National Geographic : 2005 Aug
PANELS COVERING LESS THAN AQUARTER OF THE ROOF AND PAVEMENT SPACE INCITIES AND SUBURBS COULD SUPPLY THE U.S. WITH ALL ITS ELECTRICITY. will paint the particles onto a foil-like material, where they will self-assemble to create a semi conductor surface. The result: a flexible solar-cell material 50 times thinner than today's solar panels. Roscheisen hopes to sell it in sheets, for about 50 cents a watt. "Fifty cents a watt is kind of the holy grail," says David Pearce, president and CEO of Mia sole, one of many other companies working on "thin-film" solar cells. At that price solar could compete with utilities and might take off. If prices continued to drop, solar cells might change the whole idea of energy by making it cheap and easy for individuals to gather for themselves. That's what techies call a "disruptive technology." "Automobiles were disruptive to the horse and buggy business," Dan Shugar says. "PCs were disruptive to the typewriter industry. We believe solar electric systems will be disruptive to the energy industry." Yet price isn't the only hurdle solar faces. There are the small matters of clouds and dark ness, which call for better ways of storing energy than the bulky lead-acid batteries in my system. THE COST OF A KILOWATT-HOUR Solar power will remain expensive for some time, as shown in a comparison of energy prices calculated for new plants coming online in 2013. But the cost of solar should fall as technology improves. But even if those hurdles are overcome, can solar really make the big energy we need? With solar now providing less than one per cent of the world's energy, that would take "a massive (but not insurmountable) scale-up," NYU's Hoffert and his colleagues said in an article in Science. At present levels of efficiency, it would take about 10,000 square miles of solar panels-an area bigger than Vermont to satisfy all of the United States' electricity needs. But the land requirement sounds more daunting than it is: Open country wouldn't have to be covered. All those panels could fit on less than a quarter of the roof and pavement space in cities and suburbs. WIND: FEAST OR FAMINE Wind, ultimately driven by sun-warmed air, is just another way of collecting solar energy, but it works on cloudy days. One afternoon I stood in a field near Denmark's west coast under a sky so dark and heavy it would have put my own solar panels into a coma. But right above me clean power was being cranked out by the megawatt. A blade longer than an airplane wing turned slowly in a strong south breeze. It was a wind turbine. The turbine's lazy sweep was misleading. Each time one of the three 130-foot blades swung past, it hissed as it sliced the air. Tip speed can be well over 100 miles an hour. This single tower was capable of producing two megawatts, almost half the entire output of the Leipzig solar farm. In Denmark, turning blades are always on the horizon, in small or large groups, like spokes of wheels rolling toward a strange new world. Den mark's total installed wind power is now more than 3,000 megawatts-about 20 percent of the nation's electrical needs. All over Europe gener ous incentives designed to reduce carbon emis sions and wean economies from oil and coal have led to a wind boom. The continent leads the world in wind power, with almost 35,000 megawatts, equivalent to 35 large coal-fired power plants. North America, even though it 18 NATIONAL GEOGRAPHIC * AUGUST 2005 Iai ;9- "- 3"