Using a City’s Excess Heat to Reduce Emissions

Heat from wastewater and sewage now provides about 70 percent of the space heating and hot water for the 43 buildings connected to the network, with the remaining 30 percent coming from natural gas, though the goal is to end that by 2030. The electricity powering the heat pumps is 97 percent zero-carbon, supplied by hydroelectric dams.

“Every time we take a shower, do the dishes or do a load of laundry, the water is still hot when it goes down the drain,” said Ashley St. Clair, Vancouver’s senior renewable energy planner.

“It’s flowing under our streets, and we’re already collecting it through the traditional infrastructure of wastewater pipes, and to be able to tap into that waste heat is really the ultimate circular economy.”

The project came online in 2010, just in time to heat the Olympic Village for the 2010 Winter Games, and it was the first utility-scale sewage waste heat recovery system in North America. Since then, it has expanded, with plans to further scale up to provide space heat for 22 million square feet in the coming decades.

And it cannot come soon enough: This year alone, Vancouver has experienced several bouts of extreme weather, made more likely and intense because of climate change: heat domes, wildfires and catastrophic flooding, which recently cut the city off by road and rail from the rest of Canada. Having its own heat and hot water supply has been an additional benefit of the project, Ms. St. Clair said.

Stockholm, on the other hand, has used a district heat network since the 1950s, according to Erik Rylander, the head of heat recovery for Stockholm Exergi, a heating and cooling company. Much of the city’s heat is already provided by trash incineration and wood waste from Sweden’s extensive forestry industry, but data centers are increasingly becoming part of the energy mix, he said.

Since starting in 2017, Stockholm Data Parks, a collaboration between the city and Exergi, has offered companies different locations to build new data centers and participate in the heat recovery system. The companies are paid for the heat they provide to the network.