Study of Potential of Cascade Direct Use to Utilize Exhaust Steam from Back Pressure Turbine at Ulumbu Geothermal Power Plant

Abstract

The Indonesian government has fixated Flores Island for geothermal utilization due to its potential to reach about 776 MW. Of these potentials, one that has been utilized is at PLTP Ulumbu with a 10 MW energy reservation. 2 backpressure units at PLTP Ulumbu generate power 2×2.5 MW. The exhaust on the backpressure unit of the PLTP Ulumbu has an average temperature of 99°C with enthalpy ranging from 2,430 to 2,435 kJ/kg. Instead of releasing the steam to the environment, it would be wiser to utilize the brine’s heat through cascade direct use based on Lindal Diagram. The cascading system will be arranged from high to low temperature to use excessive energy efficiently. The direct use application is selected based on the best potential-for-fit commodities and the energy of the heat source. This paper aims to perform a feasibility study of cascade direct use of geothermal energy that uses an exhaust steam backpressure turbine at Ulumbu geothermal power plant. The Ulumbu area will be transformed as the center of agricultural, stockbreeding, factory, and geothermal tourism. From potential commodities, the four applications selected are coffee bean drying, egg-hatching incubator, brick factory, and new tourism site. Additionally, several preliminary scenarios are available regarding plant development components (e.g., stakeholder and partnership type). Hence, the comprehensive determination of the ‘best scenario’ will be discussed in terms of feasibility and economic attractiveness.