HYDROGEN PRODUCTION

Hydrogen, the most common element on earth, is widely seen as the ultimate form of clean energy [1,2]. The proposition that hydrogen should be a sustainable energy medium has become known as the “Hydrogen Economy”. This term is thought to have been coined in 1970 by Neil Triner at the General Motors Technical Laboratory in Warren, USA. But the concept of using hydrogen had in fact been suggested much earlier in such diverse publications as Jules Verne’s science-fiction novel The Mysterious Island (1874) and J.B.S. Haldane’s essay Daedalus, or, Science and the Future (1923) (Fig. 1). It is further notable that Haldane proposed the use of wind power to produce hydrogen via electrolysis of water; the gas would be liquefied and stored in vacuum-jacketed reservoirs that would probably be sunk in the ground. The overall scheme of the Hydrogen Economy is illustrated conceptually in Fig. 2, which outlines the many different possible routes to hydrogen from both conventional and novel primary energy sources, the storage and transportation modes for hydrogen, and its end-uses in fuel cells (Fig 3, Fig. 4), engines, and industrial processes. This is a broad canvas and many authors restricted the use of the term Hydrogen Economy (or “Hydrogen’s Energy”) to the production of hydrogen from non-fossil sources, its distribution and storage, and its combustion in a fuel cell to generate electricity.