Molten Salt Battery Breakthrough in Denmark: Powering 100,000 Homes!

The world-first installation called MOSS demonstrator plant launched in April 2024 in Esbjerg, Denmark.  Denmark has unveiled a 1 GWh molten salt battery, developed by Hyme Energy and Sulzer, capable of powering 100,000 homes for 10 hours. This breakthrough in large-scale, long-duration energy storage uses industrial byproducts and high-efficiency heat storage to address intermittency issues in renewables, decarbonize industry, and strengthen grid resilience.

Instead of storing electricity as chemical energy like lithium-ion batteries, this system stores heat in molten hydroxide salts at 600°C (1,112°F). The stored heat is then used to generate electricity or provide direct heat for industrial processes.

It is up to 90% efficiency in combined heat and power generation. 40% electricity conversion efficiency, outperforming many thermal systems, and a two-week storage capacity, which is  ideal for grid balancing.  This innovation paves the way for scalable, renewable energy storage, making zero-carbon power grids more feasible.

Molten hydroxide salt's potential as a thermal battery is impressive—especially with its high efficiency in co-generation and its scalability due to industrial byproduct availability.

Following the success of the MOSS demonstrator, Hyme is now building a 200 MWh molten salt plant in Holstebro, Denmark.  The two-tank system is a clever way to tackle heat loss, making the technology even more viable for long-term energy storage. Plus, its application in industrial heat supply directly addresses one of the hardest-to-decarbonize sectors.

The savings and emission reductions for Arla Foods, one of Europe’s largest dairy producers, are a great example of how this technology can drive both environmental and economic benefits. It has reduced their gas consumption by 50%, significantly cutting carbon emissions.

This will save over 3 million euro / 3.1 million us dollars annually in energy costs and help meet EU decarbonization targets for industrial sectors.

This project shows how molten salt energy isn’t just about electricity – it’s about clean, direct heat for sectors that account for over 20% of global CO2 emissions.

Here’s how molten salt stacks up: The energy storage for Lithium-Ion (LI) is electrical, whereas the Molten Salt (MS) is thermal.  The duration for LI is 4-6 hours versus 10-336 hours for MS. The cost for MS is low compared to LI, due to the use of byproducts. The fire risk is high for LI and very low for MS, and the environmental impact for LI is high mining with recycling issues compared to low for MS due to recycled input.

The 1 GWh molten salt battery in Esbjerg is more than just an engineering feat—it’s a vision of what the energy future can look like: Affordable, scalable, safe, low-carbon and efficient.

By using waste to power homes and industry, Denmark has proven that sustainability and innovation can coexist at grid scale. If the rest of the world takes note, molten salt might just be the missing link in the global clean energy puzzle.

What do you think about its scalability beyond Denmark? Could it be integrated into broader energy grids or paired with green hydrogen systems for even greater impact?