Award-Winning Solar Reflectors Will Cut Production Costs

A small solar company has teamed with scientists at the National Renewable Energy Laboratory (NREL) to develop massive curved sheets of metal that have the potential to be 30 percent less expensive than today's best collectors of concentrated solar power.

In an official press release, the NREL and SkyFuel Inc. have announced their SkyTrough Parabolic Trough Solar Concentrating Collectors, an innovative replacement for old, glass-based models, and a hopeful game-changer in solar energy's bid to out-muscle gas and coal in providing electricity for American homes.

This latest breakthrough was recently honored by R&D Magazine as one of the top 100 technical innovations of the year, and by the Federal Laboratory Consortium with a 2009 Excellence in Technology Transfer Award.

How Does it Work?

Solar scientists for years have understood the advantage of the parabolic shape, which distorts the rays, concentrating the sun's heat onto a tube filled with heat-transfer fluid, which carries the heat to the boilers in a power station. The heat-transfer fluid can get as hot as 400 degrees Celsius (more than 750 degrees Fahrenheit). However, past reflectors have required glass installations, which are not always cost-effective.

"Glass is highly durable, but is heavy and hard to shape without added cost," NREL senior scientist Gary Jorgensen says. "Once industry sees the advantages of the silver polymer and is convinced the product is durable in an outdoor environment, the sky is the limit."

SkyFuel Chief Technology Officer Randy Gee says the film, trademarked ReflecTech® Mirror Film, "has the same performance as the heavy glass mirrors, but at a much lower cost and much lower weight. It also is much easier to deploy and install." The glossy film uses several layers of polymers, with an inner layer of pure silver.

The cost advantage is about 30 percent, a huge dividend in an industry that has scratched together savings one percent at a time for decades.

A Brief History:

The story goes back to the late 1990s, when Gee and Jorgensen worked with a small $25,000 federal grant to see if they could come up with an alternative reflector. They used NREL's testing facilities to sample dozens, indeed hundreds, of possible materials that potentially provided the low-weight low-cost highly flexible properties needed to drive down the cost of solar power collection.

"Within two years, we had enough data to believe we had a substantial improvement relative to predecessors," Jorgensen recalled.

Parabolic collectors have been around since the 1970s. Back then they were about seven feet wide and 20 feet long, a half dozen or so lined up to collect the sun's rays, a motorized system turning the mirrors as the sun moved across the sky.

"The natural evolution was to get larger and reduce costs," says Gee, who worked with Jorgensen in the 1980s at the Solar Energy Resource Institute, NREL's predecessor.  "Each generation got larger," pointing to the day when utility companies would want to purchase the troughs for 50- to 100-megawatt plants.

What Now?

"Just two-and-a-half years into the development cycle, it looks like our great technical team is going to be able to take a big chunk out of the costs of installing CSP systems," Gee claims. "We're not doing this in tiny steps but in big chunks."

Jorgensen has been working on renewable energy for 30 years. He calls today's climate a perfect storm … with the realization by the public of the importance of alternative energy, with politicians listening to the public, with energy demands and with security issues of not wanting to rely on foreign oil.

He remarks, "with the whole impact of global environmental change, we're truly at the pinnacle of a golden age."

Sources: NREL Press Release and Environmental Expert Report