Solar energy

Abstract

Every year the earth's surface receives about 10 times as much energy from sunlight as is contained in all the known reserves of coal, oil, natural gas and uranium combined. This energy equals 15,000 times the world's annual consumption by humans. People have been burning wood and other forms of biomass for thousands of years, and that is one way of tapping solar energy. But the sun also provides hydropower, wind power and fossil fuels - in fact, all forms of energy other than nuclear, geothermal and tidal. Technology will allow radiation from the sun to provide nonpolluting and cheap fuels, as well as electricity. It is unlikely that a single solar technology will predominate. Regional variations in economics and the availability of sunlight will naturally favor some approaches over others. Electricity may be generated by burning biomass, erecting wind turbines, building solar-powered heat engines, laying out photovoltaic cells or harnessing the energy in rivers with dams. Hydrogen fuel can be produced by electrochemical cells of biological processes-involving microorganisms or enzymes-that are driven by sunlight. Fuels such as ethanol and methanol may be generated from biomass or other solar technologies. At present, developed nations consume at least 10 times the energy per person than is used in developing countries. But the demand for energy is rising fast everywhere. Solar technologies could enable the developing world to skip a generation of infrastructure and move directly to a source of energy that does not contribute to global warming or otherwise degrade the environment. Developed countries could also benefit by exporting these technologies-if additional incentives are at all necessary for investing in the future of energy from the sun.