Design of Hágöngur 100 MWe Geothermal Power Plant in the Highland of Iceland

Abstract

Landsvirkjun is working on preliminary design of a geothermal power plant in the high temperature geothermal area at Köldukvíslarbotnar in the uninhabited wilderness west of the glacier Vatnajökull and Vatnajökull National Park. The name of the power plant is Hágöngur power station and is derived from two distinct mountains which are spectacular and characterize the landscape in the area. The geothermal area is estimated to be up to 41 km2 in size according to resistivity measurements and is about 820 m a.s.l. The framework plan envisages up to 150 MWe power plant. Landsvirkjun is designing in collaboration with the engineering firm EFLA, as a conservative approach, a conventual power plant with two 45 MWe units and 10 MWe ORC unit by use of the separation fluid. Landsvirkjun’s objective is to minimise negative impact of the power plant and rather support the society in the area. The main goal is to incorporate all constructions into the landscape, avoid ascending steam flow and reinject the effluent fluid, to mitigate environmental impact, which is Landsvirkjun's policy for sustainable use of resources. Direct cooling by use of cold water from the river Kaldakvísl, will be implemented instead of cooling towers. To keep the credibility of the prospected project, it has a great importance to be in good collaboration with the authorities concerning road crossing the highland and the board of Vatnajökull National park. A possible approach is to combine staff housing with tourist montain lodging as well as a base for highland rescue team and a gate to the National park. Within the research area, mapping, geological and geophysical research has been conducted, which was the basis for a decision to drill an exploration well in Sveðjuhraun in 2003. In the preparation phase of drilling, the path to Hágöngur area was repaired, Kaldakvísl was bridged, a new road track was built in Sveðjuhraun. Now, two drill sites are in Sveðjuhraun with a research hole on a northern one, and according to Landsvirkjun's plan, it is assumed to deviate the next exploration well on the current drilling site in Sveðjuhraun to the west under the center of the geothermal area. The first exploration well was drilled to a depth of 2360 m in 2003 and was flowtested from 2003 to 2004. It confirmed a useful high temperature area and provided the main parameters for initial reservoir assessment. The well proved a 260-320°C geothermal reservoir from a depth of 700 m to the bottom. The main feed zone is at 930 m and the enthalpy of the flow is about 1100 kJ/kg. However, higher enthalpy fluid can be expected if permeable zones are encountered at greater depth.