Climate-neutral heat: the largest thermos flask in Germany

As of 07/10/2022 08:22

By 2040, Vattenfall aims to produce fossil fuel-free and climate-neutral energy in Berlin. To this end, the company is also rebuilding the district heating system and focuses on recycling waste heat and using electricity more efficiently.

A colossus of steel and concrete soars into the skies of Spandau. Height: 45 meters. Diameter: 43 meters. Capacity: 56 million liters. The filling itself takes about two months. For the new heat accumulator at the Reuter West CHP plant in Berlin, the equivalent of 350,000 bathtubs filled with water must be filled. The huge tank should be full at the end of September, and in early 2023 it will be connected to the grid and Germany’s largest city heat storage system will be put into operation.

memory problem solved?

“We are the best store,” says Vattenfall Wärme Berlin AG CEO Tanja Wilgoß. The municipal heat storage system is a symbol of the future of heat supply – and part of the solution to the biggest problem with renewable energy: because wind energy still cannot be stored. This means that if electricity can no longer be supplied to the grid, no matter how strong the wind blows – it doesn’t make sense. And when there is no wind, nothing arises.

Vattenfall started planning the project in 2017. Already during the construction phase, the team focused on climate protection. 25% of the concrete foundations are made of recycled concrete. The largest heat and power plant in Europe is located right next to the warehouse. There, the energy of the wind and sun heats the water like in a kettle. When the water tank is connected to the grid, energy can also be temporarily stored.

It is still under construction, but the new heat storage should be connected to the grid at the beginning of next year.

Photo: Kerstin Breinig rbb

The kettle meets the thermos

Wind turbines still need to be temporarily shut down, and waste heat, which is also used in the Reuter West, is literally blown into the air if not needed by the municipal grid. The waste heat ends up in the garbage can and the wind dies. If both are not enough, expensive electricity must be purchased. After the system has finished its operation, the excess electricity is used to generate heat and stored in warehouses for a short time.

“It is actually a large thermos flask. Here I can determine when the heat is released to the households, ”says Vattenfall’s representative Wilgoß. This way, you can bring much more efficiency to your system and keep your prices lower. The water is 55 degrees when filling and 98 degrees when it can be heated.

The waste heat is added to the excess electricity from wind energy. It is also used to heat water. The new warehouse has a thermal capacity of 200 megawatts – enough for all customers in the summer. After all, every third Berlin apartment is connected to the Vattenfall Berlin district heating network, and thus receives heating and hot water. In winter, however, the warehouse is too small – then 5,200 megawatts are needed.

The waste heat storage is located at the Reuter West CHP plant in Berlin.

Photo: Kerstin Breinig rbb

Climate neutral until 2040

Vattenfall Berlin has not been using lignite to generate heat since 2017, and hard coal is also to be phased out by 2030. Instead, the city is expected to heat biomass, waste incineration, natural gas, thermal energy and large heat pumps.

To achieve the great self-goal of climate neutrality and a fossil-free heat supply in Berlin, there is still a lot to invest in until 2040. The new colossus in Spandau is just a small piece of construction.

In addition to the heat storage tanks, other ideas are and have been tested by Vattenfall in Berlin: the SaltX pilot project – a salt tank – started in 2019. After three years, the warehouse in Berlin will be dismantled and rebuilt in Stockholm. There, the chemical energy storage is to be further developed until it is ready for market launch.

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