One of Landsvirkjun’s guiding principles is the responsible utilisation of the geothermal resource. Geothermal power stations aim to utilise geothermal steam extracted from the geothermal system in the most efficient manner possible. Landsvirkjun owns and operates two geothermal power stations in the Mývatn area: the Krafla and Bjarnarflag Stations.
The safe utilisation of geothermal energy
Electricity is generated by using geothermal heat in high-temperature fields. During the utilisation process, geothermal fluid is extracted from the boreholes, which is composed of steam, water and the various gases present in the steam. Steam is extracted from the fluid via a steam separator and effluent water is then disposed of by re-injecting it back into the geothermal reservoir, releasing it deep into the groundwater stream or releasing it at the surface. Electricity generation is the main service provided by Landsvirkjun but the Company also provides hot water for the local Mývatn nature baths, for local industry and for the local hot water utility in Reykjahlíð.
The operation of geothermal power stations depends on the quality of the geothermal fluid, and many design parameters are entirely dependent upon the chemical composition of the geothermal fluid. The risk of scaling and corrosion is particularly relevant and Landsvirkjun is therefore vigilant in monitoring the geothermal system in the area. The objective is to ensure the safe utilisation of geothermal energy and to minimise any environmental impact. Samples of geothermal fluids are analysed annually to monitor these factors and additional samples are collected more frequently if the need arises.
More information on the results of annual monitoring on groundwater and discharge to surface waters can be found in the chapter on water & soil. More information on gas emissions can be found in the chapter on air quality.
Landsvirkjun provides hot water to the nature baths and industry in the Mývatn area. This is a step towards the more efficient utilisation of the natural resource.
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Overview of the utilisation of geothermal energy for electricity generation
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Electricity generation from Landsvirkjun’s geothermal stations
In 2013, approx. 5,634 thousand tonnes of steam was utilised to generate 500 GWh of electricity. The utilisation process produced 5,190 thousand tonnes of condensate water and separated water and 3,067 thousand tonnes was re-injected back into the geothermal reservoir. The amount of water in geothermal fluid has been stable for the last few years but the amount of steam has decreased. A decrease in the output of the wells is the main reason for this as the enthalpy of the well affects the proportion of water and steam in the geothermal fluid. When enthalpy levels decrease, the energy content of the fluid also lowers and more water is produced.
The re-injection of separated water can support the efficient utilisation of the geothermal system. Re-injection reduces the quantity of contaminating compounds, e.g. heavy metals released into surface waters. Re-injection measures began at Krafla in 2002 and the station began to use more powerful pumping equipment in 2012, subsequently increasing the rate of re-injection (in 2013) when compared to the preceding four years.
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Quantity of steam and water utilised for electricity generation in geothermal power stations
Amount of steam and water utilised for electricity generation 2009-2013 and the quantity of separated water re-injected during this period.
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Research drilling in preparation for potential power projects
Extensive exploration drilling has been completed in the past few years as a result of the proposed geothermal power station projects in the northeast of the country at Krafla, Bjarnarflag and Þeistareykir. Figures for the research drilling carried out at Þeistareykir by the company Þeistareykir ehf are included for the first time this year as the company is now fully owned by Landsvirkjun. There was much less research drilling at the Þeistareykir site in 2013 than in previous years. There were no re-injection measures taken during exploratory drilling but all separated water was channelled away from the area into the lava field to the west of the drilling area, where the groundwater is at a depth of 100 metres.
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Quantity of steam and water released by exploratory drilling/research wells between 2009 and 2013
Research drilling was carried out at Krafla, Bjarnarflag and Þeistareykir.
