A major new project is under way in Paris to provide ecologically clean heating for an entire district by extracting piping hot water from nearly 2km under the earth.
In a revival of the French capital’s geothermal potential, drilling has just begun in the north of the city on a desolate building site sandwiched between the traffic-clogged inner ring road and the Saint-Denis canal.
“In Paris we’re trying to adopt a strategy in which France is largely behind other European countries, because we’ve underinvested in renewable energies,” Paris Deputy Mayor Denis Baupin said.
At the construction site, a 36m yellow mast rises above a dense cluster of machinery that is usually used to drill for oil. Here the drilling is not for black gold but for hot water.
“The lower you go, the hotter the water,” said Michel Galas of CPCU, the urban heating company doing the work, as he stood next to a shaft that, when finished, will delve 1.7km into the earth.
At that depth lies a geological stratum called the Dogger from which water, heated naturally to 57°C, will be sucked up to the surface, where it will be used to heat another stock of water.
This will be pumped to apartment blocks to heat radiators and provide hot water.
“It’s energy that is 100 percent renewable,” Galas said.
The scheme will heat around 12,000 apartments and other buildings due to be built by 2011 in a new residential area in the city’s 19th district. The project will cost 31 million euros (US$40 million), 5 million euros of which will come from the state environment agency and the regional council.
Galas, whose company is jointly owned by the City of Paris and the energy group GDF Suez, pointed to a row of high-rise tower blocks on the other side of the ring road and said they too would eventually be hooked up to the system.
The use of this natural energy source will prevent 14,000 tonnes a year of carbon dioxide being pumped into the capital’s already polluted air.
That is roughly the same amount of carbon dioxide that an average car would belch out if taken on a 470,000km trip, which is longer than the distance from the Earth to the moon.
It will also provide 54 percent of the new area’s energy needs.
Galas said there were around three dozen sites using geothermal energy in the greater Paris region, nearly all dating from the 1970s and 1980s.
“For about 25 years there were no new projects because the price of a barrel of oil had gone down, but in recent years there has been a growing awareness of environmental issues, combined with a hike in the price of oil,” he said.
With the environment placed high on French President Nicolas Sarkozy’s political agenda, and with Baupin and his Green Party as the Socialists’ coalition partners in Paris, the time appeared right to return to geothermal.
Geothermal energy has been used since Roman times to heat buildings. It uses the energy recovered from the heat of the earth’s core and can be seen naturally in the form of volcanoes, geysers and hot springs. Heated water drawn to the surface can, if of sufficiently high temperature, also be used to drive turbines to create electricity.
In Iceland, about a quarter of the country’s electricity comes from geothermal power plants, while geothermal schemes provide heating and hot water for almost nine-tenths of its buildings.