Hot Times for Solar Energy

Fly into the surreal rainbow glow of the Las Vegas strip at twilight and it becomes clear why the state of Nevada has become a metaphor for the energy crossroads confronting the United States. The city’s hunger for electricity, like its visitors’ appetite for carnal indulgence, is insatiable; it is the seat of Clark County, the second fastest growing county in the United States. Nevada’s two public utilities project that the state will hit an electricity capacity shortfall of 2,100 megawatts by 2016 if more isn’t built.

The vision of a future powered by fossil fuels in one of the sunniest spots in the world strikes many people, including Harry Reid—majority leader of the U.S. Senate and a strong opponent of coal-fired plants—as ludicrous. Which is why Nevada has emerged not only as the biggest battleground over coal but the newest test bed for utility-scale solar thermal electricity. Its advocates believe it can and should become a large piece, along with other renewable-energy sources, of our energy future.

Solar thermal technology, also called concentrating (or concentrated) solar power (CSP), uses huge arrays of mirrors to focus sunlight and make steam to run a conventional turbine generator. The photovoltaic solar power systems used mostly on rooftops, in contrast, allow the energy of solar photons to create an electron flow using semiconductors. CSP provides “peak” power to feed the midday hunger for air conditioning and other loads, but with the addition of thermal storage CSP energy can also be banked for later use long past sundown. This could overcome one of the major obstacles to deploying solar power on a large scale.

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