Power line gambles on the sun

By: DAVE DOWNEY - Staff Writer | Saturday, September 23, 2006 9:47 PM PDT ∞

A San Diego utility's campaign to obtain permission from a state agency to build a 150-mile power line across the backcountry of San Diego and Imperial counties hinges in large part on a huge gamble, project opponents and energy analysts say.

The gamble is that a Phoenix company's plans for a massive solar power plant in the Southern California desert, unlike anything the world has seen up to this point, will be successful.

It seems no one doubts the potential of the blazing Imperial Valley sun to someday light homes and power air conditioners in San Diego County and southern Orange County ---- the service territory of San Diego Gas & Electric Co. ---- more than 100 miles away.

But there is considerable doubt about Phoenix-based Stirling Energy Systems' ability to deliver on its promise to complete a 300-megawatt power plant by the middle of 2010 ---- when SDG&E hopes to begin moving electricity toward the coast along its $1.3 billion Sunrise Powerlink transmission line.

The problem is, Stirling is trying to do something that no one's done before.

The nation's only large-scale solar plant, a 354-megawatt generator built in the 1980s at Kramer Junction in the Mojave Desert near Barstow employs a different technology. And the technology Stirling proposes has been employed only at the U.S. Department of Energy's Sandia National Laboratories in New Mexico.

There is an enormous difference in scale between the New Mexico project and what Stirling is planning.

In New Mexico, there are a half-dozen experimental solar dishes. In the Southern California desert, Stirling wants to build 12,000 of them in the first of three project phases, and ultimately 36,000 dishes that would collectively generate 900 megawatts. A megawatt is the standard yardstick for measuring electricity and generally is what it takes to power 750 to 1,000 homes.

"That's a huge leap," said Herb Hayden, solar technology coordinator for Phoenix-based Arizona Public Service Co., Arizona's largest electric utility, which, like SDG&E, is hoping to capitalize on a large-scale solar plant in that state one day. He has studied solar plants for 15 years.

"Even if they are successful, which is possible, I can't see how they could move that quickly without creating a lot of problems that they would have to solve along the way," Hayden said.

It is not so much a question of whether thousands of Stirling-style solar dishes would generate power, he said. Rather the question is whether those thousands could operate for long periods without breaking down and requiring expensive repairs, and could become a profitable venture.

The crown jewel


The problem is that Stirling is blazing a trail in a very competitive power generation industry, said Scott Anders, research and administrative director for the Energy Policy Initiatives Center at the University of San Diego.

"There's not much of a track record here to look at," Anders said.

A top Stirling official, however, sought to alleviate concerns in a telephone interview from Phoenix last week.

"I think we've got an awful lot of traction and there is a high probability that this plant will be built," said Robert B. Liden, Stirling's executive vice president. "I don't think we're being naive about it. We're building our whole business around our high confidence level that this technology will in fact work."

The Stirling project is often mentioned in conjunction with the Sunrise transmission line proposal, and it was the subject of extensive discussion by power-line supporters and opponents alike at a Ramona hearing earlier this month.

"We are not hanging our hat exclusively on that particular strategy," Stephanie Donovan, a spokeswoman for SDG&E in San Diego, said of the solar plant. "However, it is the crown jewel of our plan to bring renewable energy to San Diego. It is going to be the largest solar project in the United States, if not the world, when it is built out."

SDG&E is proposing to string 500-kilovolt wires from towers as tall as 160 feet along a route that would meander north and west for 150 miles, from El Centro through Warner Springs, Ramona and Rancho Penasquitos to an existing electrical substation in Carmel Valley.

The wires would create what opponents have called an unwelcome metallic skyline for rural residents and some urban dwellers, though there are plans to bury sections in the San Diego Country Estates and Rancho Penasquitos.

The Powerlink project would deliver 1,000 megawatts of electricity, roughly one-fourth of what the utility's consumers use on the hottest of summer days. The utility maintains the extra power is needed to shore up a forecasted regional shortfall early next decade.

The utility also says the line is needed to open a way for tapping nonfossil-fuel power plants in the works in Imperial County, including Stirling's project. SDG&E and other major California utilities face a state mandate of obtaining a fifth of their power from such so-called renewable sources by 2017.

Concentrating the sun's heat


Project opponents do not dispute the need for more electricity and a reduced dependency on fossil fuels. But they say there are less expensive, less environmentally destructive ways to plug the electricity gaps. And opponents say there is plenty of opportunity to build plants within San Diego County that are powered by solar, wind or other nontraditional energy sources.

The Stirling project's initial phase does not depend on the larger, Sunrise transmission line being in place, Liden said. That's because Stirling plans to build an eight-to-10-mile-long, 230-kilovolt line to connect its plant with the Imperial Valley Substation near El Centro.

He said the firm plans to deliver the plant's initial 300 megawatts over the existing Southwest Powerlink transmission line that runs from El Centro to San Diego along Interstate 8.

Liden said construction on the initial phase is scheduled to get under way by fall 2008 and wrap up by the end of 2010.

However, phases two and three, expected to add 300 megawatts apiece and be completed by late 2012 and late 2014 respectively, will require a new line for delivery to the San Diego County market, he said.

Liden said each phase is expected to cost $500 million. The plant is to be built on 5 acres of mostly federal Bureau of Land Management property and partly private land, about 10 miles north of El Centro.

Stirling isn't stopping there. The Phoenix firm has signed a contract to build, by 2012, a 500-megawatt solar plant east of Barstow for Southern California Edison, which supplies electricity to several counties, including Riverside.

Before Stirling builds either, it intends to fire up a 1-megawatt demonstration plant with 40 solar dishes near Barstow by late spring 2007 to test whether its model is ready for prime time, Liden said.

The dishes employ a technology adapted from an engine the Rev. Robert Stirling patented in Scotland nearly two centuries ago.

Each 38-foot-diameter solar dish is built around 82 rectangular, slightly curved mirror facets that focus the sun's energy onto an engine, heating an array of small steel tubes filled with hydrogen, Liden said.

"So you get this huge concentrating of solar heat," Liden said, saying the heated, expanding gas pushes pistons up and down to generate electricity.

Kicking the tires


However, one of the biggest headaches, said Hayden, is the tendency for engine seals to leak hydrogen. Such leaks can damage equipment and put them out of commission, he said.

Liden countered that experimental use has shown that seals require replacing about once every 21 months, he said.

And if one of the dishes were to break down, he said, it would turn off automatically. Because each dish operates independently, the rest of the plant would continue operating.

"Like Christmas tree lights, if one breaks, that light goes out, but the rest of the tree is still lit," Liden said.

Technology aside, Liden said Stirling has secured top-of-the-line steel, glass and construction companies to build the Imperial Valley plant and has attracted deep-pocketed investors. He said the steel contractor is Phoenix-based Schuff Steel, which helped build the new Arizona Cardinals stadium in Glendale, Ariz.

Whatever the case, Sunrise opponents remain skeptical about the solar project, which was announced this time last year.

"We've had a year to kick the tires on Stirling, and the tires don't appear to be solid at all," said Bill Powers, a San Diego engineer and activist who opposes Sunrise Powerlink.

"I believe that I am looking at a bait and switch," Powers said.

By that Powers said he meant SDG&E was using the solar plant to increase chances the California Public Utilities Commission will give it the green light to build Sunrise, when it issues a decision in late 2007. Powers suggests SDG&E is positioning itself to bring in power from other places, such as parent company Sempra Energy's natural-gas-fueled power plant in Mexicali, if the Stirling project collapses. SDG&E has repeatedly denied that assertion.

"I wish as much as anyone that Stirling was real," he said. "It is the right thing to do to fill that (power) line with renewable energy. But they're not going to do it."

Contact staff writer Dave Downey at (760) 740-5442 or ddowney@nctimes.com.

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