California Gives Green Light to Space Solar PowerEnergy beamed down from space is one step

California Gives Green Light to Space Solar Power

Energy beamed down from space is one step closer to reality，now that California has given the green light to an agreement that would see the Pacific Gas and Electric Company buy 200 megawatts(兆瓦)of power beamed down from solar-power satellites beginning in 2016．But some major challenges will have to be overcome if the technology is to be used widely．

A start-up company called Solaren is designing the satellites，which it says will use radio waves to beam energy down to a receiving station on Earth．

The attraction of collecting solar power in space is the almost uninterrupted sunshine available in geosynchronous(与地球同步的)orbit．Earth-based solar ceils，by contrast，can only collect sunlight during daytime and when skies are clear．

But space．based solar power must grapple(努力克服)with the high cost per kilogram of launching things into space，says Richard Schwartz of Purdue University in West Lafayette，Indiana．“If you're talking about it being economically viable for power of the Earth，it's a tough go，”he says．

Cal Boerman，Solaren's director of energy services，says the company designed its satellites with a view to keeping launch costs down．“We knew we had to come up with a different，revolutionary design，” he says．A patent the company has won describes ways to reduce the system's weight，including using inflatable mirrors to focus sunlight on solar cells，so a smaller number can collect the same amount of energy．

But using mirrors introduces other challenges，including keeping the solar cells from overheating，says Schwartz．“You have to take care of heat dissipation(散发)because you're now concentrating a lot of energy in one place，”he says．According to the company's patent，Solaren's solar cells will be connected to radiators to help keep them cool．

Though Boerman says the company believes it can make space-based solar power work，it is not expecting to crowd out other forms of renewable energy．Laws in California and other states require increasing use of renewable energy in coming years，he points out．“To meet those needs，we're going to need all types of renewable energy sources，”he says．

Solar-power satellites will use radio waves to beam energy down from space．

A．Right

B．Wrong

C．Not mentioned