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World’s largest thermal energy storage unit commissioned in Hungary
22/10/2025
News
Norwegian thermal battery company Kyoto Group has inaugurated its second European Heatcube project, said to be the world’s largest industrial thermal energy storage system, at KALL Ingredients’ maize processing facility in Tiszapüspöki, Hungary.
The 56 MWh Heatcube will provide KALL Ingredients with more than 30 GWh of renewable process heat per year, replacing natural gas-fired boilers with clean, low-cost energy. Kyoto says the system will reduce the plant’s CO2 emissions by up to 8,000 t/y while enhancing grid stability through flexible energy use.
At the heart of the modular thermal energy storage system (or thermal battery) technology is molten salt, which serves as the heat storage medium. The Heatcube uses renewable electricity to heat the salt above 400°C, achieving a reported 93% efficiency. The modular unit can store between 39–104 MWh of heat and discharge up to 14 MW of thermal power, delivering high-temperature steam for industrial applications such as food and chemical processing.
According to Kyoto, molten salt offers a compact, safe and sustainable alternative to pressurised steam systems. ‘As a liquid, molten salt can hold a lot of heat without taking up too much space,’ the company notes. ‘It is non-flammable and non-toxic… and allows simultaneous charging and discharging, a capability few thermal energy storage systems offer.’ This functionality allows the system to absorb surplus renewable electricity when its cheapest, without interrupting heat delivery to industrial users. ‘It effectively decouples charging from discharging, insulating operations from power market volatility,’ explains Kyoto.
The KALL Ingredients Heatcube project will operate under a 15-year heat-as-a-service (HaaS) agreement, in which customers pay for heat produced rather than capital equipment. This approach, says Kyoto, not only reduces costs for customers but also supports grid flexibility and stability.
The KALL facility is one of the newest maize processing plants in Europe. ‘Sustainability is central to our operations,’ comments Maarten Welten, Managing Director of KALL Ingredients. ‘Kyoto’s Heatcube offers a stable and cost-effective supply of clean process heat, helping us reduce energy costs and move towards full reliance on renewable energy.’
‘Thermal storage solutions like Heatcube show how industry can decarbonise while adding value to the power system. The excess of intermittent renewable energy will be massive and will shape the energy landscape of the coming decade,’ adds Arnaud Susplugas, CEO of Kyotherm, a majority investor in the KALL facility.
