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Solar energy conversion — The handy reference guide to solar energy

Do you want to know the potential for solar energy to solve our energy needs as well as eliminate greenhouse gas emissions? Bill McDonough closed his keynote lecture at GreenBuild 2006 in Denver with a comment about our (Earth’s) own nuclear power plant, 93 million miles away. Yes, of course it’s the sun.

A downloadable primer, well-written and illustrated, places the potential of the sun in perspective relative to our energy use and needs. It gives details not only of the potential applications of solar energy but also of the limitations. It places solar energy and its use on Earth in great perspective. Here are some excerpts from the article:

"The San Francisco 1906 earthquake of magnitude 7.8 released an estimated 1017 joules of energy, the amount the Sun delivers to Earth in one second."

"Earth's ultimate recoverable resources of oil, estimated at 3 trillion barrels, contains 1.7 x 1022 joules of energy, which the Sun supplies to Earth in 1.5 days."

"The amount of energy humans use annually, about 4.6 x 1020 joules, is delivered to the Earth by the Sun in one hour."

"The enormous power that the Sun continuously delivers to Earth 1.2 x 105 terawatts dwarfs every other energy source, renewable or nonrenewable. It dramatically exceeds the rate at which human civilization produces and uses energy, currently about 13 TW. "

The article nicely describes the potential for photovoltaics to satisfy our energy needs without greenhouse gas emissions. It discusses the various processes now being developed to increase the efficiency and lower the cost of photovoltaic energy, now far more costly than fossil fuels [ed: by human economic standards]. It also discusses the conversion of solar energy by plants and the potential use of the resulting “biofuels.”

For the scientifically inclined, the article is a thorough discussion of the fundamental physical processes involved. No resource we know of does such a nice job of putting solar energy in perspective. You can download the article for free from


Reference: Crabtree, G., and N.S. Lewis, 2007, Solar energy conversion. Physics Today, March 2007, 37-42. The article is available for free download here