Even the thought of the sweltering and bone-melting heat that is just around the corner makes me fret and fidget like crazy. No number of air conditioners can give you a prolonged respite from the unabated and unforgiving summer heat. But just when all technologies have seemingly shown their limits, there emerges a single sheet of plastic that claims to placate our woes.
A team of researchers from the University of Colorado Boulder engineers claims to have developed a manufactured metamaterial, something that isn’t found in nature, to perform as an air conditioner without using any energy or water consumption.
The material is a film that reflects the incoming solar energy back while allowing the surface beneath the sheet to efficiently dissipate in the form of infrared thermal radiation. The findings were published in the journal Science, and are thought to provide an eco-friendly method to supply cooling for homes, office and even as large structures as thermoelectric power plants, which require huge amounts of water and electricity to maintain the operating temperatures.
The glass-polymer hybrid material is just 50 micrometers thick, barely thicker than your average kitchen aluminum foil, and can be manufactured for as low as $0.25 per square inch, making it viable for large-scale technology.
“We feel that this low-cost manufacturing process will be transformative for real-world applications of this radiative cooling technology.”
The passive radiative cooling of the material makes it to naturally shed heat as infrared radiation without consuming energy. But this passive radiation is also effective when the sheet is used in direct sunlight due to the embedded visibly-scattering and infrared-radiant glass microspheres in the polymer sheet. A thin silver coating is also added underneath that enables maximum spectral reflectance.
“Both the glass-polymer metamaterial formation and the silver coating are manufactured at scale on roll-to-roll processes,” added Ronggui Yang, also a professor of mechanical engineering and a Fellow of the American Society of Mechanical Engineers.
“Just 10 to 20 square meters of this material on the rooftop could nicely cool down a single-family house in summer,” said Gang Tan, an associate professor in the University of Wyoming’s Department of Civil and Architectural Engineering and a co-author of the paper.
The material can also be used to improve the efficiency and lifetime of solar panels, which in direct sunlight overheat, hampering their ability to convert solar rays into electricity.
“Just by applying this material to the surface of a solar panel, we can cool the panel and recover an additional one to two percent of solar efficiency,” said Yin. “That makes a big difference at scale.”
The discovery has come after a $3 million grant given to Yang, Yin, and Tang and their team by the Energy Department’s Advanced Research Projects Agency-Energy (ARPA-E) in 2015.
“The key advantage of this technology is that it works 24/7 with no electricity or water usage,” said Yang “We’re excited about the opportunity to explore potential uses in the power industry, aerospace, agriculture and more.”
The findings were published in the February issue of Science.