Within SPOTLIGHT, a photonic device and chemical process concept has been developed and validated for conversion of CO2 and green H2 to chemical fuel methane (CH4, Sabatier process), and to carbon monoxide (CO, reverse water gas shift process) as starting material for production of the chemical fuel methanol (CH3OH) using natural sunlight and LED lighting as energy sources. Both CH4 and CH3OH are compatible with current infrastructure, and suited for multiple applications e.g. car fuel, energy storage, and starting material for the production of valuable chemicals. To be able to make conversions outlined above possible, various catalytic strategies have been investigated and implemented. Thermal catalysis is traditionally applied a lot in industry, but these processes are usually difficult couple to renewable energy (RE) sources. Electrocatalysis could benefit directly from the generation of RE (i.e. electricity form solar and wind energy), but overall efficiency lacks behind due to process inefficiency and selectivity is often low. As an alternative, photocatalysis is of interest specifically for CO2 reduction because radicals are more easily formed at the (illuminated) surface. The objective of SPOTLIGHT was to reach a process efficiency of at least 5%. SPOTLIGHT’s photonic device comprises a transparent flow reactor, optimized for light incoupling in the catalyst bed at high solar intensity and with highly selective plasmonic catalysts. Furthermore, it comprises secondary solar optics to concentrate natural sunlight and project it onto the reactor, and an energy efficient LED light engine to ensure continuous operation. SPOTLIGHT’s catalysts are plasmonic catalysts, capable of absorbing a large part of the solar spectrum. We have achieved a process efficiency of 50% for the Sabatier process and 4.5% for the rWGS process. The objective of SPOTLIGHT was to develop and validate processes that will be cost competitive with fossil and green alternatives between 2030 and 2050.
