Physics of the Future: How Science Will Shape Human Destiny and Our Daily Lives by the Year 2100

supply the bulk of energy for the world. At best, it will be an integral part of a larger energy mix. Wind power faces several problems. Wind power is generated only intermittently, when the wind blows, and only in a few key regions of the world. Also, because of losses in the transmission of electricity, wind farms have to be close to cities, which further limits their usefulness.
    HERE COMES THE SUN
    Ultimately, all energy comes from the sun. Even oil and coal are, in some sense, concentrated sunlight, representing the energy that fell on plants and animals millions of years ago. As a consequence, the amount of concentrated sunlight energy stored within a gallon of gasoline is much larger than the energy we can store in a battery. That was the fundamental problem facing Edison in the last century, and it is the same problem today.
    Solar cells operate by converting sunlight directly into electricity. (This process was explained by Einstein in 1905. When a particle of light, or a photon, hits a metal, it kicks out an electron, thereby creating a current.)
    Solar cells, however, are not efficient. Even after decades of hard work by engineers and scientists, solar cell efficiency hovers around 15 percent. So research has gone in two directions. The first is to increase the efficiency of solar cells, which is a very difficult technical problem. The other is to reduce the cost of the manufacture, installation, and construction of solar parks.
    For example, one might be able to supply the electrical needs of the United States by covering the entire state of Arizona with solar cells, which is impractical. However, land rights to large chunks of Saharan real estate have suddenly become a hot topic, and investors are already creating massive solar parks in this desert to meet the needs of European consumers.
    Or in cities, one might be able to reduce the cost of solar power by covering homes and buildings with solar cells. This has several advantages, including eliminating the losses that occur during the transmission of power from a central power plant. The problem is one of reducing costs. A quick calculation shows that you would have to squeeze every possible dollar to make these ventures profitable.
    Although solar power still has not lived up to its promise, the recent instability in oil prices has spurred efforts to finally bring solar power to the marketplace. The tide could be turning. Records are being broken every fewmonths. Solar voltaic production is growing by 45 percent per year, almost doubling every two years. Worldwide, photovoltaic installation is now 15 billion watts, growing by 5.6 billion watts in 2008 alone.
    In 2008, Florida Power & Light announced the largest solar plant project in the United States. The contract was given by SunPower, which plans to generate 25 megawatts of power. (The current record holder in the United States is the Nellis Air Force Base in Nevada, with a solar plant that generates 15 megawatts of solar power.)
    In 2009, BrightSource Energy, based in Oakland, California, announced plans to beat that record by building fourteen solar plants, generating 2.6 billion watts, across California, Nevada, and Arizona.
    One of BrightSource’s projects is the Ivanpah solar plant, consisting of three solar thermal plants to be based in Southern California, which will produce 440 megawatts of power. In a joint project with Pacific Gas and Electric, BrightSource plans to build a 1.3 billion watt plant in the Mojave Desert.
    In 2009, First Solar, the world’s largest manufacturer of solar cells, announced that it will create the world’s largest solar plant just north of the Great Wall of China. The ten-year contract, whose details are still being hammered out, envisions a huge solar complex containing 27 million thin-film solar panels that will generate 2 billion watts of power, or the equivalent of two coal-fired plants, producing enough energy to supply 3 million homes. The plant, which will cover twenty-five square miles, will be built in Inner Mongolia and is actually part of a much larger energy park. Chinese officials state that solar power is just one component of this facility, which will eventually supply 12 billion watts of power from wind, solar, biomass, and hydroelectric.
    It remains to be seen whether these ambitious projects will finally negotiate the gauntlet of environmental inspections and cost overruns, but the point is that solar economics are gradually undergoing a sea