Tuesday, February 05, 2008

Promoting solar in a big way

As the clean energy movement continues to gain traction and acceptance, a number of debates are brewing that threaten to drive wedges between some of its most staunch advocates. One divisive issue, the topic of yesterday's post, has to do with the very definition of "clean energy". Another issue is scale.

When I first became involved in what was then called the alternative energy movement back in the 1980's, the mantra was: "Small is Beautiful". The focus was on developing tools and strategies that were environmentally sound and could be deployed by either individuals and communities. That makes as much sense today as it did back then. If anything has changed it is the realization that big renewable projects are sometimes necessary and can be just as beautiful.

Solar energy has almost always been thought of as epitomizing the "small is beautiful" philosophy. Visions of photovoltaic (PV) solar panels on every available south-facing roof danced through every renewable energy enthusiast's head more than once.

Solar thermal technology works differently than PV. It converts sunlight to heat that can be used to do a variety of things including produce power, heat water for domestic or industrial uses, passively or actively heat space, or cool space with an absorptive cooling system. Many of these systems are being designed to operate at the multi-megawatt scale. The question is whether or not these projects can realize similar economies of scale as wind energy and generate power at competitive prices. (GW)

Stirling Energy takes on the solar power challenge

ALBUQUERQUE — When the sun breaks through the clouds here, solar dish No. 0 springs to action.

Like a giant sunflower, the mirrored face of the 40-foot dish will follow the sun continuously from east to west throughout the day, generating electricity for 10 to 15 homes.

The dish is a prototype for 70,000 that a small Phoenix company hopes to plant on two 7,000-acre solar farms in the California desert over the next seven years.

If fully built out, the two solar plants will be two of the biggest in the world. Together, they'd almost double the amount of solar energy produced nationwide, power 1 million Southern California homes and cleanly generate nearly as much electricity as two smog-producing coal plants.

"This is something that hasn't been done before," says Bruce Osborn, CEO of Stirling Energy Systems, the company doing the project. "We're not aware of any showstoppers. … No fatal flaws."

A 30-employee company that has sometimes struggled to make payroll, Stirling's success or failure will have global implications. States and nations want renewable sources of energy to reduce dependence on fossil fuels and to pollute less. Solar, the most expensive renewable energy, accounts for less than 1% of U.S. electricity generation.

But given high oil prices and increased concerns over global warming, anything solar is hot. Stirling's project also aims to commercialize a decades-old technology that is the most efficient at converting sun power to electricity but which has struggled with costs and reliability.

"They clearly have the technology. It's a matter of whether they can get the cost out," says Michael Niggli, chief operating officer of San Diego Gas & Electric, one of the customers Stirling hopes to supply.

Stirling's plans are ambitious. Skeptics, which include a co-founder who left in 2000, say the technology may be too costly to produce power at competitive rates.

Stirling's plans call for construction to begin in 2009 for two $1 billion farms on federal land in California's Mojave Desert northeast of Los Angeles and in the Imperial Valley east of San Diego. State and federal regulators still have to approve the plans.

In 2005, Southern California Edison and San Diego Gas & Electric, two of California's biggest utilities, signed contracts enabling them to buy all of Stirling's solar power for 20 years. The utilities have pledged to buy 800 megawatts annually with the possible addition of 950 more. Contract prices weren't disclosed, but Stirling officials have said they'd compete with what utilities pay for peak power. That's more than coal, which supplies half the USA's electricity, but less than most solar prices.

Stirling's technology is a type of solar thermal power, which uses mirrors to concentrate the sun's heat to drive a generator to produce power. The type of solar most people know is photovoltaic, in which rooftop panels use semiconductor materials that convert sunlight into electricity.

Solar thermal is well-suited to large-scale production on desert farms where the sun shines almost every day. Consulting firm Cambridge Energy Research Associates says it's likely to be the next high-growth renewable power in the USA. Nearly 5,000 megawatts may go online by 2020, Cambridge says, more than 10 times the amount produced today.

The most prevalent solar thermal technology is a "trough" system, in which hundreds of mirrored sun catchers feed one or a few engines.

Stirling Energy Systems' technology is different in that each mirrored dish is accompanied by its own engine. The Stirling engine was named after the Rev. Robert Stirling, a Scottish clergyman, who patented it in 1816 while seeking an alternative to steam engines with explosive boilers.

Technology dates to 1980s

Stirling Energy's dish system was initially developed by McDonnell Douglas in the mid-1980s before being sold to Southern California Edison. Edison sold the technology to Stirling Energy Systems, which was founded in 1996 to buy it, for less than $300,000, says Stirling co-founder David Slawson, 60.

The owner of a massage-therapy college in Oregon, Slawson says he was attracted to the cause of clean energy after waking up one morning, throwing open his window and coughing on fumes. Another Stirling co-founder was Harry Braun, author of The Phoenix Project: Shifting from Oil to Hydrogen, a book advocating that the USA shift away from fossil fuels.

Slawson, a political science major with no engineering background, spent much time recruiting investors. Sometimes, he says, cash was so tight he felt like "a robin needing to feed chicks" on paydays.

In 2003, Stirling attracted its biggest investor, Robert Nissenbaum, an organic foods pioneer and founding partner of Imagine Foods. "When I got involved, the company had a long way to go," says Nissenbaum, Stirling vice chairman, noting that lack of funds had delayed engineering progress. "Since then, we've slowly but surely gotten all the wheels in motion," he says. "We're cautiously optimistic." Stirling's chairman is Robert Clark, a former president of AT&T.

Osborn, 52, first worked on Stirling solar dish and engine technology as a 22-year-old engineer at Ford. He joined Stirling Energy Systems in 1999 but left in 2002. Market prospects for solar were dim then, he says, and the company wasn't raising enough funds to move forward. He returned in 2004, took the reins from Slawson the next year and watched interest in solar rise.

Osborn won't reveal much about Stirling's finances except to say that it's raised "tens of millions" over the years and that 2007 was its best fundraising year. He says the company has been "quietly perfecting" its technology with government engineers at Sandia National Laboratories in New Mexico, where dish No. 0 and five others have been running for two years.

Sandia and SES engineers have improved the dishes' design, squeezing out 40% of the steel and making them stronger. They've learned optimal spacing to minimize land use but maximize sun collection. The mirrors have survived lightning strikes and bullets.

Osborn agrees cost is Stirling's biggest technical challenge. Each hand-built test dish cost $225,000. That needs to drop to less than $50,000, Osborn says.

As an executive at Western Digital, Osborn oversaw products that went from prototype to high-volume manufacturing in a month. Stirling plans a "conservative" approach to dish construction, he says. It'll build two more at Sandia this year, two more next year, then 40 in the Mojave. Then, he plans to ramp up to 80 a month, then 80 a day.

Osborn says the modular nature of the system is part of its beauty. Largely built at the factory, each system could be erected in the field by a few workers within hours, he says. Improvements will be put into newer dishes as Stirling learns from older ones.

"It's not like you build the shuttle, launch it and it works or it doesn't," Osborn says. "Nothing will stop us cold in our tracks."

Outlook questioned

Whether Stirling can produce power at profitable rates remains to be seen. Its two utility customers expect their first power in 2010. Braun left Stirling to focus on wind technologies after losing faith that Stirling could compete. "It'll be way too costly," he says, given maintenance costs and the cheaper cost of generating power from wind.

Barry Butler, a materials science expert who several years ago worked for a Stirling competitor on a similar dish technology, said in written testimony to California energy regulators last year that technology like Stirling's, while promising, wouldn't likely be ready for mass rollout until 2020. He says maintenance will drive up Stirling's costs while rival solar technologies get better and cheaper.

Getting all of Stirling's power to consumers may also be difficult. For Stirling to get the 900 megawatts to San Diego Gas & Electric, the utility needs a new 150-mile transmission line. Like most power lines, it'll likely prove controversial. Southern California Edison needs to upgrade lines to add Stirling's power and what will be produced from new wind farms.

The utilities have agreed to pay Stirling so much, leaving it to Stirling to produce at a profit. Still, they benefit if Stirling succeeds. California requires retail sellers of electricity to secure 20% of their energy in 2010 from renewable sources to avoid possible penalties. The utilities also need power most on hot, sunny afternoons when Stirling's dishes will be at their peak.

"The sun is the 'great untapped resource,' says Southern California Edison's Stuart Hemphill, director of renewable and alternative power.

Osborn's heard the naysayers for years. He disputes Butler and Braun, noting that the company has made "substantial progress" since Braun left and since Butler worked on the competing system in 2002.

Of all the renewables, he says, solar will be the biggest.

"I guarantee there will be issues and challenges. But that's just part of business," he says.

At least with solar, "You don't have to worry about the fuel supply. It's free from the sky."


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