Nanoparticles improve solar collection efficiency

(Press-News.org) Washington, D.C. (April 5, 2011) -- Using minute graphite particles 1000 times smaller than the width of a human hair, mechanical engineers at Arizona State University hope to boost the efficiency—and profitability—of solar power plants.

Photovoltaic (PV) solar panels are popping up more and more on rooftops, but they're not necessarily the best solar power solution. "The big limitation of PV panels is that they can use only a fraction of the sunlight that hits them, and the rest just turns into heat, which actually hurts the performance of the panels," explains Robert Taylor, a graduate student in mechanical engineering at Arizona State University.

An alternative that can make use of all of the sunlight, including light PVs can't use, is the solar thermal collector. The purpose of these collectors—which take the form of dishes, panels, evacuated tubes, towers, and more—is to collect heat that can then be used to boil water to make steam, for example, which drives a turbine to create electricity.

To further increase the efficiency of solar collectors, Taylor and his colleagues have mixed nanoparticles—particles a billionth of a meter in size—into the heat-transfer oils normally used in solar thermal power plants. The researchers chose graphite nanoparticles, in part because they are black and therefore absorb light very well, making them efficient heat collectors. In laboratory tests with small dish collectors, Taylor and his colleagues found that nanoparticles increased heat-collection efficiency by up to 10 percent. "We estimate that this could mean up to $3.5 million dollars per year more revenue for a 100 megawatt solar power plant," he says.

What's more, Taylor adds, graphite nanoparticles "are cheap"—less than $1 per gram—but with 100 grams of nanoparticles providing the same heat-collecting surface area as an entire football field. "It might also be possible to filter out nanoparticles of soot, which have similar absorbing potential, from coal power plants for use in solar systems," he says. "I think that idea is particularly attractive: using a pollutant to harvest clean, green solar energy."

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The article, "Applicability of nanofluids in high flux solar collectors" by Robert A. Taylor, Patrick E. Phelan, Todd P. Otanicar, Chad A. Walker, Monica Nguyen, Steven Trimble, and Ravi Prasher, appears in the Journal of Renewable and Sustainable Energy.

About the Journal of Renewable and Sustainable Energy

The Journal of Renewable and Sustainable Energy, published by the American Institute of Physics, is an interdisciplinary, peer-reviewed journal covering all areas of renewable and sustainable energy-related fields that apply to the physical science and engineering communities. Content is published online daily, collected into bimonthly issues (6 times a year). As an electronic-only, web-based journal with rapid publication time, JRSE is responsive to the many new developments expected in this field. The interdisciplinary approach of the publication ensures that the editors draw from researchers worldwide in a diverse range of fields

About AIP

The American Institute of Physics is an organization of 10 physical sciences societies representing more than 135,000 scientists, engineers, and educators and is one of the largest publishers of scientific information in physics. AIP also delivers valuable resources and expertise in education and student services, science communication, government relations, career services for science and engineering professionals, statistical research, industrial outreach, and the history of physics and other sciences. Offering publishing solutions for scientific societies and organizations in science and engineering, AIP pursues innovation in electronic publishing of scholarly journals. AIP publishes 13 journals (journals.aip.org), 2 magazines—including its flagship publication, Physics Today—and the AIP Conference Proceedings series. Scitation, AIP's online publishing platform, hosts 1.6 million articles from 190 scholarly journals, proceedings, and eBooks of learned society publishers. AIP also provides the international physical science community with UniPHY, the first literature-based social and professional networking site; it features pre-populated profiles of more than 300,000 scientists and enables collaboration among researchers worldwide.

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