Solar fuels

Abstract

Global demand for energy is increasing at a fast rate especially in developing economies such as India, China, and Indonesia with heavy reliance on fossil fuels. The CO2 levels in the atmosphere have increased to over 400 ppm. This combined with increase in the intensity of other pollutants (NOx, SOx, CO, methane, particulate matter, etc.) in the atmosphere is a real concern for the environment. With the major objective of reducing concentration of greenhouse gases and other pollutants and to increase reliability and security of energy supply for a sustainable future, significant progress is being made in the development and deployment of technologies and processes around renewable energy with solar and wind playing a dominant role. However, solar energy is not available in high intensity all around the word and thus there is a need for transporting energy from one place to other. Solar fuels are energy carriers and means of transporting solar energy in the form of easily transportable fuels and these are generated by embedding solar energy in the form of heat or electricity or both in water, CO2, and fossil fuels. A number of different technologies and processes (electrolytic, solar thermal, solar thermochemical cycles, chemical looping, solar assisted reforming of natural gas, solar assisted coal/biomass gasification, photo-electrochemical, and photo-biological) for the production of major solar fuels (H2, CO, syngas, methanol, and ammonia) are briefly discussed and reviewed in this chapter.