USA

But not without government help(see story,page 52).Nevada Solar One would never have been built if the state had not set a deadline requiring utilities to generate 20 percent of their power from renewable sources by 2015.(More than two dozen states now have"renewable-portfolio standards,"and earlier this year Congress was debating a federal one.)During peak demand-a hot afternoon in Las Vegas,when production costs are highest-the solar plant´s electricity is almost as cheap as hot of its gas-fired neighbor.But that´s only because a 30 percent federal tax credits helped offset its construction costs.Aiming to bring down costs and reduce the need for incentives,NREL´s engineers are studying mirrors made from lighweight polymers instead of glass and receiving tubes that will absorb more sunlight and lose less heat.They´re also working on solar power´s biggest problem:how to store some of the heat produced during daylight hours for release later on."In the Southwest particularly,peak loads are in the daytime,but don´t end when the sun goes down,"said Mark Mehos,an NRELprogram manager.People come home from work,turn on lights and air conditioners.Before long they may be plugging in electric cars.Last year the first commercial solar plant with heat storage opened near Guadix,Spain,east of Granada.During the day,sunlight from a mirror field is used to heat molten salt.In the evening,as the salt cools,it gives back heat to make more steam.In Arizona the Solana Generating Station will also use molten salt for storage.When it goes on line in 2012,three square miles of parabolic troughs will produce 280 megawatts for Phoenix and Tucson.Solana is being built by aSpanish company,Abengoa Solar-and indication of just how far,in the development of this technology,the United States has fallen behind.Jätkub...Ainult lollakad ostavad elektrit...sest elektrit saab tasuta!