加州建世界最大的太阳能电厂

WASHINGTON — The world's largest solar thermal plant is set to go online in California by the end of the year. While wind and sun-generated energy are generally considered clean, unlike coal-generated energy, environmentalists now worry that large-scale solar development could harm fragile desert ecosystems.

Ivanpah is a field of mirrors, shimmering like a mirage in California's Mojave desert, about 60 kilometers southwest of Las Vegas. Joe Desmond is a senior official at BrightSource Energy, the company that's building the plant.

"This is actually one of the highest concentrations of sunlight in the world, out here in Ivanpah," explained Desmond.

The plant will deploy 170,000 heliostat mirrors to focus solar energy on boilers located on top of three power towers. The steam generated in these boilers will drive turbines to produce energy.

Desmond said the steam can reach temperatures of more than 260 degrees Celsius.

"We can store the sun's thermal energy in the form of molten salt, so we can produce electricity even when the sun goes down. There is a lot of interest in concentrating solar power around the globe in environments where you have lots of sun, such as China, South Africa, the Middle East, North Africa," explained Desmond.

Environmentalists generally support the idea of solar plants, but many want habitats like the one where Ivanpah is being built to stay intact.

"Even though the desert seems big, when you start cutting it up, it can really affect how the species and the animals and the plants are able to survive in the long run," said Lisa Belenky, senior attorney for the Center for Biological Diversity, a private advocacy group with offices in several U.S. states.

Belenky said some environmentalists are worried about the effect of the Google-backed Ivanpah Solar Project on the sensitive plant and animal life in this part of Mojave. BrightSource Energy has already spent more than $50 million to relocate the endangered desert tortoise, which lives in the area, but Belenky feels this is not the right solution.

"We should be reusing areas that have already been disturbed [like] old mining sites, for example... either on homes, on businesses, you can.... [place them] on parking lots," said Belenky, offering alternative locations for solar power collection.

Brightsource has already pre-sold energy to parts of southern California. It plans to start running the plant at the end of the year.