The Nesjavellir geothermal field is a high-enthalpy geothermal system within the Hengill area of SW-Iceland. Construction of the geothermal power plant began in 1987 and the first stage of the thermal plant was commissioned in 1990, following an intensive drilling and testing phase in the 1980s. The last 30 MWe turbine generator unit was commissioned in 2005. Mannvit Engineering of Iceland played a leading role in the design & development of the Nesjavellir Geothermal Power Plant, a combined heat and power plant.