MechChem Africa May-June 2023

Excess heat: a greener and safer route out of the energy crisis According to a Danfoss Impact White Paper – Issue 2 – excess heat is the world’s largest untapped energy source. MechChem Africa extracts the highlights.

the combined heat generation of Germany, Poland and Sweden in 2021. If we look only at waste heat sources over 95 °C and within 10 km of existing district heating infrastructure, there is already po tential for 64 TWh. This corresponds to 12% of annually supplied energy in the EU through district heating infrastructure. The potential is also striking when look ing at specific urban areas. Take Essen in the Ruhr district in Germany, for example, where there are approximately 50 industrial sites in surrounding urban areas that produce 11.98 TWh of excess heat per year. This is roughly the amount energy required to heat 1.2-million homes, close to half the house holds in the area. Three industries – cement, chemicals, and steel – account for almost 60% of industrial energy demand worldwide, with emerging and developing economies, particularly in China, accountable for 70 to 90% of these commodities. These heavy industries offer great potential in terms of efficiency since the excess heat from them is at high temperatures and easy to reuse. The industrial sector, therefore, could shift the needle on global energy efficiency by reusing excess heat, and there are multiple ways to do this. Historically, excess heat from the likes of steel and power plants has been more widely reused due to the very high temperatures. But, as technology has evolved, many more sources of excess heat at lower temperatures have become viable. Large cities without industry also have nu merous sources of excess. Take datacentres, for example, which have become the lifeblood of today’s global digital economy, forming the backbone of the flow of information in cities and powering a range of activities from infrastructure and transport to retail and manufacturing. Datacentres are also heavy consumers of electricity. In 2020, datacentres in the EU27 + UK consumed 100 TWh of electricity or around 3.5% of the region’s total electricity demand. According to the IEA, datacentres and data transmission networks now account for nearly 1% of all energy related greenhouse gas emissions worldwide. Conservative esti mates from 2020 counted 1 269 datacentres across the EU2 + UK, producing a total of 95 TWh of accessible excess heat per year. The same goes for supermarkets, an integral

Since 2019, the SuperBrugsen Supermarket in Sonderborg, Denmark has been fully covering its own heating and hot water needs by using the rejected heat from its high temperature CO 2 refrigeration systems.

A pandemic; extreme droughts, floods and heatwaves due to global warm ing; a devastating war in Europe; an energy crisis threatening to push the global economy into recession; and a tragic earthquake in Turkey and Syria. It does seem as though the world is staggering from one crisis to another, says Astrid Mozes, Presi dent Regions for Danfoss in her foreword to a Danfoss Impact White Paper arguing the merits of the untapped potential of reusing excess heat. Cutting off Russian gas supplies has left Europe struggling to find alternatives: firing up old coal-fired power stations and sign ing new nuclear and liquefied natural gas (LNG) leases. “The tragic reality is that these measures delay and complicate the green transition the world so desperately needs,” says Mozes. “There is a readily available, greener, cheaper and safer alternative,” she assures. In the European Union (EU) alone, excess heat, a by-product of most industrial and commer cial processes, amounts to 2 860 TWh/year, almost corresponding to the EU’s total annual energy demand. Excess heat can be reused to supply facto ries with heat and warm water or exported to neighbouring homes and industries. Using it is energy efficiency in its purest form. Even though efficiency measures con stitute the fastest and most cost-effective tool for mitigating the energy crisis, very few initiatives have pushed for better use of the vast amounts of wasted excess heat energy.

Every time an engine or machine runs, it gen erates heat, as does keeping food fresh in cooling displays and freezers; or cooling the thousands of datacentres around the world. This excess heat is currently released into the air without any effort to reuse it. The potential of energy efficiency is stag gering so why are we not already seeing a massive global push for improving efficiency, one that includes the reuse of wasted energy? Accelerating decarbonisation of the industrial sector The industrial sector accounts for 39% of all global energy-related carbon emissions and with its current rate of energy efficiency im provements of 1.0% per annum, the sector in not on track to meet the Net Zero milestones, which require improvements of 3.0%. The structural challenge for factories all over the world is to meet growing production demand while curbing emissions. In addi tion, the current energy crisis has placed the industrial sector under great pressure since the share of energy costs for production has increased significantly. Efficiency progress is slowing in the in dustrial sector. From 2015 to 2020, the rate of improvement in the energy needed to produce each US$ of industrial value dropped from almost 2% per year from 2010-15 to just under 1%. Unharnessed potential in the industrial sector lies in using its excess heat. Excess heat from heavy industrial sites in the EU amounts to over 267 TWh/year. To put that into perspective, this is more than

24 ¦ MechChem Africa • May-June 2023