It may seem incredible that an entire hospital can be powered by energy captured from city sewers. But it is happening in Toronto, Ontario, where the world’s largest wastewater energy-transfer project is almost complete and the city is on the path to becoming one of the world’s leaders in water/wastewater energy projects.

Noventa Energy, which is carrying out the project at the 118-year-old Toronto Western Hospital, says the carbon-free thermal energy will supply up to 90% of Western’s heating and cooling needs, while reducing its direct greenhouse gas emissions by about 8,400 metric tonnes each year. That’s equivalent to removing 1,811 cars from the road.