simulations show that Selective Catalytic Reduction (SCR) achieves 80% NO₂ reduction efficiency, higher than Selective Non-Catalytic Reduction (SNCR) at 40%. For SO₂ reduction, Wet and Sea Water Flue Gas Desulfurization (WFGD and SWFGD) reach 95%, while Semi-Dry FGD (SDFGD) achieves 90%. Activated Carbon Injection (ACI) for mercury (Hg) reduction achieves 60%, and up to 85% when combined with FGD. For auxiliary power consumption, at 0.01–0.03% of gross power for NO₂ reduction, 0.25–0.50% for SO₂ reduction, and 0.17–0.22% for Hg reduction. Investment costs are 50–120 USD/kW for SNCR, 5–20 USD/kW for SCR, 10–35 USD/kW for ACI, and 32–110 USD/kW for FGD. The study results are expected to guide emission reduction policies in power generation sector.

Pareto Analysis of Loss Output in Geothermal Power Plant Equipment for Prioritizing Auxiliary Equipment Investment Based on Operational Redundancy

2025-05-19T23:18:41+08:00

This study aims to perform a Pareto analysis of output loss in Geothermal Power Plant equipment to identify priority investments in auxiliary equipment based on operational redundancy. The Pareto method is used to analyze the contribution of each piece of equipment to output loss and determine which equipment should be prioritized for further investment. The analysis shows that 20% of equipment, such as cooling towers and pumps, contributes the most to output loss. Based on these findings, it is recommended that investment should be focused on equipment that significantly impacts Geothermal Power Plant performance, with the goal of improving operational efficiency and reducing downtime. The Efficiency Optimization System (EOS) is used to monitor the performance of the plant in near real-time, identify inefficiencies, and provide improvement recommendations based on Pareto analysis to support decision-making in maintenance and investment.

Thermal Discomfort and Its Impact on Urban Residential Electricity Use: A Case Study in Bandung, Indonesia

2025-05-30T17:01:06+08:00

Urban energy demand in tropical highland settings is increasingly sensitive to climatic stressors, particularly the combined effects of temperature and humidity on thermal comfort. This study quantifies the influence of the Thermal Humidity Index (THI) on monthly electricity consumption in Bandung, Indonesia, between January 2012 and May 2024. Daily THI values were derived from 2-meter air temperature and relative humidity observations, aggregated into monthly means, and paired with utility records of residential electricity use. Spearman rank correlation analysis indicates a moderate positive association (ρ = 0.35, p < 0.001) between elevated heat-stress conditions and increased consumption. However, this relationship is partly obscured by concurrent growth in household electrification, appliance ownership, and urbanization.

Despite these confounding trends, the findings highlight a growing reliance on mechanical cooling in Bandung, a city historically known for its naturally temperate climate. The results underscore the importance of incorporating dynamic thermal stress and demographic shifts into future energy planning. While Spearman's correlation offers a valuable starting point, future research should adopt multivariate or time-series models to better isolate causal factors. Furthermore, the behavioral assumption linking THI to air conditioning use remains unvalidated in this study; incorporating user-level data or surveys would enhance the robustness of the conclusions. Overall, this study contributes to the broader understanding of climate-sensitive energy behavior and offers a transferable framework for urban energy forecasting in tropical regions.

Development of a Power Generating Incinerator via Direct Conversion From Thermal to Electricity for Local Community Consumption

2025-05-30T12:11:39+08:00

Indonesia is facing increasing electricity demand driven by economic growth and nationwide electrification initiatives. Simultaneously, waste management challenges, particularly in urban areas, necessitate innovative and sustainable solutions. This study proposes the integration of thermoelectric generator (TEG) technology into a small-scale waste incinerator to convert waste heat directly into electricity. The MASARO incinerator, developed for community-scale waste treatment, serves as the case study and operates at high combustion temperatures ranging from 800°C to 1200°C. To overcome the thermal limitations of commercial TEG modules, an intermediate system comprising multilayer insulation is designed to reduce the contact surface temperature to below 300°C. A total of 3,591 TEG modules can be installed on the 5.75 m² surface area of the transition cone and flue gas duct. The study utilizes theoretical modeling, numerical simulation, and literature review to analyze system performance under five temperature scenarios. Results indicate that daily energy output ranges from 3.6 Wh to 9.0 Wh under a 4-hour operation cycle, with overall system efficiency below 0.001%. Despite its low efficiency, the system offers a clean, fuel-free, and decentralized energy solution by utilizing otherwise wasted thermal energy. This approach presents a viable micro-power generation alternative for rural and off-grid communities in Indonesia, supporting national goals for renewable energy and sustainable development.

Co-Firing Performance Simulation of Refuse-Derived Fuel (RDF) in a 400 MW Pulverized Coal Power Plant

2025-05-19T17:36:23+08:00

This study evaluates the technical and economic feasibility of co-firing Refuse-Derived Fuel (RDF), locally known in Indonesia as Bahan Bakar Jumputan Padat (BBJP) with coal in a 400 MW Pulverized Coal (PC) power plant located in Cilegon, Indonesia. Simulations using Aspen Plus software assessed fuel consumption, thermal efficiency, emissions, and production costs. The BBJP used has an average calorific value of 3,589 kcal/kg and sulfur content of 0.13%, compared to the coal’s 4,557 kcal/kg and 0.55% sulfur. Co-firing with up to 20% BBJP reduced coal consumption by 35.3 tons/hour while increasing overall fuel mass flow. Sulfur dioxide (SO₂) emissions decreased from 442 mg/Nm³ to approximately 370 mg/Nm³ at a 10% BBJP blend. Economically, co-firing slightly lowered total fuel costs and reduced the cost of electricity production from Rp450.90/kWh to Rp447.74/kWh. These findings indicate that BBJP co-firing is a viable strategy to reduce emissions, support Indonesia's decarbonization efforts, and improve operational cost efficiency in coal-fired power plants.

Optimization and Emission Reduction Analysis Using Hybrid PLTD-PLTS Technology in the Wangi-Wangi Diesel Power Plant

2025-05-19T17:50:48+08:00

The transition to cleaner and more sustainable energy sources presents a major challenge in the power sector, particularly in remote areas that still rely on Diesel Power Plants (PLTD). While PLTD offers operational reliability, it also has significant drawbacks, including high fossil fuel consumption, large operational costs, and substantial carbon emissions. Therefore, integrating PLTD with Solar Power Plants (PLTS) in a diesel-hybrid system emerges as a potential solution to optimize energy efficiency and reduce environmental impact. This study aims to analyze the optimization and emission reduction of diesel-hybrid technology at PLTD Wangi-Wangi using the Life Cycle Assessment (LCA) approach with a Gate-to-Gate system boundary. The analysis is conducted using HOMER for technical hybrid system simulation and assess environmental impacts, particularly in terms of CO₂ emissions. This research evaluates different energy mix scenarios, namely 30%, 50%, and 70% PLTS penetration, to determine the potential fuel consumption reduction and its impact on system stability. With the right strategy, implementing a PLTD-PLTS hybrid system can be a viable solution for decarbonization and energy resilience, especially in island regions like Wakatobi.

System Design for a Sustainable Returned Materials Management System at PT PLN UID East and North Kalimantan

2025-05-20T00:46:02+08:00

The Indonesian government through Presidential Regulation No. 111 of 2022 encourages the implementation of the Sustainable Development Goals (SDGs), including the efficient and responsible management of material resources. PT PLN (Persero), as a major energy provider, has responded through various sustainable transformation initiatives, including waste management based on the 3R principle. However, challenges are still faced in the management of returned materials, especially demolished materials (ATTB) at the distribution unit level such as PLN UID East Kalimantan and North Kalimantan. Problems such as the absence of standard classification procedures and the accumulation of unutilized materials indicate the need for a more effective system. Based on this, the problem formulation in this study is How is the design of a return material management business process that accommodates the 6R principles (Reduce, Reuse, Recycle, Repair, Refurbish, Remanufacture)? This research adopts the 6R-based closed-loop sustainable manufacturing approach to design a new digital-based business process for managing returned materials. The main focus is on designing a systematic classification mechanism into four categories based on technical, life, warranty, and economic aspects. This approach is expected to improve operational efficiency, support digital transformation, and strengthen PLN's contribution to the national sustainability agenda.

Thermochemical Study of Combustion Behavior and Ash of Hybrid Coal

2025-06-05T10:54:14+08:00

This study aims to analyze the thermochemical behavior of combustion and ash characteristics of hybrid coal, which is a mixture of low-rank coal (LRC) and biomass. The research focuses on evaluating ash composition and the potential for slagging and fouling under combustion conditions relevant to coal-fired power plants (PLTU). Simulations were conducted using FactSage software with the Equilib and Phase Diagram modules to determine ash melting fractions, thermodynamic equilibrium analysis, and the effect of temperature variations on ash chemical behavior.

The results indicate that the use of hybrid coal can improve combustion efficiency and produce ash with characteristics distinct from those of pure coal combustion. Minerals such as potassium and sodium in biomass influence ash melting points, thereby affecting the risk of slagging and fouling. From an economic feasibility perspective, hybrid coal was also analyzed in terms of production costs, which were compared to PLN’s basic cost of electricity supply (BPP). This study suggests that hybrid coal has significant potential as a more environmentally friendly and economical alternative fuel, provided that mitigation strategies for slagging and fouling are carefully addressed.

Analysis of Sub-criteria Relationships in the Selection of Fly Ash Utilization Methods at PLTU Tarahan Lampung Using Dependence and Driving Power Analysis (DDPA)

2025-05-19T15:55:23+08:00

The utilization of fly ash and bottom ash (FABA) as part of the waste management strategy in the power generation sector continues to be encouraged to support the implementation of a circular economy. Coal-fired steam power plant (PLTU) Tarahan as one of the generating units owned by Perusahaan Listrik Negara (PLN) Group produces a significant amount of fly ash every year, but its utilization is still limited. This research aims to identify key criteria and sub-criteria that influence each other in the alternative selection system for fly ash utilization methods at PLTU Tarahan. Dependence and Driving Power Analysis (DDPA) method was used to analyze the relationship between sub-criteria based on inputs from 23 expert respondents from academics, practitioners, and regulators. The validation results produced 4 main criteria and 27 sub-criteria that were analyzed in the affordability and reachability matrix. The mapping result showed that several sub-criteria fall into the linkage cluster—characterized by high driving and dependence power—spanning technical, environmental, economic, and social criteria. These sub-criteria need strategic attention as changes to these elements can affect the system. This study recommends the need for advanced analytical approaches such as Analytic Network Process (ANP) to prioritize fly ash utilization methods in a comprehensive and sustainable manner.

Techno-Economic Optimization of Excess Green Hydrogen Production at Tanjung Jati B Coal Fired Power Plant

2025-05-19T18:01:54+08:00

With the increasing global demand for energy, the level of emissions and the impact of energy growth on ecosystems and climate change have become major global issues. In this context, green hydrogen offers a promising clean and sustainable energy solution.

This study analyses the feasibility of the hydrogen production system at the existing Hydrogen Plant of the Tanjung Jati B coal-fired power plant (TJB CFPP) to produce excess hydrogen gas categorized as green hydrogen. Integration of current electrolysis systems with solar energy sources will play a pivotal role in this study. This study employs a quantitative approach by collecting data from previous studies and operational reports from the TJB CFPP.

This study investigates six optimization scenarios for excess green hydrogen production, each combining electricity sources with electrolysis technologies. The integration of available electrolysis systems with an existing solar power plant has demonstrated the potential to produce excess green hydrogen at a competitive Levelized Cost of Hydrogen (LCOH). Notably, one scenario achieves an LCOH close to 4 USD/kg, significantly lower than the current average green hydrogen LCOH in Indonesia, which stands around 10 USD/kg.

Cost Recovery Frameworks for Geothermal Projects: Insights from Oil and Gas and Their Relevance to PLN’s Geothermal Operations in Indonesia

2025-05-30T16:54:15+08:00

Some of PLN’s Geothermal Working Area (GWA) has suboptimal resource quality, which leads to high exploration costs and longer development times that hinder national geothermal targets. To address this, PT Perusahaan Listrik Negara (Persero) (PLN) has established a strategic partnership model called the Geothermal Exploration & Energy Conversion Agreement (GEECA) to improve efficiency and share exploration risks with partners, including cost recovery schemes similar to those in oil and gas. The development processes for oil, gas, and geothermal projects are similar: identifying reserves, exploration drilling, facility development, production, and site closure. The risks associated with geothermal, oil, and gas projects share similarities. The cost recovery scheme and GEECA include a mechanism for reimbursing exploration costs to partners or contractors. While they share fundamental concepts, the reimbursement methods differ significantly. In the cost recovery system, reimbursement occurs from production income before profits are shared between the government and the contractor. In contrast, GEECA employs a more definitive approach, ensuring that PLN will reimburse all exploration costs within two years after the power plant starts commercial operations. In Indonesia's geothermal development, especially with PLN's GWA, GEECA can enhance the appeal of partnerships. For other GWAs, PLN should consider enriching the data to reduce uncertainty and attract more partners.

Techno-Economic Study of Green Hydrogen Production Process at Krueng Isep Micro-Hydro Power Plant (MHPP) in Nagan Raya, Aceh

2025-05-30T14:55:34+08:00

This study aims to evaluate the potential of green hydrogen production using Alkaline Electrolyzer (AEL) technology powered by electricity from the Krueng Isep Micro-Hydro Power Plant (PLTMh) in Aceh, Indonesia. AEL was selected due to its commercial availability, high technological maturity, competitive capital costs, and strong operational durability. The study was conducted through simulation using Aspen HYSYS V14 under two input power scenarios: 40,5 kW, based on validated operating data from the Tanjung Jati Electric Steam Power Plant, and a scaled-up scenario of 25 modules from the original hydrogen plant at Tanjung Jati, reaching 1.012,5 kW. Both scenarios were simulated under constant operating conditions of 10,3 bar and 60,5°C. Simulation results show that increasing input power significantly boosts the hydrogen production rate, from 0,50 kg/h to 12,52 kg/h. However, this also increases the specific energy consumption from 291 GJ/kg to 7,277 GJ/kg, indicating energy efficiency challenges at larger scales. Economically, higher input capacity requires greater CAPEX but yields a higher Internal Rate of Return (IRR) of 16% compared to 12%, while maintaining the same Payback Period (PbP) of 5,59 years. In addition, the Net Present Value (NPV) is substantially higher at larger scale. In conclusion, AEL technology is technically and economically viable for green hydrogen production based on micro-hydro sources. Improving energy efficiency and managing operational costs are key strategies to support Indonesia’s transition toward a clean and sustainable energy future.

Enhancing Geothermal Energy Utilization Through Binary Power Plant and Absorption Chiller Technology: Songa Wayaua Case

2025-06-10T00:46:07+08:00

The Songa Wayaua Geothermal Power Plant (PLTP) is planned for development with a 2x5 MW capacity using single-flash technology. The residual energy contained in the brine from the separator outlet can be further utilized before being reinjected. Referencing a study by PT. PLN (Persero), the brine stream from the single-flash plant, with a mass flow rate of 29.33 kg/s and a temperature of 164.9°C, will be directed into a cascaded system. This system comprises an Organic Rankine Cycle (ORC) for additional power generation and a Lithium Bromide-Water (LiBr-H₂O) absorption chiller for cooling purposes. This approach is particularly promising given the Songa Wayaua geothermal field's coastal proximity, making it suitable for future applications like fish refrigeration systems. The proposed design is projected to generate an additional 312.17 kW of power using Pentafluoropropane (R-245fa) as the working fluid. The ORC system's outlet temperature is maintained at a maximum of 125°C, allowing it to be subsequently used as the heat source for the absorption chiller. This chiller is estimated to produce a cooling capacity of 835.91 kW, with a Coefficient of Performance (COP) of 0.76 and an effectiveness (e) of 0.78. The results of this study indicate that the proposed system can significantly increase the overall energy efficiency and expand the application scope of the geothermal potential. This allows for the direct integration of geothermal energy with the local fishery industry, fostering a direct, mutually beneficial relationship between PT. PLN (Persero) and the community surrounding Songa Wayaua.

Performance and Emissions Analysis of Hydrogen Co-Firing in Combined Cycle Power Plants

2025-06-04T09:33:03+08:00

Indonesia's goal to become a net zero carbon emitter by 2060 requires substantial investment in carbon emission reduction. While energy storage systems are popular among regulators for managing energy from variable renewable energy (VRE) sources, hydrogen co-firing in Peaker power plants, such as gas turbines, can reduce investment costs by utilizing existing infrastructure. This paper examines the implementation of hydrogen co-firing in gas turbines under various scenarios based on hydrogen volume percentages. We simulate co-firing with 10%, 20%, 30%, 40%, and 50% hydrogen. The results show that higher hydrogen percentages increase power output but produce lower exhaust gas temperatures and mass flow, which must be considered in combined cycle power plant simulations.

Application of United Nations Framework Classification for Resources (UNFC) in Ulumbu Geothermal Field, East Nusa Tenggara, Indonesia

2025-05-20T01:05:09+08:00

The Ulumbu Geothermal Field, located in East Nusa Tenggara and operated by PT PLN (Persero), is strategically supporting Indonesia’s renewable energy goals. Ulumbu Geothermal Power Plant currently operates at a total capacity of 10 MW (4 × 2.5 MW) and has an estimated additional potential of at least 40 MW for future development. Although the field has been in operation for several years, PLN has not yet implemented an internationally recognized classification framework such as the United Nations Framework Classification for Resources (UNFC) to manage its geothermal assets. This paper explores the application of the UNFC to the Ulumbu Geothermal Field by assessing its geothermal resources through three fundamental criteria of environmental-socio-economic viability (E-axis), technical feasibility (F-axis), and degree of confidence in the estimate (G-axis). Utilizing publicly available data and internal reports, the study evaluates how the field’s current status aligns with each UNFC axis. The results provide classification of the Ulumbu geothermal resources according to UNFC and highlight the challenges and opportunities of adopting such a system in PLN. The findings suggest that applying UNFC can enhance project transparency, optimize decision-making, and support more sustainable geothermal development in Indonesia.

Numerical Modeling of the Songa-Wayaua Geothermal Reservoir Incorporating Seawater Intrusion Effects

2025-05-30T16:32:57+08:00

The Songa-Wayaua Geothermal Working Area (GWA), located in South Halmahera, North Maluku, is a high-enthalpy geothermal system with planned development for 2 × 5 MW power generation. Despite considerable progress in exploration and early-stage modeling, challenges remain in accurately simulating subsurface behavior near the coastline, particularly with regard to seawater intrusion and its impact on reservoir performance. This study presents the development of an updated numerical reservoir model using the Brynhild module within the Volsung geothermal simulation platform. By integrating geological, geophysical, and geochemical data, a refined 3D conceptual model was constructed in Leapfrog and subsequently imported into Brynhild. The model incorporates a multi-component equation of state (H₂O + CO₂ + NaCl) to capture the thermodynamic effects of saline intrusion. Boundary conditions and reservoir properties were carefully calibrated to replicate natural state conditions and surface manifestations. Simulation results successfully reproduce pre-exploitation temperature and pressure profiles and demonstrate the extent and direction of seawater intrusion. History matching mass flow and chloride concentrations further validates the model’s ability to represent dynamic reservoir behavior. This integrated modeling approach provides critical insights for sustainable geothermal development in coastal settings.

The Feasibility Test for the Use of Rice Husk Biomass in Steam Power Plants (PLTU)

2025-05-19T17:05:10+08:00

This study analyzes the feasibility of implementing biomass-based co-firing technology in coal-fired power plants as a strategy to reduce greenhouse gas emissions and support a cleaner energy transition. With the increasing environmental impact of coal-fired power plants, biomass co-firing presents a viable solution to reduce dependence on fossil fuels. This research includes an analysis of the calorific value, potential emission reductions, and evaluation of the costs associated with the application of the technology. Rice husks show the potential to produce syngas with a turbine power of 99.7 MW at a humidity of 10.47% with an emission of 118,201 kJ/hr, but the efficiency decreases at higher humidity affected by the weather. This rice husk co-firing strategy of about 5% produces 116-122 MW of turbine power with CO₂ emissions of 160,605 kJ/hr-175,480 kJ/hr, making it an effective energy transition solution and contributing to Indonesia's renewable energy targets.

Optimization of Biomass Gasification in a Dual Fluidized Bed Reactor: A Modeling Approach Using Aspen Plus

2025-05-20T00:02:19+08:00

The growing demand for sustainable energy has positioned biomass gasification as a promising thermochemical conversion technology, particularly in Dual Fluidized Bed (DFB) reactors, which are known for producing high-quality syngas with low tar and nitrogen content. This study presents the development and validation of a biomass gasification model using Aspen Plus, integrating thermodynamic and kinetic parameters to simulate the conversion of three biomass types: BBJP (solid refuse-derived fuel), sawdust, and wood chips. The model’s accuracy was validated against experimental data for both Single Fluidized Bed (SFB) and DFB configurations, demonstrating strong accuracy, with R² values exceeding 90% for key gas components. The simulation results indicated that the DFB configuration significantly enhanced hydrogen (H₂) production, with the highest yield achieved using BBJP (59.84 mol%) at approximately 750°C, followed by sawdust (56.7 mol%) and wood chips (56.08 mol%). Additionally, the study found that a steam-to-biomass ratio of 0.7 optimizes H₂ production, beyond which performance decreases due to syngas dilution. Energy analysis revealed the DFB system produced higher Lower Heating Values (LHV) than the SFB system, with sawdust yielding 23.07 MJ/kg, indicating strong potential for practical application. The model provides valuable insights into optimizing biomass gasification processes, advancing renewable energy technologies, and supporting sustainable power generation initiatives, particularly in Indonesia.

Economic Analysis of Biogas Utilization as Co-firing in Coal Powerplant

2025-05-22T11:42:19+08:00

By signing the Just Energy Transition Partnership (JETP) joint statement in 2022, Indonesia pledged to cut CO₂ gas emissions in the energy sector. This commitment challenges Indonesia to achieve net-zero CO₂ emissions by 2060, especially in the energy sector. As Indonesia's biggest electricity provider, PLN was implementing this pledge through the Accelerate Renewable Energy scheme, an energy transition program. This program will raise the proportion of renewable energy used in Indonesia's electricity generation. In 2040, Indonesia plans to produce 20,923 MW of power from renewable energy sources. With a total production capacity of 46.82 million tons of CPO, Indonesia is the world's largest producer of palm oil and has the ability to generate renewable energy generation from biogas from Palm Oil Mill Effluent (POME). Methane, which can be used as a renewable energy source, provides up 50–75% in the biogas generated by the POME fermentation process. To ascertain the economic viability of using biogas from POME through two schemes. 1. By delivering the fermented biogas to the closest coal power plant for direct co-firing at the existing coal power plant. 2. Biogas power plants generate electricity on-site, and the electrical energy generated is then combined with that of other power plants via an interconnection transmission line. The study's findings demonstrate that, over an 88-kilometer distance, on-site power generation is more cost-effective, produces more energy, and reduces emissions to the greatest extent possible. Emissions decreased by 579.78 kg/h when electric power produced 2.0 MW, and the internal rate of return was 20.75%. With an IRR value of 4.98 percent, direct cofiring generated 1,80 MW of electricity while lowering emissions by 522,73 kg/h.

PCBs Cross-Contamination in Transformer Oil: Mitigation for Environmental and Health Protection

2025-05-19T17:20:49+08:00

Polychlorinated Biphenyls (PCBs) are hazardous compounds that have been widely utilized in transformer oil for insulation purposes. Due to their persistent, toxic, and non-biodegradable nature, improper handling of PCBs can result in contamination of surrounding electrical equipment, posing serious risks to the environment and human health. This study aims to evaluate current PCB management practices and develop effective methods to prevent cross-contamination. The methodology involves electrical testing on active (online) transformers and surface wipe sampling on offline units stored in warehouses. The findings are expected to facilitate early detection of contamination, improve management efficiency, and support the implementation of preventive protocols. The results underscore the urgency of robust PCB management to mitigate environmental degradation and protect public health through safe handling, testing, and storage strategies.

Analysis of Biomass Co-Firing Performance at the Labuhan Angin Steam Power Plant

2025-05-30T17:05:50+08:00

This study analyzes the performance of biomass co-firing technology at the Labuhan Angin Steam Power Plant (PLTU), focusing on the use of palm kernel shells and sawdust as alternative fuels to partially replace coal. The primary objective is to evaluate the combustion performance of these fuel mixtures, particularly in terms of energy efficiency and exhaust emissions, including CO₂, NOₓ, and SO₂. A descriptive-comparative quantitative method was employed, using secondary data sourced from the operational co-firing trial report at Labuhan Angin PLTU. Key parameters examined include thermal efficiency, fuel consumption, biomass-to-coal mixing ratio, and emissions generated during combustion. The results indicate that co-firing with palm kernel shells leads to a decrease in combustion temperature and fluctuations in furnace pressure, although these remain within safe operational limits. For sawdust, a slight decline in thermal efficiency was observed as the biomass ratio increased; however, combustion remained stable up to a 5% mixing ratio. Moreover, SO₂ emissions decreased with higher biomass content, suggesting potential for reduced atmospheric pollution. In contrast, reductions in NOₓ emissions were minimal, and particulate emissions tended to rise with increasing biomass ratios. Overall, the findings demonstrate that co-firing with palm kernel shells and sawdust can be effectively implemented at Labuhan Angin PLTU, provided that operational adjustments are made to maintain combustion efficiency and meet emission standards. The study also highlights the importance of careful technical management to mitigate potential negative impacts on combustion stability and emission profiles.

Simulation of H₂O-to-Hydrogen Conversion Using Photocatalytic Technology

2025-06-03T12:11:35+08:00

Hydrogen is increasingly recognized as a critical component of the global energy transition due to its potential as a clean and sustainable energy carrier. This study investigates photocatalytic water splitting using TiO₂ as a semiconductor and methanol as a sacrificial agent to produce hydrogen. A simulation-based approach using Aspen HYSYS V14 was employed to evaluate process efficiency under varying operating conditions and reactor configurations. Two system configurations—base and recovery—were analyzed using a constant feed of 3,000 kg/h of water and 1,000 kg/h of methanol. The simulation revealed that hydrogen production is significantly influenced by temperature and water-tomethanol ratio. The recovery configuration, operating at 348.15 K with a 3:1 waterto-methanol ratio, yielded the highest hydrogen production rate of 335.02 kg/h. In addition to hydrogen, the process generated valuable by-products—formaldehyde (733.12 kg/h) and formic acid (0.56 kg/h)—which enhance the system’s economic and environmental sustainability when integrated into a circular economy framework. The overall gross profit is estimated at USD 4.16 million per year. These findings highlight the potential of optimized photocatalytic systems for scalable, low-emission hydrogen production and provide a foundation for future experimental validation and large-scale implementation.

Design of a Computational Tool for Organic Rankine Cycle Performance Estimation Based on Geothermal Field Data

2025-05-19T17:58:11+08:00

This study evaluates the thermodynamic feasibility of additional power generation from separated brine at a high-temperature geothermal plant in Indonesia, referred to as the “XYZ geothermal plant” to maintain site confidentiality. The plant operates with a single-phase liquid-dominated reservoir, with temperatures ranging from 250 °C to 270 °C and a brine reinjection temperature of approximately 170 °C at a flow rate of 1400 tons per hour.

To ensure safe reinjection conditions, the Silica Scaling Index (SSI) was applied to determine the minimum allowable brine temperature. A finite difference-based Python simulation tool was developed to model heat transfer in the ORC system and assess performance across different working fluids and operating pressures. The results show that n-pentane achieves the best performance, producing a net power output of 5596 kW and a thermal efficiency of 17.21% at an optimal pressure of 1.80 MPa. Isopentane follows closely, while R-1233zd(E) performs less favorably due to pressure constraints.

Model validation against manual calculations resulted in deviations below 0.6%, confirming the simulation’s accuracy. This tool provides a fast and reliable method for evaluating ORC performance and supports practical decision-making for geothermal plant operators. It is intended to assist utilities such as PLN in optimizing geothermal resource utilization.

Kinetic Study of Bio-Oil Production from Pyrolysis of Rice Husk and Corncob Mixture Using Thermogravimetric Analysis

2025-05-20T00:14:55+08:00

The efficient production of bio-oil from lignocellulosic biomass requires a deep understanding of pyrolysis kinetics, particularly during stages critical for bio-oil formation. This study investigates the pyrolytic behavior and kinetic parameters of a rice husk and corncob mixture (1:1 mass ratio), focusing on the decomposition phases that significantly influence bio-oil yield. Thermogravimetric analysis (TGA) was performed at heating rates of 10, 20, and 30 °C/min to analyze biomass decomposition process. Activation energy (Ea) was determined using the Kissinger-Akahira-Sunose (KAS) and Flynn-Wall-Ozawa (FWO) isoconversional methods over a conversion range (α) of 0.1 to 0.6, corresponding to the primary degradation stage responsible for bio-oil production. The Coats-Redfern method was applied to identify the reaction mechanism in the α range of 0.2 to 0.6. Ea values calculated using the KAS and FWO methods ranged between 147 to 200 kJ/mol. The Diffusion 3D model, identified through the Coats-Redfern approach, showed Ea values consistent with those from the isoconversional methods. Cross-method validation and comparison with existing literature confirm the robustness of the kinetic parameters. These findings contribute to the design of sustainable energy production systems by providing updated kinetic insights for optimizing biomass pyrolysis processes at both laboratory and industrial scales.

Mine Mouth Coal Gasification into Low Carbon Hydrogen

2025-05-30T16:47:25+08:00

Coal is fossil fuel which is utilized as fuel to generate electricity via coal-fired power plants (CFPP). There are many government programs that have been planned for the development of CFPP, especially Mine Mouth CFPP’s Program. The aim of this program is to utilize coal directly at the mine mouth. But indonesia's support for the Paris Agreement 2015 has the potential to delay and even cancel the Mine Mouth CFPP’s Program, so that coal mines are planned to be used will be abandoned. Therefore, the government has started to create several coal downstreaming programs so that coal resources in Indonesia can continue to be utilized optimally, one of these programs is through the coal gasification program. Several reactions occur at coal gasification processing; an optimal composition or optimal ratio is required to produce optimal main product and minimize side products. The objective of this paper is to evaluate the optimal ratio steam flow rate for coal gasification simulation. The optimal ratio of steam flow rate to be reacted on Water Gas Shift (WGS) reactor so that optimal products are produced is 0.381 kg steam/kg coal with a CO₂ purity level above 90% and H₂O isn't squandered a lot.

Analysis of Carbon Footprint on The Supply Chain Activities of Main Transmission Material (MTU) PT PLN (Persero)

2025-05-19T15:36:56+08:00

This study aims to develop a method for creating a carbon footprint inventory for substation equipment using a gate-to-gate Life Cycle Assessment (LCA) approach. The analysis looks at Main Transmission Equipment (MTU) in Air Insulated Switchgear (AIS), which includes circuit breakers, disconnecting switches, current/voltage transformers, and lightning arresters that operate at voltage levels between 70 and 500 kV. Emission calculations were carried out by inventorying each process from port arrival, internal transfer, manufacturing, testing, and packaging to gate-out delivery. Manufacturers in China import several equipment components, which involve international marine transport to Indonesia. The results indicate that the factory testing stage is the emission hotspot across all equipment categories due to the intensive use of high-capacity electricity. The largest emission value was recorded for 500 kV circuit breakers, reaching 1,279.38 kgCO₂e per unit, driven mainly by their complex manufacturing and energy-intensive testing requirements. In total, international sea transport and electricity consumption during testing dominate the carbon footprint profile. These findings provide input for PLN’s green procurement strategy and vendor evaluation system toward net zero emissions by 2060.

Performance Analysis of Woodchip Cofiring in a 100 MW CFB Boiler at Tarahan Power Plant Unit 3

2025-05-19T17:49:17+08:00

The transition to renewable energy in Indonesia is being accelerated through biomass cofiring in coal-fired power plants (CFPP), advertising a low-investment strategy to decrease greenhouse gas emissions. This study presents the performance analysis of cofiring between coal and woodchip at PLTU Tarahan Unit 3, which utilizes a Circulating Fluidized Bed (CFB) boiler. The experiment was conducted using three cofiring scenario of 10%, 15%, and 20% woodchip beneath a steady 95 MW load condition. Comprehensive evaluations were carried out including fuel characterization, boiler performance, emission measurements, and economic analysis. The results showed that cofiring up to 20% woodchip was technically feasible without major modifications to the boiler system. Emissions of SO₂ and NOₓ decreased in proportion to the biomass share, and operational stability was maintained. Although the specific fuel consumption (SFC) slightly increased, the production cost remained competitive due to the low cost of biomass. The study concludes that woodchip cofiring is a viable and sustainable alternative for supporting Indonesia’s net zero emission goals while optimizing the use of existing infrastructure.

A Review of The Final Turbine Inspection Report at the Lahendong Geothermal Power Plant

2025-06-11T05:14:54+08:00

In this paper, the author employs a review method based on the results of a turbine inspection conducted by the maintenance service unit of PT Indonesia Power in 2023. The review presents a comprehensive evaluation of the condition of rotor blades in the steam turbine of the Lahendong Unit 1 Geothermal Power Plant. The objective of this study is to assess the material integrity through a series of non-destructive testing (NDT) methods, as part of the Remaining Life Assesment (RLA) of the turbine components. The inspection included visual inspection, magnetic particle inspection (MPI), ultrasonic flaw testing, penetrant testing, in-situ metallography, hardness testing, as well as XRD and XRF analysis. Significant findings include pitting corrosion, rubbing, material loss, water droplet erosion, and cracks in several rotor stages. Microstructural analysis revealed the presence of martensite, retained austenite, and carbides, with indications of cavities along grain boundaries that have progressed to directional oriented cavities and even microcracks. Based on Neubauer’s classification, several blades have reached stage 4 and 5 (end of life), indicating substantial degradation. These findings provide a strong technical basis for predictive maintenance strategies and re-blading decisions in the next overhaul.

Analysis of Continuous Cell Lines Vero, BHK21, and RK13 as Alternatives to MRC5 for Rubella Virus Propagation: A Study on Cell Proliferation and Titer Virus

2025-05-28T18:51:25+08:00

Rubella virus remains a relevant global health concern, particularly due to its teratogenic effects when infection occurs during early pregnancy, potentially leading to congenital rubella syndrome. In vaccine development, the choice of host cell substrate plays a crucial role in ensuring both the safety and scalability of production. Currently, MRC5 human diploid fibroblast cells are widely utilized; however, they present certain limitations, including a finite lifespan and ethical concerns regarding their origin. This research aims to investigate the feasibility of three continuous cell lines, Vero, BHK21, and RK13, as potential alternatives to MRC5 for rubella virus cultivation. The study encompasses analysis of proliferation studies (morphology, viability, cell density, and population doubling time/PDT) and viral titer quantification post-infection. Each cell line was assessed for morphology, viability, cell density, and population doubling time (PDT). The most promising candidate based on proliferation characteristics was further tested for its ability to support rubella virus replication. Viral titers were measured using CCID₅₀ methods. The results of this study demonstrated that each cell line exhibited distinct morphological characteristics reflecting their tissue of origin, with excellent viability levels averaging above 95%. Among the candidates, Vero cells demonstrated the highest average cell density and the most favorable PDT value (1.6 days), warranting their inclusion in the subsequent virus inoculation phase. Rubella virus propagated in Vero cells achieved a titer of 5.53 logCCID₅₀/mL on day 14, which was higher than the 4.53 logCCID₅₀/mL observed in the MRC5 control group. Vero cells demonstrated strong potential as an alternative to MRC5 for rubella virus production, offering advantages in terms of proliferation, viral yield, and long-term sustainability. These findings contribute valuable insights for the development of more sustainable, scalable, and ethically sourced rubella vaccines, supporting global immunization initiatives.

Techno Economic Analysis of Hydrogen Production at the Songawayaua Geothermal Power Plant

2025-06-09T14:26:53+08:00

This study evaluates the techno-economic feasibility of integrating green hydrogen production with geothermal energy at the Songawayaua Geothermal Power Plant (GPP) in North Maluku, Indonesia. Although Indonesia holds a geothermal potential of 23.9 GW, utilization remains limited—especially in remote, low-demand regions—leaving substantial untapped resources. This research proposes a 30 MW geothermal development scenario, allocating 10 MW for grid electricity and 20 MW for hydrogen production using Proton Exchange Membrane (PEM) electrolysis, representing a novel configuration in the national context.

The techno-economic analysis reveals that electricity sales alone result in a negative Net Present Value (NPV) of USD –110 million under current tariff regulations. Conversely, hydrogen production achieves an output of 2,800 tons/year with a Levelized Cost of Hydrogen (LCOH) of USD 1.47/kg. The integrated system becomes economically feasible at a hydrogen selling price of USD 8.53/kg (NPV = 0) and commercially viable at USD 13/kg (IRR = 12%).

This study contributes new insights by quantifying critical economic thresholds and price sensitivities in geothermal-hydrogen integration. Unlike previous studies that examine each system separately, this work presents an integrated pathway that enhances renewable energy utilization and supports Indonesia’s Net Zero Emissions (NZE) 2060 target.

The Impact of Local Temperature Variations on the Efficiency and Power Output of Solar Power Plants in Lombok Island

2025-05-30T17:08:40+08:00

Indonesia, located in the equatorial region, possesses vast solar energy potential reaching up to 200,000 MW. However, its utilization remains significantly low at only 0.08% of the total potential. In remote regions like Lombok Island, solar power plants serve as a strategic solution for clean and sustainable electricity, especially where access to fossil fuels is limited and costly. This study investigates the impact of local temperature variation on the efficiency and power output of PLTS in Lombok, a tropical region with high solar irradiance (4–6 kWh/m²/day) and elevated daytime temperatures (26–33°C). Using temperature and solar radiation data from 2019 to 2024, along with electricity output records from three major Solar Power Plant facilities (Pringgabaya, Selong, Sengkol, each 7 MWp), the research applies statistical correlation and regression modeling to quantify the relationships among temperature, irradiance, and energy output. The findings are expected to reveal a negative correlation between increased ambient temperature and photovoltaic efficiency due to rising electrical resistance in solar cells. Conversely, higher irradiance generally enhances power output, although its benefits may be offset by excessive heat. This study also incorporates Dipole Mode Index (DMI) analysis to understand the regional climatic influence on local temperature trends. DMI is selected due to its direct representation of the Indian Ocean Dipole (IOD) phenomenon, which significantly affects weather patterns, sea surface temperature, and consequently, regional thermal variations in the Indonesian maritime continent. By focusing on DMI, this research captures a dominant mode of interannual climate variability that is particularly relevant to temperature fluctuations in Lombok. Furthermore, the study provides quantitative results for the Lombok region, including the percentage impact of each variable on power production. It also analyzes the seasonal and intraseasonal variations of temperature and solar radiation to identify periods of optimal and suboptimal solar plant performance. These findings are expected to support predictive energy output modeling and inform technical recommendations such as thermal mitigation strategies and material optimization for improving solar power performance in tropical environments. These insights are crucial for supporting Indonesia’s energy transition and achieving greater integration of renewable sources in its national energy mix.

The Potential of Carbon Trading and Carbon Tax Analysis to Enchance the Economic Feasibility of Geothermal Power Plant in Indonesia

2025-05-30T16:52:53+08:00

Global climate change, driven by the increasing concentration of greenhouse gases in the atmosphere, has emerged as one of the most pressing challenges confronting humanity. The energy sector, particularly its continued reliance on fossil fuel combustion for electricity generation, is a major contributor to greenhouse gas emissions. In response to the urgent need to mitigate these negative impacts, various countries and international organizations have developed policies and mechanisms aimed at reducing carbon emissions. One such mechanism is the carbon trading system, a market-based instrument that enables countries or companies to buy and sell carbon emission allowances. Under this scheme, entities that successfully reduce emissions beyond their assigned targets may sell their surplus allowances to others who are unable to meet their reduction obligations. This approach fosters both efficiency and innovation in emissions reduction, with economic incentives serving as a primary driver. Geothermal Power Plants, as a renewable energy source, play a pivotal role in reducing dependence on fossil fuels. Compared to fossil power plants, Geothermal Power Plants generate significantly lower levels of carbon emissions. Therefore, analyzing the potential integration of Geothermal Power Plants into the carbon trading system could offer financial incentives and enhance the economic viability of geothermal energy. This mechanism has the potential to support the further development and expansion of geothermal power infrastructure.

Thermodynamic Analysis and Ash Behavior of Biomass Cofiring with Kaolin Additives in Coal-Fired Power Plant

2025-05-24T17:08:38+08:00

The implementation of biomass cofiring in coal-fired power plants (CFPPs) has become a key strategy in Indonesia's energy transition, aimed at reducing carbon emissions while maintaining energy security. However, the introduction of biomass—particularly those with high alkali and chlorine content—poses significant operational challenges, including increased slagging potential. Slagging can deteriorate boiler performance, reduce heat transfer efficiency, and increase maintenance costs. This study investigates the thermodynamic effects of kaolinite (Al₂Si₂O₅(OH)₄) as an additive for mitigating slagging in the cofiring process at PLTU Suralaya.

Using FactSage 7.2, a thermochemical equilibrium modeling software, this research simulate ash behavior and slag formation under various blending ratios of coal, biomass, and kaolinite. The model evaluates the formation of liquid phases and predicts the interactions between potassium-rich biomass ash and kaolinite. Results show that kaolinite effectively captures alkali elements, promoting the formation of high-melting-point aluminosilicates such as leucite and kalsilite, thereby reducing the amount of low-temperature eutectic compounds responsible for slag formation.

This research provides a predictive approach to slagging control through additive selection and supports the optimization of biomass cofiring strategies in CFPPs. The findings are expected to contribute to more stable and efficient operation of power plants integrating renewable biomass fuels.

The Development of Vendor Performance Evaluation and Strategies Design Systems Using Fuzzy Best Worst Method (FBWM) and TODIM in PT PLN (Persero)

2025-05-19T16:08:08+08:00

In realizing its vision and mission, as well as in supporting electricity national fulfillment, PT PLN (Persero) is necessary to be supported by supply chain management, ranging from procurement to delivery activities. In the procurement process, one of the important aspects is the management of vendors, including the evaluation of their performance, to enable PT PLN (Persero) in selecting good performance vendors and determining appropriate development strategies for its vendor improvement. This paper discusses the development of vendor performance evaluation system by setting the criteria, sub criteria, and by a fuzzy multi-criteria decision making (MCDM). In the other hand, fuzzy best-worst method (BWM) is to determine importance weights of the evaluation criteria, while TODIM to asses vendor performance and subsequently to determine vendor development strategies based on its performance. Finally, this study is to develop framework in vendor performance evaluation system and strategies design.

Inventory Management Efficiency Strategy at UID Banten: A Study of Vendor Managed Inventory (VMI)

2025-05-30T17:16:38+08:00

Inventory management is critical to guaranteeing the efficiency and reliability of power distribution at PT PLN (Persero), notably at the Unit Induk Distribusi (UID) Banten. Challenges such as restricted storage space, installation delays owing to permit limits, and the buildup of heavy items such as medium-voltage cables have all had a substantial influence on operational performance. The purpose of this research is to investigate the feasibility of using Vendor Managed Inventory (VMI) as a strategic strategy to improve inventory efficiency at UID Banten. VMI enables suppliers to manage inventory levels based on real-time consumption data and demand projections, resulting in lower holding costs, increased stock availability, and reduced inventory buildup. Using literature review, the success of VMI implementations suggests that adopting VMI can provide substantial benefits, including streamlined warehouse operations, improved supplier collaboration, and greater responsiveness to demand fluctuations. However, several prerequisites, such as digital infrastructure readiness, data transparency, and mutual trust between stakeholders, must be met for successful VMI adoption. This study provides strategic recommendations for UID Banten to assess and prepare for VMI implementation as a means of achieving long-term inventory and distribution efficiency.

Analysis of Geothermal Fluid Pipe Behavior in Dry Steam Geothermal Power Plant under Dynamic Load

2025-06-02T09:31:22+08:00

This study investigates the dynamic behavior of a dry steam geothermal fluid piping system located in a seismically active region of West Java, Indonesia. Given the potential for resonance under earthquake-induced dynamic loads, modal analysis was conducted using ANSYS finite element software to determine the piping system's natural frequencies and mode shapes. The piping system, spanning 186 meters, was modeled with fixed and roller supports to reflect realistic boundary conditions. Analysis results revealed that while the first mode (10.31 Hz) falls within the critical earthquake frequency range, its low mass participation indicates minimal influence on system response. In contrast, the twenty-fifth mode (31.12 Hz) exhibits deformation patterns more aligned with expected seismic excitation, with its frequency exceeding the dominant earthquake spectrum. Thus, the system is not considered highly susceptible to resonance. This study underscores the importance of modal analysis in assessing seismic resilience and confirms the structural adequacy of the piping design under dynamic loads.

Impact Of Dry Flue Gas Loss on Thermal Efficiency in Pulverized Coal Boilers

2025-05-24T16:38:55+08:00

Coal-fired power plants (CFPPs) dominate Indonesia’s electricity generation, contributing 67.2% of the national supply, yet they pose substantial challenges in terms of energy efficiency and environmental impact. Boilers, as the largest energy-consuming component in CFPPs, play a critical role in determining overall plant performance. This study aims to improve the thermal efficiency of a 315 MW subcritical pulverized coal boiler by optimizing two key operational parameters: excess air and flue gas temperature. Using actual field data and heat loss-based calculations following standardized energy audit methodology, the study quantifies the efficiency gains achievable through modest adjustments. The results show that a 5 °C reduction in flue gas temperature leads to a 0.31% increase in boiler efficiency, while a 5% reduction in excess air improves efficiency by 0.29%. These findings underscore the significant impact of controllable combustion parameters on energy performance and highlight low-cost opportunities for efficiency enhancement. The study not only identifies the sensitivity of boiler efficiency to excess air and flue gas temperature but also offers practical insights for operational optimization. Implementing such measures can reduce fuel consumption and operating costs while contributing to emission reduction, thereby supporting a more sustainable and cost-effective operation of coal-fired power plants in Indonesia.

Techno-Economic Analysis of Kamojang Geothermal Power Plant as A Green Hydrogen Producer

2025-05-19T23:07:05+08:00

The utilization of renewable energy is becoming increasingly important in addressing the challenges of climate change and the need for clean energy. The potential to produce hydrogen from renewable energy sources, such as geothermal, offers an attractive solution to support the transition to clean energy. In this paper, the author uses a case study approach to analyze the hydrogen production potential of the Kamojang Geothermal Power Plant. The analysis method includes modeling the potential for hydrogen production based on the characteristics of the Kamojang Geothermal Power Plant, while the economic analysis includes planning investment costs, operational and maintenance costs, and Levelized Cost of Hydrogen. Based on the operational condition, it shows that the Kamojang Geothermal Power Plant has the potential to produce hydrogen using Alkaline Water Electrolysis technology. The economic analysis reveals that the hydrogen production infrastructure requires investment costs for Green Hydrogen Plant Infrastructure, operational costs must be considered to optimize LCOH and revenue from hydrogen sales can increase company profits in line with the PLN Group's Beyond kWh program. The results of this study are the basis for consideration, both from technical and economic aspects, in planning and implementing hydrogen production projects from renewable energy sources. The implication of this analysis is that the Kamojang Geothermal Power Plant has the potential to become a hydrogen producer in the future, where the hydrogen can be used commercially to support the PLN Group's Beyond kWh program and provide benefits to the environment by producing low-emission electrical energy fuel.

Integrating Coal Gasification into Gas Engine Power Plant: A Techno Economic Study at PLTMG Bangkanai

2025-05-30T17:10:04+08:00

Indonesia aims to achieve a 29% emission reduction by 2030 by reducing its reliance on coal-fired power plants. Gas-fired power plants offer a cleaner option with lower CO₂ emissions compared to coal-fired power plants (PLTU). The Bangkanai Gas Engine Power Plant (PLTMG) with a capacity of 310 MW currently operates with a capacity factor (CF) of only 28.47% due to limited gas supply. The gas demand at PLTMG Bangkanai is 66.04 BBTUD, while the available gas supply is only 20.33 BBTUD. On the other hand, Indonesia has substantial coal reserves, especially on Kalimantan Island, totaling 14 billion tons. This study investigates the technology of converting coal into Synthetic Natural Gas (SNG) to address the gas supply shortage at PLTMG Bangkanai. The coal-to-SNG process includes coal gasification, water gas shift (WGS) reaction, and methanation reaction. The modeling was performed using Aspen Plus software. The gasifier design used is an entrained-flow gasifier with a coal feed rate of 120 t/h, a gasifier temperature of 700 °C, and a pressure of 1 bar. The simulation results show that the SNG product has a high heating value (HHV) of 45.58 MJ/kg and a total gas production of 46.04 BBTUD, which is sufficient to meet the gas shortage at PLTMG Bangkanai of 45.72 BBTUD. The economic analysis for coal-to-SNG processing, including the gas pipeline to the power plant, reveals a CAPEX of US$ 102,120,735 and OPEX value is US$ 107,542,643 per year. The IRR value obtained was 16.18% and the payback period was 5.14 years assuming the SNG selling value was 7.5 USD/MMBTU.

Projected Rainfall Trends and Variability in the Mrica Catchment under the SSP5-8.5 Scenario

2025-05-30T16:51:00+08:00

This study analyzes changes in rainfall, inflow discharge, and electricity production at PLTA Mrica using historical data (1985–2014) from CHIRPS (Climate Hazards Group InfraRed Precipitation with Station data) and six global climate models (GCMs) under CMIP6 (Coupled Model Intercomparison Project Phase 6). Future projections are based on the SSP5-8.5 (Shared Socioeconomic Pathway 5 – fossil-fueled development) scenario to represent a worst-case pathway, enabling assessment of maximum potential climate impacts on hydropower reliability [2] scenario for the period 2021–2100. A delta-based statistical downscaling method is applied to produce high-resolution rainfall projections. This method is deterministic in nature; it applies a fixed anomaly (delta) between future and historical climatologies onto observed datasets, without simulating transient atmospheric processes as done in prognostic models. It is computationally efficient and widely used for impact studies where capturing long-term mean changes is prioritized over day-to-day weather variability [2][3]. The results indicate an increase in rainfall during the wet season and a significant decline during the dry season, particularly from January to March, with projected rises of up to +2.5 mm/day, or approximately +30–40%, compared to the historical baseline. Conversely, the dry season (June–September) is projected to experience a decline of up to 1.5 mm/day, equivalent to a reduction of 25–40%, depending on the month and future time slice. Historical data indicate that monthly rainfall of at least 100–120 mm is generally required to sustain sufficient reservoir inflow for optimal electricity generation at PLTA Mrica, especially during the dry season. Variability in rainfall, particularly prolonged dry spells or delayed wet season onset, can lead to inflow shortages, reducing turbine operation hours and ultimately affecting annual energy output. This study highlights the importance of using climate data such as projected rainfall thresholds and variability to guide reservoir operations, optimize electricity production, and reduce risks during dry periods. Integrating such information supports more adaptive and resilient hydropower planning under future climate uncertainty.

Dispersion Modeling of Gas Emission and Total Suspended Particulate in Java’s Coal-Fired Power Plant Using AERMOD

2025-06-10T14:47:33+08:00

This study analyzes the dispersion of SO₂, NOₓ, and total suspended particulates (TSP) from a coal-fired power plant using the AERMOD model. Meteorological and terrain data were processed via WRPLOT, AERMET, and AERMAP. Results show that SO₂ and NOₓ predominantly disperse eastward and southward, with peak concentrations recorded around 1.5 km south of the emission source. Maximum SO₂ concentrations reached 1,937.27 µg/m³ (1-hour), 298.59 µg/m³ (24-hour), and 55 µg/m³ (annual), with exceedances of regulatory limits for short- and medium-term periods. NOₓ concentrations peaked at 15,494.63 µg/m³ (1-hour), 1,909.30 µg/m³ (24-hour), and 175 µg/m³ (annual), surpassing the respective limits of 1-hour and 24-hour standard. In contrast, TSP concentrations remained below the 24-hour limit, with a maximum of 109.42 µg/m³. Model evaluation showed good performance for SO₂ (RMSE and MAE <10%, bias within –0.3 to 0.3), while NOₓ was overestimated and TSP underestimated due to AERMOD’s limitations in simulating chemical reactions and terrain effects. The study recommends incorporating non-fugitive sources, high-resolution land data, and chemical transformation modules to enhance model accuracy and support effective air quality management in complex terrain.

Process Optimization of Carbon Capture and Storage in Coal Fired Power Plant with Heat Integration

2025-05-22T11:47:41+08:00

This study evaluates the optimization of Carbon Capture and Storage (CCS) implementation in a subcritical Coal Fired Power Plant (CFPP). The objective of this paper is to investigate how heat integration can reduce energy consumption of CCS systems and analyze their impact on the overall energy penalty of CFPP. The research focuses on a CFPP with an installed capacity of 3×330 MW and a design efficiency of 38.4%. The results of the baseline case without heat integration indicate that achieving a 90% CO₂ capture rate using an MDEA+PZ solvent requires a reboiler energy consumption of 3.46 MJ/kgCO₂, which results in an energy penalty of 34% relative to the total energy generated by the CFPP and reduces the overall plant efficiency to 27.4%. Process optimization was identified through the utilization of waste heat. Among all the scenarios evaluated, Case 6, which integrates a rich solvent preheater and an inter-stage heater, achieves the highest energy savings, with up to a 40% reduction in reboiler energy consumption and a 10.7% decrease in the overall energy penalty of the CFPP. These findings highlight that strategic heat integration significantly mitigates the energy impacts of CCS implementation which could reduce energy penalty of CFPP.

The Projections of Solar Energy Potential in Indonesia under Climate Change Scenarios : A CMIP6 Multi-Model Ensemble Analysis

2025-05-30T17:08:01+08:00

Indonesia holds significant solar energy potential, making it a key resource in the country’s pathway toward net-zero carbon emissions by 2060. However, climate variability introduces uncertainties that may impact long-term solar energy production and investment planning. This study investigates the projected impacts of climate change on Indonesia’s solar photovoltaic (PV) potential for the period 2030–2060, utilizing outputs from five global climate models (GCMs) of the Coupled Model Intercomparison Project Phase 6 (CMIP6). Two emission scenarios were considered: SSP1-2.6 (low emissions) and SSP5-8.5 (high emissions). Key climate variables influencing PV performance surface downwelling shortwave radiation, near-surface air temperature, and wind speed were analyzed. Model outputs were regridded to a 0.25° spatial resolution and bias-corrected through statistical downscaling. Results reveal spatially variable responses of PV potential to future climate change, with a projected decrease during the rainy season and an increase during the dry season in specific regions. These findings highlight the necessity of integrating climate projection uncertainties into national renewable energy strategies, ensuring adaptive and resilient solar energy development in Indonesia under future climate conditions.

Techno-Economic Assessment of a 400 MWp Floating Photovoltaic System Integrated with Pumped Hydro Energy Storage (PHES) on Lake Toba

2025-06-04T09:25:56+08:00

Indonesia’s commitment to achieving Net Zero Emissions by 2060 has driven the exploration of large-scale renewable energy solutions, including the integration of floating photovoltaic system and energy storage system. This study analyzes the techno-economic feasibility of a 400 MWp floating photovoltaic (FPV) system combined with Pumped Hydro Energy Storage (PHES) at Lake Toba, North Sumatra. This study presents a novel hybrid configuration not yet implemented in Indonesia. Multi-platform simulations were conducted using PVsyst for energy yield estimation and HOMER Pro for techno-economic optimization. The research provides new insights into the feasibility and optimal configuration of hybrid FPV-PHES systems to support Indonesia’s renewable energy transition. The research employs PVsyst to evaluate the energy performance of the FPV system, while HOMER Pro was used for economic optimization across three scenarios: 400 MWp Floating PV only, Floating PV combined with 407 MWh PHES, and Floating PV combined with 511 MWh PHES. Simulation results from PVsyst showed an annual energy output of 5.72 GWh and a performance ratio of 80%, with relatively low temperature losses due to the water-based cooling effect. Among the scenarios, Scenario 2 (407 MWh PHES) offers the most favorable outcome with a Levelized Cost of Energy (LCOE) of Rp 1,298/kWh, ROI of 5%, IRR of 7.5%, and a payback period of 10.58 years. Grid simulations also confirm system stability under dynamic conditions. Environmentally, the hybrid system reduces greenhouse gas emissions by 8.87 million kg CO₂ annually. The results indicate that the FPV–PHES configuration is technically feasible, economically attractive, and environmentally beneficial, making it a strong candidate to support Indonesia’s energy transition goals.

Techno-Economic Feasibility Study of Solar PV Integration at PLTGU Tanjung Batu, East Kalimantan

2025-05-19T17:35:03+08:00

The growing global demand for electricity and the environmental impact of fossil fuels have prompted Indonesia to seek cleaner energy solutions. Despite high solar energy potential, the expansion of large-scale photovoltaic (PV) systems in Indonesia is hindered by land and investment constraints. This study evaluates the techno-economic feasibility of integrating a rooftop solar PV system at PLTGU Tanjung Batu using PVsyst simulation, focusing on system performance and financial viability through NPV, IRR, and Payback Period calculations. Results show an annual output of 232,562 kWh, PR of 81.36%, and a payback period of 18.4 years, indicating long-term viability with proper fiscal support.

Analysis of MetOcean Changes in the Coastal Waters Surrounding Paiton Coal-Fired Power Plant, East Java

2025-05-30T17:00:34+08:00

The Paiton Coal-Fired Power Plant (CFPP), located on the northern coast of East Java, Indonesia, has been operational since 1994 and is suspected of influencing the surrounding coastal environment. This study analyzes changes in MetOcean parameters, including sea surface temperature (SST), wind patterns, and wave characteristics, in the Paiton coastal area between 1993 and 2024. Results indicate a clear seasonal variation in SST following the Indonesian monsoon cycle, with warmer temperatures during the rainy season and lower temperatures during the dry season due to coastal upwelling. A warming trend of approximately 0.0178°C per year has been identified, with additional increases possibly linked to thermal discharges from the plant's cooling system. Wind analysis shows a dominant flow from the east to southeast during the dry season, with speeds of 2–3 m/s, influencing evaporation rates and corrosion risks for infrastructure. Wave data reveal that most waves are locally generated, with heights between 0.2 and 0.4 meters, and only rare occurrences of waves exceeding 0.4 meters. These oceanographic dynamics collectively affect the operational efficiency and cooling performance of the CFPP. Continuous oceanographic monitoring and integrated environmental management are essential to support the sustainable operation and long-term resilience of coastal power generation facilities.

Modeling Pricing Problem on Clothing Industry Using Game Theory: Domestic Vs Import Products

2025-06-02T09:34:25+08:00

Indonesian textile and clothing industries is one of nation strategic industrial sector which consists of two industries in which are connected in a single supply chain: textile industries and clothing industries. Government as a regulator may intervene to protect domestic product from its competition by applying tariff on the import product. This research attempts to model competition between domestic products and import products on a domestic market. Game theory is used as an approach to model the problem of pricing strategy faced by domestic industries. The problem is modeled as a leader-follower game which represents a price negotiation problem between the market and the clothing industry. The research contributes to literature in research of pricing games by using Constant Elasticity of Substitution (CES) function. Utility functions used in the model are revenue maximization and utility maximization for the clothing industry and consumer, respectively. Three tariff scenarios are simulated to observe tariff impacts on the game solution. The highest revenue achieved while applying the maximum import tariff on clothing products. Consumer’s utility is decreasing as tariff increases. Sensitivity analysis reveals game’s optimal strategy depends heavily on the preference and substitution parameters.

Feasibility Study of Integrating Green Hydrogen Plant with Geothermal Power Plants in Renewable Energy Microgrid

2025-05-19T23:16:41+08:00

In alignment with Indonesia’s national energy transition goals, PT PLN (Persero) has initiated a de-dieselization program aimed at replacing diesel generators with renewable energy sources, such as photovoltaic (PV) and geothermal power, as outlined in the Electricity Supply Business Plan (RUPTL 2021). This study investigates the economic feasibility of the proposed 10 MW Atadei Geothermal Power Plant (GPP), located within the Lembata microgrid in East Nusa Tenggara, a system currently challenged by increased PV penetration and the resulting “duck curve” phenomenon. This condition significantly reduces net load during midday, thereby constraining the minimum operational thresholds of geothermal generation. Two operational scenarios are evaluated: (1) reduced-capacity baseload operation, and (2) the integration of green hydrogen production to utilize excess power. Based on a post-dispatch average capacity factor of 77%, approximately 13% of geothermal generation remains unutilized. Incorporating green hydrogen production with Proton Electrolyzer Membrane (PEM) as a demand-response strategy enhances system flexibility, resulting in a net present value (NPV) of USD 0.16 million and an internal rate of return (IRR) of 12.5%. To maintain project viability, a minimum hydrogen price of USD 6.9 per kilogram is required. The findings underscore the potential of flexible, demand-side applications—particularly hydrogen production—to support both operational reliability and economic sustainability in isolated renewable energy systems

Preliminary Exergy Analysis for Performance Optimization at Ulubelu Geothermal Power Plant Unit 1

2025-05-20T00:41:25+08:00

Indonesia lies within the Ring of Fire, renowned for volcanic activity and geothermal energy potential estimated at 23.7 GW. By 2023, 18 geothermal power plants were operational with a combined capacity of 2,597 MW. The Ulubelu Geothermal Power Plant, supplying 25% of Lampung’s electricity, serves as a case study for a preliminary exergy analysis. Using Cycle-Tempo simulation, a thermodynamic model was developed to replicate actual operating conditions and evaluate exergy flows and losses. The system’s total exergy input was 50,136 kW, with 16,367 kW (32.6%) destroyed due to irreversibilities, resulting in an overall exergy efficiency of 67.34%. The turbine achieved the highest functional exergy efficiency (82.43%) but also accounted for the largest relative exergy loss (12.43%). Substantial inefficiencies were identified in the condenser (14.88%) and ejector (1.66%). These findings reveal critical sources of exergy destruction, forming the basis for targeted performance improvements. Optimization strategies are prioritized for the turbine and condenser, where losses are most significant.

Optimization of the Biomass Supply Chain for Co-Firing at Adipala Power Plant to Improve Cost Efficiency

2025-05-30T16:57:57+08:00

The utilization of biomass as a renewable energy source is becoming increasingly important to reduce dependence on fossil fuels and decrease carbon emissions. However, the efficient distribution of biomass in the co-firing system at the Adipala Steam Power Plant (PLTU) faces significant challenges related to high logistics costs. This study aims to optimize the distribution costs of biomass in the co-firing system at PLTU Adipala using Linear Programming (LP) methods. The primary objective of this research is to determine the optimal amount of biomass needed to meet the energy requirements of the power plant with efficient distribution costs, as well as to identify supply chain strategies that can enhance cost efficiency. The method employed is a Linear Programming optimization model that considers factors such as transportation costs, supply capacity, and energy needs. The results indicate that the application of LP can reduce logistics costs by up to 15% and improve the efficiency of biomass distribution. These findings make a significant contribution to enhancing the efficiency of biomass supply chain management at PLTU Adipala and can serve as a reference for the development of renewable energy policies in Indonesia. In conclusion, the application of LP in biomass supply chain management can provide efficient and sustainable solutions while promoting the reduction of carbon emissions in the energy sector.

Comparative Study of Solid Fuel for Co-Firing Biomass Coal in Steam Power Plant between Produced by TOSS and MASARO Methods

2025-06-05T10:57:25+08:00

The growing electricity demand and Indonesia’s commitment to reducing greenhouse gas emissions have accelerated biomass co-firing initiatives in coal-fired power plants (PLTUs). This study presents a comparative assessment of two municipal waste-to-fuel technologies: TOSS (Waste Processing Technology at the Source) and MASARO (Zero Waste Management). The analysis covers technical, economic, and environmental aspects, using a daily waste input of 100 tons. TOSS produces more biomass pellets (33.23 tons/day) than MASARO (25.686 tons/day). Waste projections in Babakan, Cirebon—from 20,862 tons/year in 2024 to 24,652 tons/year in 2034—suggest long-term feedstock sustainability. Co-firing trials by PLN confirm the energy feasibility of both pellet types, with low ash and slagging potential, particularly for MASARO’s RDF. Economically, both methods are viable, but MASARO offers greater profitability due to product diversification, with a Net Present Value of IDR 384.484 billion and an Internal Rate of Return of 99.15%. Environmentally, MASARO enables greater methane emission avoidance (5.802 million tons CO₂eq/year) compared to TOSS (4.722 million tons CO₂eq/year). In conclusion, TOSS is preferable for maximizing pellet output, whereas MASARO provides a more holistic solution for sustainable waste management, with stronger economic and environmental performance.

Urgency of Detailed Environmental Impact Assessment Using Appropriate Technical Methods for Coal-Fired Power Plants (CFPP) in Indonesia: A Life Cycle Assessment (LCA) Approach

2025-05-19T15:54:18+08:00

Coal-fired power plants (CFPP) remain a key source of electricity in Indonesia, but they significantly contribute to environmental issues, especially greenhouse gas emissions and air pollution. As awareness of these environmental impacts grows, the study of Life Cycle Assessment (LCA) applications for CFPP has become increasingly important for comprehensively evaluating their operational effects on the environment.This study aims to assess how the LCA method has been applied to CFPP in Indonesia by various researchers. It focuses on the consistency of methodologies used, examining the availability and representativeness of data, scope, functional units, inventory data, impact category selection, weighting, and data processing techniques in line with the fundamental principles of LCA. The analysis shows that most studies rely on secondary data processed using LCA software such as OpenLCA and SimaPro. The findings indicate that the primary impact category analyzed is greenhouse gas emissions, using a functional unit of 1 kWh of electricity. While mitigation efforts, such as co-firing technology, have been implemented, there is still a pressing need for enhanced environmental management policies.

Prediction of Hydropower Plant Electricity Production Dependence on Weather Conditions Using Machine Learning Approach

2025-06-03T10:16:32+08:00

To optimize the hydropower plant operations in the Sulawesi Generation Unit of PLN, this study proposes a data-driven approach to analyze electricity production by incorporating weather data. Utilizing historical data from January 2014 to December 2023, relevant indicators were extracted using machine learning algorithms. The integration of hydropower generation data, dam operational data, temperature, and rainfall enabled the prediction of electricity output through various models, including SARIMAX, Random Forest Regressor, Support Vector Regression, and Extreme Gradient Boosting. The dataset, consisting of 120 rows and 18 variables, demonstrated that combining diverse yet correlated data sources improve prediction accuracy. The best-performing model was validated and applied to forecast on new, unseen data. The findings indicate that machine learning offers a strategic advantage for PLN's decision-making in managing interconnected hydropower operations within the national power grid.

Techno-Economic Analysis of Exhaust Steam Utilization – Ulumbu Geothermal Power Plant Using Organic Rankine Cycle (ORC) with Pentane as Working Fluid

2025-06-10T01:24:29+08:00

Ulumbu Geothermal Field is one of the existing water-dominated geothermal field in Indonesia, high enthalpy (230°C - 240°C) and located on Flores Island, East Nusa Tenggara. PT PLN as developer for Ulumbu Geothermal Field operates an existing geothermal power plant with 4x2,5 MW capacity, utilizing two types of steam turbines: condensing (2x2,5 MW) and back pressure (2x2,5 MW). The exhaust steam from back pressure turbines has a temperature around 98°C - 105°C, with a maximum steam flow rate approximately 62 Tons per hour. Several studies have been conducted by PT PLN for utilization plan of Ulumbu exhaust steam, for direct and indirect use. This research aims to assess the optimum power that can be generated by ORC (Organic Rankine Cycle) plant, regarding the parameters on site, such as thermodynamics of exhaust steam, ambient temperature, and water availability. ORC (Organic Rankine Cycle) system used in this research is ORC (Organic Rankine Cycle) with Pre-Heater, Evaporator, Expander, Condenser and Pump. Using pentane as working fluid and ASPEN HYSYS for simulation, this ORC (Organic Rankine Cycle) can generate about 2.77 MW, with 9.38 % thermal efficiency. The development cost for this project approximately 9.9 million USD, with IRR Value of 13.97%, dan NPV of 2.86 million USD, if the electricity is sold at 11.71 cent/kWh for first 10 years and 9.96 cent for next 15 years, regarding to Indonesian Government tariffs for Nusa Tenggara.

Encouraging Geothermal Investment in Indonesia: Evaluating Government Strategies to Address Exploration Risks and Comparative Insights from Successful Countries

2025-05-30T14:48:23+08:00

Exploration is the most expensive and high-risk phase in the geothermal development chain. This condition has resulted in low private sector participation, particularly during the early stages of development. This study aims to evaluate the Indonesian government's policy strategies to address geothermal exploration risks and conduct a comparative analysis with successful approaches implemented in Kenya, the Philippines, and Turkey. Using a qualitative-descriptive method, the study draws on policy literature and actual exploration data to examine regulatory frameworks, fiscal incentives, and public risk-sharing mechanisms. The findings reveal that while Indonesia has initiated exploration through government agencies such as Center for Mineral, Coal, and Geothermal Resources “PSDMBP” and offers fiscal incentives and risk guarantees (via Geothermal Risk Mitigation Facility “GRMF” and PT Penjaminan Infrastruktur Indonesia “PII”), the implementation still faces major challenges, including limited budget, weak inter-agency coordination, bureaucratic inefficiencies, and restricted access to geoscientific data. In contrast, exploration models in Kenya (public exploration via Geothermal Development Company “GDC”), the Philippines (Build-Operate-Transfer “BOT” scheme with feed-in tariffs), and Turkey (cost-sharing with the private sector) show more integrated and investor-friendly approaches. This study concludes with strategic recommendations, including the establishment of a state-owned exploration company, improved data transparency, regulatory reforms, and the implementation of output-based fiscal incentives to enhance geothermal investment attractiveness in Indonesia.

Characterizing the Two-Phase Geothermal System of the Ulumbu Field Through Updated Data and Numerical Reservoir Modeling to Support Capacity Expansion Planning

2025-06-01T22:11:10+08:00

The Ulumbu geothermal field in Flores, Indonesia, exhibits a two-phase system characterized by steam-dominated conditions at shallow depths and liquid-dominated conditions at greater depths. An existing facility currently generates 4 × 2.5 MW, with a planned expansion of 2 × 20 MW as outlined in the 2021–2030 RUPTL. However, uncertainties concerning subsurface structure, heterogeneous permeability, and long-term reservoir sustainability necessitate a comprehensive re-evaluation. Earlier studies relied on exploratory conceptual models with limited geoscientific data. The studies introduced the first natural state model using TOUGH2, confirming the presence of a steam cap overlying a liquid-dominated zone.

This study presents an updated and integrated conceptual and numerical model of the Ulumbu geothermal system based on recent geoscientific, geophysical, and well data. Numerical simulation was conducted using the Volsung simulator to improve natural state representation and inform future development. A potential upflow zone is identified beneath the Lungar area, directly connected to the heat source and underlying a steam-supplying two-phase zone. The model achieves calibration with well data, reproducing key reservoir characteristics: a ~600 m thick steam cap (saturation 0.6–0.7, ~260°C), a ~200 m thick boiling zone (~290°C), and a deeper liquid-dominated reservoir (~300°C) below –1000 m asl. While this study successfully reconstructs the natural state of the system, future production simulations are still required to confirm long-term deliverability and the feasibility of 2 × 20 MW expansion.

Techno-Economic Optimization of Hydrogen-Based Hybrid Power System for Semau Island

2025-05-19T18:02:37+08:00

Island regions such as Semau Island, East Nusa Tenggara, face significant challenges in providing reliable, clean, and sustainable energy. Diesel Generator (DG)-based systems remain dominant but generate high emissions and lack energy storage components. This study analyzes the technical and economic performance of three Hybrid Renewable Energy System (HRES) scenarios: (1) DG–PV–BESS, (2) DG–PV–HESS, and (3) PV–BESS–HESS, using HOMER Pro simulation

The first scenario yields the lowest Levelized Cost of Energy (LCOE) at 0,159 USD/kWh, but with the highest CO₂ emissions at 584.862 kg/year and B40 fuel consumption of 225.777 L/year. The second scenario offers an Internal Rate of Return (IRR) of 29%, a payback period of 4,1 years, an LCOE of 0,217 USD/kWh, and CO₂ emissions of 540.715 kg/year. The third scenario, which is fully renewable, results in an LCOE of 0,213 USD/kWh, zero emissions, a renewable fraction of 100%, and the lowest Levelized Cost of Hydrogen (LCOH) at 8,34 USD/kg.

Hydrogen integration has proven to reduce battery usage (minimizing potential chemical waste), extend battery lifespan, and improve overall system sustainability. This study supports the adoption of hydrogen-based HRES as an efficient, reliable, and environmentally friendly clean energy transition solution for island communities.

Promotion Planning for Power Capacity Upgrade During Low-Demand Periods Based on Classical Forecasting and Material Stock Evaluation

2025-05-30T16:52:22+08:00

PT PLN (Persero) routinely implements power capacity upgrade promotions; however, these initiatives are often carried out without sufficient consideration of actual demand conditions and material availability. Such a practice can lead to service delays and inventory imbalances. This study develops a decision-making model to determine the optimal timing for power upgrade promotions based on demand forecasting and the estimated requirement of a key material component—Miniature Circuit Breakers (MCBs). The Additive Holt-Winters method is employed to identify low-demand periods, while the uplift forecasting approach serves as a conceptual reference for evaluating potential demand increases. Material requirement estimation serves as a foundation for assessing alignment with available stock levels. This model is expected to support PLN in planning efficient, data-driven promotions aligned with operational constraints.

Biomass Supply Chain in the Co-firing Process of Coal Power Plant (Case Study: PLTU Indramayu)

2025-05-30T14:57:22+08:00

This study investigates the potential of biomass utilization in the co-firing process at the Indramayu coal-fired power plant (PLTU) to enhance energy sustainability. Biomass sources such as rice husks and wood shavings were analyzed for their impact on power generation, emissions, and supply logistics. Operational performance was modeled using Aspen Plus, while Lingo was used to optimize the biomass supply chain. The findings reveal that biomass suppliers near PLTU Indramayu currently provide only 4,330 tons/month, falling short of the 14,070 tons/month needed for 5% co-firing resulting in a 9,740-ton deficit. Aspen Plus simulations show that co-firing up to 5% biomass maintains thermal efficiency and emission compliance, while significantly reducing CO₂, SO₂, and NOₓ emissions, making it both technically and environmentally viable. A supply chain optimization model estimates a minimum procurement cost of IDR 936.66 billion, considering supplier location, transport, and production capacity. To close the biomass gap, the report recommends developing Energy Plantation Forests (HTE), requiring around 2,338 hectares. Two potential land areas (1,400–1,600 ha each) have been identified to meet this need.

Optimization Strategy for Power Plant Asset Management Using Reliability Analysis and Life Cycle Cost: Case Study of Steam-Dominated Geothermal Power Plant Unit 1 at PT RST

2025-05-19T23:05:46+08:00

PT RST is one of the largest power generation companies in Southeast Asia, with a total capacity of 21.08 GW. One of its units, the Steam-Dominated Geothermal Power Plant Unit 1, has been operating for over 40 years, presenting increasing challenges in maintaining reliability and cost efficiency. The aging condition of critical equipment in this facility necessitates a strategic asset management approach to support informed decision-making in maintenance and replacement planning.

This study integrates reliability analysis with economic life assessment to develop an optimized strategy for equipment replacement. The Equivalent Uniform Annual Cost (EUAC) is used to determine the most economical service life of each equipment unit, while the reliability index is calculated using a Weibull-based Non-Homogeneous Poisson Process (NHPP) model via AeROS software. Key input variables include equipment failure history, repair time, downtime, acquisition cost, and operation and maintenance (O&M) costs.

By combining cost and reliability indicators, a structured equipment replacement strategy is formulated, classifying assets into four categories: retain, prepare for replacement, immediate analysis required, and further evaluation. This integrated approach supports data-driven asset management decisions and contributes to improved performance and reduced electricity production costs at Steam-Dominated Geothermal Power Plant Unit 1

Numerical Modelling of Gaussian Femtosecond Laser Pulse Propagation

2025-06-13T09:53:45+08:00

Ultrashort laser is a powerful tool that has found its use in various fields such as nanotechnology manufacturing. Its ultrashort burst of light generation combined with high peak power allows clean cutting, etching, and modification of nanomaterials with little remnants. The need for numerical modelling of ultrashort laser becomes a priority to accelerate development in research. The Finite Difference Time Domain and the Perfectly Matched Layer are used to simulate a propagating ultrashort Gaussian beam targeting the focal point. This results in the availability of information in given space and time. The results yield good accuracy and can serve as a baseline for continuous research in the subject.

Hazard And Operability Study for Determining Safety Integrity Level on Surface Above Ground System and Unit 1 And Unit 2 Geothermal Power Plant in Ulumbu Field

2025-06-13T17:29:04+08:00

This study applies the Hazard and Operability (HAZOP) method to identify potential process risks and determine the Safety Integrity Level (SIL) of the Surface Above Ground System (SAGS) and Units 1 and 2 at the Ulumbu Geothermal Power Plant. Using process documentation, maintenance records, and operational data from 2020–2024, eight critical nodes were analyzed. Risk was evaluated using a matrix based on severity and likelihood, with failure probabilities derived from Mean Time to Failure (MTTF) and the OREDA database. The SIL assessment was conducted in accordance with IEC 61511. Results showed that most nodes operated under SIL 2, indicating a generally adequate safety system. However, several nodes—particularly those in the demister and lube oil systems—fell under SIL 1, suggesting the need for improvement. The study recommends additional shutdown valves to enhance protective functions, particularly in scenarios involving rupture disks. Overall, the findings provide insights into system vulnerabilities and support recommendations for improving the safety integrity of geothermal plant operations.

Reliability Enhancement of Power Transmission Under Sulfuric Corrosive Conditions - Case Study at Geodipa Dieng Geothermal Plant

2025-06-10T02:50:28+08:00

The Dieng Geothermal Power Plant (PLTP), operated by Geodipa Energi, plays a strategic role in supporting Indonesia’s transition toward renewable energy. The 150 kV Dieng Substation is responsible for transmitting electrical energy from the PLTP to the national grid. However, recent inspections have revealed corrosion-related damage to several transmission equipment units, including substation components and 150 kV overhead lines (SUTT), likely caused by exposure to sulfur compounds emitted from geothermal activity. Such corrosion poses a serious threat to the operational reliability and service life of transmission infrastructure. This study employs a failure analysis and risk-based approach to investigate the corrosion mechanisms affecting transmission assets. The methodology includes material identification and a series of diagnostic tests such as visual inspection using a stereo microscope, Optical Emission Spectroscopy (OES), hardness testing, tensile strength evaluation, metallographic analysis, and Energy Dispersive Spectroscopy (EDS). These analyses are used to determine the extent of degradation, assess the impact on equipment performance, and formulate mitigation strategies. Risk-based recommendations are developed to enhance system reliability under corrosive geothermal environmental conditions. The results of this study provide a comprehensive framework that can be used as a reference for corrosion management in geothermal-based transmission systems or other high-corrosion zones in Indonesia.

Evaluation of Environmental Impact and Social Return on Investment (SROI) from Fly Ash Utilization as Fertilizer at PT PLN Nusantara Power UPK Tarahan

2025-05-30T17:10:43+08:00

This study evaluates the environmental, social, and economic impacts of utilizing fly ash in organic fertilizer production. As part of Corporate Social Responsibility (CSR) program at PT PLN Nusantara Power UP Tarahan. Fly ash, by-product of coal combustion, is used to enhance soil quality while reducing industrial waste. This study employed mixed-methods research design to assess plant growth, soil quality, and community-level outcomes. The quantitative methods (field experiments and laboratory testing), followed by statistical analysis using one way ANOVA and Fisher’s LSD test. Qualitative methods, including surveys and interviews, were used. The incorporation of 10% fly ash into organic fertilizer significantly improved soil nutrients and plant growth. Soil nitrogen content increased to 0.70%, available phosphorus rose to 363.50 ppm, potassium (K₂O) reached 394.85 mg/100g, and the Cation Exchange Capacity (CEC) improved to 24.05 cmol/kg. Environmental valuation indicated notable savings from reduced waste disposal and pollution prevention. The Social Return on Investment (SROI) ratio exceeded 1. This is indicating that every unit of investment generated greater value in social and environmental benefits. These findings support the financial viability and long-term sustainability of the program, emphasizing its positive impact on both the environment and local communities.

Technical Feasibility Analysis of Sawdust as Co-firing Fuel at Labuhan Angin Steam Power Plant

2025-05-30T17:07:32+08:00

This study aims to analyze the technical feasibility of using sawdust as co-firing fuel in the Labuhan Angin Steam Power Plant (PLTU). The main focus is on the physical and chemical characteristics of sawdust and its impact on the performance of the power plant. This study is non-experimental and uses secondary data obtained from the operational trial report of sawdust co-firing documented in the company's internal technical report. The analysis was carried out through daily operational data, including coal consumption, electrical load, furnace temperature, and Specific Fuel Consumption (SFC) measurements. The results show that the addition of sawdust up to 5% does not reduce the stability of the power plant operation. Coal consumption decreased as the percentage of sawdust increased, without sacrificing electrical power output, which remained stable in the range of 65–68 MW. The furnace temperature also remained stable, even at a mixture of 5% showing higher stability than other mixtures. Although SFC increased slightly in the sawdust mixture, the system efficiency was maintained well. This is due to the characteristics of sawdust which is flammable and produces cleaner emissions, although its calorific value is lower than coal. This study concludes that sawdust has the technical feasibility to be used as a co-firing material up to 5% without disrupting the performance of the generator. However, adjustments are needed to the feeding system and combustion control for optimization. These results strengthen the potential of sawdust as an alternative environmentally friendly energy in the energy transition towards more sustainable generation.

Techno-Economic Study of Floating Solar Power Plant on Singkarak Lake, Indonesia

2025-05-21T17:52:23+08:00

The planning and development of solar power plants is one of the renewable energy and government’s key initiatives to support Indonesia’s national vision of achieving Net Zero Emissions by 2060. To optimize the implementation of the floating PV project at Lake Singkarak, West Sumatra, three scenarios with different planned capacities were proposed: Scenario 1 with 92 MW, Scenario 2 with 184 MW, and Scenario 3 with 276 MW of installed floating PV capacity. A comprehensive techno-economic study was conducted to analyze these three scenarios. The analysis concluded that Scenario 2 is the most optimal, achieving a Levelized Cost of Electrical (LCoE) of 825,47 IDR/kWh, and maintaining system stability with a frequency of 49,3 Hz during simulations involving sudden weather changes that caused a temporary loss of electricity generation from the floating PV system.

Evaluation System Co-firing Coal and Biomass Woodchip in Coal-Fired Power Plant Punagaya

2025-05-19T17:24:06+08:00

This study evaluates the co-firing system at the PLTU Punagaya Unit 1. The primary focus of this study is to evaluate fuel characteristics, specific fuel consumption (SFC), and exhaust gas emissions when the biomass percentage is 5%. Literature review and analysis of operational data from the power plant and laboratory test results were used to evaluate the feasibility of using biomass woodchip. The study results indicate that biomass woodchip, which has a lower calorific value and higher moisture content, affects combustion stability and specific fuel consumption (SFC). However, biomass woodchip can still be used without significant performance degradation with optimal combustion settings. Additionally, there is a significant reduction in SO₂ and NOx emissions, supporting environmental sustainability targets. This study's findings on the use of biomass woodchip at the PLTU Punagaya can continue to be utilized. However, further studies are needed on biomass pretreatment methods and blending with other biomass types to reduce the potential for slagging and fouling. This research supports Indonesia's carbon emission reduction policy in the energy sector through renewable energy.

Supplier Selection and Order Allocation Based on Multi-Criteria Decision-Making Using AHP, Fuzzy TOPSIS, and Multi-Choice Goal Programming to Improve Local Content (TKDN)

2025-05-30T17:05:05+08:00

PT PLN Pusharlis menghadapi tantangan dalam pemilihan dan alokasi pemasok untuk komponen Control Board yang digunakan di Stasiun Pengisian Kendaraan Listrik Umum (SPKLU). Pemilihan pemasok yang tidak tepat dan alokasi pesanan yang tidak efisien dapat mengakibatkan keterlambatan pengadaan dan peningkatan biaya operasional. Penelitian ini bertujuan untuk mengembangkan model pengambilan keputusan terintegrasi yang memfasilitasi pemilihan pemasok yang paling sesuai dan alokasi pesanan yang optimal berdasarkan permintaan yang diproyeksikan. Tahap awal melibatkan peramalan permintaan Control Board menggunakan metode ARIMA. Proses pemilihan pemasok dan alokasi pesanan kemudian mengadopsi kerangka kerja pengambilan keputusan multikriteria. Analytical Hierarchy Process (AHP) diterapkan untuk menentukan bobot setiap kriteria, pemasok diperingkat menggunakan Fuzzy Technique for Order Preference by Similarity to Ideal Solution (Fuzzy TOPSIS), dan alokasi pesanan akhir dioptimalkan melalui Multi-Choice Goal Programming (MCGP). Kriteria evaluasi meliputi kinerja ekonomi, kepatuhan etika, dampak lingkungan, dan Persyaratan Kandungan Dalam Negeri (TKDN). Berbeda dengan pendekatan konvensional, kriteria TKDN dalam kajian ini dikembangkan sebagai indeks multiatribut, yang tidak hanya mencakup persentase bahan baku dalam negeri tetapi juga proses produksi lokal, pemanfaatan tenaga kerja, dan adopsi teknologi. Model yang diusulkan diharapkan dapat mendukung operasi SPKLU yang lebih akurat dan berkelanjutan.

Kata Kunci: ARIMA, AHP, Fuzzy TOPSIS, Multi-Choice Goal Programming, SPKLU, peramalan

Preliminary Techno-Economic Study Of Biodiesel Production From Black Soldier Fly Larvae Cultivated On Marine Biowaste

2025-06-05T11:00:09+08:00

Global energy security and greenhouse gas (GHG) emissions have become critical concerns worldwide, with the demand for conventional fossil fuels rising significantly. PT. XYZ, an electricity producer with a net capacity of 4 × 660 MW, generates approximately 110 tons of marine biowaste annually, posing waste management challenges. The delicate biowaste generated during electricity production will be processed as feed for Black Soldier Fly Larvae (BSFL), which will subsequently be converted into fatty oil for biodiesel production. BSFL are selected for waste handling due to their high efficiency in decomposing organic matter, producing a uniform feedstock suitable for biochemical conversion which have high free fatty acid content that promising to be biodiesel production process resources. Biodiesel production with 94% purity using acid catalyst and non-catalyst, super critical process is used as base model in simulation, resulting in the optimum temperature, pressure, alcohol: fatty oil molar ratio and economical feed rate for each process respectively is 100°C & 260°C, 0,6 MPa & 19,5 MPa, 8:1 & 10:1 and 400 kg/h & 300 kg/h. Broader, integrated biowaste treatment system, enabling higher feedstock availability, enhanced biodiesel production capacity as a important step into green energy transition while also addressing the waste issue.