The Geothermal Power Plant at Hellisheidi, Iceland

Abstract

The concept of Hellisheiði power plant was to co-generate electricity for power intensive industry and hot water for district heating. The power plant consists of six 45 MWe high pressure and one 33 MWe low pressure turbine generator units and 133 MWt thermal production. The thermal plant is planned to be 400 MWth. Geothermal fluid from production wells is gathered in central separation stations. The geothermal steam is used in six high pressure units. The separated water is flashed again and the low pressure steam is used in the low pressure turbine but the separated water is piped to the thermal plant. The condensers of four high pressure turbines are used to preheat fresh water. The preheated water is fully heated in heat exchangers with separated water and then treated in de-aerators to suit the requirements of the district heating distribution system. Before entering the re-injection wells the separated water is diluted with condensate. Co-generation of electric and thermal power therefore utilized the resource economically. In this paper we give an overview of the process, the design and the layout of the Hellisheiði power plant. The main process design is described, as well as the intended operation for utilizing the geothermal resource optimally.