Paris sewers to heat schools, president's palace

* Energy from effluence under Paris to provide heating

* Presidential palace next on list to use technology

By Alexandria Sage

PARIS, April 5 (Reuters Life!) - The Paris sewers -- whose murky labyrinths have been reviled and romanticized through history -- are at the centre of a renewable energy experiment to harness heat for buildings, including the presidential palace.

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 waste water 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.