Large energy stores in the form of hot water could moderate Sweden’s electricity prices during cold winter days.
It is about using the hot water energy for district heating and releasing electricity production when it is needed most.
Västerås is in the process of building the world’s largest hot water storage in a rock room under the ground.
In a secret place 30 meters underground in Västerås, we get to visit a rock room, which in the 70s was built as a standby storage for oil, now it will be a storage for heat.
Rickard Svensson, who is the project manager from Mälarenergi, shows how the water is replenished through pipes that lead down into the rock room. When finished, it will contain 300,000 cubic meters of water, the equivalent of 7,000 swimming pools.
– What we are going to do is create a huge thermos where we can store hot water, and hot water contains a lot of energy that we can use. We store hot water and then we can take the hot water back when we need it, he says.
Can’t afford to do electricity on cold winter days
Västerås has several large cogeneration plants that produce both electricity and district heating, but when it gets really cold you have to make even more heat and then you can’t “afford” to make electricity. This is where the giant thermos comes in, where the hot water is heat exchanged to district heating.
– It then corresponds to us being able to supply the city of Västerås for up to a week in winter, says Rickard Svensson.
Several municipalities are considering using rock rooms
In Sweden, there are many similar cogeneration plants, but when it is the coldest and the electricity is most needed, not even half of the cogeneration plants produce any electricity. At the same time, there are many empty old oil storages in rock rooms similar to the one in Västerås.
– I think that many of the players who have both electricity and heat think it is interesting to look at this opportunity to be flexible, and thus be able to help the price of electricity go down by adding more electricity production, says Åsa Elmqvist, who is an expert in energy systems at Energiforsk.
– With this large warehouse behind us, we can then maintain electricity production at the level we want and at the same time deliver the heat we need to the city of Västerås, says Rickard Svensson.
So then there will be more electricity to Sweden in sensitive moments?
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