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The spinout from nuclear power startup Seaborg has developed a promising solution for storing energy in 700-degree hot hydroxide salt. The solution produces both electricity and steam on a large scale – and is so close to reality that the first plants are currently being built.

The world is calling for more green energy. Not just more wind turbines and solar panels, but solutions that can store energy when it’s not sunny or windy. In fact, McKinsey suggests that Europe needs 400 times the storage capacity we have today.

Hydrogen created with renewable energy – so-called Power2x – is seen as the future of energy storage by many. However, the startup Hyme has a solution for energy storage closer to entering the market. It stores energy in a 700-degree drain cleaner, and the first prototype is expected to be ready in Esbjerg next summer.

»It is the first plant in the world to run on hydroxide salt (drain cleaner) and the commercial interest is overwhelming. We’re not actually ready to take on the interest – we need to prove that our first plant is a success first,« says Ask Emil Løvschall-Jensen, CEO and co-founder of Hyme.

The first components for the test facility have just been ordered. At the same time, Hyme has been awarded another project on Bornholm, where the storage technology will replace an old cogeneration plant. As soon as December 2024, this storage will supply both energy and hot water to Rønne – with a storage capacity equivalent to 10 per cent of Bornholm’s renewable energy.

The storage solution from Hyme is relatively compact: With storage the size of »Rundetårn«, the solution will be able to supply electricity and heat to central Copenhagen for 10 hours. Because the solution operates at temperatures of 700 degrees, Hyme can supply both electricity and steam to district heating and industry.

Deep tech creates solutions

The concept behind the Hyme solution is simple: when there is surplus energy from wind turbines or solar panels, the hydroxide salt is heated to 700 degrees and when the energy is needed, the heat is extracted again using a turbine.

Drain cleaner has been known as a good candidate for energy storage since the 1950s. It can be heated to 1400 degrees before boiling, and it’s hugely cheap because it can be produced from salt water and is a by-product of chlorine production. It just has one major challenge that has led most to write off the method:

»It breaks down stainless steel at these temperatures – unless you have the processes under control. And that’s what we’ve been developing methods for over the past 4-5 years,« explains Løvschall-Jensen.

Hyme has only been around for about a year, but the technology is based on years of research. The company is a spinout of the nuclear power company Seaborg, which developed and patented the technology for use in its nuclear reactor.

»When you get to do research and development, a lot of things come with it – for example, a spinout like Hyme – that wasn’t planned from the start. New opportunities arise because we’re doing something that’s difficult and that no one has done before. And I’m not sure this is the last energy spinout from Seaborg,« says Løvschall-Jensen, who is also a co-founder of Seaborg.

Close to the market

If the first two test plants show the same good results as in the laboratory, Hyme will have a commercially mature plant. This means commercial energy storage on a scale of up to 1 GWh, which is not available today. Storage capacity that could be ready in 2026.

»One of the things I’m most proud of on the big stage is that we’re able to store energy on a medium that can be produced from salt water. When you talk scalability, there’s no limit to how big we can make it. Then we still have to show that we are competitive on price, which is why we are doing a pilot plant,« says Løvschall Jensen.