The future of energy supply: where we are, where we should go

The massive exploitation of coal and conventional oil and natural gas has made possible an unprecedented improvement of the quality of life in some parts of the world during the last century. At present, still over 80% of the primary energy supply is provided by fossil fuels, but a series of physical, environmental and economic constraints is forcing us to plan a radically new energy system. A brief overview of presently available alternatives will be critically illustrated, with particular emphasis on unconventional fossil fuels and renewable energies, showing that the latter - and particularly solar energy - is the radical solution to the energy conundrum. The transition to a solar-powered world will be a long and difficult process [1,2] in which four key strategies have to be implemented: (1) increasing the share of electricity in energy end use [3]; (2) establishing technologies for the manufacturing of solar fuels [4]; (3) enhancing the efficiency in energy production and use [1,2]; (4) reducing the energy consumption in affluent countries. It will be further emphasized that the recycling of the equipment used for converting renewable energy flows must be dramatically increased, if we want to secure materials available in very limited supply (e.g. precious metals) also to future generations [5,6]. In this complex scenario, chemistry will play a prominent role in finding solutions, as it will be illustrated with selected examples, related to materials for solar energy conversion and efficient lighting technologies [7,8]. The energy transition compels the mobilization of huge human and economic resources in several scientific and technological fields, in connection to a knowledge-driven political action that must govern what is probably the most complex challenge ever faced by mankind. [1]N. Armaroli and V. Balzani, Energy for a Sustainable World. From the Oil Age to a Sun Powered Future, Wiley-VCH, Weinheim, 2011. [2]N. Armaroli, V. Balzani and N. Serpone, Powering Planet Earth - Energy Solutions for the Future, Wiley-VCH, Weinheim, 2013. [3]N. Armaroli and V. Balzani Energ. Environ. Sci., 2011, 4, 3193-3222. [4]A. Harriman Eur. J. Inorg. Chem., 2014, 573-580. [5]P. Nuss and M. J. Eckelman PLoS One, 2014, 9. [6]B. K. Reck and T. E. Graedel Science, 2012, 337, 690-695. [7]R. D. Costa, E. Orti, H. J. Bolink, F. Monti, G. Accorsi and N. Armaroli Angew. Chem. Int. Ed., 2012, 51, 8178-8211. [8]F. Monti, E. Pavoni and N. Armaroli, "Nanomaterials for Lighting and Solar Energy Applications", in Nano-Structures for Optics and Photonics, eds. B. Di Bartolo, J. Collins, and L. Silvestri, Springer, Dordrecht, The Netherlands, 2015, pp. 373-414.