Swedes Search for Geothermal Energy in Meteorite Crater

ESKILSTUNA, Sweden, December 18, 2000 (ENS) - Sweden will spend at least $777,000 to investigate the possibility that an old meteorite crater contains enough energy to heat the city of Stockholm.

One billion years ago, a meteorite hit the earth on the southern part of the island of Björkö in Lake Mälaren. The crater is 10 kilometres (6.2 miles) in diameter. The impact of a meteorite can cause fragments in the bedrock, resulting in porosity that is up to 10 times greater than normal. In such volume, the rock contains water where the temperature rises 15ºC for every kilometre of depth, which corresponds to an energy potential of 4,000 terrawatts.


Island of Björkö (Photo courtesy Birka)
Scientists estimate that the Björkö structure contains a heat volume which could provide 70 percent of the energy needs to heat the city of Stockholm on a sustainable basis. The crater is situated between eight and 13 kilometres from three of the city's existing district heating power plants: Hässelby, Fittja and Igelsta.

The Swedish National Energy Administration (STEM), following a decision by the Energy Development Board, has granted funding of up to 7,515,000 kroner (US$777,214) to the Björkö Energiprojekt.

The funding will allow a closer study of the structure of the crater and the potential for geothermal energy recovery, as well as the structure's suitability as a heat exchanger. The study involves drilling three exploratory holes in the crater.

"The Björkö energy project entails a not inconsiderable economic risk which the business community is scarcely in a position to take on at this point in time,” says Thomas Korsfeldt, director generation of STEM. “However, the potential of the project is great enough that it justifies taking the risk, especially in light of the Energy Administration's commission to support the transition to a sustainable energy system.”

The project is being conducted under the auspices of the Department of Geodesy & Photogrammetry at the Royal Technical Institute in Stockholm.

The endeavor is headed by a team of researchers from the Royal Technical Institute, Stockholm University and the Scandinavian Water Environment Council.

A critical path of filing reports will allow the project to be abandoned if the results are negative.

"By providing funding, the National Energy Administration can pave the way to an interesting use of energy that is sustainable in the very long term if the results are positive," adds Korsfeldt. "If this phase is successful, I assume that the business community will be willing to take on primary responsibility for continuing the project."

Assistance is being provided by a reference group representatives of Birka Energi, Sydkraft, Svensk Geofysik, the Chalmers Institute of Technology, the Lund Institute of Technology and the Stockholm County Administrative Board.

Studded with more than 1000 islands, Lake Mälaren is a popular resort area. On the shores of the lake are a number of cities, including Stockholm. The Viking city of Birka, the first big town in Sweden, was founded on the island of Björkö in Lake Mälaren. It dates orginally from about A.D. 750 and was abandoned shortly before 1000. Birka is included in the UNESCO list of World Heritage sites.