Cost-of-living crisis: How district heating networks in Scotland could speed move to greener living and cut energy bills

It doesn’t look like much right now, but the site of an old coal mine on the outskirts of Edinburgh is about to be transformed into a sustainable new town offering “the best of both worlds” – city life and country living.

It’s also promising a warm glow in the form of cheaper, and greener, energy.

Shawfair, being built near the village of Danderhall in Midlothian, will stretch across 2.7 square miles of land previously occupied by Monktonhall colliery, which closed down in 1998.

The £200 million development will eventually have 4,000 new homes, primary and secondary schools, various shops, bars and restaurants, leisure facilities and office space.

The area is being fitted out with a pioneering district energy network that will harness warmth from a nearby waste disposal plant and use it to provide heating and hot water for buildings in the neighbourhood and beyond.

The initial phase of the network will supply around 3,000 properties in Shawfair town, powered by waste heat from Millerhill Recycling and Energy Recovery Centre.

A large section of the 2.5 miles of pipework has already been laid. But construction, which kicked off earlier this year, has been challenging due to the large number of former mineshafts in the area.

However, these underground workings – once a major contributor to climate change – may eventually be an asset in the journey towards decarbonisation, with the potential for storing energy.

An artist's impression of Shawfair, a new town being built on the site of a former coal mine just outside Edinburgh

Midlothian Energy, a joint venture between Midlothian Council and renewable energy firm Vattenfall Heat UK, is spearheading the scheme.

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The company also plans to create a wider regional heating network stretching into south Edinburgh and East Lothian in years to come. For this they will utilise waste heat from other sources – the abandoned mineshafts in particular.

Heating is the biggest single source of greenhouse gas emissions in Scotland, responsible for 13 per cent of the total. This is primarily down to heavy reliance on fossil fuels – the primary driver of man-made climate change – for generations.

Laying the pipework for the heating network at the Midlothian site has been challenging due to its mining heritage, but the abandoned shafts hold the potential for more green energy. Picture: Vattenfall

As part of its drive to hit net zero by 2045, the Scottish Government has set targets to achieve 2.6 terawatt hours (TWh) of thermal energy output from heat networks by 2027, equating to about 3 per cent of today’s non-electrical heat consumption.

This rises to 6TWh by 2030 – around 8 per cent of current use. So what is district heating and how can it be used to cut emissions and help Scotland hit its environmental goals?

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Heat networks carry heat from a central source to consumers via a system of underground pipes carrying hot water. A network can cover a large area, like an entire city, or be fairly local, supplying a small cluster of buildings.

Construction work has already begun at Shawfair, which will eventually have 4,000 homes, schools, shops, bars and restaurants, leisure facilities and office space. Picture: Guy Hinks/Vattenfall

Eoghan Maguire, Vattenfall Heat UK’s director for Scotland, explains why he believes district heating networks have an essential role to play in decarbonising heating on a city scale.

In urban areas a network linked to a central source of warmth is cheaper to install than fitting systems such as heat pumps or boilers in each separate building.

Hooking up to local energy sources makes a network more resilient to fuel price shocks – such as the current volatility, caused by Russia’s war on Ukraine – and breakdowns of individual generation systems.

District heating networks can facilitate speedier decarbonisation of homes since green technology can be designed in to supply a large number of properties, which individually could take a significant length of time to switch away from fossil fuels. And importantly, the end customers should get cheaper heating and hot water.

Maguire says installing district heating in new-build developments is a “no-brainer”. But even older properties can be retrofitted, with success stories from work carried out in cities such as Amsterdam.

The most important factor is identifying a local source of waste heat that can provide a reliable supply to a place where there is a concentration of demand.

A pioneering district heating network which harnesses waste heat is being installed at Shawfair to provide hot water and heating to homes and businesses. Picture: Vattenfall

“Heat networks are technology agnostic,” Maguire said. “What they allow you to do is move heat that would otherwise literally go up into the air for the birds, move that waste heat into people's homes and do so in a low-carbon manner.

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“Fundamentally, you want to put heat networks in areas where there is a high level of heat demand. And what you try to do is match that with a heat source, because in reality what heat networks do is just move heat, and the heat sources are key.

“So if you look at Shawfair, the heat source is the energy-from-waste plant which is out there. But that's not the only source of heat that you can put on to a heat network.”

There are myriad possibilities, he says, with anything from data centres and whisky distilleries to sewers, rivers and anaerobic digestion facilities generating heat that might usually go unused.

In the Swedish city of Uppsala, Vattenfall has even hooked up with a coffee-roasting business to provide heat. He insists the debate, which is generally centred around gas boilers versus electric heat pumps, is a “false dichotomy” and much greater emphasis should be placed on district heating.

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“Networks offer a real clear way of delivering heat that is already available into homes, rather than having to create it,” he said. “Secondly, it is cheaper.

“It should cost less to deliver waste heat rather than having to generate it from individual air source heat pumps. Because what you can do is centralise your heat pump and actually take waste heat from a sewage works, for example.”

Shawfair is Vattenfall Heat UK’s first venture in Scotland, but the Swedish-owned company is involved in a number of projects in Europe.

Decarbonising heat is a big challenge, Maguire admits, requiring a “variety of levers” to be pulled.

“It's a complex problem – complex with a capital C,” he said. “As a result, it's going to require complex solutions – using various different methods.

“If you've got a geographically specific luck, if you’re close to a large waste source of heat, you should be able to use a heat network to allow you to deliver affordable heat.”

He says the technology can be particularly beneficial in lowering bills for high-rise tower blocks, which generally rely on expensive electrical heating, and social housing. But he stresses the need for government backing.

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“Decarbonising homes is not just about technology, it’s about hearts and minds," he said. “You cannot just do this – people have to come on the journey with you.

“In order to help that happen, we need to be very clear and open in terms of what the benefits are and what the cons are, what the considerations are for heating.

“But also actually supporting these targets through policy and grants. It’s that steady ship which allows for long-term investment.

“When you’ve got resources with the ability to generate energy locally, it means you’re removed from that level of fuel market volatility, and that’s a huge benefit for customers to know what the price is going to be for their heating for the next 15 to 20 years.

“If an area goes green, it will be good for the whole community, bringing jobs, cheaper fuels and energy security free from the volatile international energy market. What you are looking to try and do here is ultimately deploy what is strategically significant infrastructure which by its very nature is done locally.”

Maguire added: “Scotland’s ambitious net-zero target of 2045 cannot be met unless district heating is deployed at scale. The collaboration between organisations working to deliver this project means that the vision for this brand-new town can become exemplary for district heating in Scotland and beyond.

“This project is such an important first step in our vision for the region.

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"Vattenfall have developed a strategy to deliver city-wide district heating that is capable of supplying heat to the equivalent of 170,000 homes in Midlothian, Edinburgh and East Lothian by 2050, matching the scale of our heat networks in Europe.”

Coal mines supplied the energy and raw materials that powered industry in the 19th and 20th centuries, as well as the fuel to heat domestic properties. But when extraction ends and pumps are stopped, the disused shafts fill with water, which is heated through natural geothermal processes.

Heat can be transferred from the mine water to clean water in a district heating network and piped to nearby homes and businesses.

Midlothian Energy and Vattenfall Heat UK are working with the Coal Authority to explore using heat from a planned mine water treatment scheme at Dalkeith – one of several similar projects under consideration in Scotland.

Peter Wormald, principal heat and by-product manager at the Coal Authority, welcomed the collaboration.

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He said: “Scotland’s coalfield communities could be at the forefront of sustainable heating and cooling, creating green jobs, green skills and green innovation from the mines beneath, whilst making coalfield communities a key part of Scotland’s low-carbon future.”

Heat is expected to be delivered to homes in Shawfair by June next year, with the primary phase of the network expected to save in excess of 2,500 tonnes of carbon emissions annually – the same effect as taking 1,200 cars off the road. The project will benefit from more than £7m of Scottish Government support.

Zero carbon buildings minister Patrick Harvie said: “With thousands of people in Shawfair set to receive environmentally friendly heating, this project is a great example of the role heat networks will play in helping meet our decarbonisation targets.

“We are proud to have supported this project with £7.3m from our Low Carbon Infrastructure Transition Programme and I look forward to seeing it grow in scale, supplying heating to even more buildings as the network expands.”