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While a shift to renewables is vital to achieving our climate targets, complete dependence on sources like solar and wind still presents a significant challenge: developing efficient and sustainable storage. A German research organisation managed by Fraunhofer IZM focuses on tackling this challenge with a zinc battery technology that stores electrical power but produces green hydrogen on demand. To understand these goals, the research groups partners with two commercial firms (Zn2H2 and Steel PRO Maschinenbau) to work on the Zn-H2 project. The group researched and tested zinc batteries that are more affordable compared to their lithium-ion counterparts.
They also contain completely recyclable and available materials i.e. steel, zinc and potassium hydroxide. Researchers then combined alkaline water with the electrolysis process generating a new technology. Dr Robert Hahn of Fraunhofer IZM explains that during the chemical process inside the battery, the water oxidises into oxygen, and the zinc oxide reduces to metallic zinc, which reverts to zinc oxide during discharge. The water is reduced and releases hydrogen.
The researchers have performed multiple tests on individual battery cells to determine efficiency and stability. By the year-end, they intend to test eight interconnected cells, each containing a capacity of approximately 12V and 50Ah. According to the team, the first test aims to deliver 50% efficiency when storing power and 80% when producing hydrogen, with a life expectancy of around ten years. Their goal is to accelerate to an industrial scale, creating a rechargeable hydrogen storage system capable of storing energy in metallic zinc form and converting it back to electrical power and hydrogen when required.
They also believe the lower costs of zinc batteries make the technology an appealing alternative for commercial green energy storage systems.
The Zn-H2 project is due to end in September 2025, aiming to accelerate our green energy transition. Utilising the power of green hydrogen (which represents only 1% of global hydrogen production at present) will support the decarbonisation of high-emission industries and supply the necessary electricity and heat for domestic consumption.