The key factor when it comes to solar power plant efficiency – be they of the photovoltaic or concentrated solar power (CSP) variety – is the amount of light that can be captured by the light-absorbing material and converted into electricity or heat. Researchers at the University of California, San Diego (UCSD) have developed a novel nanoparticle-based material that promises to improve the efficiency of CSP plants with its ability to absorb and convert over 90 percent of the sunlight it captures into heat.
Unlike photovoltaic (PV)-based solar power plants, which convert light directly into electricity, CSP plants generally use sunlight, concentrated onto a small area, to generate heat and drive a steam turbine to generate electricity. Because this is similar to the process used by fossil fuel power plants, CSP technology has the potential to be retrofitted to existing power plants to make them more environmentally friendly. The technology also has advantages over PV plants with its ability to generate electricity 24 hours a day by storing heat captured during the day in thermal tanks.
CSP plants commonly uses large numbers of mirrors to focus sunlight onto a tower spray painted with a black paint material that is designed to maximize sunlight absorption. However, being subjected to such high temperatures day after day degrades the material, meaning such plants usually need to be shut down once a year or so to allow the degraded light-absorbing material to be chipped off and a new coating applied and cured.
To overcome this problem, the US Department of Energy's (DOE's) SunShot program challenged UCSD researchers to develop a material able to operate at higher temperatures than existing materials and for much longer. With financial support from the SunShot program, a multidisciplinary team at UCSD developed a material using particles ranging in size from 10 nanometers to 10 micrometers.
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