UK Startup Caldera Develops Heat Storage Tech Using Recycled Aluminium and Volcanic Rock
UK-based startup Caldera has introduced a modular heat storage technology, Megacell, which uses a composite of recycled aluminium and volcanic rock to store heat for industrial processes and on-site photovoltaic energy. The technology is being promoted as a key tool for decarbonising industries by replacing conventional gas boilers with on-demand heat from renewable sources.
Megacell is designed to store heat at temperatures of up to 500°C and produce steam, offering a practical alternative for industries looking to move away from gas-powered systems. The system uses solar power to generate heat and store it within a thermal core made from a proprietary mix of recycled aluminium and volcanic rock. According to Caldera, this approach to thermal storage is on par with other systems using rock, sand, or concrete.
The core of the system is housed within a vacuum-insulated chamber, which helps maintain high temperatures while minimising heat loss. The vacuum eliminates heat transfer through conduction and convection, while a special material inside the unit prevents radiative losses. The stored heat can then be used to produce hot water or steam at temperatures of up to 210°C.
Megacell comes in three standard storage capacities—1.3 MWh, 4 MWh, and 5.3 MWh—offering flexibility for different industrial needs. The modular design allows for multiple units to be combined, creating storage capacities of up to 100 MWh. The smallest unit measures 6 m x 14 m x 7.3 m, while the largest is 6 m x 14 m x 9 m, with weights ranging from 27 tonnes to 82 tonnes. Caldera has already constructed the first 4 MWh demonstrators at its facility in Hampshire.
This technology is expected to play a role in decarbonising aluminium production, one of the sectors contributing significantly to greenhouse gas emissions. The ability to store renewable energy as heat offers a pathway to reducing direct and indirect emissions in industries that rely heavily on energy-intensive processes.
