Development of a light-driven system for ex-situ biomethanation

The SOLMET project aims to develop an innovative technology for the direct conversion of solar energy into biomethane (CH₄), using only CO₂ and water as feedstocks. This approach creates a direct ‘solar-to-gas’ process that bypasses the conventional, loss-prone ‘solar-to-power’ and ‘power-to-gas’ methods. Current power-to-gas systems face significant challenges in terms of efficiency, scalability and sustainability. Conventional biomethanation relies on hydrogen production via electrolysis, which entails high investment and operating costs, particularly for smaller plants. The assumption that low-cost ‘surplus energy’ is available to power electrolysers often proves to be incorrect in practice. Furthermore, existing systems suffer from the short service life of the electrodes, which degrade rapidly under sunlight, thereby increasing maintenance costs and compromising stability. Photocatalytic processes for methane production have so far received little attention and have not yet been scaled up beyond the laboratory level. The main objective of SOLMET is to develop and validate an efficient, cost-effective and sustainable system for the production of biofuels and the storage of renewable energy. At the heart of the innovation lies a unique hybrid system that combines photocatalysis with methanogenic archaea. Instead of expensive electrolysis, an integrated photo-bioelectrochemical system is being developed. A key innovative step is the use of durable and cost-effective materials.