Incremental Development Strategy of Geothermal Field Using Wellhead Unit Technology: Case Study Ulumbu Geothermal Field

Abstract

Geothermal development in Indonesia is still dominated by the utilization of conventional geothermal power plants with large capacities. Generally, it requires a long time development phase and often experiences delays before an operation. This study aims to provide alternative field development options with an incremental development strategy. This study was conducted to show how a wellhead unit's effective incremental development strategy compared to conventional power plants by applying the probability approach for the Ulumbu geothermal field's case study in East Nusa Tenggara. Besides, this study also provides a comprehensive economic condition of the obtained revenue and project investment costs. Therefore, geothermal power plant development could be more feasible and minimize the barriers in the investment. The methods used in this study is a technical and economic approach, from total project investment cost and the financial return achieved for each development strategy. The technical analysis compares the power plant's specific steam consumption (SSC) and the generated capacity. The total investment is determined for different development strategies of 40 MW (conventional) scenario 2×20 MW, 40 MW (incremental) scenario 8×5 MW, and 40 MW (incremental) scenario 16×2.5 MW using condensing power plant. The economic analysis shows P50 for the investment cost in millions of US$/MW is 5.84, 5.58, and 5.60, respectively. Regarding the tariff-based, which is 80% under Average Cost of Electricity Generation (BPP) of the relevant local grid, P50 for the Rate of Return is 16.85%, 17.33% 17.21%, respectively. Evaluation done by comparing investment cost, economic parameters, tariff variation, and risk assessment, for incremental development scenarios of 8×5 MW and 16×25 MW is feasible as development alternative scenario of Ulumbu field.