Residents of a new development project in Ottawa-Gatineau use industrial waste to keep their homes warm — specifically, the wasted heat from the local paper mill, where heat is discarded all around us.

But it doesn't have to be that way; it can be captured to heat buildings in a more efficient and climate-friendly manner.

This is exactly what is happening at the Zibi project along the Ottawa River in Ottawa-Gatineau. So far, 615,000 square feet of residential and office spaces on both sides of the river are heated using wasted heat from the nearby Kruger Products factory in Gatineau, Quebec, and more buildings are under construction.

What using wasted heat for heating looks like

It is something that interests Jay Foubert, who lives on the ninth floor of a 15-story building on the Gatineau side of Zibi. In fact, this is one of the reasons Foubert, an engineer by training who worked in the electric vehicle sector, chose to move into the building two years ago.

He said, "Certainly, that was a big part of my decision; anything you can do to reduce your environmental impact is something I care about."

His tower is part of a district heating system operated by Zibi Community Utility and Hydro Ottawa, a network that allows many buildings to share one heating and cooling system instead of each having separate boilers and chillers.

A network of water pipes distributes the industrial heat generated from heat and hot water; it also provides cooling in summer using Ottawa River water.

Foubert said air conditioning is not very common in apartments in the area, and that the cooling system is "very necessary" as summers get warmer due to climate change.

Foubert controls the temperature in his apartment using a thermostat, like anyone else.

He said, "I find the comfort inside my unit exceptional." "The system is very responsive, very efficient, and very quiet."

He added that his energy bills are similar to what he paid using a traditional heating system in his previous apartment in Ottawa. "So I am very happy with that."

The journey of the heat

The Kruger Products factory makes giant rolls of tissue paper from recycled paper and other fibers that are turned into paper towels and tissues at other factories.

Stefan Lamoureux, Vice President of Operations and Special Projects at Kruger, said the plant burns natural gas to heat water from the Ottawa River to make paper, then to dry the paper.

The wasted heat from this process can be seen as columns of steam rising from the factory chimney on cold winter days. It caught the attention of Scott Demarck, partner with developer Theia Partners.

The company was building a new mixed-use project called Zibi "practically next door," and he recalls thinking: "How can we harness that and bring it here? It is silly to waste it into the atmosphere and burn gas or anything to generate heat."

When Zibi reached out to Kruger about using the wasted heat, Lamoureux said the idea "fits perfectly" with the company's long-term energy reuse strategy.

Engineers from Kruger and Zibi worked together and decided to take heat from a later part of the process. After making the paper, the water, which is between 25 and 30 degrees Celsius, is cooled in a huge "settling tank" from which steam rises before returning to the Ottawa River.

Technicians installed heat exchangers on Kruger's property to transfer some of that heat to the heating network water across the provinces. Demarck explained, "We do not take their water, just the heat." Kruger’s water is discharged into the river cooler than before.

Meanwhile, the heat continues to reach the central heating station of Zibi Community Utility, located on the same street.

At the plant, the heat is processed as needed and directed to different parts of the system, and in winter, the warm water goes to Zibi’s Quebec buildings, which extract heat with their water source heat pumps.

Because electricity is more expensive in Ontario and because more greenhouse gas emissions are produced by gas plants in the province, Zibi heats the water for its Ottawa buildings in advance to 42 degrees Celsius in Quebec, then sends the water to Ontario via pipes installed under Booth Street Bridge. Fans blow heat to individual units as needed.

In summer, the system largely bypasses Kruger, exchanging heat directly with the cold Ottawa River to provide air conditioning.

The system was built with funding from the Federation of Canadian Municipalities, Natural Resources Canada, Hydro Quebec, and Hydro Ottawa, and began operation in 2021, but construction continues, and it is expected to ultimately quintuple its current size to heat a total of four million square feet.

Other options, from nuclear power, steel, waste, and sewage

Capturing heat from industrial processes to heat spaces and water is not common in North America, but Zibi says it is the first of its kind in North America to use post-industrial waste heat recovery in a primarily planned community.

But other parts of the world have been using industrial heat this way for some time. Sweden is famous for supplying its cities with energy and heating through waste-to-energy plants, which dispose of the country’s garbage and generate electricity and district heating.

In Dunkirk, France, the ArcelorMittal steel plant has been providing heat to a hospital, schools, commercial buildings, and public and private housing since 1985. In Haiyang, China, a nuclear plant has provided heating to the entire city since 2020. Now a long-distance district heating pipeline is being built to reach another million residents in more distant places.

Interest is also growing in Canada. Last year, the Quebec government announced $162 million for projects that recover wasted heat for other uses. It noted that industrial facilities, wastewater treatment plants, and other heat producers discharge 300 petajoules of thermal energy annually — about the same amount of heat needed by large buildings and greenhouses across Quebec each year. It stated that each petajoule could instead heat 10,000 homes.

Heat found in wastewater — produced by industry, washing, bathing, and dishwashers — has been used in Vancouver’s district heating system since 2010, which is now expanding. The new system under construction by Toronto-based Noventa Energy Partners at Toronto Western Hospital is expected to be the largest private wastewater energy project in the world. The first phase is due to be completed by June.

Steven Condie, Chief Technology Officer at Noventa, said the project is expected to save the hospital $685,000 annually in energy bills, and is also expected to reduce about 8,400 metric tons of greenhouse gas emissions annually, equivalent to removing 1,811 cars from the road.

Michael Weigen is Director of the Pöltzmann Institute, a Canadian nonprofit conducting and advocating for energy research in communities. He believes these projects are just the beginning.

He recently spoke to the nuclear industry about the possibility of recovering heat from nuclear plants in Canada. For example, it is estimated that the waste heat from the Pickering nuclear station in Ontario could heat the entire city of Toronto.

Similarly, a study conducted by the institute concluded that blast furnaces at steel plants in Hamilton could heat most of the downtown core in that city. Other possible sources of wasted heat could include refineries in Regina, other types of power plants, or even smaller facilities like data centers.

Weigen said, "I now think interest is growing, awareness of the possibilities is growing, and each community has different opportunities."