Can Sunshine Power the U.S.?

With growing concern over climate change, alternatives to coal and natural gas combustion have never looked better. Many fast-growing metro areas that happen to be heavy on electricity consumption, such as Las Vegas, Los Angeles, and Phoenix are located conveniently in sunny areas and are becoming increasingly interested in solar thermal technology. In fact, the first plant to be built in decades started providing 64 megawatts of electricity to the neon lights of Vegas this summer.

With few clouds, the American Southwest sun pours more than eight kilowatt-hours* per square meter of its energy onto the landscape. Vast parabolic mirrors in the heart of California's Mojave Desert concentrate this solar energy to heat a specialized oil to around 750 degrees Fahrenheit (400 degrees Celsius). This hot oil then transfers its heat to water, vaporizing it. The resulting steam turns a turbine to produce electricity. In all, nine such mirror fields, known as concentrating solar power plants, can supply more than 350 megawatts of electricity yearly.

However, physicist David Mills, chief scientific officer and founder of Palo Alto, Calif.–based solar-thermal company Ausra, has much bigger plans than just powering the southwest. He says that by concentrating the sun's power, we could provide all of the electricity needs of the U.S., including a switch to electric cars feeding off the grid. "Within 18 months, with storage, we will not only reduce [the] cost of [solar-thermal] electricity but also satisfy the requirements for a modern society," Mills claims. "Supplying [electricity] 24 hours a day and effectively replacing the function of coal or gas."

The company is positive that it can do this at a cost of just 10 cents per kilowatt-hour, similar to the price of electricity from burning natural gas in California—especially if a cost was imposed for the emission of carbon dioxide, the leading greenhouse gas, which the state's Public Utilities Commission is considering doing.

Ausra will rely on a different kind of concentrating solar power plant to deliver this grand development. French physicist Augustin Fresnel showed in the 19th century that a large lens, like the parabolic troughs of the existing solar-thermal plants, can be broken down into smaller sections that deliver the same focus. Mills' design applies this by using a compact linear Fresnel reflector, which allows for greater ground coverage, lower weight and greater durability than precision-shaped parabolic mirrors. They’re not fragile like some other solar technologies.
"You can drop stones on it and they bounce off," Mills says. "We would be able to build these in Florida in the hurricane zone."

This Fresnel solar thermal plant eliminates the need for super hot oil by directly heating water to a lower temperature of roughly 535 degrees F (280 degrees C) at a higher pressure, about 50 bars, or 50 times atmospheric pressure. Then, it uses the resultant steam to turn the same low-temperature turbines as those employed in nuclear reactors.

The amount of electricity produced is simply a function of sunlight and the number of mirrors. "We're moving from 80- to 100-megawatt designs to 700 megawatts and above," says John O'Donnell, Ausra's executive vice president.

Mills and his colleagues presented their calculations in a paper presented recently at the Solar Energy Society World Congress in Beijing. They say that solar-thermal power plants could match the electricity needs of both California and Texas. And, by combining a system that would meet the needs of California and Texas, solar-thermal plants could supply 96 percent of the national electricity demand. "The entire energy use of 2006, the current technology including storage would use a patch of land 92 miles by 92 miles," O'Donnell says. "Ten percent of the [Bureau of Land Management] land in Nevada is enough."

Ausra is planning to announce several partnerships by the end of the year and has already acquired the land to build one such solar-thermal plant at an undisclosed location in southern California. If its storage system works and proves cost-effective, Ausra might just help usher in a solar revolution.

"We have the ability to transition to a zero-carbon electricity future without moving the electricity price around," O'Donnell says. "That hasn't been part of anybodys conventional wisdom."

Posted by Rebecca Sato.

Related Galaxy Posts:

Our Energy Future: Space-Based Solar-Powered Lasers
Science + Business = Real Clean Energy Solutions
Will Salt Water Replace Fossil Fuels & Solve the World's Energy Crisis?
Green Energy Invention “Breaks the Laws of Physics”

Related blog posts:

http://blogs.business2.com/greenwombat/2007/09/solar-nation--2.html,
http://www.treehugger.com/files/2006/11/can_solar_power.php,
http://climate.weather.com/blog/9_13402.html

Story Link:
http://www.sciam.com/article.cfm?chanId=sa013&articleId=1FC8E87E-E7F2-99DF-3253ADDFDBEC8

Comments

[Jim]

Ethanol is quicker to market than solar,driling, or thermal.
In 6 months you have 1200 gals from one acre of unusable farmland.
The infrastructure is here now, no new tech,and less money to implement
We have 900 mil acres of unusable farmland. 5% of that would supply our transport needs.
Ethanol is what we need now.
More http://peswiki.com/index.php/Review:Alcohol_can_be_a_Gas

[brooks]

ethanol is not feasible as a long-term solution. sure, we don't have to drill for it, but it brings pollution problems all its own. if we're to go green, we should go GREEN, as in, low- to zero-emission technology: solar, wind, tidal, hydrogen, geothermal.

[nepharous]

This is the future. I agree that ethanol is unfeasable.

[George]

We need to get away from things we have to burn to create energy, and that includes ethanol. We have the technology right now to eliminate combustion-type energy sources forever, all it takes is the will of the people to demand it from their governments.

[Vegas Vic]

92 x 92 miles !? That's 8,464 sq miles. Vegas area is only 600 sq miles in area.
By the time environmentalists are through with you in court protecting the fringe-toed lizards & desert tortoises we'll be using dilythium crystals for power!

[EvilCosmicMonkey from Knoxville]

Indeed, we need to put fossil fuel on the shelf to gather dust. We don't have anymore dinosaurs to die & create petroleum, etc.

Solar power won't work outside the Sun Belt, or else it would be VERY limited in efficiency. I can't imagine the Grain Belt or Rust Belt being effectively powered by it for the long haul.

What about wind power or nuclear energy ? Nuclear is being made safer as an alternative.

What about solar satelites to " beam " energy from solar satellites down to specific points on earth ?

[Xellas]

Well John, it's because most people would have to take a second morgage to AFFORD that kind of setup. Also, in large areas of the country (The northeast in particular) there simply aren't enough bright, clear days to make significant headway against your electric bill.

That's why this setup is so exciting... BIG plants with very high efficiency could generate electricity in those areas that have the sun needed, and then just transmit that power across the grid to houses in areas that don't. If his system works even half as well as he claims, we could cut literally HALF our domestic coal/gas use out without raising the cost of electricity at all. That would dramatically slash the USA's carbon emissions, making us a leader in green tech.