| Keywords |
Life Cycle Analysis, environmental protection, Global Warming Potential, Acidification, Land Use, Water Footprint, emission reduction, environmental impact, hotspots |
| Abstract |
Star Energy Geothermal Darajat II, Limited (SEGD) is located at Darajat geothermal field, Garut, West Java. SEGD operates steam field and two power plants (Unit II and Unit III) with capacity of 95 and 121 MW, respectively, and supplies 55 MWe steam to Unit I owned by PT. Indonesia Power. Electricity produced is transmitted to Java-Bali-Madura grid managed by the State Electricity Company to fulfill energy demand for 600 thousand homes or equivalent to 1.7 million people. As part of its commitment on environmental protection, SEGD performed environmental performance assessment through Life Cycle Analysis (LCA) study in 2021. The goals of the study are identifying hot spot(s) for further both environment and product improvement and to update Government of Indonesia’s National Database. The LCA study applied cradle to grave approach within system boundary from drilling activities (Cradle), processing system (Core) such as steam pipes, turbine, generator, transformer, cooling system, gas removal system and cooling tower, to electricity and steam sales meters (Grave). The study also included supporting facilities i.e., condensate reinjection system, office, water & wastewater treatment, and waste disposal facilities. Basis of Functional Unit used in the study was 1 kWh electricity, or 1 ton steam produced. Life Cycle Impact Assessment (LCIA) was done by using SIMAPRO v.9 software, with 76% of the total processed data was primary data. Impact categories and indicators applied referred to ReCiPe 2016Midpoint (H) V1.04 (for Global Warming Potential, Ozone Depletion, Acidification, Land Use, and Water Footprint), CML-IA baseline method V3.06 (for Abiotic Depletion, Eutrophication, and Human Toxicity), and Cumulative Energy Demand (CED) method for evaluating direct and indirect energy use throughout the life cycle of the facility. Based on the potential environmental impact assessment, hotspots in drilling activities (Cradle) such as CED, Land Use, Water Footprint, and abiotic depletion were found to be lower than similar industry average according to GPPs data compiled by Milousi (2018). As for plants operation (Core), the main hotspot was Global Warming Potential dominated by Non-Condensable Gas (CO2, H2S, NH3) release from Cooling Tower. The calculated GWP value (2.55E-02 kg CO2 eq/kWh) that is far below the average power plant emission of 122 g CO2eq / kWh according to data from 85 geothermal power plants in 11 countries compiled in Geothermal Power Generating Plant CO2 Emission Survey by Enel Green Power in 2001 (IGA, 2012). SEGD consistently performs emission reduction initiatives e.g., continuing Clean Development Mechanism (CDM) program, freshwater substitution to condensate for well work and drilling activity, performing energy efficiency program such as ejector motive steam optimization and house load reductions. Hotspot identification through LCA helps the company in prioritizing projects to improve environmental performance and product quality. There is still room for improvement to further refine the LCA quality by increasing primary data quantity for comprehensive representation. Nevertheless, the study has given a good picture on how we run the facilities in a more eco-friendly manner. |