Clean Power

Published on November 21st, 2012 | by James Ayre


New Solar Energy Technology Can Create Steam Without Even Having To Boil Water

November 21st, 2012 by  

This article has been reposted from Solar Love with full permission.

A revolutionary new way to create steam simply by using sunlight has been discovered by researchers. The method is able to bring an entire container of fluid to boiling point, even a container of icy cold water.

The new method has many potentially very useful applications. These include the creation of very inexpensive and compact devices that can purify water, the sterilization of medical equipment, sewage treatment, and more energy-efficient alcohol distillation.

“This research opens up a revolutionary new application of nanoparticles in solar energy,” said Paul Weiss, Ph.D., editor-in-chief of ACS Nano, the journal in which the new study was published. “The authors show that sunlight can be used to create steam with virtually no wasteful heating of the surrounding liquid. The potential societal benefits are staggering. They include more energy-efficient distillation of alcohol, a new and highly practical strategy for desalination and water purification and compact solar-driven sources of steam for sterilization and sanitation in resource-poor locations,” said Weiss.

The method is based on the use of metallic nanoparticles that can absorb very large amounts of light, which results in a significant rise in their temperature. That’s a very useful ability, and has generated a lot of interest amongst researchers. Other potential applications include cancer treatment, “laser-induced drug release,” and enhanced bio-imaging.

Previous research on the potential uses of nanoparticles in solar power technologies has focused almost entirely on using them to increase the ability of fluids to conduct heat. There hadn’t been any research done on the abilities of nanoparticles that are mixed into fluids. But as the new research shows, by mixing them directly into a fluid you can create very interesting effects.

“The new report explains that nanoparticles illuminated by light can quickly rise to temperatures above 212 degrees Fahrenheit, the boiling point of water. Steam forms around the surface of each nanoparticle, billons of which can be placed in water or other fluids. Eventually, the vapor escapes from the particle, forming nanobubbles that float to the top of the surface and escape as water vapor or steam, vapors of ethanol in the case of distillation of alcohol for beverages or fuel, or other vapors.”

The report documents, in detail, the varying amounts of steam that are generated in sun-exposed water solutions containing different types of nanoparticles. The two types experimented with were a silicon dioxide/gold type and a carbon type. Both solutions began producing steam in 5-20 seconds after being exposed to sunlight. “The gold nanoparticle solution produced steam in small ‘microexplosive’ bursts. The scientists used the gold nanoparticles to distill alcohol from water and got higher yields of alcohol than would have occurred by boiling the solution.”

The efficiency of the technology is one of its most impressive qualities, over 82 percent of the sunlight that was absorbed by the nanoparticles went directly to generating steam. The overall energy efficiency of the process was 24 percent, and that is without any kind of effort to optimize it.

“These results clearly indicate that solar steam generation is a process that has significant potential for use in a wide variety of energy- and sustainability-relevant applications,” the report states. “Solar-driven, stand-alone waste processing or water purification systems could be developed based on this process. High-temperature (about 240 degrees F. and above) steam produced directly using sunlight could also be used for compact sterilization or sanitation purposes, from the processing of medical waste to the cleaning of medical or dental equipment, minimizing the resource, time and input chemical requirements demanded by current methods. With further development, this approach may be adaptable to higher pressures and other working fluids to drive turbines in solar energy harvesting applications. This approach may also be modified to harvest radiant energy from sources other than the sun, for instance, for the capture of waste energy from geothermal, residential or biological sources.”

The new discovery was just outlined in the American Chemical Society (ACS) journal ACS Nano.

Source: Rice University
Image Credits: Jeff Fitlow/Rice University

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About the Author

's background is predominantly in geopolitics and history, but he has an obsessive interest in pretty much everything. After an early life spent in the Imperial Free City of Dortmund, James followed the river Ruhr to Cofbuokheim, where he attended the University of Astnide. And where he also briefly considered entering the coal mining business. He currently writes for a living, on a broad variety of subjects, ranging from science, to politics, to military history, to renewable energy. You can follow his work on Google+.

  • sarath paul

    hi sir
    i have got an dought…
    can u pls give more information about solar concentrators?? hoe much will be its efficiencyy??? i want to do abt this solar concentratots as ma project by making this concentrators as one of the alternate source for producing steam in power boler….so can u pls tell how much is it capacity?? upto how much tons of steam can be produced if we implement concntrator in powre boiler…currently the boiler is running by using coal as fuel at an capacity of 60 tons steam in one hour…so can uu plss share the meensioned details and info…so i can do ma project without any confusion
    thanking you

  • Rob S.

    “The method is able to bring an entire container of fluid to boiling point without the use of any heat.”

    I think that statement conflicts with something I know as physics!

    • not sure how that got in there / where it came from — just updated the sentence 😀

      • UKGary

        There is clearly an error here in how the process is described.. I would say that in reality what is happening is that a very small proportion of the fluid is heating very rapidly so that it undergoes a rapid phase change whilst making very little difference to the bulk temperature of the fluid..

        If it were possible to construct nano particles to preferentially attach to molecules which it is desirable to separate from bulk fluid, and have the particle absorb heat as described, you could perhaps as an example distil alcohol out of a water based solution by selectively vapourising alcohol with only a small temperature rise occurring in the bulk fluid saving much of the energy which would otherwise be required to heat the bulk fluid.

        You would also tend to have better separation as the bulk fluid which is mostly water would not heat enough to develop a significant vapour pressure.

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