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

Little ANTs: Researchers build the world's tiniest engine May 3rd, 2016

An Experiment Seeks to Make Quantum Physics Visible to the Naked Eye May 3rd, 2016

Quantum sensors for high-precision magnetometry of superconductors May 3rd, 2016

New drug-delivery approach holds potential for treating obesity May 2nd, 2016

Discoveries

Little ANTs: Researchers build the world's tiniest engine May 3rd, 2016

An Experiment Seeks to Make Quantum Physics Visible to the Naked Eye May 3rd, 2016

Quantum sensors for high-precision magnetometry of superconductors May 3rd, 2016

Non-animal approach to predict impact of nanomaterials on human lung published Archives of Toxicology publishes workshop recommendations May 2nd, 2016

Announcements

Little ANTs: Researchers build the world's tiniest engine May 3rd, 2016

An Experiment Seeks to Make Quantum Physics Visible to the Naked Eye May 3rd, 2016

Quantum sensors for high-precision magnetometry of superconductors May 3rd, 2016

New drug-delivery approach holds potential for treating obesity May 2nd, 2016

Automotive/Transportation

New spin Seebeck thermoelectric device with higher conversion efficiency created April 26th, 2016

All powered up: UCI chemists create battery technology with off-the-charts charging capacity April 21st, 2016

Ruthenium nanoframes open the doors to better catalysts April 4th, 2016

Heat and light get larger at the nanoscale: Columbia-led research team first to demonstrate a strong, non-contact heat transfer channel using light with performances that could lead to high efficiency electricity generation April 2nd, 2016

Home

All powered up: UCI chemists create battery technology with off-the-charts charging capacity April 21st, 2016

Transparent wood could one day help brighten homes and buildings March 31st, 2016

ORNL researchers invent tougher plastic with 50 percent renewable content March 24th, 2016

New research unveils graphene 'moth eyes' to power future smart technologies: New ultra-thin, patterned graphene sheets will be essential in designing future technologies such as 'smart wallpaper' and Internet-of-things applications March 1st, 2016

Industrial

Novel anti-biofilm nano coating developed at Ben-Gurion U.: Offers significant anti-adhesive potential for a variety of medical and industrial applications April 25th, 2016

Model aids efforts to reduce cost of carbon nanostructures for industry, research April 5th, 2016

Molecular-scale ALD discovery could have industrial-sized impact: New atomic layer deposition technique reduces waste March 31st, 2016

Transparent wood could one day help brighten homes and buildings March 31st, 2016

Solar/Photovoltaic

NREL finds nanotube semiconductors well-suited for PV systems April 27th, 2016

Flipping a chemical switch helps perovskite solar cells beat the heat April 26th, 2016

Manipulating light inside opaque layers April 24th, 2016

Thin-film solar cells: How defects appear and disappear in CIGSe cells: Concentration of copper plays a crucial role April 23rd, 2016

Construction

Nanotechnology is changing everything from medicine to self-healing buildings: Nanotechnology is so small it's measured in billionths of metres, and it is revolutionising every aspect of our lives April 2nd, 2016

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

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