There are two geothermal plants in Denmark. One is situated at Thisted and the other on Amager. A third geothermal plant is under construction at Sønderborg.
The geothermal plant at Thisted was commissioned in 1984. This plant utilizes water at a temperature of around 45°C from sandstone layers at a depth of approximately 1,250 m. The hot water is cooled to approximately 12°C through a heat exchanger before being returned to the subsoil. The geothermal plant is connected to the town’s waste-based CHP plant. The geothermal component of the plant can produce the equivalent of the annual heat consumption of approximately 2,000 households.
On Amager, heat production from the geothermal plant that is located adjacent to the Amager power station began in 2005. This plant produces hot water at a temperature of around 73°C from sandstone layers situated at a depth of approximately 2,600 m. The water is cooled in a heat exchanger to approximately 17°C, before being returned to the subsoil. The annual heat production from the hot water in the subsoil is equivalent to the consumption of around 4,600 households.
Two wells are planned to be drilled in the Sønderborg area, which will be used by a new geothermal plant at Sønderborg. The intention is to replace natural gas-based district heating production with geothermal heating. The plant will be established in connection with the existing waste-to-energy CHP plant at Sønderborg. Work is in progress for the startup of geothermal heat production from the new plant some time during 2011.