Solar Fuels

Solar Fuels (SF) are obtained from the conversion of the sunlight into fuels such as methanol or hydrogen, offering great potential to meet worldwide future energy demands. Additionally, they can be easily stored to respond to fluctuating energy needs having application in the transport, building and industrial sectors. In this perspective, the European Union has at COP21 joined Mission Innovation with the aim of reinvigorating and accelerating global clean energy innovation, notably looking at the potential of solar fuels produced through different technological approaches and pathways.

There are several technological paths for SF production: redox cycles, use of solar particle receivers/reactors or even from carbon neutral feedstocks. The latter is particularly relevant as it links to agriculture/agroforest fields, especially the valorization of agricultural wastes. Such hydrocarbons’ reforming/partial oxidation to syngas can be more effectively driven by concentrated solar power (CSP). In particular, the use of Thermal Energy Storage (TES) systems present in CSP plants can support the mitigation of the availability of solar energy. In fact, one of the difficulties regarding SF production are the constraints on a continuous production of solar fuels on a daily and seasonal basis.

Additionally, CSP plants can also be used for High-Temperature electrolysis (H2 production) systems by providing energy as heat at high temperatures (up to 600ºC).

These vectors (syngas, H2) can then be used by itself or as a feedstock for further thermochemical processes such as water-gas shift, Fischer-Tropsch, methanol synthesis, etc, for the production of synthetic fuels.