Geneva launches hunt for geothermal sources
The Local · 26 Oct 2015, 22:30
Published: 26 Oct 2015 22:30 GMT+01:00
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The programme is part of the 20-million-franc GEothermie 2020 project launched last year by the Services Industriels de Genève (SIG) to find naturally occurring sources of hot water beneath the earth’s surface.
Heat can be extracted from this water to power electrical power generators or to provide heating.
SIG said that initial tests last year in an eight-kilometre zone between the municipalities of Chancy and Bernex concluded that hot water is available in the Lake Geneva basin in limestone rock at levels less deep than previously thought — as little as 500 metres below ground.
The exploration involves beaming sound waves into the earth to detect, in a manner similar to sonar imaging, where the areas of hot water can be most readily accessed.
The work, which SIG said will have no harmful impact on residents, will continue through November and will then resume next year with more targeted exploration.
Countries such as Germany and Italy have pioneered the use of geothermal energy for power generation.
But currently, no electricity is being generated in Switzerland from geothermal sources, according to the Swiss Federal Office of Energy (SFOE).
“One of the main obstacles to the development of this technology is the fact that very little is known as yet about the local conditions underground,” SFOE says on its website.
The Centre for Hydrology and Geothermics at the University of Neuchâtel says that generating electricity from geothermal energy requires temperatures of around 150C.
In Switzerland that means drilling down 5,000 metres, the centre said.
Individual buildings can be heated through boreholes dug to a depth of 50 to 300 metres with heat exchangers.
SIG said the potential for geothermal energy is high.
It is a source of energy that is “local, clean, renewable and continuously available” with “numerous thermal and electrical applications”.
The canton of Geneva estimates it could, over time, cover two-thirds of its heating needs through geothermal energy.
SIG said developing this form of power is a priority as a way of reducing Geneva’s dependence on fossil fuels and to develop energy independence.
Geothermal energy is already used to heat more than 50,000 buildings in Switzerland, including individual homes, apartment buildings, offices and hotels.
But attempts to develop larger geothermal projects by drilling boreholes into the ground have failed in the cities of Basel and Saint Gallen.
A planned power plant in Basel was scrapped in 2009 after earlier drilling triggered earth tremors.
Saint Gallen also abandoned a geothermal project last year because of concerns about seismic risks.