E.F. Schumacher wrote Small is Beautiful 36 years ago, when political shifts in the Middle East suddenly awakened the world to the reality that its petroleum might not last forever. In the years that followed, we were supposed to start driving smaller cars, wearing cardigans in the house, plastering our rooftops with solar panels. Congress passed the Public Utility Regulatory Policies Act (PURPA) in 1978, requiring utilities to buy electricity from independent renewable generators at competitive rates. Millions of solar roofs were set to bloom.

But it didn't happen. Instead, cars got big again and the sweaters came off, along with the solar panels on Reagan's White House roof. And large, centralized fossil-fuel plants solidified their hegemony: Between 1980 and 1999 in the United States, 155 new coal plants came online. Photovoltaics and wind could not begin to compete with the price of electricity generated from coal. Consequently, PURPA did little to promote any kind of renewable energy except combined heat-and-power.

Coal's steady pulse of cheap electrons seduced us into doubting whether efficiency itself was worth the trouble. While a few states have followed California's lead in "decoupling" utility profits from electricity sales, for most of our electrical history, utilities made a profit per kilowatt-hour. Along with those profits came a parade of gadgets to encourage profligacy: electric can-openers and toothbrushes, garage-door lifters, dishwashers and air conditioners, all of them creating a need where there once wasn't even a desire. GE, as its slogan went, brought good things to life.

In an essay published in the 1983 book Nuclear Power: Both Sides, Amory Lovins described how French energy-efficiency planners in the 1970s figured out that most of their electricity went into heating buildings. Because France fueled almost all of its generators with oil, and oil supplies were suddenly in peril, efficiency experts started looking to other sources -- waste heat from on-site generators, passive solar, natural gas -- to warm the country's buildings.

At the same time, however, the country's energy supply planners, "who were far more numerous and influential in the French government," discovered nuclear power. By the mid-1980s, the country had more than 50 reactors, generating so much electricity that heating buildings with it didn't seem so wasteful anymore. In fact, "the only way they would be able to sell all that electricity would be for electrical heating."

Lovins' point was this: If you start at the consumer end, you can calculate how much energy we need to live and build what you need to supply it. If you start at the supply end, you predict future demand by adding numbers to the current demand. And you can only satisfy that demand with ever-larger supplies of power.

If it's hard to separate reliable electricity from behemoth generators, it's harder still to think of getting by without coal, oil or natural gas. As former Energy Secretary James Schlesinger and Energy Department veteran Robert L. Hirsch wrote in a recent editorial for the Washington Post, "Solar and wind electricity systems must be backed up 100 percent by other forms of generation to ensure against blackouts. And in today's world, that backup power can only come from fossil fuels."

They're partly right: In general, wind farms and solar plants generate power at the mercy of nature. But as onion fuel demonstrates, backup power can come from multiple sources. It can even come from the sun.

About 2,500 miles across the Pacific, Darren Kimura has a cough. "It's the 'vog'," he says on the phone, a condition that occurs when ash from Hawaii's Kilauea volcano mixes with moisture-laden southern breezes. "I'm allergic to it."

Still, he soldiers on to explain the mechanics of the organic Rankine cycle, the process his company, Sopogy, uses in its compact concentrating solar thermal power generators to make and store electricity.

"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, R, 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.