Big solar is a big dream. Critics say solar energy is too expensive to build and there’s not enough government support behind the idea.
But John O’Donnell is going a different route, turning solar thermal energy into a practical innovation that is already gaining momentum. His secret ingredient? Mirrors.
Based in Palo Alto, California, O’Donnell’s solar energy company, Ausra, is poised to become a leader in a young technology just barely past the teething stage. O’Donnell’s take on solar thermal uses miles of mirrors to focus the rays of the sun onto pipes to heat water and run massive steam turbines.
There are no emissions, no radioactive waste and no incredibly high overhead, because Ausra buys commodity materials such as glass instead of the parabolic trough commonly used by other energy companies (solar thermal energy collectors shaped like trough or tubes, made from coated silver or aluminum).
In December, Ausra announced it has started building an assembly plant in Las Vegas to construct parts to build a solar power plant. That plant is projected to generate 177 megawatts of power for Pacific Gas & Electric. One megawatt can power 750 homes.
“Sunlight is a huge source of energy that people have been trying to harness for hundreds of years,” O’Donnell, executive vice-president of Ausra, says in a phone interview. “And now we have to worry about a climate change problem and capping emissions, so solar thermal is ideal.”
O’Donnell goes on to praise Ausra’s method of storing energy as steam in a pressurized vessel. It typically retains 95 per cent of the solar energy, compared to 65 per cent for an electric battery.
In addition, tests with the International Energy Agency Task 35 project found that adding a solar thermal component to a solar panel array boosts the total solar efficiency to over 50 per cent. O’Donnell says solar photovoltaic panels may be the best-known form of this alternative energy source, but they’re too expensive for mass adoption.
Solar has been on the tip of many tongues because of its enormous promise. It’s heralded as a cost-effective alternative to coal power plants because the sun reaches its peak in late afternoon, when power demand peaks as well.
California has recognized the technology’s potential and is already seen as a trailblazer in alternative energy. The state wants 20 per cent of its power to come from renewable sources (such as the sun and the wind) by 2010, and one-third by 2020.
Part of making that happen involves lowering the costs of delivery. The magic number every solar thermal company is seeking is 10 cents per kilowatt hour (kwh). Natural gas plants cost about 9 cents per kwh. O’Donnell is confident his technology can reach that desired cost level, making solar thermal energy more attractive than gas and coal mainstays.
He’s quick to credit an Aussie for Ausra’s plan of flat mirrors heating steam turbines. University of Sydney professor David Mills wrote a paper several years ago about a field of mirrors focusing the sun’s rays on fixed tubes held by poles above the mirrors.
These mirrors are easier and cheaper to build than parabolic troughs and can be made strong enough to withstand hurricanes. Instead of using the troughs’ oil-filled tubes – which sap power to pump the oil – Mills focused the sun’s heat to turn water directly into steam.
The technology amazed O’Donnell, and he invited Mills to test the theory on a few small-scale projects.
“There are simple technologies based on what people have been working on for hundreds of years that can be deployed right now without breaking the economy,” O’Donnell declares.
But what about politicians who stiff-arm solar energy solutions?
“Any government policy that doesn’t grapple with this issue is just driving full-speed toward a cliff,” O’Donnell says. “And when doing that, you have several options: you can close your eyes, and, yes, that works for a while. Some people argue we should step on the brakes and stop this industrial society altogether.
“But everyone should realize we have developed technologies to avoid the cliff. It doesn’t have to be so fatalistic.”