Comment: Maximising waste heat potential – a regional infrastructure approach – The Engineer


To harness waste heat’s full potential in the UK, a shift towards public-private partnerships and a scale-up in ambition to a regional or national level is essential, says Andy Sloan, managing director, COWI in the UK.

Europe is currently sitting on a goldmine of untapped energy resources. Each year, about 2,860 terawatt-hours per year (TWh/y) of accessible heat is wasted – an amount nearly equal to 90 per cent of the annual heating and hot water needs of the EU27+UK’s residential and service sector buildings. The question is: how can the UK leverage this vast, unused resource effectively?

Historically, the UK has shown it can think big when it comes to heat. The first district heating network in the UK, developed in the 1960s, efficiently harnessed waste heat from Battersea Power Station, benefiting thousands of homes and businesses in Pimlico, London. However, while countries like Denmark accelerated district heating deployment from that point, the UK instead shifted its focus to expanding its gas infrastructure. Today, Denmark connects approximately 65 per cent of its homes to district heating, in stark contrast to the UK’s stagnation at around three per cent, with a not overly ambitious target of achieving 18 per cent by 2050.

Denmark’s approach in recent years exemplifies commitment to sustainability in urban planning. The nation has become increasingly ambitious with district heating schemes, employing long-distance pipelines to transport waste heat from varied sources such as industrial sites and power plants to densely populated areas and significant heat consumers.

Connecting waste heat with heat offtakers

A notable instance of Denmark’s long-distance district heating network is the ‘triangle area’ – a 123km network operated by TVIS, spanning four municipalities. This network, which takes heat from multiple sources, including a power plant and a refinery, efficiently redistributes heat to over 60,000 domestic customers and various industrial sites. Network extensions are made regularly, and approval has just been granted for a 7km extension.

In contrast, the UK has only recently begun to recognise the potential of waste heat. Recent commitments, such as the £65m funding for projects piping waste heat from data centres to over 10,000 homes, signal a growing interest. Yet, there are thousands more opportunities to divert waste heat from being released into the air or sea and put to good use. Nevertheless, fully capitalising on waste heat’s potential requires a paradigm shift from the current zoned approach, which often overlooks economies of scale and the utilisation of heat sources outside designated zones.

Potential in Scotland: Pioneering long-distance heat networks

Scotland’s ambition to connect an additional 650,000 homes to district heating by 2030 provides a unique opportunity. This goal could be met either through larger schemes employing long-distance pipework to harness low- or no-cost waste heat, or by developing numerous smaller systems. There are pros and cons to both approaches however, establishing many smaller sites would be less efficient, more complex, and time-consuming, with limited access to diverse heat sources.

Some view the initial outlay for regional or national heat infrastructure as a barrier, however there is also an enhanced level of certainty to the return. Investors can be certain that the heat load will remain. Cities like Glasgow, with a long-standing demand for heating and hot water, ensure sustained heat load. Furthermore, the burgeoning data centre market, projected to grow five per cent annually until 2028, and the commitment of major players like Microsoft and Google to net-zero objectives, make waste heat off-take partnerships increasingly viable.

Long-distance heat infrastructure’s adaptability to various heat sources helps mitigate the impact of gas price fluctuations. An example is the Port of Esbjerg’s district heating network, transitioning from coal-fired to wind farm-powered heat pumps. Soon, waste heat from the production of green hydrogen at the Port will also supply the network.

Scaling up: Learning from Denmark

The UK, still in the early stages of its district heating journey, stands to benefit from deepening its connection with Denmark. Denmark’s pragmatic approach to district heating focuses on long-term sustainability and efficiency, providing valuable insights for the UK’s energy strategy. Embracing long-distance heat networks, or ‘Heat Highways’, to maximise waste heat usage, Denmark is increasingly future-proofing its heat supply.

To harness waste heat’s full potential in the UK, a shift towards public-private partnerships and a scale-up in ambition to a regional or national level is essential. Such a strategy not only supports the UK’s net-zero goals but also promises a more efficient and cost-effective energy future, leveraging the lessons from Denmark’s experience in district heating.

Andy Sloan, managing director, COWI in the UK

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