Hydrogen Production and Storage
This paper offers an overview of the technologies for hydrogen production. The technologies discussed are reforming of natural gas; gasification of coal and biomass; and the splitting of water by water-electrolysis, photo-electrolysis, photo-biological production and hightemperature decomposition. For all hydrogen production processes, there is a need for significant improvement in plant efficiencies, for reduced capital costs and for better reliability and operating flexibility.
Water electrolysis and natural gas reforming are the technologies of choice in the current and near term. They are proven technologies that can be used in the early phases of building a hydrogen infrastructure for the transport sector. Small-scale natural gas reformers have only limited commercial availability, but several units are being tested in demonstration projects. In the medium to long term, centralised fossil fuel-based production of hydrogen, with the capture and storage of CO2, could be the technology of choice. However, the capture and storage of CO2 is not yet technically and commercially proven. Further R&D on the processes of absorption and separation are required.
Other methods for hydrogen production are further away from commercialisation and need additional R&D. The production of hydrogen from biomass needs additional focus on the preparation and logistics of the feed, and such production will probably only be economical at a larger scale. Photo-electrolysis is at an early stage of development, and material costs and practical issues have yet to be solved. The photo-biological processes are at a very early stage of development with only low conversion efficiencies obtained so far. High-temperature processes need further materials development that focuses on hightemperature membranes and heat exchangers.