Sunshine, sewage to power cities of the future

LILLE, France (Reuters) - "These are the three giant stomachs of Lille."

Amid the hum of machinery and warm odor of putrefying autumn leaves, official Pierre Hirtzberger is explaining how three giant fermenters can convert household food waste, trimmings from parks and gardens and the slops from school and hospital canteens into enough methane gas to power about a third of the buses in the French city.

"The process is exactly the same as in the stomach of a cow," he said, gesturing toward three biodigesters which each hold 20,000 cubic meters of rotting liquefied waste.

"The objective is to fuel 100 of Lille's buses on this biogas, out of a total fleet of 350," Hirtzberger, head of the city's urban waste research and development, told Reuters.