next generation solar

NORWICH — Bill Bender got an early Christmas present this year. Last week, his company, Solaflect, signed a contract with the U.S. Department of Energy for nearly $1 million to develop the next generation of “concentrated solar power” technology. Bender’s innovative design cuts costs by using 65 percent less steel than traditional solar installations.

     “To us, it’s a lot of money,” Bender said yesterday from his Norwich home, where he’s turned his backyard into a test site for mirrored panels that reflect and concentrate sunlight, much like a giant magnifying glass. “This is a big kick start.”

     The award comes from SunShot, an initiative from the National Renewable Energy Laboratory to make alternative energy less costly. Solaflect won one of two awards nationwide for concentrated solar power.

     But some taxpayers have grown wary of federal investment in private solar technology. Ear lier this year, the California-based company Solyndra fell flat on its face after receiving $528 million in federal loan guarantees. Although Solaflect’s $1 million is small in comparison, Bender — a Dartmouth graduate, Rhodes scholar and Ph.D. economist — is quick to defend the government’s role in developing alternative energy sources.

    “The government has made investments in the oil and gas industries, in railroads … in developing aircraft. Nuclear power has had way more government investment than solar. The Department of Energy has had a couple failures, but … if you believe in global warming and believe something should be done, it’s appropriate for the government to make investments,” he said. “The rest of the world is investing heavily in this. It’s a question of whether the U.S. is going to be there or not.”

     Solaflect’s award comes with some caveats. In order to receive the money, Bender needs to meet certain benchmarks to help the Department of Energy meet its own goals of making solar energy cost-competitive with coal power and other non-renewable sources of energy by the end of the decade.

     Specifically, Solaflect must achieve a single goal: lower the cost of a square meter of concentrated solar power technology from around $250 to as little as $120 in three years. By 2020, Bender thinks he can get it down to $70 per square meter.

     “It’s a very aggressive goal,” Bender remarked. “But this is the game we’re in.”

His solution is one that would make sense to most engineers. But to understand it, it helps to get a sense of what concentrated solar power looks like. There are several variations; Bender has focused on the “power tower” system.

     Instead of the photovoltaic panels that come to mind when most people think of solar energy, the system uses a circular array of mirrored panels, called heliostats, to reflect sunlight to a focal point on a central receiver — a “power tower.” Each of the mirrored panels readjusts every 25 sec onds or so to track the sun’s rays. Once the concentrated light reaches the receiver, it can be used to heat water or generate electricity much like a conventional power plant.

     In the experimental model in Bender’s backyard, five heliostats, each composed of 172 square feet of mirrored panels, concentrate enough light to heat a black metal receiver to 800 degrees Fahrenheit, or to start a piece of plywood smoking in less than two minutes.

     Bender’s model is a fraction of the size of working power tower systems, such as the one he visited this year near Seville, Spain. Commercial-scale installations can include tens of thousands of heliostats and produce hundreds of megawatts of electricity. And, significantly, the technology employs tanks of molten salt to store heat, avoiding the intermittency problems that plague traditional solar installations.

     “This is not theoretical technology anymore,” Bender said. “It’s working.”

But most concentrated solar power technology uses heavy, expensive steel trusses to hold the mirrored heliostats. Working off the assumption that suspension bridges are more effective than truss bridges, Solaflect has developed a way to support the heliostats with steel suspension cables.

     The design uses about 65 percent less steel, greatly reducing the cost of the installation. On large scale projects, installation prices could be cut nearly in half.

     “The mirror is not expensive,” Bender commented. “It’s holding the mirror up in the wind that’s expensive.”

     To ensure that his suspension system can withstand high winds, Bender has tested the design on a mountaintop in Vermont’s Northeast Kingdom and on a windy plateau in Wyoming, and the results have been favorable. Solaflect also tries to source locally as much as possible, marking a shift from the photovoltaic market, which is supported largely by Chinese manufacturing, Bender said.

     Solaflect is on the verge of moving from research and development into the commercial business world. Bender is eager to work with Vermont cheesemakers or brewers to install concentrated solar technology to heat hot water, but declined to reveal which companies are considering signing on as pilot sites.

     A Rutland native, Bender first took a solar technology course while in college in the 1970s. Then he largely for got about it, working instead as an international consultant for food and nutrition policy in developing countries and founding a successful web analytics company.

     When he, his wife and their four children (now ages 7 to 19) bought a house in Norwich in 2000, he realized that the sunny, south-facing roof of his hilltop home would be ideal for a home solar installation. But the estimates he got were “ridiculous.” He realized that if the cost was deterring him from pursuing renewable energy, it was also likely deterring others, prohibiting a widespread transition from fossil fuels.

     So, with his children’s help, he began tinkering in the backyard. At first, he used mirrors from Home Depot and tried out “a lot of stupid ideas.” But eventually, one of the ideas worked. What started as a hobby began to develop into a passion, and, in 2007, a business. Solaflect now boasts five employees, including two engineers.

     “I think this matters for our future and for the future of our kids,” Bender said. “I’m passionate about it and that’s why I do it. Any source of energy is going to affect the environment in some way, but I don’t know how you could argue that anything is cleaner than this.”

     Clean, maybe. But effective? Can solar be a viable energy source on a large scale? Bender thinks so.

     “As an economist, I think a lot about externalities,” he said, explaining that the health and environmental costs of coal and the military cost of fighting wars for oil in the Middle East are not factored into the price of those resources. If the coal and oil industries paid the real cost of their actions, Bender thinks solar power would be competitively priced today.

      “But even if they don’t,” he added, “our goal is to be competitive by the end of the decade. If we can be cheaper than coal, then we’ll displace coal.”