How waste heat can help meet our growing energy demand

There is a great untapped potential in waste heat, says professor Majid Bahrami. Not only could harnessing warm air generated by buildings and industry help create a sustainable energy system, but also a reliable source of revenue.

The future, increasingly, is electric. But the electrification of the transport sector, building heating systems, data centres, along with population growth and economic expansion is precipitating a steep rise in the demand for electrical energy. “At a certain point there will be a capacity issue with the existing electrical grid,” says Majid Bahrami, professor and Canada research chair at the school of mechatronic systems engineering at Simon Fraser University.

Why not maximize what we already have? Society generates enormous amounts of heat, with much of it going to waste. It’s estimated that close to 3,100 thermal terawatt hours of feasible waste heat is currently not being utilized, which could save as much as $200 billion each year.
Bahrami and his team are working to harness waste heat to not only increase overall energy efficiency in buildings, district energy systems, greenhouses and industry, but also lower costs, environmental impact and emissions. (Find out how Canadian startups are also working to tackle this issue in the recent MaRS Tech Trend report.)

Here, Bahrami shares the potential of heat transformers, the latest tech developments and how they could help both communities and industry.

Let’s start at the beginning. Could you walk me through how sorption heat transformers work?

Almost all big industries generate heat to operate and make their products. For the most part, low-grade heat — that’s heat that’s lower than 90 degrees Celsius — is unused. Currently, around 90 percent of global energy use is related to the generation or manipulation of heat, and approximately 60 percent of that is discharged as waste.

The new technology I’m working on can take in that low-grade heat and convert it for cooling or heating purposes. It cycles back in the form of usable energy. The sorption heat transformer can also store waste heat long term with minimal loss — kind of like a thermal battery.

The waste heat can also be used in a district energy network to convert the thermal energy and send it through pipelines to a cluster of buildings to provide either heating or air conditioning without requiring electricity.

Is there an upper or lower temperature requirement for the process to work most efficiently?

Currently, the optimal input temperature range for our sorption heat transformers to generate a cooling effect is between 80 and 90 degrees Celsius. We are, however, actively refining the design to lower this requirement. Our goal is to reduce the necessary input temperature to 70 degrees Celsius or even lower, which would significantly broaden the applications and energy sources that can drive the process.

How could this technology help the industrial sector lower its emissions?

This is a renewable source of energy that can help industry power operations and decarbonize. Waste heat is also a reliable resource. In most industries, waste heat is generated — it’s always there. There’s also a timing issue. If you want a 100 percent clean electric grid, it will take 20 years to upgrade the network at enormous cost. But a company can use the harvested waste thermal energy for its own purposes and surplus could be sent to the local municipality to integrate into their district energy system. This means we can maximize existing infrastructure and resources before expanding the electric grid.

Are some heavy industries better suited to these kinds of generators than others?

Any heavy industry that produces waste heat will benefit from this kind of technology. Unused heat can generate clean energy, heating or cooling, for the industry itself and it could also be transferred to a nearby municipality as a renewable power source and revenue source.

How might this technology benefit municipalities?

Buildings are responsible for most of a city’s greenhouse gas emissions. More than half of Vancouver’s carbon pollution — 54 percent — comes from its buildings because natural gas is the energy source. For a city to reduce its climate footprint, it will have to address building-related emissions.

My team and I are now working with the City of Burnaby in B.C. Metro Vancouver burns 250,000 tonnes of garbage a year. The high-grade heat from burning all this garbage is converted, generating enough electricity to power 16,000 homes. But the waste heat is currently unused — it could produce enough energy to heat the entire City of Burnaby without emitting additional greenhouse gases. The municipality has started building more district energy pipelines that will feed into a cluster of high-rises. In a district energy system, heat can be transferred to a fluid (it’s mostly water), the temperature increased and then sent through the pipes to the high-rises where it is again transferred for heating both water and space. Our sorption heat transformer technology can also be used to convert the heat that district energy delivers for air conditioning. With this method you can reduce the AC cost, decarbonize buildings year-round — provide heat for when it’s cold, cooling when it’s hot using a district energy system. It’s a sustainable energy system and a source of revenue.

So, what are the limitations to deploying this system?

You can only do so much in a university lab. We don’t yet have a commercially available product — only a prototype. Our mission now is to scale up so that we can lower the cost of the heat transformer and make it more efficient.

Technology continues to evolve over time, with components becoming even smaller and more effective. What sectors would benefit from nanotechnology?

At present, our heat transformers use special micro-structured materials designed to improve efficiency, as well as heat exchangers that work more effectively. We intend to make these systems more affordable and improve performance by using more advanced materials and by designing surfaces that work even better to transfer heat and mass.

These next-generation heat exchangers and reactors could offer significant advantages across multiple sectors, such as cooling, energy storage, dehumidification, carbon dioxide capture, atmospheric water harvesting, wearable technologies and even medical devices where efficiency, weight and miniaturization are crucial.

What are the latest developments in this area?

Research efforts in heat transformation are underway globally, especially European and U.S. universities. In Canada, we see increasing interest in pilot projects, particularly in sectors like district energy systems for municipalities and sustainable agricultural applications in greenhouses. Although Europe and other regions may emphasize different research pathways, Canada’s approach aligns well with our strengths in clean energy and sustainable practices, allowing us to leverage international advancements effectively while developing solutions tailored to local needs.

Could energy efficiency measures make this technology obsolete?

No matter how much you reduce energy demand, you’ll always have some demand. The question is, how will you meet it? Energy conversion systems require a larger vision; you need government support and partners in the industrial sector. You need a way of integrating new energy sources into existing networks. But I’m a dreamer.

MaRS Discovery District’s latest Tech Trend report explores the innovative solutions startups and corporate partners are developing to utilize waste streams and lower carbon emissions. Read the full report here.