USA

BACK IN THE 1980s,an engineer named Roland Hulstrom calculated that if photovoltaic panels-the other big solar technology-covered just three-tenths of percent of the United States,a 100-by-100-mile square,they could electrify the entire country.People thought he wanted to pave the Mojave with silicon."The environmentalists got up in arms and said,You can´t just go out and cover a hundred miles square,"Hulstrom said recently as he sat in his office at NREL.But that´s not what he meant."You can cover parking lots with photovoltaic.You can put it on house roofs."Twenty years later,PV panels still contribute only a tiny amount to the nation´s electricity supply.But on rooftops in California,Nevada,and other states with good sunshine and tax incentives,they´re sight almost as familiar as air conditioners-and though not yet as developed as solar thermal,they may have a brighter future.Right now the panels are expensive,and they provide an efficiency of only about 10 to 20 percent,compared with the 24 percent of parabolic troughs.History more than physics is to blame.After the solar bust in the mid-1980s,many of the best engineers migrated to the computing industry,which uses the same raw material-silicon and other semiconductors.Following what is called Moore´s law,microprocessors doubled in capability every couple of years,while solar languished.Now some of the engineering talent is moving back to solar.Researchers at NREL are exploiting the fact that different semiconductors capture different colors from a beam of sunlight.Bylayering compounds called gallium indium phosphide and gallium indium arsenide and using a lens to concentrate sunlight,they built a PV cell last year that is 40.8 percent efficient(a world record,since broken).But it´s far from ready for mass production."The technology is incredibly sophisticated,"said ray Stults,an associate director of the laboratory."We can make it right now for$10,000 per square centimeter,but not many people are going to buy it."
Jätkub...
Ainult lollakad ostavad elektrit...sest elektrit saab tasuta!