Geothermal Emission Accounting and CER Valuation for Carbon Trading: A Technical Case Study at Ulumbu Power Plan

Abstract

This study investigates the potential for carbon trading through the quantification of Certified Emission Reductions (CER) at the Ulumbu Geothermal Power Plant (PLTP Ulumbu). Laboratory analysis of non-condensable gases (NCG) from multiple operational units revealed that carbon dioxide (CO₂) constitutes over 95% of the dry gas content by weight. Using measured NCG flow rates, CO₂ composition, and energy output, annual CO₂ emissions were calculated and compared against Indonesia’s national grid baseline emission factor of 0.833 tCO₂/MWh. The results demonstrate that PLTP Ulumbu emits significantly lower CO₂ levels than conventional fossil-fuel-based grid power generation. Five analyzed units collectively generate over 118,000 tons of CO₂ reduction annually, indicating strong eligibility for CER under clean development mechanisms. These findings support the role of geothermal energy in climate mitigation and carbon market integration. The study also emphasizes the importance of routine emission monitoring to ensure transparency and credibility in carbon accounting. The economic value of these CERs can contribute to improving the financial sustainability of geothermal operations.