Germany Powers Factory with Giant Heat-Storing Bricks

Industrial factories have a dirty secret: even as solar and wind power take over electricity grids, most still burn natural gas around the clock to make the steam their processes depend on.

That's changing in northern Germany, where energy company Rondo and chemical manufacturer Covestro just started building what sounds almost too simple to work. They're installing a massive battery made of bricks that charges up when renewable electricity is abundant and cheap, stores that energy as heat, then delivers steady high-temperature steam whenever it's needed.

The 100-megawatt-hour system at Covestro's Brunsbüttel chemical site will be one of the largest industrial heat batteries in the world when it comes online by the end of 2026. It will supply about 10% of the facility's steam needs and cut carbon emissions by 13,000 metric tons each year.

Germany's renewable energy boom created the perfect opportunity for this technology. The country experienced 573 hours of negative electricity prices in 2025, a 25% jump from the year before, because wind and solar sometimes generate more power than the grid can use.

Rondo's heat battery soaks up that surplus electricity by heating specially designed bricks, the same proven material steelmakers have used for heat storage for centuries. When the factory needs steam, the stored heat runs a conventional boiler without burning any fossil fuels.

The Ripple Effect

The breakthrough matters far beyond one German factory. Steam production accounts for a massive chunk of industrial energy use worldwide, and most of it still comes from burning gas or coal because factories need reliable heat 24/7.

This project shows renewables can handle that job. Schleswig-Holstein's energy and climate minister Tobias Goldschmidt said the state's rapid renewable buildout is making industrial projects like this possible while strengthening energy independence.

The system also helps balance the grid by using electricity when it's plentiful and storing it for later. That makes renewable energy more valuable and reliable for everyone.

Covestro plans to decide whether to expand the technology across its other facilities based on how well the Brunsbüttel battery performs. Rondo Energy CEO Eric Trusiewicz called it a demonstration that clean industrial heat can be highly reliable while supporting Europe's industrial base and energy security.

The project received backing from Breakthrough Energy Catalyst and the European Investment Bank, signaling serious confidence in brick batteries as a climate solution.

One factory in northern Germany just proved that sometimes the most cutting-edge answer comes wrapped in the oldest materials.