segunda-feira, maio 05, 2008

Solar Thermal Electicity

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Up, Down.
See previous: May Day.

aka Concentrated Solar Power (CSP)

Nevada = 110,567 sq mi, 92 x 92 = 8,464 = 7.6%
Gigaton Gt = 10(9) tons, =1,000,000,000 tons = 1 billion tons.

"I said, 'That's the best news
That I've ever heard.'"

     Bob Dylan, Isis.

Because ... because ... because ... maybe later on I will explain, not right now ...

Solar Thermal at Wikipedia.
Out of Africa: the Riddle of Solar Electricity.
Ausra Makes Solar Thermal Simple and Cheap.

Solar Thermal at Wikipedia.

Out of Africa: the Riddle of Solar Electricity, IEEE, Spectrum Online.

One of the hottest new approaches to generating electricity today is "solar thermal," a form of capturing sunlight in order to convert water into steam, which in turn drives a conventional electricity-producing turbine. Solar thermal, as a concept, has been around since the 19th century, but in recent years the technology has undergone a revolution, helped by new designs and materials.

I visited last week with Ausra, one of the leaders in the solar thermal revival. Founded by an Australian inventor named David Mills, the company moved from Australia to Palo Alto, California a few years ago at the urging of legendary Silicon Valley financier Vinod Khosla who believed the company would thrive with more capital and the prospect of partnerships with American electric-utilities.
Khosla's vision seems to be coming true. Ausra specializes in providing large-systems to electricity grids and last year the company struck a deal to build a solar thermal plant for PG&E.

The PG&E plant remains years away from generating electricity but Ausra is already getting inquiries from all over the world. The key selling point: national electricity grids, suffering from shortages, can immediately benefit from solar thermal.

While India and China have the greatest needs for electricity going forward, sub-Saharan Africa is suffering from an unprecedented shortage, with South Africa -- the region's biggest economy -- suffering the most. Solar thermal as a technology would seem ideal for sub-Saharan Africa.

Indeed, Ausra is fielding requests from African governments and electricity companies -- and giving a stock answer, John O'Donnell, an executive vice president for the company, told me.

The answer to the Africans is "be patient."

"We're just saying we want to get proven in the U.S. before we take the next step," he says. "We don’t want to get overstretched."

For Africa, with its difficult business and geographic conditions, "you want well-proven systems," O'Donnell says.

"But once some of the technical risks are taken out and we're more experienced, solar thermal is clearly going to be part of the solution to Africa's electricity needs."

Ausra's approach -- providing electricity to a national grid -- runs counter to virtualy all of the current solar approaches in Africa, which is why solar thermal as a technology is worth watching closely. At present, solar in Africa is very small-scale and most often deployed at the level of villages (that are off the grid) or individual homes or buildings in cities (where excess electricity is not even fed back into the grid).

The trouble with these small solar systems is that they are costly, and especially so relative to the electricity generated.

O'Donnell describes proponents of small, off-grid solar in Africa as "romantic dreamers." He thinks the main show in solar should move away from simplistic notions about rural self-sufficiency and instead concentrate on helping to fill the growing demand in African cities for electricity.

Until now, solar in Africa has been dominated by romantics. O'Donnell predicts that will change. "Every African country is looking at solar thermal," he says. "The question is the maturity of the technology, over the next five years, we should begin to get the answers that Africans want to hear."

Ausra Makes Solar Thermal Simple and Cheap, Tekla S. Perry, IEEE Spectrum, May 2008.

Photo: Ausra
FLAT, CHEAP, AND UNDER CONTROL: Ausra’s steerable flat mirrors focus sunlight on a tube to make steam for a generator.

A start-up decades in the making may accelerate the solar-energy revolution.

Solar-thermal power has never seemed as technologically smart as photovoltaic technology. After all, a Neanderthal man could warm himself in the sun, but it took Einstein to explain the photoelectric effect.

But these days the idea of using sunlight to heat fluids to generate electricity is suddenly looking like a bright idea. At least 10 solar-thermal power plants are being developed for installation in the United States, and another 17 are under construction or being planned in Algeria, China, Egypt, Israel, Mexico, Morocco, South Africa, and Spain. With a typical plant generating somewhere between 50 and 500 megawatts, that's a lot of clean power due to come online. (New photovoltaic installations worldwide totaled a record 2826 MW in 2007, according to Solarbuzz.)

There are lots of ways to build a solar-thermal system, parabolic troughs or dishes being the most familiar. But a former Australian academic, David Mills, founder of the solar-thermal firm Ausra, in Palo Alto, Calif., thinks he has a better idea, and at least one major utility—Pacific Gas & Electric, in San Francisco—agrees. In November, the utility signed an agreement to purchase power generated by a 2.6-square-kilometer 177-MW power plant Ausra is building in the Nevada desert. Ausra says it has many more such deals in the works.

Mills's design, called the Compact Linear Fresnel Reflector, uses much less land than others. The mirrors appear to be solid but are actually made up of many smaller, movable reflectors, each with a slight curve. The system uses nearly flat mirrors at ground level that focus the sun's light onto water-filled steel tubes. When the water boils, it directly drives a steam turbine to generate electricity. Typical solar-thermal systems use heat transfer; water- or oil-filled tubes pass the heat to another system, which then boils water to drive steam turbines.

“I have a favorable opinion of [Ausra's] technology, largely because of the relative simplicity of manufacturing flat mirrors compared with parabolic mirrors. Also, because the mirrors are closer to the ground, they are less subject to wind loads,” says Michael Locascio, a senior analyst with Lux Research, in New York City.

Last April Ausra powered up the production line at a 12 000-square-meter manufacturing plant in Nevada. It's the first facility in the United States dedicated to producing the components of solar-thermal systems, including reflectors, towers, and specially insulated steel tubes. The new factory can build enough equipment to fill more than 10 km2 with solar-thermal collectors annually, enough to produce 700 MW of power or to power 50 000 homes. Eventually, Mills expects Ausra to sell equipment to others; for now, Ausra will consume the output.

Ausra sounds like a young company on the fast track, and in a way it is. It got its first round of venture capital financing last year—US $43 million. But in another way, Ausra's been slowly building for decades. Mills has been working with solar energy since the 1970s. Back then he was a principal research fellow at the University of Sydney, doing work in optics. There he started a research program to develop advanced coatings for evacuated-tube solar collectors, cleverly constructed glass tubes that let solar energy in but don't let heat out. Today his tubes are widely used in water heaters in China.

In 2006, John O'Donnell, a serial technology entrepreneur, contacted Mills. At first Mills told him, basically, to get lost. But O'Donnell was persistent, and in October of that year, he convinced Mills to come to California for a meeting with venture capitalists. Just three months later, Mills left the house in Sydney where he'd lived for more than 20 years and moved to Palo Alto; his wife and children followed a month later.

These days he heads up R&D for Ausra; until recently he ran the company's engineering efforts as well. “I'm 61,” he says. “It's a bit late in life to do a start-up, but when you work at something all your life, you do hope something comes of it and that you can influence change.”

Ausra Web Site.