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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 megawatt(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 eosynchronous(与地球同步的)orbit. Earth-based solar cells, by contrast, can only collect sun light during daytime and when skies are clear.
But space-based solar power must grapple(努力克服)with the high cost per kilo-gram of launching things into space, says Richard Schwartz of Purdue University in West Lafayette, Indiana. "If you"re talking about it being economically viable or power of the Earth, it"s a tough go." he says.
Cal Boer man, 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 minors 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 Boer man 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.

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

单选题 Solaren is going to design 200 solar-power satellites.

单选题 Space-based solar cells could collect solar power only when skies are clear.

单选题 One advantage of space-based solar power system is that it is economical.

单选题 Inflatable mirrors are used to reduce the space-based solar power system.

单选题 Space-based solar power will rule out other forms of renewable energy sources.

单选题 Many countries will grant permission for the use of spaced-based solar power soon.