Hydrogen can also be produced by splitting water through various processes, including electrolysis, photo-electrolysis, high-temperature decomposition and photo-biological water splitting. The commercial production of hydrogen by electrolysis of water achieves an efficiency of 70–75%. However, the cost of hydrogen produced by this route is several times higher than that produced from fossil fuels (Dutton, 2002; International Energy Agency, 2006). Renewable sources of energy (e.g. wind, tidal, biomass) might provide local sources of hydrogen, but certainly will not meet the massive volumes of hydrogen required globally for the new energy source. The use of nuclear energy (both fission and fusion) to supply future needs for hydrogen energy is also under consideration. A recent US Department of Energy report suggests that solar is most likely the only source of energy capable of producing the amount of hydrogen required to supply a hydrogen economy (US Department of Energy, 2004).