Tapping the sewers - Dutch go down the loo to find new heat source

I once lived in a building where every morning the double flush of the upstairs neighbour's toilet reverberated loudly through our kitchen. Now, instead of being a source of heated neighbourly relations, Dutch sewage waste is seen as a reliable source of heat for millions of homes that the government wants to be unhooked from the country's gas system by 2050.

- Senay Boztas

Lieven de Key, a housing corporation in Amsterdam, is planning what is believed to be the first sewer warmth project that will tap into a main district sewage pipe to warm 1,600 existing social and student homes. After the Dutch words for sewer, riool, and warmth, this sustainable, 24/7, year round heat source is dubbed riothermie.

After some initial scepticism, the company was slowly won round to the idea of urban heating, said the development manager Rienk Postuma. They talked to a company called Liander, which builds underground connections, and to the water board, "and then the idea was born to put water-fuelled heat pumps in the buildings, winning back heat from the collective sewer for this part of Amsterdam".

"We have a photo of the street covered with snow, and the manhole covers all without snow," said Jeroen Rademaker, the project leader. "Warm sewage water flows 24 hours a day and we should capture it. This can happen wherever there is a big sewage pipe."