HOT|COOL NO. 6/2024 "ENERGY STORAGE"

WASTE HEAT — THE OVERLOOKED RESOURCE WAITING TO BE HARNESSED

By Oddgeir Gudmundsson, Director, Climate Solutions, Danfoss A/S, Nordborg

Jan Eric Thorsen, Director, Climate Solutions, Danfoss A/S, Nordborg

In an era of energy innovation, it’s almost paradoxical that vast amounts of heat generated by urban infrastructure and industrial processes continue to go to waste. Supermarkets, data centers, large office buildings, subway stations, and even wastewater treatment plants constantly release valuable thermal energy into the atmosphere. Yet, despite the growing focus on sustainability, this untapped heat escapes largely unnoticed, dissipating into the air.

But let’s think about them!

Given the variety and sheer scale of waste heat sources surrounding us, a simple question arises: Why aren’t we capturing and repurposing this abundant energy resource? The potential is enormous, and the energy efficiency and sustainability benefits are equally compelling. The challenge now lies in recognizing waste heat as the asset it truly is and turning it into a cornerstone of our energy systems. Why do we not capture the abundantly available waste heat and use it for something useful? The answer to that question can vary depending on whom is being asked, but in many cases, the answer will be in the following directions: A. It is not economical compared to using normal high-quality energy carriers, such as natural gas, coal, electricity, etc. B. Waste heat recovery is not our business. C. Once we have modernized our processes there will be so little waste heat that it is not worth capturing it. D. There are no options to deliver it to anyone who can use it. E. It is too complicated to capture it! F. No need; decarbonized electricity is just around the corner... Of course, there can be some merit in some of the answers, particularly if basing it on the past and turning a blind eye to the future.

A) It is not economical compared to using normal high-quality energy carriers, such as natural gas, coal, electricity, etc. Clearly, this would represent a closed and ignorant mindset, as those readily available fossil fuels are not a long-term viable option. It would even be simple to argue that if their real cost to society were included, they would not have been a viable option for a long, long time. Once decarbonization really takes off, it will become clear that utilizing waste heat sources will become essential for enabling an ecologically and economically sustainable transition of the energy system. B) Waste heat recovery is not our business. The traditional approach is, as the statement indicates, not to bother about the waste heat and treat it as an unavoidable waste product. Historically, there have been no monetary benefits from capturing and reusing the waste heat due to the low cost of primary fuels during the era of fossil fuels, and thus, there was no basis for taking up the business. With the changing energy landscape and phase-out of fossil fuels, the focus on waste heat utilization is obvious. Nonetheless, the primary challenge is intact: waste heat utilization is not

10 HOTCOOL no.6 2024

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