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."