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"In the 'organic' Rankine cycle, you use organic fluids," he explains, such as liquid propane, which changes based on the temperature. As with large-scale concentrating solar thermal plants, sun-tracking mirrors in Sopogy's technology focus sunlight on a container of fluid. As the fluid flashes to gas, it spins a turbine. While batteries store electrons, a Sopogy collector simply stores heat, "like a thermos," says Kimura, so the miniature solar collector can extend the solar day and generate power through the vog. "Storing thermal energy is cheap, and the system lasts for 30 years."
A typical Sopogy unit weighs 150 pounds, measures about 12 feet by 5 feet and puts out 250 kilowatts at 392 degrees Fahrenheit. The unit doesn't even need flat land: Sopogy has tucked a 1-megawatt system into four lava-encrusted acres at the Natural Energy Laboratory on the Big Island. Kimura tells only potential clients the full price of the system, but he promises that a Sopogy collector can generate electricity at 20 cents per kilowatt-hour, 10 cents less than photovoltaic solar. As with photovoltaics, that cost will drop as manufacturing scales up.
Kimura is a slightly built 34-year-old, who looks even younger in person. But he's studied energy ever since his parents helped build Hawaii's space observatories, putting their son to work wiring the utility substations that powered the telescopes. At an early age, he realized that his state had energy problems.
"We can't build more power plants, but we've had a soaring demand for power," he says. "I had an incentive early on to care about efficiency."
Later, he worked on a voltage-regulation device that would even out loads from distributed generators across small local grids. In Portland, Ore., in the 1990s, he helped the federal government develop efficiency standards for Energy-Star appliances.
Nine years ago, Kimura came back to Hawaii to apply his expertise to the state's peculiar energy problems. Hawaii has long been nearly 100 percent dependent on oil, but Gov. Linda Lingle has set an ambitious goal of securing 70 percent of the state's energy from renewables by 2030.
"We have a very limited amount of land and unique conditions," Kimura says. "We need to use our local resources. We needed to do something conventional and simple, something a plumber could understand, because you can't fly a consultant in from California every time you have a problem."
Because a Sopogy system is "just metal and a steam turbine," Kimura says, it's possible to "manufacture them in an automotive parts factory with the same equipment, the same press, the same laborer who once made the car frame window."
The Hawaiian government has given Kimura $10 million to fund more research, and the vice president of the state's major utility, the Hawaiian Electric Co., has been an enthusiastic backer. With recent publicity about large concentrating solar plants in California's Mojave Desert, requests for quotes from Sopogy have gone from one a month to 15 a week. Kimura has tested the system in Abu Dhabi, in Washington state and in Spain. This summer, the company will install 50 megawatts of solar power spread over several small installations in Toledo, Spain.
Kimura's system is not the only way to get small-scale non-photovoltaic electricity from the sun. An Arizona company called Stirling Energy Systems has built six 25-megawatt solar generators using engine technology originally invented by Robert Stirling, a Scottish minister, in 1816. Mirrored dishes focus the sun's heat on hydrogen gas, which turns small electric generators as it expands and contracts. The gas never escapes or runs out; it's not being burned so much as put to work.
But Stirling is thinking big: The company has contracts with both Southern California Edison and San Diego Gas & Electric to supply 1,600 megawatts of power in installations of 300 megawatts or more by 2012, backed by $100 million invested by an Irish developer in April 2008. But that sum represents less than a 20th of the system's estimated cost, and the technology has yet to be demonstrated on such a large scale. In poor developing countries, though, with few capital reserves, small concentrating solar generators have already been deployed by the Solar Turbine Group of Cambridge, Mass. The nonprofit has installed two such systems, one and three kilowatts each, to provide electricity and hot water to rural villages in the Southern African country of Lesotho. More will follow.
Big business obstacles
A few years into deregulation in California, when people were getting stranded in elevators and produce rotted in coolers during blackouts, distributed energy seemed once again to be the wave of the future. The push toward small and local began when the state partially deregulated the electricity markets in 1996; it continued on through 2000, when the Public Utilities Commission established uniform statewide standards for distributed systems to connect up to the grid.
Yet for all the technologies that have sprung up around that effort, from microturbines to photovoltaics poured into shingles, California's major investor-owned utilities have not exactly encouraged their customers to invest in their own small generators. Indeed, as former state Energy Commissioner John Geesman put it two years ago, "There's an ongoing schizophrenia in state energy policy between what we say we want to do and what we actually allow to happen." Eloquent state reports hail the advantages of distributed energy, but the state regulates utility profits in such a way that customer-owned generation shrinks utilities' earnings. The current rules make a $700 million steam-generator replacement at a nuclear power plant, or a $2 billion transmission line, appear to be sound investments, because the utility can bill customers for their cost and upkeep.
"Large utility-owned power plants, transmission and distribution lines, electric and gas meters all contribute to the revenue stream (of investor-owned utilities)," says Bill Powers, an electrical engineer and energy consultant in San Diego, Calif. "The more a utility owns, the more it earns."
The profit is not trivial: The California Energy Circuit reports that Pacific Gas & Electric chief executive Peter Darbee earned $8.7 million last year, 5 percent more than the year before, despite a reported $79 billion in average annual losses due to blackouts.