7. Can hydrogen be the solution?
Apart from limiting the growth of population, hydrogen is more and more regarded today as an attractive alternative to replace fossil fuels in the future (Johnston et al, 2005). Basically it can be produced from water and it regenerates water after exploitation as source of energy according to the following scheme: electric energy + H2O → H2 + ½ O2 → H2O + energy. So far, hydrogen is primarily produced from fossil resources and catalysts. Catalytic electrolysis will be of particular interest only if the energy needed to dissociate water in hydrogen and oxygen is produced by low heat-producing renewable sources of electricity (Gardner, 2009). What is presently missing to decide whether a source of energy is better than another relative to AHR is a heat-cycle assessment from cradle to grave, as it is currently done with life-cycle assessment to compare processes and materials that impact the environment (Muralikrishna & Manickam, 2017). So far, it seems that no quantitative information is available relative to heat-cycle of wind turbines and of other CO2-free sources of electricity in comparison with the other sources of energy in terms of thermal impact on the climate. Hydro-electricity may be of particular interest in this regard. However, one can wonder whether large enough amounts of hydrogen will be producible from CO2-free sources of energy. It will be the task of specialists in thermodynamics working together with climatologists and chemists to make the necessary assessments.