🔋 Denmark's first molten salt battery can power 100,000 homes for 10 hours

• Denmark has launched a 1 GWh molten salt battery that can store renewable energy for up to two weeks with minimal loss.
• The system uses industrial byproducts from chlorine production and achieves 80-90 percent efficiency for co-generation of heat and electricity.
• A 200 MWh facility is now being built in Holstebro to supply Arla Foods with thermal energy and reduce gas consumption by 50 percent.

Thermal energy storage with molten salt

The MOSS demonstration facility in Esbjerg started in April 2024 and can store 1 GWh of energy. The system converts electricity from renewable sources into heat by heating molten hydroxide salt to around 600°C.

The facility delivers up to 90 percent efficiency for co-generation of heat and electricity. When only electricity production is counted, the system achieves 40 percent efficiency, which matches or exceeds many fossil systems.

Energy is stored in a two-tank system where one tank holds hot salt and another cooler liquid. When energy is needed, the heat is used to create steam that either drives a turbine for electricity production or is fed directly to industrial processes.

Industrial byproducts become energy storage

The battery uses molten hydroxide salt, a low-cost byproduct from chlorine production. Denmark and other industrial countries produce tons of this material annually that was previously treated as waste.

The salt has high heat capacity and can store more energy per volume than many alternatives. The material is non-flammable and non-toxic, making it safe to handle. High availability makes the system economically scalable.

The system can store energy for up to two weeks with minimal loss thanks to advanced insulation and heat retention technology. This makes it suitable for balancing the electrical grid during seasonal lows in renewable energy production.

Arla Foods reduces gas consumption with new facility

Following the success of the MOSS demonstrator, Hyme Energy is now building a 200 MWh molten salt facility in Holstebro. This will supply Arla Foods, one of Europe's largest dairy producers, with thermal energy.

The project will reduce Arla's gas consumption by 50 percent and save over 3 million euros annually in energy costs. The facility also helps meet EU decarbonization targets for the industrial sector.

This shows how molten salt energy is not just about electricity but about clean, direct heat for sectors that account for over 20 percent of global carbon dioxide emissions.

Advantages over lithium-ion batteries

For large-scale, long-duration and low-cost storage, molten salt batteries prove superior to lithium-ion batteries. Molten salt systems can store energy for 10 to 336 hours compared to lithium-ion's 4-6 hours.

The cost per kWh is lower for molten salt because it uses byproducts. Fire risk is very low compared to lithium-ion batteries' high fire risk. Environmental impact is also less because molten salt uses recycled material instead of the mining and recycling problems that lithium-ion has.

The system is modular with tanks that can be scaled up, while lithium-ion batteries' scalability is more limited.

Industrial decarbonization through heat storage

Most industries depend on heat rather than electricity. Steel, cement, paper, food and chemical industries require steam or process heat between 150°C and 800°C. Today this heat is often produced by natural gas or coal.

Molten salt batteries can deliver the same heat cleanly and continuously. Denmark's project is one of the first real steps toward decarbonizing industrial heat at large scale, something many climate models say is essential to reach global targets.

Global replicability

The system does not rely on rare materials and uses existing industrial infrastructure such as tanks, steam pipes and pumps. It is modular and can scale from a few MWh to multi-GWh systems.

The technology can be paired with solar, wind or nuclear energy. Any country with industrial salt byproducts or large-scale renewable energy can adopt this system. It is particularly viable in Europe, the US, China and India.

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