The war in Ukraine has forced us to rethink where we get our energy from as Europe tries to ditch Russian gas. But could large heat pumps help heat thousands of homes and businesses? Two big schemes are about to get under way in Gateshead and London, and the hope is that they can provide a cheaper, greener source of heat.
“Coal mining was huge in the North East,” says Jim Gillon, walking through a construction site in Gateshead.
“And where we are standing there are six different mines under our feet.”
Jim is the Energy Services Manager for Gateshead City Council, and he’s giving this former fossil fuel site an eco-friendly makeover for an ambitious new heating plan.
He points to a well that goes down 150 m below the muddy ground. Like many old coal mines, it is now flooded with water. But water is naturally warm at 15°C, and this warmth is key.
A few meters away a giant heat pump has been installed.
It’s a bit of clever engineering. In the same way that heat can pass from one person to another when they shake hands, heat from the mine water is transferred to another liquid circulating in the heat pump system.
Compressors then squeeze and crush the liquid, raising the temperature to 80°C.
This heat is sent through pipes to be used by buildings in the local area. The water from the mine is returned underground so that the process can start again.
The small individual heat pumps that people install in their homes work on the same principle. They take some heat, either from the air or from the ground, and then increase the temperature, providing heat for that home.
But the heat pump at Gateshead is so large that at full capacity it can provide heat for the equivalent of 5,000 homes.” We are very pleased to have taken the legacy of coal mining and are turning that negative asset into a future positive source of energy. Jim says.
Buildings connected to the green district heating scheme have heat exchangers instead of boilers.
They convert the heat that comes from the heat pumps to the water in the pipes, to be used in kitchens and bathrooms and to run through radiators.
Jacqueline Bell had one installed in her Gateshead home about five years ago; it is connected to another local low-carbon network.
She says that it was very complicated to install the new system, the pipes had to be rerouted in the walls of her apartment, but she is happy with the end result.
“I think my whole apartment is much, much warmer than it used to be. And the cost is also much, much cheaper,” he says.
Energy bills are a key concern for many consumers right now.
Gas prices were already rising sharply last year, but the war in Ukraine is pushing them to record highs as uncertainty grows over Europe’s gas supply from Russia.
The search for alternative sources of energy has begun. Michael Lewis, CEO of EON UK, thinks green district heating schemes could help.
“They fundamentally change the landscape,” he says.
“It means we’re going off natural gas. So not only is it a climate benefit, but it also means our energy prices are no longer tied to the volatile international gas market.”
EON has installed its own large heat pumps in the heart of London.
The Citigen plant is hidden behind the imposing façade of the Port of London Authority building. Over the years it has provided energy using first coal, then oil, and more recently gas.
It will now supply a renewable source of heat by harnessing hot water from an aquifer below the city.
“Heat pumps are low-carbon because they are mostly powered by electricity, and in our case the electricity will be renewable,” explains Leke Oluwole, general manager of Citigen.
He says the scheme provides green heating to many buildings in one fell swoop.
“Instead of having 1,000 homes to decarbonise, you have one central location to decarbonise, which will help with the net zero targets we have in the UK.”
Heating the UK’s 30 million buildings currently contributes nearly a quarter of our greenhouse gas emissions, according to the government’s Building and Heat Strategy.
“If we’re going to tackle climate change then we really need to fundamentally rethink the way we heat our buildings,” says Dr Fleur Loveridge from the University of Leeds.
For many homes, this will mean installing individual heat pumps. The government has announced the ambition to install 600,000 each year by 2028.
But in places where housing is much denser, green grid heating schemes might be more suitable.
“District heating systems in the UK only account for around 2% of our heating at the moment,” explains Dr Loveridge.
“If we’re going to reach our net-zero emissions by 2050, we probably need to increase that to around 18%.”
“Green district heating is an absolutely essential feature of our future heating mix,” he adds.
She says the schemes are not limited to places where there are mines or flooded aquifers, although there are many such groundwater sites across the UK.
“Anywhere you can access the ground for the ground heat source will also work,” he explains.
“Where there are surface water bodies, such as rivers or lakes, that can also work. Seawater has even been used to power district heating systems.
“So it’s applicable in many places, but not absolutely everywhere.”
The huge heat pumps in London and Gateshead will soon be switched on and the heat generated will begin flowing into local homes and businesses.
But it is clear that these schemes are only the beginning. Many more will be needed if the UK is to meet its climate change targets.
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