TECHNO-ECONOMIC STUDY OF THE APPLICATION OF THE BOTTOM BINARY CYCLE IN A GEOTHERMAL FIELD

• Main Author: Rinus Pratama Putra, Aditya
• Format: Theses
• Language: Indonesia
• Online Access: https://digilib.itb.ac.id/gdl/view/83126
• Institution: Institut Teknologi Bandung

The increasing global energy demand every year has driven the development of renewable energy, such as geothermal energy. Indonesia is known for having 40% of the world's geothermal reserves, equivalent to 28910 MW. However, as of 2023, only 8% or 2284 MW of geothermal power plants are installed in Indonesia. Binary technology is the most applied technology in geothermal power plants, as 203 of 573 installed geothermal power plants worldwide are operated with binary technology. Binary technology is defined as the combination of the geothermal fluid cycle from the production well to the reinjection well and an Organic Rankine Cycle (ORC). The organic working fluid is employed as the fluid that absorbs heat from the geothermal fluid in the ORC. The binary system has only a few numbers of applications in Indonesia. The ORC technology utilizes low enthalpy geothermal fluids or hot brine separated from two-phase geothermal fluid. The observed geothermal field is dominated by water, which contains more brine than steam. This abundance of brine produced in geothermal power plants has the potential to be used as a source of energy to boost electricity production. The goal of this research is to investigate the potential of increased electricity generation from unutilized brine in a geothermal field, by utilizing heat from the brine to vaporize the working fluid in the Organic Rankine Cycle (ORC). This research focuses on selecting organic working fluids and evaluating fundamental process configurations for implementing a bottoming binary cycle in a geothermal power plant. The investigated working fluids are n-pentane and i-pentane. This working fluid was chosen since it is the most commonly used working fluid in Indonesian geothermal power plants. A comparison was also made using n-butane and n-hexane as the alternative working fluid. The configurations studied include the Organic Rankine Cycle (ORC) with and without a recuperator. The research shows that the case that produces the highest net-generation (W-plant) is ORC nbutane with a recuperator (22,05 MW). The IRR and NPV show that the best investment is ORC n-pentane with recuperator (15% dan $ 16.440.118, respectively)