Energy companies Fortum and St1 have started collaboration aimed to build Finland’s first industry-scale pilot heat plant using geothermal energy. The geothermal heat plant is estimated to have a production capacity of up to 40 megawatts of geothermal energy, enough for Fortum to cover up to 10% of the district heat needs in Espoo (270,000 inhabitants). No fuels are used in geothermal heat production, so the plant will not produce any emissions into the atmosphere.
In this case, geothermal energy is produced by drilling two holes several kilometres deep into the ground. Water is fed down one hole, and as the water heats up underground it rises through the other hole. The thermal energy in the heated water is piped through a heat exchanger at the heat plant into the district heat network. The water gets so warm in the process that it can be used directly in district heat production without heat pumps.