The last dome-building eruption, in which magma reached the surface and added to the huge mound of lava on the crater floor, was in October 1986. By the end of 1995 direct thermal use of geothermal energy in Germany amounted to an installed thermal power of roughly 323 MWt. Of this sum, approximately 48 MWt are generated in 24 major centralized installations. Small, decentralized earth-coupled heat pumps and groundwater heat pumps are estimated to contribute an additional 285 MWt. This would bring direct thermal use in Germany close to an installed thermal power of 467 MWt.
Final energy is defined as the fraction of primary energy which is supplied to the final consumer.
It is less than the corresponding primary energy because of losses, mainly due to conversion and distribution. The town government of Kokonoe intends to exploit as far as possible the geothermal hot water from these power stations, together with thermal energy from the many hot springs existing in the town, to develop agriculture and tourism, and to improve the living environment. The use of geothermal hot water associated with geothermal power generation started in 1965 when, in response to a request from a local farmer, Kyushu Electric Power Co made hot water from exploration wells available in the Yutsubo area of the town to heat greenhouses. In the beginning, raw geothermal hot water was supplied to users but, because the geothermal hot water contains arsenic, regulations were introduced which stated that all raw geothermal hot water must be reinjected deep into the ground. As a result, since 1974, river water heated by heat exchange from the geothermal fluid is supplied to a large number of users for horticulture, domestic heating and hotel and leisure facilities.