| Abstrak/Abstract |
Ulubelu geothermal power plant (GPP) in Indonesia reinjects 2,577 t/h of brine in one
of its injection well pads with a temperature of 166oC and a pressure of 7.38 bar. Therefore, the
brine still contains considerable waste heat that can be utilized through waste heat recovery
(WHR) techniques. Organic Rankine cycle (ORC) and supercritical carbon dioxide (CO2)
Brayton cycle (SCBC) are technologies that can be used to convert waste heat into electricity.
ORC is already widely used for WHR applications. Meanwhile, SCBC is an emerging
technology with the advantage of using CO2 as the working fluid in a closed-loop system. While
CO2 is inert and non-flammable, supercritical CO2 has very high specific heat and density, so
compact-sized equipment can be used. This study aims to compare the simple ORC, recuperative
ORC, simple SCBC, and recuperative SCBC power cycle configurations for brine WHR at the
Ulubelu GPP based on the technical and economic aspects. The results show that recuperative
ORC produced the highest net output power and thermal efficiency (27,363 kW and 15.96%,
respectively). Meanwhile, recuperative SCBC has the best economic performance with the
lowest CAPEX (1,404 USD/kW-net), the highest NPV (414.7 million USD) and IRR (29%), and
the shortest payback period (4.83 years) |
