Nanoparticles improve solar collection efficiency

Apr 05, 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) 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 , 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 of solar collectors, Taylor and his colleagues have mixed a billionth of a meter in size—into the heat-transfer oils normally used in solar thermal power plants. The researchers chose 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."

Explore further: Tiny graphene drum could form future quantum memory

More information: 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.

Provided by American Institute of Physics

4 /5 (2 votes)

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User comments : 9

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TAz00
not rated yet Apr 05, 2011
The researchers chose graphite nanoparticles, in part because they are black and therefore absorb light very well


Don't you mean, they absorb light very well, and therefore are black.
Jaeherys
not rated yet Apr 05, 2011
That statement works both ways. If something is black you can assume that it absorbs visible light well.
Quantum_Conundrum
not rated yet Apr 05, 2011
Evacuated tubes are already black.

This would serve no purpose other than to gum up and clog up the system.
apex01
not rated yet Apr 05, 2011
So if these graphite particles increases the heat collecting efficiency by 10 percent, does that mean PV panels with 20% efficiency will be 30% efficient?
Jaeherys
not rated yet Apr 05, 2011
It would seem the answer is no as the effect on efficiency varies directly as a function of temperature.

http://www.reuk.c...nels.htm
http://en.wikiped...ficiency
fuviss_co_uk
not rated yet Apr 05, 2011
So if these graphite particles increases the heat collecting efficiency by 10 percent, does that mean PV panels with 20% efficiency will be 30% efficient?


I'm also not sure. Maybe they're talking about 10% of this 20%
HaveYouConsidered
not rated yet Apr 05, 2011
No, the effect on efficiency varies inversely with temperature. The higher the PV temperature, the lower its power generation efficiency. If you're going to make PVs arbitrarily darker by adding graphite you're just creating an unusually expensive black surface vs. other ways to make a black surface, to collect heat from.
jamesrm
5 / 5 (1) Apr 05, 2011
Did any of you read the article?

they are adding it to the oil/fluid in a "solar thermal collector"
Now go read about Blackbody radiation and get a clue
Jaeherys
not rated yet Apr 05, 2011
@HaveYOuCOnsidered
Thanks for the correction.