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Toronto wants buildings to tap into its sewage for heating

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This week:

  • Toronto wants buildings to tap into its sewage for heating
  • Great Lakes ice cover hits a new low
  • A new eye in the sky to track methane

Toronto wants buildings to tap into its sewage for heating

Looking down a deep hole
This borehole at Toronto Western Hospital will allow Noventa Energy to tap into a Toronto sewer main to extract heat from wastewater to heat the hospital. (Noventa Energy)

Many buildings buy and burn gas or other fossil fuels to keep warm. But there’s actually a free, carbon-free source of heat underfoot that they could be tapping into instead — sewage pipes. 

Along with wastewater, those pipes carry a lot of “waste” heat from buildings, including warm water from showers and dishwashers. For example, as I was writing this, it was around 0 C outside the CBC building Toronto, but the water in the nearby sewage pipes was roughly 17 C, according to the city. In most places, that heat is literally going down the drain. But it doesn’t have to be that way.

Heat from wastewater has been providing space heating and hot water to buildings in Vancouver’s Southeast False Creek neighbourhood since 2010. The project is now connected to 4,920 residential suites in 34 buildings, with plans to expand into other neighbourhoods.

Such projects make use of technology like heat pumps. While they can extract heat even from very cold air, they’re most efficient when their heat source already contains a lot of warmth, such as the ground deep below the surface, the depths of a lake — or wastewater.

It’s a source many cities are now trying to tap into, including Moncton, Charlottetown, and Toronto.

Construction on what’s billed as “the world’s largest raw wastewater energy project” is underway at Toronto Western Hospital

When it switches on in June, it’s expected to supply 90 per cent of the campus’s heating and cooling, said Stephen Condie, chief technology officer and head of operations at Noventa Energy Partners, the Toronto company behind the project.

“What that does is it allows us to shut down [gas] boilers at Toronto Western Hospital,” Condie said. That’s expected to cut greenhouse gas emissions by 8,400 tonnes a year, equivalent to removing 1,811 cars from the road. 

By providing cooling in the summer, the system is also expected to save 250,000 cubic metres of water per year (enough to supply 1,087 average Toronto households) that would otherwise be evaporated by the hospital’s chillers.

Right now, across the street from the hospital, a pit as wide as a helipad and about 13 storeys deep is tapping into a large sewer pipe full of heat called the Midtown Interceptor. 

The wastewater will be piped into heat exchangers, transferring the heat to clean water, so it can be extracted by heat pumps. The hot water will then be piped over to the hospital.

Condie estimates that will save the hospital $685,000 a year in utility bills.

The project, funded by Noventa and the Canadian Infrastructure Bank, is the first of its kind in Toronto, the city says. 

It got city staff thinking there might be many similar opportunities around the city, said James Nowlan, the City of Toronto’s executive director of environment and climate. 

“All we [needed] to do is figure out where those opportunities were.”

Whether you can make use of sewage heat depends on the location of the wastewater pipes relative to your building, their size and flow, and the water temperature. It turned out Toronto Water already had that information to help it oversee the wastewater system.

A map of the area near the CBC building with little blue markers showing local sewage resources.
Toronto’s Wastewater Energy Map shows how much energy is in the sewer pipes near you, and how much heating and cooling they could provide. (City of Toronto)

Toronto’s Wastewater Energy Map shows how much energy is in the sewer pipes near you, and how much heating and cooling they could provide. 

So the city used it to create an online Wastewater Energy Map of the city — one that Nowlan believes is the first of its kind in the world.

When you enter an address, it shows you the location of nearby pipes, the amount of flow in them, the water temperature and the available heating and cooling capacities, in megawatts. 

Since the map went quietly online in October 2022, the city has received about 20 inquiries about it from energy companies and engineering consultants working on larger projects that could make use of this kind of energy, Nowlan said. 

“It’s a pretty good indication that there’s interest.”

Emily Chung

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Reader feedback

A number of readers wrote in response to Vivian Luk’s story about China’s clean tech boom.

Kevin Lin wrote:

“I would like to applaud you for presenting a fundamentally positive narrative on China; something that is increasingly rare in Western mainstream media. However, I do feel that the content still contains some subtle negative bias that should be clarified…. While you’ve used a per capita metric here to illustrate China’s above average emission on a global per capita basis, you neglected to put it within the context of other countries such as the United States and Canada, which would show a far worse ratio…. Finally, it’s important to acknowledge when discussing China’s emissions, that China is the largest manufacturing country in the world. That means it is manufacturing goods not just for itself but for other countries to consume. So it would be rather disingenuous to point the finger at a country for its emissions, while at the same time consuming all the products produced by it at your local Walmart.”

Sarah Richardson wrote:

“Thanks for your latest on China’s efforts. In terms of LNG, there’s a paper under peer review that re-examines its footprint when accounting for leakage etc., and it’s not good – comparable to coal if not worse! It already seems to be influencing policy south of the border. Also, I’d love for you to examine what the Canadian equivalent of the US’ Inflation Reduction Act would look like – especially given that it’s the most effective piece of legislation they’ve ever had to tackle climate change. Thanks again!”

For a future issue, we’re interested in your tips to live more sustainably and save money at the same time. Do you have some to share?

Write us at

Have a compelling personal story about climate change you want to share with CBC News? Pitch a First Person column here.

The Big Picture: Great Lakes ice coverage hits new low

A line graph showing the percentage ice cover by month in 2024 and from 1973 to 2023.

Ice cover on the Great Lakes usually peaks in late February or early March. But this year, it bottomed out, grazing 3.46 per cent, on March 3, when the data used in this graphic were downloaded. 

Satellites have kept tabs on the lakes’ iciness for more than 50 years, recording their freeze-ups and thaws. Some years are especially ice-covered. In 1979, for example, more than 94 per cent of the surface of the Great Lakes froze. The highest it reached this year, however, was 16 per cent, the fourth-lowest on record. 

A map of the Great Lakes with red splotches indicating ice cover

Long-term trends show that ice coverage has declined about 25 per cent since 1973, and that the ice season has shortened by 27 days, chipping away at ice fishing, pond hockey and other frosty lake-top diversions.

Warmer air temperatures and the lakes’ “heat memory” — the summer heat they sop up and hang onto — influence winter ice coverage. So, yes, human-caused global warming is at play here. But this year’s strong El Niño likely also worsened the freeze-over.

Hannah Hoag

Hot and bothered: Provocative ideas from around the web

New satellite will track elusive methane pollution from oil and gas industry globally

An animated rendering of a satellite hovering above the Earth. A beam shoots down as it scans for hotspots of methane, a potent greenhouse gas.
This is an image from an animation of MethaneSAT, a satellite designed to hunt for ‘super-emitters’ of the potent greenhouse gas. (MethaneSAT)

A privately funded satellite is set to push methane tracking into a new era, after launching into space this past Monday.

A collaborative mission involving the Environmental Defence Fund, Google, the government of New Zealand and several other partners, MethaneSAT will track methane emissions around the globe in attempts to identify and quantify sources spewing the climate-heating greenhouse gas. 

For 20 years after its release into the atmosphere, methane gas is 80 times more harmful than carbon dioxide in its ability to increase global temperatures. But currently, the scale of methane pollution is unclear.

“We don’t have a really granular picture on the true amount of methane that’s being emitted from individual sectors and sources and exactly where those emissions are coming from,” said Katlyn MacKay, a Canadian scientist with the Environmental Defence Fund. 

“MethaneSAT fills a critical data gap that current missions aren’t capable of.”

MethaneSAT’s mission is focused on methane from oil and gas production and consumption, which is the biggest source of the polluting gas, after agriculture.

The project team estimates the satellite will be able to quantify total regional emissions, globally, and capture and attribute data on individual oil and gas field emission for 80 per cent of global production sites. This builds on current methane-tracking technology that has yet to offer a full picture of the scale and precise origin points of the heat-trapping gas. 

Experts around the world are watching this mission closely, including Jonathan Banks, the Clean Air Task Force’s global director of methane pollution prevention. He says MethaneSAT fills a significant need, as current reporting is “wildly underestimating the amount of emissions.”

Read more about MethaneSAT from Jill English, the international climate producer for CBC News.

Stay in touch!

Thanks for reading. We’ll be taking a short break next week and will be back on March 21. Are there issues you’d like us to cover? Questions you want answered? Do you just want to share a kind word? We’d love to hear from you. Email us at

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Editors: Emily Chung and Hannah Hoag | Logo design: Sködt McNalty

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