Posted: January 25, 2007

Researchers race to perfect green power with nanotechnology

(Nanowerk News) In a basement laboratory here at the University of Minnesota, a group of researchers can see the future of energy in the invisible particles of a new kind of solar cell.
Prof. Eray Aydil and his team of scientists are using nanotechnology to make a more efficient cell for turning the sun's rays into electricity (see an earlier Nanowerk Spotlight last year about Dr. Aydil's work: "Nanowires could lead to improved solar cells").
Such efforts may be crucial to the success of a legislative plan requiring power utilities to generate a quarter of their energy with renewable sources over the next two decades. While wind will account for much of that clean power, solar power and other technologies called for in the legislation aren't yet feasible, making it far from certain Minnesota can go as green as it wants.
"It's a very important problem," Aydil said about harnessing renewable sources. "It affects all aspects of life, affects our standard of living, affects the planet. And we have to have a long-term vision and faith that we will solve this problem."
Minnesota isn't unique in its drive to speed up the use of renewables. More than 15 states now have mandates for generating electricity with renewables sources, according to the Renewable Energy Policy Project in Washington, D.C. One of them, California, is calling for 20 percent of its electricity to be generated from renewable sources in just three years.
Many, like this northern state, are crossing their fingers that the technology will catch up to the goals. In the view of George Sterzinger, executive director of REPP, "the best thing states can do is step up and put pressure and create a market."
Minnesota currently has a renewable energy objective that calls for utilities to make a good-faith effort to generate 10 percent of their power from renewable sources by 2015. Upping it to "25 by 2025 is aggressive, but achievable," Gov. Tim Pawlenty said when he announced his proposal.
Pawlenty, environmentalists and small-town lawmakers basically agree that such a move would be a giant step toward reducing carbon emissions while giving rural areas another way to broaden their agriculture-based economies.
"Similar to how ethanol has grown in Minnesota as an alternative fuel, there are renewable forms of electricity, as well, that we can tap to get (rural areas) a piece of the action," said state Rep. Aaron Peterson, a DFLer from Madison in western Minnesota and a sponsor of the legislation.
Lawmakers are working out the differences in competing bills, such as whether the target should be 2025 or five years earlier, as Democrats propose. Pawlenty's plan and a Democratic version in the House and Senate include fines for failure to comply, though they aren't considered large.
Backers believe a compromise bill will pass since the idea has the support of the Republican Pawlenty and the newly DFL-controlled Legislature. Moreover, President Bush called for more use of green power, both for electricity and fuel, in his State of the Union address
A recent study by the Minnesota Public Utilities Commission concluded that wind could account for much, if not all, of the renewable energy. But the bills also include biomass, hydrogen, hydroelectric and solar power as renewable sources that should be tapped. Some utilities have said they need the flexibility, especially those with plants in parts of the state that aren't very windy.
"Some stuff is in (the legislation) because we want to make sure we don't exclude any new technologies," explained Ken Bradley, a senior policy associate at St. Paul-based Fresh Energy, which advocates the use of more renewables. "If there is a breakthrough, then it makes (meeting the mandate) more possible."
Even so, he acknowledged, the technologies "are at very different places."
Currently, about 6 percent of Minnesota's electricity comes from renewable sources -- mostly wind.
Xcel Energy Corp., which provides about half of the state's electricity, already taps the wind for some of its power and would do more of that to meet the new mandate. The company said solar and hydrogen technologies are not yet feasible and that many biomass projects are still largely experimental.
"The technology is changing very quickly, so whether in 13 years we will see hydrogen resources -- you tell me," said Rick Evans, Xcel's director of regional government affairs.
Xcel Energy has incorporated some biomass -- such as a St. Paul heating and cooling system that uses wood chips -- into its system. Elsewhere, a plant in Benson will soon burn turkey manure to create electricity, and the Iron Range towns of Virginia and Hibbing are also using biomass for their cities' heating and cooling systems.
And, of course, hundreds of wind turbines rise from the prairie in southwestern Minnesota, providing green energy for power companies and new livelihoods for rural residents.
But that leaves much more room for the practical application of still-developing technologies.
Solar power, for instance, has been in the nation's conscience at least since Jimmy Carter put panels on the White House roof, and California is pressing ahead with plans to outfit one million homes and businesses with solar panels over the next decade.
But the technology remains more expensive than coal or nuclear power, and current solar panels work best in sunny climates. In 2001, solar energy accounted for less than 0.1 percent of the world's electricity, according to the federal Department of Energy.
Researchers in the Chemical Engineering and Materials Science Department, working through the university's Initiative for Renewable Energy and the Environment, hope to change that some day.
In a windowless lab, graduate student Emil Pommer uses a lamp that mimics daylight -- called a Xenon arc lamp -- to shine different colors onto cells, measuring how the cells capture different parts of the solar spectrum.
To the naked eye, the thumb-sized cells look like glass slides smeared with a milky film. The complex material, however, could be a key component to future cells that concentrate more of the sun -- though their use is five years or more away.
As Prof. Aydil put it, "In some sense, we can't fail."
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