Indonesia's state energy firm PT Pertamina aims to double its geothermal capacity by around 2027-2028, which might cost an estimated $4 billion, as the country tries to reduce its dependency on fossil fuels, executives said on Monday. The Indonesian government is keen to tap into its geothermal resources which have the potential to generate more than 28 gigawatts of power. Energy ministry data shows the country has only reached 2.28 gigawatt of installed capacity as of last year. Developing geothermal energy is part of the government's strategy to increase the proportion of renewables in the country's energy mix to 23% by 2025 from around 12% currently. Indonesia, which is currently among the ten biggest greenhouse gas emitters in the world, also aims to reach net-zero emissions by 2060. Pertamina plans to double its geothermal capacity from around 700 MW currently, chief executive Nicke Widyawati told media during a visit to its Lahendong geothermal fields in North Sulawesi on Monday. To accelerate development, Pertamina plans to build about 210 MW of its targeted additional capacity through investment in a Binary Organic Rankine Cycle (ORC) plant which costs less and can be developed quicker, as it utilises unused brine from existing geothermal wells that is otherwise typically reinjected into the earth. "We found that (by using this technology) the brine could produce enough heat to generate more electricity," she said, maximising output from their current geothermal wells. "2025 is only three years away, if we have to develop by drilling it will take at least five years," she said, referring to the government's timeline on ramping up renewable energy. Pertamina is running a trial of a 500 kW binary generator at its Lahendong field which was developed within a year. The generator would be utilised at other fields, Nicke said. The binary plant typically costs up to $2.5 million per megawatt, she added. Pertamina will also add around 500 MW by developing new wells, which typically cost between $5-7 million per megawatt, said Dannif Danusaputro, chief executive of subsidiary Pertamina Geothermal Energy (PGE). Nicke said Pertamina is open to partnering with investors in its geothermal development. Asked about the initial public offering plan for the PGE unit, she said the process "still ongoing", without sharing further details. A cabinet minister overseeing state companies has previously aimed for an IPO in the second quarter this year. https://www.reuters.com/business/energy/indonesias-pertamina-aims-double-geothermal-capacity-ceo-2022-04-25/