The use of geothermal resources for electricity generation began in Larderello, Italy, in 1904 with an experimental generator producing 10 kilowatts of electricity (kWe) (Keller & Valduga, 1946). This initial effort led to the establishment of the first commercial unit generating 250 kWe from the geothermal fluids of two wells at 200-250 °C in 1913 (Lund, 2005). For decades, Italy was the only producer of geothermal electricity on an industrial scale until 1958 when New Zealand introduced an 11.2 Megawatts electric (MWe) facility at Wairakei (Stimac et al., 2015), which was also the first to use the "wet" steam (or flash steam) as opposed to dry steam, marking a significant expansion in geothermal energy (Lund, 2005).
After the end of World War II, the geothermal power industry saw a growth rate of 6.2%, and geothermal power plants spread globally during the 1960s. For example, Mexico, the United States, and Russia (the former Soviet Union or USSR) have adopted these energy solutions. In particular, Russia pioneered the world's first binary-cycle power plant in Kamchatka in 1967. Then, other countries including Japan, Iceland, and China joined the league of geothermal power producers by 1970 (Lund, 2005; Pambudi & Ulfa, 2024).
Initially, the geothermal sector mainly relied on steam from high-temperature sources above 150 °C. However, technological advancements allowed for the utilization of lower temperature resources at 90 °C. This was made possible thanks to using organic working fluids instead of water in the organic Rankine cycle process to improve efficiency. These are often integrated into district heating projects, expanding the range and effectiveness of energy applications. However, the optimal and flexible design of such systems under uncertainties of the future energy markets remains challenging (Wieland et al., 2023).
