Nanotechnology Now

Our NanoNews Digest Sponsors

Heifer International

Wikipedia Affiliate Button


DHgate

Home > Press > New type of solar structure cools buildings in full sunlight

Professor Shanhui Fan (center) with graduate students Aaswath Raman (left) and Eden Rephaeli (right).Photo: Norbert von der Groeben
Professor Shanhui Fan (center) with graduate students Aaswath Raman (left) and Eden Rephaeli (right).

Photo: Norbert von der Groeben

Abstract:
A Stanford team has designed an entirely new form of cooling panel that works even when the sun is shining. Such a panel could vastly improve the daylight cooling of buildings, cars and other structures by radiating sunlight back into the chilly vacuum of space.

New type of solar structure cools buildings in full sunlight

Stanford, CA | Posted on March 27th, 2013

Homes and buildings chilled without air conditioners. Car interiors that don't heat up in the summer sun. Tapping the frigid expanses of outer space to cool the planet. Science fiction, you say? Well, maybe not any more.

A team of researchers at Stanford has designed an entirely new form of cooling structure that cools even when the sun is shining. Such a structure could vastly improve the daylight cooling of buildings, cars and other structures by reflecting sunlight back into the chilly vacuum of space. Their paper describing the device was published March 5 in Nano Letters.

"People usually see space as a source of heat from the sun, but away from the sun outer space is really a cold, cold place," explained Shanhui Fan, professor of electrical engineering and the paper's senior author. "We've developed a new type of structure that reflects the vast majority of sunlight, while at the same time it sends heat into that coldness, which cools manmade structures even in the day time."

The trick, from an engineering standpoint, is two-fold. First, the reflector has to reflect as much of the sunlight as possible. Poor reflectors absorb too much sunlight, heating up in the process and defeating the purpose of cooling.

The second challenge is that the structure must efficiently radiate heat back into space. Thus, the structure must emit thermal radiation very efficiently within a specific wavelength range in which the atmosphere is nearly transparent. Outside this range, Earth's atmosphere simply reflects the light back down. Most people are familiar with this phenomenon. It's better known as the greenhouse effect—the cause of global climate change.
Two goals in one

The new structure accomplishes both goals. It is an effective a broadband mirror for solar light—it reflects most of the sunlight. It also emits thermal radiation very efficiently within the crucial wavelength range needed to escape Earth's atmosphere.

Radiative cooling at nighttime has been studied extensively as a mitigation strategy for climate change, yet peak demand for cooling occurs in the daytime.

"No one had yet been able to surmount the challenges of daytime radiative cooling—of cooling when the sun is shining," said Eden Rephaeli, a doctoral candidate in Fan's lab and a co-first-author of the paper. "It's a big hurdle."

The Stanford team has succeeded where others have come up short by turning to nanostructured photonic materials. These materials can be engineered to enhance or suppress light reflection in certain wavelengths.

"We've taken a very different approach compared to previous efforts in this field," said Aaswath Raman, a doctoral candidate in Fan's lab and a co-first-author of the paper. "We combine the thermal emitter and solar reflector into one device, making it both higher performance and much more robust and practically relevant. In particular, we're very excited because this design makes viable both industrial-scale and off-grid applications."

Using engineered nanophotonic materials the team was able to strongly suppress how much heat-inducing sunlight the panel absorbs, while it radiates heat very efficiently in the key frequency range necessary to escape Earth's atmosphere. The material is made of quartz and silicon carbide, both very weak absorbers of sunlight.
Net cooling power

The new device is capable of achieving a net cooling power in excess of 100 watts per square meter. By comparison, today's standard 10-percent-efficient solar panels generate the about the same amount of power. That means Fan's radiative cooling panels could theoretically be substituted on rooftops where existing solar panels feed electricity to air conditioning systems needed to cool the building.

To put it a different way, a typical one-story, single-family house with just 10 percent of its roof covered by radiative cooling panels could offset 35 percent its entire air conditioning needs during the hottest hours of the summer.

Radiative cooling has another profound advantage over all other cooling strategy such as air-conditioner. It is a passive technology. It requires no energy. It has no moving parts. It is easy to maintain. You put it on the roof or the sides of buildings and it starts working immediately.
A changing vision of cooling

Beyond the commercial implications, Fan and his collaborators foresee a broad potential social impact. Much of the human population on Earth lives in sun-drenched regions huddled around the equator. Electrical demand to drive air conditioners is skyrocketing in these places, presenting an economic and an environmental challenge. These areas tend to be poor and the power necessary to drive cooling usually means fossil-fuel power plants that compound the greenhouse gas problem.

"In addition to these regions, we can foresee applications for radiative cooling in off-the-grid areas of the developing world where air conditioning is not even possible at this time. There are large numbers of people who could benefit from such systems," Fan said.

Andrew Myers is associate director of communications for the Stanford University School of Engineering.

####

For more information, please click here

Contacts:
Andrew Myers

650-736-2245

Copyright © Stanford School of Engineering

If you have a comment, please Contact us.

Issuers of news releases, not 7th Wave, Inc. or Nanotechnology Now, are solely responsible for the accuracy of the content.

Bookmark:
Delicious Digg Newsvine Google Yahoo Reddit Magnoliacom Furl Facebook

Related News Press

News and information

Graphene is strong, but is it tough? Berkeley Lab scientists find that polycrystalline graphene is not very resistant to fracture February 7th, 2016

Lithium battery catalyst found to harm key soil microorganism February 7th, 2016

Scientists take key step toward custom-made nanoscale chemical factories: Berkeley Lab researchers part of team that creates new function in tiny protein shell structures February 6th, 2016

Discovery of the specific properties of graphite-based carbon materials February 6th, 2016

Discoveries

Graphene is strong, but is it tough? Berkeley Lab scientists find that polycrystalline graphene is not very resistant to fracture February 7th, 2016

Lithium battery catalyst found to harm key soil microorganism February 7th, 2016

Scientists take key step toward custom-made nanoscale chemical factories: Berkeley Lab researchers part of team that creates new function in tiny protein shell structures February 6th, 2016

Discovery of the specific properties of graphite-based carbon materials February 6th, 2016

Announcements

Graphene is strong, but is it tough? Berkeley Lab scientists find that polycrystalline graphene is not very resistant to fracture February 7th, 2016

Lithium battery catalyst found to harm key soil microorganism February 7th, 2016

Scientists take key step toward custom-made nanoscale chemical factories: Berkeley Lab researchers part of team that creates new function in tiny protein shell structures February 6th, 2016

Discovery of the specific properties of graphite-based carbon materials February 6th, 2016

Automotive/Transportation

Researchers develop completely new kind of polymer: Hybrid polymers could lead to new concepts in self-repairing materials, drug delivery and artificial muscles January 30th, 2016

An alternative to platinum: Iron-nitrogen compounds as catalysts in graphene January 28th, 2016

LC.300 Series Nanopositioning Controller from nPoint January 28th, 2016

Vesper Collaborates with GLOBALFOUNDRIES to Deliver First Piezoelectric MEMS Microphones: Acoustic sensing company works with top foundry to support mass-market consumer products January 21st, 2016

Home

Industrial Nanotech, Inc. Announces New Office in Arizona to Service the Company's New Regional and National Home Builders in Arizona and Nevada October 2nd, 2015

Industrial Nanotech, Inc. Provides Update on PCAOB Audited Financials July 27th, 2015

Solar cells in the roof and nanotechnology in the walls June 16th, 2015

Industrial Nanotech, Inc. Continues Global Development Focus on Original Equipment Manufacturer (OEM) Applications: Industrial Nanotech Continues Connecting With Manufacturers Who Seek Out Their Patented Thermal Insulation and Protective Coatings June 11th, 2015

Industrial

Nature Materials: Smallest lattice structure worldwide: 3-D lattice with glassy carbon struts and braces of less than 200 nm in diameter has higher specific strength than most solids February 3rd, 2016

New sensors to combat the proliferation of bacteria in very high-humidity environments January 23rd, 2016

Teijin to Participate in Nano Tech 2016 January 21st, 2016

Corrosion-Fighter Tesla NanoCoatings Pioneers 2x1 Wet-on-Wet Process January 20th, 2016

Solar/Photovoltaic

Simplifying solar cells with a new mix of materials: Berkeley Lab-led research team creates a high-efficiency device in 7 steps January 29th, 2016

An alternative to platinum: Iron-nitrogen compounds as catalysts in graphene January 28th, 2016

Scientists provide new guideline for synthesis of fullerene electron acceptors January 28th, 2016

Nanostructural Changes in Solar Cells to Increase Their Efficiency January 28th, 2016

Construction

New type of nanowires, built with natural gas heating: UNIST research team developed a new simple nanowire manufacturing technique February 1st, 2016

SiC Nanoparticles Applied to Modify Properties of Portland Cement January 14th, 2016

Application of Graphene Structures to Produce Fireproof, Anticorrosive Nanocoatings October 21st, 2015

Carbon Nanotubes Applied to Create Electrical Conductivity in Woolen Fabrics September 30th, 2015

NanoNews-Digest
The latest news from around the world, FREE




  Premium Products
NanoNews-Custom
Only the news you want to read!
 Learn More
NanoTech-Transfer
University Technology Transfer & Patents
 Learn More
NanoStrategies
Full-service, expert consulting
 Learn More











ASP
Nanotechnology Now Featured Books




NNN

The Hunger Project







Car Brands
Buy website traffic