Mar 7, 2007, 12:28 GMT
Cologne, Germany - Work began Wednesday on Germany's first large housing estate to be heated by ground-source heat pump (GSHP), a new technology that extracts heat from the soil in winter.
The estate in Cologne is to contain 383 single-family homes and apartments for a further 1,000 people when completed.
Interest is running high in Germany in renewable energy sources with concern growing that the burning of fossil fuels is causing global warming.
In the past, GSHP technology has been used on single homes and office buildings, but housing buyers have avoided it because they regarded it as untested. Christa Thoben, economy minister of North Rhine Westphalia state, said the project made GSHP mainstream.
Drillholes are bored up to 100 metres into the soil and fluid is circulated through pipes to extract the soil heat, which is constant from summer through winter.
This geothermal technology can be used anywhere in the world, unlike deeper wells into superheated rock that are only practicable at places where hot springs are common and the Earth's mantle is very thin.
GAG, the publicly owned company building the 65-million-euro (85- million-dollar) estate on former factory land, said residents would be able to halve their heating bills. The main running cost would be electricity to operate the pumps.
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