Reducing emissions requires a multi-pronged approach. We need to power our homes and businesses with green energy, move away from fossil fuels on the roads and be more innovative in how we produce and store energy. Nestled in the former Lufthansa cargo hall at Tegel Airport in Berlin, STOFF2 has a plan to generate green hydrogen, and a new storage technology that makes it possible. “We have a long track record in the renewable energy and energy storage industry, and we knew that these energy sources would generate huge amounts of excess power that can be put to good use to produce green hydrogen,” says Sebastian Sipp.

This German company has developed an electrolyser that stores energy and generates hydrogen, combining battery and electrolysis functions in a single device. The company created its first electrolysis prototype several years ago, performing what it calls “zinc intermediate step electrolysis”. Electrolysis is the process of using electricity to split water into hydrogen and oxygen. 

The expansion of wind and solar power plants in Germany from 2020 provided the launchpad to start STOFF2. Storing the excess energy generated from wind and solar is no easy task, and energy storage facilities in Germany can only hold this extra energy for about 15 minutes. Any extra electricity that is not used in Germany or sold to other countries is lost. In contrast, gas can be stored in containers for four months or even longer. Green hydrogen thus offers a greener, more cost-effective alternative for long-term energy storage


However, although electrolysis technologies have expanded in recent years, the issues associated with hydrogen storage or compression have only been partly resolved. While hydrogen is the lightest chemical element, it is a challenge to transport and store because the gas must be liquefied at temperatures below -253°C. What’s more, hydrogen has to be stored in high-pressure tanks.

STOFF2’s new electrolyser system is powered by excess renewable energy. It takes the electricity produced at peak times for wind and sunlight and stores it in solid zinc. STOFF2 calls this storage function the “zinc intermediate step,” or Zink-Zwischenschritt in German. The system is safer because it does not store the energy in gaseous form. When needed, the energy stored in the zinc layer is released as hydrogen. The zinc dissolves back into the electrolyte and hydrogen is produced at the gas electrode.

Our electrolyser is flexible enough to adapt to the green energy needs of municipal utility companies, transport operators, industrial or chemical companies and renewable energy generators, who want greener and more stable energy supplies,” Sipp says. “Demand for our product is rising, and we’re looking to expand our manufacturing capacity and continue developing our technology.

EIB Advisory experts are helping Sipp’s company find financing to expand, improve the business plan, strengthen investor material and investigate demand for the product. “The advisory support from the EIB has been instrumental in propelling our growth trajectory, bolstering our financial capabilities and improving our overall activities,” Sipp says.