Engineers from the University of Colorado Boulder have come up with a scalable-manufactured randomized glass-polymer hybrid metamaterial for daytime radiative cooling.
Translated into the English language less all the gobbledygook, it basically means that the CU Boulder team was able to develop a new material engineered to serve the purpose of a cooling unit like air conditioner without the use of energy and water.
What is also remarkable about this eco-friendly material is that it has some properties that have not been observed in nature.
“The key advantage of this technology is that it works 24/7 with no electricity or water usage,” said Professor Ronggui Yang of the Department of Mechanical Engineering in CU Boulder.
Gang Tan, a co-author of the research and associate professor in the University of Wyoming’s Department of Civil and Architectural Engineering, also added that 10 to 20 square meters of the new material can already act like an air conditioner for a single-family residential house when placed on the rooftop.
In the United States alone, almost 75 percent of residential homes make use of an air conditioner and this costs the homeowners a total of about $29 billion every year as per the U.S. Department of Energy. In turn, these air conditioner units consume around six percent of the electricity produced in the country and are also responsible for emitting over 115 million metric tons of carbon dioxide into the air annually.
How Does It Work?
The material works in two ways when placed on the surface of a structure. It acts like a cooling unit by reflecting incoming solar rays back into the atmosphere, while letting the surface give off its own heat (infrared thermal radiation) without energy consumption in a process called passive radiative cooling.
The engineers also added “visibly-scattering but infrared-radiant glass microspheres into a polymer film,” and a thin silver coating underneath in order to counter the negative effect of solar energy on passive radiation, especially for those structures directly hit by the sun.
Meanwhile, for the benefit of all the erudite and academics out there with a background in engineering, here is the abstract of the published work on this new material posted in the journal Science on February 9. Enjoy the jargons.
“Passive radiative cooling draws heat from surfaces and radiates it into space as infrared radiation to which the atmosphere is transparent. However, the energy density mismatch between solar irradiance and the low infrared radiation flux from a near-ambient-temperature surface require materials that strongly emit thermal energy and barely absorb sunlight. We embedded resonant polar dielectric microspheres randomly in a polymeric matrix, resulting in a metamaterial that is fully transparent to the solar spectrum while having an infrared emissivity greater than 0.93 across the atmospheric window. When backed with silver coating, the metamaterial shows a noon-time radiative cooling power of 93 W/m2 under direct sunshine. More critically, we demonstrated high-throughput, economical roll-to-roll manufacturing of the metamaterial, vital for promoting radiative cooling as a viable energy technology.”
Applications of the New Material Other Than As Air an Conditioner
While the new material has the potential to make a huge impact in terms of providing an eco-friendly and more economical alternative to air conditioners and other cooling units in residential areas and thermoelectric power plants to keep their machineries in the right operating temperature without a huge consumption of water and electricity, the CU Boulder’s team is also exploring the other applications of the new material.
They have now filed for a patent of the new technology and are looking ahead in terms of what the other uses of this engineered material commercial-wise. The material is a glass-polymer hybrid measuring just slightly thicker than aluminum foil and can be produced in rolls.
“We’re excited about the opportunity to explore potential uses in the power industry, aerospace, agriculture and more,” said Yang.
The material can also be applied to solar panels in order to make them run more efficiently and have longer serviceable life. Solar panels work in direct sunlight and by applying the new material on their surfaces, the panels can be cooled, avoiding overheat, and make them more efficient in converting solar energy into electricity.
The CU Boulder engineers behind the material are now hoping to build a 200-square-meter “cooling farm” prototype in their area by the end of the year.
[Featured Image by Matt Rourke/AP Images]