EVALUATION OF ULUMBU GEOTHERMAL DEVELOPMENT DRILLING PLAN OF UNIT 5 (20 MW) THROUGH EXPECTED MONETARY VALUE ANALYSIS

• Main Author: Burhanuddin Aulia Asy'ari, M.
• Format: Theses
• Language: Indonesia
• Subjects: Teknik (Rekayasa, enjinering dan kegiatan berkaitan)
• Online Access: https://digilib.itb.ac.id/gdl/view/87898
• Institution: Institut Teknologi Bandung

This study examines the development of the Ulumbu geothermal field in Flores, Indonesia, managed by PT PLN (Persero) as a renewable energy source. Currently, the field has four operational geothermal power plant units (PLTP) with a total capacity of 10 MW, utilizing steam from the existing well, ULB-2. A feasibility study estimates the field's potential power output at 78.1 MW, a capacity acknowledged in Indonesia’s Ministry of Energy and Mineral Resources’ 2021–2030 Electricity Supply Business Plan (RUPTL). According to RUPTL, there are plans to develop PLTP Units 5 and 6, each with a capacity of 20 MW, bringing the total projected power output from the field to 50 MW. This research focuses on the initial stages of developing PLTP Unit 5 (20 MW), which includes drilling ten wells: five production wells, two contingency wells, and three reinjection wells. The project faces two potential drilling locations: (1) Lungar, which is suspected to hold greater geothermal potential but has not been confirmed through drilling, and (2) Wewo, which already has productive wells. To identify the optimal drilling location, this study employs an Expected Monetary Value (EMV) analysis on two alternative decision trees, considering both the Probability of Success (POS) and financial impact as measured by Net Present Value (NPV). Initial calculations by consultants showed negative EMV values for both alternatives: -6.618 million USD for Wewo and -8.852 million USD for Lungar. Factors potentially influencing these negative results include low electricity sales prices, low well capacity, and high investment costs. Further analysis, taking these factors into account, yielded positive EMV values for both options: 23.34-28.00 million USD for drilling in Lungar first and 29.97-31.96 million USD for drilling in Wewo first. Based on these results, drilling in Wewo is recommended due to its higher EMV value and lower resource uncertainty risk. The study also highlights project challenges and risks, particularly concerning the long-term sustainability of the Wewo reservoir. Pressure and flow rate data from the existing ULB-2 well suggest the potential for a long-term decline in power output capacity. To avoid overestimating well capacity, the production capacity is conservatively estimated at 5 MW per well. With an assumed drilling success rate of 70%, a minimum of five productive wells, along with two contingency wells, would be required to reach the 20 MW target capacity. Additionally, the electricity price used for NPV and economic analysis calculations is thought to be a key factor behind the initial negative EMV results. A higher electricity price assumption could significantly improve the project’s economic viability. Ultimately, this study concludes that the development of PLTP Ulumbu Unit 5 is feasible, with Wewo as the preferred drilling location. This option yields the highest EMV and poses more manageable risks. In addition, considering the possibility of obtaining a larger well capacity, for example 8 MW/well, a higher EMV-2 value of 39.94-44.08 million USD for the development of Unit 5 (20 MW) is produced, indicating that there is a possibility of producing a more profitable project feasibility. This study recommends further studies related to the well drilling POS based on geological risk analysis, including changes to the detailed scenario of the decision tree, optimizing Capital Expenditure with more optimal technology, and conducting further EMV calculations using the Monte Carlo probabilistic method. The EMV analysis and optimal decision tree selection aim to provide a basis for more informed decision-making in the Ulumbu geothermal field's development and similar geothermal projects.