District heating: a hot idea whose time has come

Article published in The Guardian

Look for wasted urban heat and you see it everywhere. Cities worldwide are finally starting to address this with collective methods to stay toasty.

Switching on the central heating, as I did last night, is always tense. Will the radiator valves start leaking? Will the boiler balk at heating my flat as well as my hot water? What’s the cost/benefit difference between raising my gas bill versus investing in more thermal underwear?

But in many cities, it isn’t individuals like myself that have to wrestle with these hot issues – it’s the city itself that does. All round the northern hemisphere, the great switch-on of urban heating systems is happening, as cities that have invested in municipal-scale heating infrastructure fire up their industrial-sized boilers and rise to the annual challenge of keeping their inhabitants warm.

It’s known as district heating: the collective provision of heat to all inhabitants of a city. The use of heat rises in winter and drops in summer, of course. To manage this seasonal demand, some cities invest in infrastructure: they remove the responsibility to buy and maintain boilers from the consumer, and build a system of pipes that snakes under the city, connecting consumers to neighbourhood energy centres and thermal stores.

There are efficiency gains and carbon savings to be won through this arrangement, but it’s a complex process – and how cities keep people warm says a lot about how they perceive the social contract between city and citizen.

The first district heating system was designed within a liberal market framework. In 1877, inventor Birdsill Holly pioneered the sale and distribution of heat in Lockport, New York. Holly recognised that urban life was full of thermal energy, and that you could recover heat from industrial processes and sell it using pipes to connect supply with demand – effectively creating a second saleable commodity. The Soviets were equally interested.

By the 1930s, they had recognised that good urban planning was key to heating cities: new Soviet cities wrought from the wilderness used massive, city-scale networks to channel heat from heavy industry into workers’ homes. Across the former socialist world, huge city-scale heating systems were designed along with national programmes of industrialisation: power-generating facilities and manufacturing plants were sited near the people who worked in them and could consume the energy produced, making it easier to lay pipes to channel waste heat from factories into residential neighbourhoods. Being a worker meant having the right to be warm, and the state built the infrastructure to ensure it.

Nordic cities in Europe also got in on the game, combining a culture of co-operativism with a commitment to reduce dependency on fossil fuels, in part due to concerns over fuel security. Copenhagen, for example, got serious about managing heat in the face of the OPEC fuel crisis of the 1970s. Building on their model of co-operativism, the Danes legislated that urban inhabitants had to connect to city systems for the collective good of minimising waste and cutting national energy imports.

Today, 98% of the city’s heating needs are met through heat networks, and these are now being used to deliver Denmark’s commitment of fossil-free heating and electricity by 2035. The Danish model is celebrated as proof that once cities have pipes installed, they can gradually change what is connected to either end. This could be superefficient, low-energy buildings that don’t need much heat, or carbon-neutral energy sources such as geothermal, or innovations to store “surplus wind” as thermal energy.

Even London got in on the action – at first. As the city was being flattened in the blitz, engineers recognised an opportunity to rebuild a more resource-efficient city by changing the way Londoners heated themselves. Replacing coal fires with cleaner central heating had obvious benefits to health and air quality – but engineers also saw that if this could all be managed at a neighbourhood level, there were other advantages: fuel savings, space savings, less smog, fewer horses in the streets (horses ferried coal into homes and ash out of them), women liberated from the drudgery of keeping hearths stoked and homes warm.

But, although engineering communities were championing district heating in the 1930s and 40s for all those reasons, not many many heat networks made it off plan before the UK discovered natural gas, and starting piping that into homes instead.

The UK, in fact, is fairly unique in not taking heat seriously, as anyone who has shivered their way through winter in a draughty British home can testify. Incredibly, almost half of all energy used in the country is spent making heat, and yet, as an IPSOS Mori opinion poll has shown, over a third of the population describe their homes as cold and damp with the worst conditions in privately rented accommodation. The UK has very few heat networks, having discovered natural gas in the 1960s and focused on a national gas grid instead. Fuel is delivered to homes, and the individual consumer buys a boiler and consumes as much thermal energy as they deem affordable.

One exception is a large district heating network in Pimlico, built in the 1950s and still operating today. It was created to supply 1,600 social housing units with heat produced across the river in Battersea Power Station. The coal-fired plant closed decades ago, and more than the flats have now been sold to private owners. But the heating infrastructure, having proved resilient to fuel-price shocks, has been exempt from this privatisation: the flats may change hands, but the radiators inside are still owned by the state. Thanks to the network, this patch of London emits 8% less CO2 than if everyone was using their own boiler. (Ironically, plans are being discussed to send heat back across the river, as the old power station at Battersea is turned into flats.)

The Pimlico network could in fact be a model for the future. Now that Britain is running low on gas, and with rising concerns over the power of energy companies to extract profit rather than take energy conservation seriously, the “individual boiler” system is being rethought. London, for example, is attempting to reduce its reliance on national infrastructure. By 2025 it aims to supply 25% of the city’s energy through decentralised energy sources, like local heat networks.

This transition is being managed in line with the UK’s liberal market philosophy: heat networks can help turn a waste stream into a revenue stream. Indeed, if you start looking for wasted heat in the city, you see it everywhere: the industrial facilities sited near rivers and seas so they can dump heat into the water; the processing centres that get so hot they need constant chilling; even the shower water that spends seconds running over your body and then takes all that thermal energy down the drain. Innovators, entrepreneurs and policymakers all see better management of heat as an opportunity. London has gone so far as to produce a heat map to help connect potential sources of energy with consumers.

Many cities have come up with creative responses to the heat problem. Paris has the enviable position of sitting atop a geothermal aquifer, which is being used to supply heat networks. Oslo has recently added a giant heat pump to its district heating network: similar to a fridge running in reverse, the pump lowers the temperature of nearby fjord water and raises the temperature of the water circulating in the city’s heat network.

Other cities are less well-endowed naturally, but have some impressive manufactured sources. London’s tube, for example, vents a steady supply of 25оC heat all year, and this will soon be used to warm some of the capital’s homes. New neighbourhoods can get creative with locally specific resources, like the eco-district in Turkey which will be heated by pistachio shells. And of course one city-dweller’s sewage can be another’s hot shower, as Vancouver and Whistler’s Olympic Villages have shown.

Even more heartening is to see that the 1990s push for privatisation is starting to give way to an emerging interest in re-municipalisation. Last year, Berlin brought its water utility back into municipal ownership, and held a referendum on doing the same with its energy supply after almost two decades of private ownership. The yes vote was overwhelming at 83%, but the initiative failed due to low voter turnout.

Hamburg, however, has succeeded where Berlin failed. In 2013 the city bought back its energy grids. This surge in interest means that in Germany, home to two of Europe’s largest energy companies, the distribution networks for electricity, gas and heat are now predominantly owned by municipalities.

And just last week, the UK government launched its £10m Urban Community Energy Fund, which will give grants to community groups who want to take over energy infrastructure in the city. This could mean putting solar panels on the roofs of housing blocks, as social enterprise Repowering London is doing, or developing an anaerobic digester to convert local food waste into green gas and use this to generate heat and power.

Living in an old, central district of London, I don’t have the option this winter to throw out my boiler and connect to a city heat supply. Even if a pipeline does eventually come to my neighbourhood, connecting my old building to it may not be the best energy solution for the city. Community energy, which asks citizens to stop being passive consumers of energy and to start being more actively involved, could be another way forward – to help cities become more self-sufficient and use locally available energy sources, rather than rely on imported fossil fuels. Regardless, whether it is one solution or a patchwork, I’m heartened by the fact that my city has started to question the scale and ownership of infrastructure used to power individual consumption. It’s those questions that are the first step towards a lower-carbon and lower-cost future.