'Huge thermos' to help heat Berlin homes

FRANK JORDANS (Associated Press)AP
The vast tank in Berlin has been compared to a huge thermos, storing 56 million litres of hot water.
Camera IconThe vast tank in Berlin has been compared to a huge thermos, storing 56 million litres of hot water. Credit: AP

A rust-coloured tower rising from an industrial site near the banks of Berlin's Spree river could help provide some warmth for Germans in the coming winter.

With a height of 45 metres and holding up to 56 million litres of hot water, utility company Vattenfall says the tower will help heat Berlin homes even if Russian gas supplies dry up.

"It's a huge thermos that helps us to store the heat when we don't need it," said Tanja Wielgoss, who heads the Sweden-based company's heat unit in Germany. "And then we can release it when we need to use it."

While district heating systems fuelled by coal, gas or waste have been around for more than a century, most aren't designed to store significant amounts of heat. Instead, they burn as much fossil fuel as needed, contributing to the greenhouse gas emissions that are driving global warming.

By contrast, the new facility unveiled at Vattenfall's Reuter power station will hold water brought to almost boiling temperature using electricity from solar and wind power plants across Germany. During periods when renewable energy exceeds demand the facility effectively acts as a giant battery, though instead of storing electricity it stores heat.

"Sometimes you have an abundance of electricity in the grids that you cannot use anymore, and then you need to turn off the wind turbines," said Wielgoss. "Where we are standing we can take in this electricity."

The 50-million-euro facility 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. The vast, insulated tank can keep water hot for up to 13 hours, helping bridge short periods when there's little wind or sun.

It will also be able to use other sources of heat -- such as that extracted from wastewater, said Wielgoss. While it will be Europe's biggest heat storage facility when it's completed at the end of this year, 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.

"Due to its geographic location the Berlin region is even more dependent on Russian fossil fuels than other parts of Germany," she told The Associated Press. "That's why we're really in a hurry here."

"First of all to become climate neutral," she said. "And secondly, to become independent (of energy imports)."

Figures released on Thursday by Germany's utility industry association BDEW shows 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.

Part of the decline was due to milder weather, but the industry group said even accounting for warmer temperatures there was a measurable drop that it attributed to bumpier economic conditions, appeals from the German government to save energy and individuals' personal efforts.

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