Germany is creating a “huge thermos” boiler which is powered by renewable energy and will pump hot water to the city's homes during winter.
The rust-coloured tower, which is 45 metres high and holds up to 56 million litres, is on an industrial site near the banks of the Spree in Berlin.
The power-to-heat thermal tank is the largest to date in Europe and creates the creates equivalent energy of 60,000 household boilers, engineers say.
Vattenfall, the Swedish utility company that built the tower, says it will help to keep Berlin homes warm this winter, even if Russian gas supplies are unavailable amid the conflict in Ukraine.
“It’s a huge thermos that helps us to store the heat when we don’t need it,” said Tanja Wielgoss, who heads the Swedish company’s heat unit in Germany. “And then we can release it when we need to use it.”
The tower is greener than most other district heating systems, which are powered by fossil fuels such as coal which increase global warming.
Unveiled on Thursday at Vattenfall’s Reuter power station, it will hold water brought to almost boiling temperature using electricity from solar and wind power plants across Germany.
It effectively acts as a giant battery, although instead of storing electricity it stores heat. This would ease the burden on consumers should energy costs rise higher in the coming months.
The ongoing energy crisis has spurred the UK government to reconsider opening a natural gas storage plant in Yorkshire that was mothballed in 2017. The reserves there could supply nearly two weeks of gas should Russia switch off the energy pipeline to the West.
“Sometimes you have an abundance of electricity in the grids that you cannot use any more, and then you need to turn off the wind turbines,” said Ms Wielgoss. “Where we are standing we can take in this electricity.”
More than 600,000 Berlin dwellings are connected to a communal heating network, a legacy of the Soviet-era infrastructure that was installed after the Second World War.
Many former communist countries still use this system, with hot water provided by local authorities through the winter.
The €50 million ($52 million) plant will have a thermal capacity of 200 Megawatts — enough to meet much of Berlin’s hot water needs during the summer and about 10 per cent of what it requires in the winter.
Berlin is hoping to completely phase out coal by 2030 and the plant is part of this goal.
It will be Europe’s biggest heat storage facility when completed at the end of this year. But an even bigger one is already being planned in the Netherlands.
Berlin’s top climate official, Bettina Jarasch, said the faster such heat storage systems are built, the better.
“The war in Ukraine and the energy crisis teach us that we need to be faster,” said Ms Jarasch.
“First of all to become climate neutral. And secondly, to become independent (of energy imports).”
Figures released on Thursday by Germany’s utility industry association BDEW show efforts to reduce natural gas use are having an effect.
Consumption of gas dropped by 14.3 per cent in the first five months of this year compared to the same period in 2021.
Ms Wielgoss said she was confident that Vattenfall’s customers will not go cold this winter, despite the looming gas squeeze from Russia as Moscow retaliates for Western sanctions by reducing the gas flowing through key pipelines.
“Consumers in Germany are very well protected,” she said. “So they for sure will not suffer any shortages. But of course, we plead with everybody to really start saving energy.
“Each kilowatt hour we save is good for the country.
Vattenfall's heat business in Berlin owns and operates 10 heat and CHP (combined heat and power) plants, 80 small-scale CHP facilities, and various other assets. It employs roughly 1,700 people.
