In this first introductory lecture, the global energy context is discussed, to demonstrate the urgency of replacing fossil fuels - oil, gas and coal. The potentials of the various renewable energies (geothermal, wind, solar, currents and tides, hydroelectric) are assessed and compared. This leads to the conclusion that only solar energy is quantitatively capable of meeting the planet's growing energy needs (25 TW of power by 2050). Harnessing this energy, by converting it into electricity and/or fuels, requires considerable investment in the fields of photovoltaics (conversion of solar energy into electricity) and batteries for electricity storage, the use of biomass (2nd and3rd generation fuels, biodiesels), and hydrogen. The latter is an interesting fuel for fuel cells, and can be used as a form of solar energy storage when solar energy is used for water reduction (electrolysis coupled with a photovoltaic panel) or for water decomposition (photolysis of water into oxygen and hydrogen).
The photolysis of water is a process that occurs in many living organisms (photosynthesis), which know how to exploit non-noble metals such as nickel, iron and manganese as catalysts. One of the major challenges in the field of electrolysis and photolysis of water lies in the discovery of new catalysts based on non-noble metals, which can be aided and stimulated by an understanding of the structure and operation of biocatalysts.
