The smartest way to reduce our heating costs and emissions is by utilising industrial waste heat and other freely available heat. Harnessing these resources requires embedding excess heat capture into our urban planning – and building heat highways to feed our community heat networks.
Here in the UK, we’re battling an unhealthy, deep-seated addiction to natural gas. Around 85% of our homes rely on gas central heating, making this highly polluting fossil fuel the central pillar of our national energy landscape. But with fuel poverty at crisis levels, net zero approaching, and new legislation phasing out gas boilers, now is the time to chart a more affordable and sustainable path forward.
One option for many homes is to invest a considerable sum in an electric heat pump. However, while this may reduce heating bills in the short term, it merely trades one single energy source for another. And after recent global turmoil, who knows what electricity might cost in five years, let alone ten? At the same time, renewables like solar and wind are growing rapidly, but so are the energy demands of industrial electrification, EV charging, and large-scale data centres. Combine these factors with our ageing, outdated power grid, and it’s clear that renewable electricity will always be a coveted resource..
To eradicate fuel poverty and reach net zero, we need cheap and sustainable heat – combined with infrastructure that enables us to utilise it on a large scale. As Denmark has proven so successfully, combining district heat networks with heat transmission highways can help us kick our gas habit once and for all.
The Rise of District Heating
Across the UK, heat networks are primed for remarkable growth. They currently supply about 3% of our domestic heating, but studies estimate this figure will need to reach up to 60% to achieve net zero. However, factors such as grid constraints, our reliance on natural gas, and our underutilisation of alternative heat sources mean they currently do not (and cannot) supply the cheapest and greenest heat possible.
The answer lies in leveraging the abundant, low-cost waste heat we already produce. The sources can include excess heat from commercial and industrial processes, surplus renewable energy generation, freely available geothermal heat, and surface water heat from our rivers and surrounding oceans. Utilising these sources requires making waste heat capture part of our urban planning and building longrange heat transmission systems, known as heat highways.
Unlocking Our Incredible Waste Heat Potential
Heat highways form the vital link between large heat producers and community heat networks. These underground piping systems can harvest surplus heat from across an entire region and transport it cheaply and efficiently to major population centres. These inter-city heat highways, combined with citywide heat networks, form ‘no regret’ infrastructure that is heat source agnostic and can operate reliably for over 40 years.
And unlike natural gas – around 50% of which we currently import – the UK already has an abundance of waste heat sources. They include power stations, wastewater treatment plants, abattoirs, data centres, industrial bakeries, and many others. Creating synergies with these producers can secure large volumes of clean, low-cost heat while creating sustainable revenue streams for UK businesses.
Maximising Our Renewable Energy Generation
Every year, the UK spends incredible sums curtailing wind farms, which is when they are deliberately shut down due to producing more power than our grid can manage. In fact, from January 2021 to April 2023, the UK spent £1.5 billion to curtail over 6.5 terawatt-hours of wind power. But what if, instead of using taxpayer money to waste clean electricity, we built heat highways to convert it into heated water that can be stored for later use and transported to our homes and businesses when needed?
This approach mimics our existing energy system. The fossil fuels we use today are merely forms of stored energy that have developed naturally over millions of years. To accelerate our transition to renewables, we must strive to utilise every watt of intermittent green energy we produce, which requires storing as much excess as possible. Heat highways directly fill this need, allowing us to cost effectively convert surplus renewable electricity into thermal energy in the form of heated water.
Excess renewable electricity can also be used to power large-scale industrial heat pumps that utilise surface water from rivers and oceans surrounding our cities. One optimal location is Cockenzie in Scotland’s East Lothian district, around 20 kilometres from Edinburgh. This seaside town is home to the substation of a new 1.1-gigawatt offshore wind farm due to begin operation in 2026. By adding an industrial ocean-source heat pump, the site could generate zero-carbon heat using excess wind power that would otherwise go to waste. Combined with a heat highway and large-scale thermal storage, Cockenzie could supply Edinburgh with significant volumes of clean, low-cost heating all year round.
In addition to their decarbonisation benefits, heat highways are fast to build and offer significant economies of scale. These factors are a boon for green city planning, as it’s often simpler to secure funding for large-scale infrastructure than dozens of smaller projects.
Building a Diverse Heating Ecosystem
Aside from industrial waste heat and heat from excess renewable electricity, there are many other heat sources we’ve yet to fully utilise in the UK. These include combined heat and power plants, energy from waste (EfW), and biomass systems, all of which can be significantly cheaper and greener than natural gas.
However, investing in just one asset may only supply heat for 15-20 years, or relying on a single wind turbine may offer the same financial depreciation to an EfW plant. As a result, it’s far more advantageous to invest in larger, energy-agnostic infrastructure like heat highways. These can leverage multiple heat inputs and minimise the depreciation risks of any single asset. Heat highways offer greater flexibility, energy security, and lower costs – making them inherently future-proof.
Connecting multi-source heat transmission systems to new district heat networks can ensure a resilient, low-carbon heat supply that eliminates the need for on-site generation. This is especially important in the UK, with our large stocks of ageing terraced housing. These commercial synergies can unlock longterm heat offtake agreements that financially benefit waste heat producers and heat network operators.
Forming Successful British Heat Utilities
As UK heat networks continue growing in number and size, they are becoming investable assets that can be aggregated into large-scale heat utilities. Much like those that currently provide our electricity, water, and gas, heat utilities are mandated to procure and supply a designated amount of heat to a defined region. They can be instrumental in reducing consumer heating costs while helping the UK achieve net-zero emissions.
Due to volatile electricity prices, it’s essential for heat utilities to maintain supply-side flexibility and avoid relying solely on commercial heat pumps. As a solution, heat highways and large-scale thermal storage can unlock a diverse range of heat sources across an entire region. This approach ensures heat utilities always use the cheapest and greenest heat available, reducing costs and emissions for all network users.
Sustainable Progress with ‘Green Energi Havens’
The UK’s energy transition is also creating opportunities to generate shared community wealth. For example, there’s growing interest in transforming our abandoned industrial sites into vibrant hubs of sustainable energy and innovation, called Green Energi Havens. They can be catalysts of green industrial clustering, using renewable electricity to produce hydrogen and supporting symbiotic industries such as e-fuels, green plastics, carbon-neutral fertilisers, and many others. The waste heat from these hubs can then be captured by heat highways and delivered to local homes and businesses.
Building Green Energi Havens can unlock the full potential of British energy and create circular economies where nothing goes to waste. When located near major cities, these hubs can fuel economic growth, create green jobs, and bolster energy security by reducing our reliance on imported oil and gas.
Emulating Denmark’s Green Heating Blueprint
A country-wide network of affordable and sustainable heating may seem far-fetched, but we don’t need to look very far to see it in action. Denmark has a long and successful history of utilising industrial waste heat, made possible by commercial investments in heat highways. Today, over two-thirds of Danish households are connected to district heating and thousands more join every year.
Denmark’s willingness to utilise various heat sources has been instrumental in growing its heat networks over the last 100 years. For example, many district heating companies have funded network expansions by selling waste heat and electricity from their CHP plants. The Copenhagen metropolitan area now features a green heat grid supplied by four CHP plants, three waste-to-energy facilities, two heat accumulators, and reserve and peak load plants. This innovation has resulted in Denmark paying a fraction of the UK’s heating costs while powering over 75% of its district heating with renewable sources.
Heat Networks: The Future of UK Heating
Natural gas may help keep us warm, but our addiction to this highly polluting fossil fuel has also plunged millions into fuel poverty, stoked international conflicts, and intensified global warming. And while there are sources of waste and surplus heat all around us, we need smart investments in future-proof infrastructure to bring this sustainable vision to life.
The answer lies in expanding our district heat networks, building heat highways, and developing largescale heat utilities that leverage a diverse range of heat sources. By channelling our British innovation, UK heating won’t just thrive – it can become the greenest and most affordable in the world.