News Blog

Ausra, a solar thermal specialist from Australia, on Thursday said it will try to build solar power plants in the U.S. over the next seven years that collectively will generate a gigawatt worth of power. Three hundred megawatts worth of that capacity is already committed to FPL Group, a utility concentrated in Florida, according to Ausra.

Another likely customer is Pacific Gas & Electric. The California utility has committed to signing contracts for a gigawatt worth of solar thermal power over the next five years. PG&E is talking to a number of solar thermal companies about this, including Ausra.

These plants, along with the other solar power plants in the planning stages, will greatly expand the footprint for solar thermal power. Solar thermal plants concentrate sunlight onto mirrors to collect heat, and then use the heat to create steam or gas from an enclosed liquid. The pressure from the gas then turns a turbine to create electricity.

The biggest solar plant in the world right now, in California's Mojave desert, can generate around 354 megawatts. It was built 22 years ago. Acciona Solar Power earlier this year inaugurated the first solar thermal plant in over a decade anywhere in the world. It sits outside of Las Vegas.

Large plants--like the 300 megawatt plant Ausra will build for FPL--could also help bring down the cost. Right now, solar thermal power costs more than regular power from gas or coal-burning plants. But scientists, venture capitalists and analysts have said that solar thermal plants can be comparable in cost if built large enough. The rough estimate is that a 500 megawatt solar plant, or a couple of 300 megawatt solar plants built close to each other, could be comparable with traditional electricity. The cost projections, however, all vary according to environmental conditions, proximity of large cities to the power plant and construction costs.

Utility company Southern California Edison is erecting a 500-megawatt plant scheduled to open in 2009.

Large conventional power plants can often put out around 500 megawatts.

Besides building large power plants, Ausra, which recently raised $40 million, says it can cut the costs in other ways. Unlike a lot of solar thermal companies, Ausra doesn't used curved mirrors to collect sun or oil to fill its heat collectors. Instead, it uses cheaper flat mirrors and water.

Earlier this month, Ausra CEO Peter Le Lievre told an audience at the Going Green conference that a solar thermal plant in the desert measuring 92 miles by 92 miles built with his company's technology could provide all of the electricity in the country.

"We are more than two times more efficient when it comes to land," he said. "We are at 10 cents a kilowatt hour today," he said. With mass manufacturing, we will fall below gas (natural gas plants) and beat coal."

The company is currently trying to get a permit to build a 175-megawatt plant in California that would take up a square mile.

Of course, this could all change. Utilities are buying solar thermal because of state mandates. Ausra also faces several competitors.

The Solar Turbine Group is trying to bring refrigeration to emerging nations by harnessing the power of the sun.

The organization, which consists largely of MIT alumni, has devised a solar thermal generator that can be brought to market for $12,000 or less. A typical system can generate 600 watts of electricity or 20 kilowatts of energy for heating and cooling, according to Sam White, director for STG. The same system can also produce both at the same time, albeit less of each.

Parabolic mirror for capturing the sun

(Credit: Solar Turbine Group)

Like other solar thermal systems, STG uses mirrors. Mirrors concentrate heat from the sun onto a tube filled with a liquid (in this case glycol). The heat from the liquid can then be used in two ways. One, the heat can be transferred to another liquid. The second liquid gets vaporized and ultimately gets used to turn a turbine to create electricity.

Two, heat from the glycol can be used to boil refrigerant.

Although many villages in emerging nations don't have electricity, a lack of refrigeration is perhaps a more dire problem. Without refrigeration, food-borne diseases spread more rapidly. Farmers also can't store their crops in hopes of getting a better price, noted White. Thus, something like this could help improve health and local economies.

One reason the Northern Hemisphere (in my mind) moved ahead of the Southern Hemisphere is that the people there had to only figure out heating, a relatively straightforward process, rather than cooling. (I came up with that idea one day in Malaysia after walking into an air-conditioned Burger King after four hours in the midday sun.)

Hawaii's Sopogy is marketing similar devices in developed countries.

The company has installed a few prototypes in Lesotho and wants to put some in India. What has the group learned? That they have to show locals applications where and how the generator can be used. Locals just don't come up with the ideas on their own at first. "That was probably the most useful insight," he said.

The low cost comes in part because many of the parts required to build one of its solar generators are actually old car parts, White said. There's another problem solved: putting salvage to good use.

(Credit: Ausra)

DAVIS, Calif.--Ausra CEO Peter Le Lievre says it will only take a little bit of desert to light up the United States.

Ausra has developed technology for converting heat from the sun into electricity. The trick is that it's far more efficient, the company claims, than traditional solar thermal technologies from companies such as Solel and Acciona.

The process works as follows: Water goes into a tube that sits over an array of flat mirrors in the desert. By the time it gets to the end of the tube, the water turns to steam, which then turns a generator. Ausra can use water, rather than oil like other companies, because its tube can withstand high pressures. You can read more about Ausra here, including the $40 million the company got.

Le Lievre told an audience at the Going Green conference that a 92-mile square (92 miles a side, which works out to be a little less than 8,500 square miles) in the desert--a very small amount--could provide all of the electricity in the country. "We are more than two times more efficient when it comes to land," he said. Update: We originally gave the wrong dimensions for that land area. The numbers are now correct.

Ausra's system is also cheaper, he claims. "We are at 10 cents a kilowatt hour today," he said. With mass manufacturing, we will fall below gas (natural gas plants) and beat coal."

Those are big words. Solar thermal now costs about twice as much as regular electricity. Regular electricity goes for around 5 to 8 cents a kilowatt hour.

Ausra will have a chance to prove its case. The company, which wants to build a 175-megawatt plant in California that would take up a square mile, is getting the permits now and hopes to have it operating in three years.

Here's a convergence device you probably haven't heard much about at technology conferences, but it's interesting.

SolarAttic sells a system--the Pool Convection System 2--that sucks hot air out of the attic of your house and pumps it into a heat exchanger to heat your pool. In the summertime, the temperature in your attic can get up to 150 degrees Fahrenheit, says SolarAttic vice president James Kantorowicz.

A SolarAttic pool heater

(Credit: SolarAttic )

"It also helps cool down the house by transferring that heat out of the attic," he said.

The system costs around $5,000 (including installation), which makes it comparable to the better solar thermal pool heaters out there on the market. The solar thermal heaters--which gather heat from the sun with rooftop panels--will not cool off your house much, though, Kantorowicz adds.

Techincally, both systems do the same thing. in SolarAttic's case, it is harvesting solar energy from warmed air, and the energy is concentrated by the attic, but there's that additional benefit of getting the heat out of the home. But, unlike solar panel systems, SolarAttic's device needs an electric fan.

Of course, it won't heat your pool in the winter, but fewer people swim then anyway.

The single-fan unit you see there will heat a 75,000-gallon pool, he added.

Solar thermal is heating up.

Infinia, which makes a Stirling engine that can generate electricity or household heat by harvesting heat from the sun, has raised $9.5 million, the company said Thursday. Investors include Idealab and Khosla Ventures. As part of the deal, Infinia bought Stirling Cycles, one of Idealab's companies.

Stirling engines were invented in the 19th century as an alternative to steam engines. A Stirling motor has a closed cylinder that houses a gas, such as hydrogen, and a piston. Applied heat expands the gas to move the piston that, in turn, pumps other mechanisms, such as a crank, to create energy.

The Kennewick, Wash.-based company's main product will be a dish--which will look like a large satellite TV receiver--that will use the sun's heat to generate electricity. It can also generate heat.

The product is slated for final design later this year and commercial release in 2008.

Other solar thermal companies (also called concentrated solar power) use the sun's heat to warm oil in a closed tube. The oil is then used to create steam, which turns a turbine.

Some scientists and venture capitalists believe that electricity produced at solar thermal power plants can be as cheap as conventional electricity. Solar thermal plants, however, only work in dry, desert environments--like outside of Las Vegas or in the deserts of Algeria--and are quite large and expensive. Nevada Solar One, a recently inaugurated 64-megawatt plant, cost $250 million.