One of Landsvirkjun’s guiding principles is the responsible and sustainable utilisation of the geothermal resource. Landsvirkjun owns and operates two geothermal power stations in the Mývatn area, the Krafla and Bjarnarflag Stations.
Landsvirkjun conducts extensive research on the utilisation of geothermal energy in these areas. This includes research on current utilisation, planned utilisation in the Þeistareykir area, potential future utilisation in the Hágöngur and Bjarnarflag area and research pertaining to the expansion of the Krafla Geothermal Station.
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 geothermal system. Steam is extracted from the geothermal fluid via a steam separator and effluent water is then disposed of by releasing it at the surface or by re-injecting it deep into the geothermal reservoir. The Company also provides hot water for the local Mývatn nature baths, for district heating in Reykjahlíð.
Landsvirkjun closely monitors the geothermal systems in the Mývatn area. The aim is to ensure the secure and sustainable utilisation of the geothermal resource and to reduce any environmental impact. Geothermal reservoir models, based on extensive exploration and monitoring data, are developed to describe the condition and status of the geothermal systems. The chemical composition of geothermal fluid is monitored by taking samples on an annual basis and additional samples are collected if the need arises. More information on the annual monitoring of groundwater, the chemical composition of geothermal fluid and the disposal of effluents into surface water can be found in the chapter on Water and Soil. More information on gas emissions can be found in the chapter on Air Quality.
Landsvirkjun provides hot water for the local Mývatn nature baths, for local industry and for district heating in Reykjahlíð as a step towards the more efficient overall utilisation of the natural resource.
Electrical generation from geothermal stations
In 2014, approx. 5,498 thousand tonnes of steam was utilised to generate 484 GWh of electricity.
In 2014, approx. 5,498 thousand tonnes of steam was utilised to generate 484 GWh of electricity. The utilisation process produced 5,667 thousand tonnes of condensate water and separated water and 4,296 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. The amount of water increased by 9% in 2014 whereas the amount of steam decreased slightly by 3% which is similar to that of previous years.
A decrease in the output of wells is generally the main reason for any decrease 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 increased level of water can be attributed to the utilisation of two water-rich reserve wells at Krafla. These were activated as a result of low water levels in Landsvirkjun’s reservoirs in 2014.
More efficient resource utilisation and less environmental impact
In 2014, a gas extraction system was added to Krafla’s operations, increasing the steam efficiency by 5% or 1.5 MW. A steam ejector is used to extract non condensable gases that accumulate in the condenser. Removing non condensable gases improves steam utilisation and the station’s overall power output. A new well was also added to the utilisation.
Improvements to the equipment at the Krafla Geothermal Station resulted in a 5% increase in steam utilisation (1.5 MW).
The re-injection of separated water can support the efficient utilisation of the geothermal system. Re-injection also reduces the quantity of contaminating compounds, e.g. heavy metals released into surface waters. The re-injection (deep) of separated water from Krafla increased significantly in 2014 when compared with previous years. Over 90% of the separated water produced by utilisation is now re-injected.
Utilising natural resources more efficiently
The deep drilling project at Krafla was conducted between 2008 and 2009 by the Icelandic Deep Drilling Project (IDDP). The IDDP is an international research project carried out by national and international parties. The objective is to drill down to reservoirs at super-critical conditions, at a depth of between 4 and 5 km. However, the drilling project came to an abrupt end when magma was penetrated at a depth of 2,100 metres.
The Icelandic deep drilling well is the hottest well in the world and can produce six times more energy than conventional wells.
A decision was made to continue research to investigate the possibility of utilising steam found just above the magma. Research showed that the well could supply 30 MW or six times more than a conventional well. The well is the hottest in the world and steam can reach a temperature of 450°C. The well was shut off in 2012 when the well head failed to withstand the strain created by utilising such high temperature steam. Research continues on the development of equipment appropriate for the utilisation of deep wells (4-5 km) and on super-heated wells which utilise geothermal reserves found just above shallow magma. This type of utilisation presents a number of challenges but the opportunities and benefits from this type of production could be numerous.
The hottest well in the world
Experimentation and research conducted on the deep drilling well at Krafla has revealed new ways of approaching geothermal utilisation. This type of well would allow utilisation at higher temperatures, resulting in more efficiency and less environmental impact.