Paris wants green sources to fuel 30 percent of its energy
needs by 2020 and a new heating project at a primary school is the city’s first
using power from sewers, where temperatures average between 12 and 20 degrees
Celsius (53 to 68 Fahrenheit).
The technology takes advantage of the warm wastewater
flowing into the sewers from showers, dishwashers and washing machines. A steel
plate containing heat-conveying fluid is submerged in the waste and feeds a
heat exchanger pump — in this case located in the school’s cellar — which
circulates heat through an existing network of radiators.
Engineers say the process is safe, non-polluting and — more
importantly, does not smell.
“It’s very modern, intelligent from the point of view of
sustainable energy and it’s really a hallmark of the dynamism of Paris,” said
Paris Mayor Bertrand Delanoe, outside Wattignies school on the city’s
southeastern side.
Paris is not the first place to turn to sewage as a source
of energy — the technology has been used elsewhere in France, as well as in
Norway, Japan and Canada, where it helped heat the 2010 Olympic Village — but
it is one of the most high profile.
Indeed another future beneficiary of sewer-generated heat in
Paris will be none other than President Nicolas Sarkozy, whose Elysee Palace
plans to use its own sewer heat system from mid-2011, a spokeswoman there told
Reuters.
Home in the 19th century to rats, pickpockets, intrepid tour
groups and the odd corpse, the Paris sewers were described by Victor Hugo as “the
conscience” of the teeming city and were immortalized in his epic novel Les
Miserables, as well as in Gaston Leroux’s “The Phantom of the Opera” a few
years later.
Today, the sewers pump 285 million cubic meters of waste
water per year through a vast maze some 2,400 km in length, and tourists still
descend into the city’s bowels to view the system first hand.
The heating technology is not universally applicable,
however, as the harnessed heat can only be used within 200 meters of its source
— making it impractical for city districts lying far away from the sewage
network.
That means that only 10 percent of Paris could be heated
through sewer energy, said Denis Penouel, the city’s head of water and
sanitation.
Another challenge for developers is the big initial cost of
setting up the infrastructure. “It’s a project that consumes a lot of capital,”
said Thierry Franck de Preaumont, president of CPCU, the local heating utility
involved in the project.
The Wattignies school project, which cost 400,000 euros
($568,360), will take care of 70 percent of its heating needs.
Next up are a handful of similar projects at a municipal
swimming pool and a local town hall.
