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For some of them, when you mix two or more together, the melting point of the mixture drops dramatically – so low that scientists call them “molten salts” because they are so easy to melt. This low melting point enables the salt mixtures to be stored and used in a liquid state.
Molten salts can hold a lot of heat, without taking up too much space. In addition, due to their liquid form, they are pumpable and easily usable in highly efficient heat exchangers. This makes them ideal for storing renewable energy as heat – a key benefit during periods when the sun does not shine or there is no breeze.
In the autumn of 2025, BASF provided the salt mixture for the world’s first industrial, salt-based thermal energy storage system, the so-called Heatcube. It was built by Kyoto Group close to Budapest, Hungary, to supply heat to a corn-processing facility. The Heatcube works like a battery that stores energy – not in the form of electricity, but as high-temperature heat – in molten salt. The salt mixture is heated by an electric heater to over 400 degrees Celsius as soon as large quantities of low-cost, renewable electricity become available on the grid. The resulting heat can be used for on-demand steam generation or stored for periods of low renewable availability and higher prices.
The Heatcube works like a battery that stores energy – not in the form of electricity, but as high-temperature heat – in molten salt. The salt mixture is heated by an electric heater to over 400 degrees Celsius as soon as large quantities of low-cost, renewable electricity become available on the grid. The resulting heat can be used for on-demand steam generation or stored for periods of low renewable availability and higher prices.
Industries need large amounts of steam for their processes – whether in chemicals, food, or other sectors. When that steam is produced from fossil fuels, it generates significant CO2 emissions. CO2‑free steam technologies are, therefore, an important step toward industrial decarbonization. For example, the Heatcube in Hungary will supply more than 30 GWh of clean process heat for steam each year, replacing natural gas and potentially cutting CO2 emissions by up to 8,000 tons annually.
BASF is evaluating the use of this technology especially at smaller sites with direct connection to renewable energy sources and will start to scale up its investments on power-to-heat technologies starting from 2028/2029. Technologies with molten salt heat storage are part of this evaluation.
Yes, we are seeing an increasing pipeline of molten salt energy storage projects and are in contact with several companies in this field developing projects especially in Europe. We are also working with academic partners like the German Aerospace center to optimize the use of our salts in this application.
