Danish energy island Bornholm presents breakthrough storage technology for molten salts

Denmark’s “energy island” of Bornholm is said to be home to what it says is a “groundbreaking” storage technology based on molten salts, which its developer plans to use as a future source of large-scale renewable heat and electricity.

Hyme Energy will deploy its molten hydroxide salts system at an operating combined heat and power (CHP) plant in Rønne as part of an EU-funded project to demonstrate a range of breakthrough storage technologies.

Hyme says it is the first company to be able to use molten hydroxide salts as a medium for long-term energy storage (LDES), thanks to a technology carried over from its nuclear-sector sister company that allows its highly corrosive nature to be controlled during peak periods -Temperature storage applications.

This paves the way for using “abundant, non-toxic” materials, which are available as a by-product of seawater and are about 10 times cheaper than nitrate salts commonly used in other storage systems, according to the Danish company.

The Hyme demonstrator plant, scheduled to come online in 2024, will have a storage capacity of up to 20 MWh and will provide heat, electricity and ancillary services to the grid.

This was announced by the company’s CEO, Ask Løvschall-Jensen Load: “We will deliver steam directly into the biomass plant that is there today, into the existing turbine system, with the required quality, consistency and stability.

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“This will be the first validation that we can completely replace a coal or biomass boiler, replace it with LDES and deliver steam to the same turbine that is already on site.”

The company sees the Bornholm demonstrator as an important milestone on the way to GWh-scale deployments potentially associated with large-scale renewable energy sources such as offshore wind and supplying large-scale industries with high-temperature heat.

Løvschall-Jensen said molten hydroxide salts “have been neglected as a storage medium so far” due to their corrosive nature, but if they got this under control, they could open the way to compact, highly efficient storage.

“Long Duration, Large Scope”

“Long duration – 6-8 hours up to 24 hours of discharge and gigawatt hour scale – we’re good at that.

“The larger we build, the more we benefit from the compactness of the salt and the cost-effectiveness of the storage medium.

“We’re going to be at large scale, at utility scale, at industrial scale.

“In terms of round-trip efficiency, we are developing something tailored for cogeneration. If we use CHP in an environment like a repurposed thermal power plant, we achieve 90% circulation efficiency. That’s a strength,” added Løvschall-Jensen.

Our strength is the high temperature of the salt, up to potentially 700 degrees.

Hyme’s natural primary target is industrial heat customers. “They’re the ones who are completely dependent on natural gas – with processes above 200°C they just don’t know what to do yet.

“Our strength is the high temperature of the salt, potentially up to 700 °C.”

Løvschall-Jensen said Hyme has already spoken to wind and solar developers about future potential links between green power generation and its systems.

The Hyme CEO is also aware of the massive offshore wind developments planned around Bornholm for the Denmark has grand plans as part of its “energy islands” strategy.

“My dream is that if there is a surplus of offshore wind power, we can help that Hyme can be located close to it. We have flexible loading, storing and unloading.

“We could ensure that excess wind power is delivered to industry or the grid in up to 24 cycles.”

The Danish company also believes its system and other storage technologies could provide a cost-effective template for retrofitting a large number of fossil-fuel power plants around the world as they retire the polluting elements of their assets, tap into their sites and grid connections, and reinvent life .

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Hyme aims to become a new player in the large energy storage space. Photo: Hyme


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