Local residents took the initiative to utilise the area, but the history of the Þeistareykir project dates back to 1999, when the privately owned company "Þeistareykir ehf" was established. Landsvirkjun acquired 32% of the company in the autumn of 2005, gradually increasing its holdings until it acquired the entire company in the spring of 2010.
Design work began on the project 2011 and extensive preparation measures began three years later. The first turbine unit and associated equipment were purchased in February, 2015. A decision was subsequently made to execute phase two of the project in August of that same year which included the purchase of a second 45 MW turbine unit.
Construction work on the project began in 2015, reaching its peak in 2016/2017 when almost 240 employees worked on-site. The first phase of the project was completed when the first turbine was commissioned at the end of 2017 and phase two was expected to reach completion by the autumn of 2018.
The Þeistareykir geothermal area offers extensive opportunities for geothermal utilisation and has an estimated capacity of anything up to 200 MW. The main goal of the Þeistareykir Project has always been to build a cost-effective and reliable power station working in harmony with its environment.
An abundance of thermal energy is continuously emitted by the Earth’s core. The water cycle transports thermal energy from deep in the Earth’s crust and up to the surface. Energy extraction requires drilling to lengths of approximately 2km into the earth. The geothermal fluid extracted from these wells is a mixture of boiling water and steam and also contains gases and dissolved minerals.
The steam separator separates the steam from the water and the steam is then utilised for energy production. The steam is then transported to the turbine unit which consists of a generator and turbine. The steam drives the blades in the turbine which rotate the generator, thus creating electricity. The condenser cools the steam from the turbine, creating condensate and cooling towers spray the hot condensate from the condenser onto cooling racks where the air cools it. Separated water is re-injected back into the geothermal reservoir where the water cycle continues.
Inhabitants and resources
The first reference to inhabitants in the Þeistareykir area and on the Mælifell Farm can be found in the church inventory of the Múlakirkja Church. The source indicates that the area was inhabited during the 14th and 15th century.
Mælifell was a farm beneath a ‘fell’ with the same name beneath the Lambafjall Mountains in the Middle Ages. The area was abandoned at the end of the 15th century. The area then served as a summer grazing area with outbuildings for the farm Reykir in the Reykjahverfi area. Traces of the farm, summer outbuildings and ruins can be seen to the west of Mælifell.
The Þeistareykir area was probably continuously inhabited during the 16th and 17th centuries. The area was inhabited intermittently during the 18th century and was abandoned in 1873. The Þeistareykir land was utilised until 1955. The farm has been utilised as a summer grazing area for the Aðaldæla & Reykdælahreppur County since 1914 and five thousand sheep graze there during the summer.
There are 58 registered heritage sites on the Þeistareykir land and an outlaying church is believed to have been built in the area during the 14th and 15th centuries, although the location is unknown. The area is considered to be one of the most notable heritage sites in Iceland.
Distinct geological formations
The Þeistareykir area has a very active fumarole area. Hot springs can be found to the north of the Bæjarfjall Mountain, stretching eastward up to Bóndhól and the Ketilfjall Mountain and westward alongside Tjarnarás. Clay pools and solfataras are the most common types found in the area. The geothermal area in Þeistareykir is registered in the Icelandic Nature Conservation Register.
Stóravítisdyngja (Þeistareykjabunga) is one of the largest shield volcanoes in Iceland; approx. 20- 50 km ³. It originates from Stóravíti and Langavíti and the lava area borders with the Gæsafjall Mountains to the south, the Lambafjall Mountains to the west, the Kelduhverfi area to the north and by the Hrútafjall Mountains to the east. The surface are of the lava is approx. 525 km2.
The Þeistareykir lava flowed from the crater in Stórahver and the lava is mostly pahoehoe lava and covers an area of 28 km². The average thickness of the lava is less than 40 m and the volume is approx. 1 km³. The main characteristics of the lava include the so-called rounded hills and a long curved chain of lava formations northward from the crater. The Þeistareykir lava field is the youngest lava field in the area or approx. 2,400 years old. Older lava in the area can be traced back to the end of the Ice Age between10, 000 to 14,000 years ago.
Sulphur mines in the Þeistareykir area
Gun powder production began in Europe in the 14th century. Gun powder and firearms changed European warfare forever. Sulphur is an important raw material of gunpowder. Dutch and English merchants collected sulphur from Iceland but the Danish king eventually took over the sale of all sulphur in 1560. The Danes were involved in an ongoing war with neighbouring countries and we can assume that Icelandic sulphur became one of the foundations of the Danish empire.
Sources reveal that sulphur export was active in the 13th century in Iceland and traces have been found during sulphur cleaning projects in Gásum in Eyjafjörður. Sulphur was also processed in Krýsuvík, on the Reykjanes Peninsula, but the main processing line was in the Þingeyjar Municipality. The Þeistareykir mines were closest to the export harbour in Húsavík but more sulphur- rich mines were found in the Mývatn area; the Hlíðarnámur Mines by the Námafjall Mountain, the Fremrinámur Mines to the east of the Bláfjall Mountain and the Krafla Mines. However, sources also reveal that work procedures were so poor that extraction was hampered by the damage caused to the mines.
The sulphur was processed in Húsavík during the 17th, 18th and 19th centuries and so-called ‘sulphur houses’ were still standing in 1870. Húsavík has been an industrial and export harbour since then.
The sulphur business was not profitable. The dividends from one shipment of sulphur could reach half a billion today but the farmers in the Þingeyjar area received little reward for mining and delivering the sulphur to Húsavík.
Eventually, sulphur mines in Sicily became more popular than the sulphur mines in the rather primitive high temperature areas in Iceland. Sulphur mining was discontinued in Þeistareykir towards the end of the 19th century but attempts were made at selling unprocessed sulphur in the middle of the 20th century. The project was cut short and this marked the end of Iceland’s sulphur trade.