Nesjavellir geothermal plant generates electricity and hot water by utilizing geothermal water and steam. The plant output is 120 MWe and 300 MWt/1800 litres per second.
Exploration and planning for utilization started as early as 1947 and was continued for two years. A few experimental boreholes were drilled for the evaluation of the exploitable power and the chemical composition of the steam. Following a time of intermission, exploration and research continued with some regularity from 1965 to 1986. The construction of the geothermal power station was commenced in 1987 and the cornerstone was laid in May 1990. Like the rest of the Hengill area, Nesjavellir is popular for recreational activities. Reykjavik Energy has organised the outdoors areas of its land there, marking hiking and riding trails. Archaeological finds and other historical cultural artifacts have been registered, a total of 375 sites at Nesjavellir and Ölfusvatn. Two hikers' shelters, open to everyone, have been built in the Hengill area.