Nanotechnology Now

Our NanoNews Digest Sponsors


Heifer International

Wikipedia Affiliate Button


DHgate

Home > Press > Steam from the sun: New spongelike structure converts solar energy into steam

On the left, a representative structure for localization of heat; the cross section of structure and temperature distribution. On the right, a picture of enhanced steam generation by the DLS structure under solar illumination.

Courtesy of the researchers
On the left, a representative structure for localization of heat; the cross section of structure and temperature distribution. On the right, a picture of enhanced steam generation by the DLS structure under solar illumination.

Courtesy of the researchers

Abstract:
A new material structure developed at MIT generates steam by soaking up the sun.

The structure — a layer of graphite flakes and an underlying carbon foam — is a porous, insulating material structure that floats on water. When sunlight hits the structure's surface, it creates a hotspot in the graphite, drawing water up through the material's pores, where it evaporates as steam. The brighter the light, the more steam is generated.

Steam from the sun: New spongelike structure converts solar energy into steam

Cambridge, MA | Posted on July 21st, 2014

The new material is able to convert 85 percent of incoming solar energy into steam — a significant improvement over recent approaches to solar-powered steam generation. What's more, the setup loses very little heat in the process, and can produce steam at relatively low solar intensity. This would mean that, if scaled up, the setup would likely not require complex, costly systems to highly concentrate sunlight.

Hadi Ghasemi, a postdoc in MIT's Department of Mechanical Engineering, says the spongelike structure can be made from relatively inexpensive materials — a particular advantage for a variety of compact, steam-powered applications.

"Steam is important for desalination, hygiene systems, and sterilization," says Ghasemi, who led the development of the structure. "Especially in remote areas where the sun is the only source of energy, if you can generate steam with solar energy, it would be very useful."

Ghasemi and mechanical engineering department head Gang Chen, along with five others at MIT, report on the details of the new steam-generating structure in the journal Nature Communications.

Cutting the optical concentration

Today, solar-powered steam generation involves vast fields of mirrors or lenses that concentrate incoming sunlight, heating large volumes of liquid to high enough temperatures to produce steam. However, these complex systems can experience significant heat loss, leading to inefficient steam generation.

Recently, scientists have explored ways to improve the efficiency of solar-thermal harvesting by developing new solar receivers and by working with nanofluids. The latter approach involves mixing water with nanoparticles that heat up quickly when exposed to sunlight, vaporizing the surrounding water molecules as steam. But initiating this reaction requires very intense solar energy — about 1,000 times that of an average sunny day.

By contrast, the MIT approach generates steam at a solar intensity about 10 times that of a sunny day — the lowest optical concentration reported thus far. The implication, the researchers say, is that steam-generating applications can function with lower sunlight concentration and less-expensive tracking systems.

"This is a huge advantage in cost-reduction," Ghasemi says. "That's exciting for us because we've come up with a new approach to solar steam generation."

From sun to steam

The approach itself is relatively simple: Since steam is generated at the surface of a liquid, Ghasemi looked for a material that could both efficiently absorb sunlight and generate steam at a liquid's surface.

After trials with multiple materials, he settled on a thin, double-layered, disc-shaped structure. Its top layer is made from graphite that the researchers exfoliated by placing the material in a microwave. The effect, Chen says, is "just like popcorn": The graphite bubbles up, forming a nest of flakes. The result is a highly porous material that can better absorb and retain solar energy.

The structure's bottom layer is a carbon foam that contains pockets of air to keep the foam afloat and act as an insulator, preventing heat from escaping to the underlying liquid. The foam also contains very small pores that allow water to creep up through the structure via capillary action.

As sunlight hits the structure, it creates a hotspot in the graphite layer, generating a pressure gradient that draws water up through the carbon foam. As water seeps into the graphite layer, the heat concentrated in the graphite turns the water into steam. The structure works much like a sponge that, when placed in water on a hot, sunny day, can continuously absorb and evaporate liquid.

The researchers tested the structure by placing it in a chamber of water and exposing it to a solar simulator — a light source that simulates various intensities of solar radiation. They found they were able to convert 85 percent of solar energy into steam at a solar intensity 10 times that of a typical sunny day.

Ghasemi says the structure may be designed to be even more efficient, depending on the type of materials used.

"There can be different combinations of materials that can be used in these two layers that can lead to higher efficiencies at lower concentrations," Ghasemi says. "There is still a lot of research that can be done on implementing this in larger systems."

###

Written by Jennifer Chu, MIT News Office

####

For more information, please click here

Contacts:
Kimberly Allen
MIT News Office

617-253-2702

Copyright © Massachusetts Institute of Technology

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 Links

Gang Chen:

Archive: A new way to harness waste heat:

Archive: Solving a mystery of thermoelectrics:

Archive: Cooling when there’s too much heat:

Related News Press

News and information

Oxford Instruments Asylum Research and McGill University Announce the McGill AFM Summer School and Workshop, May 12-13, 2016 May 4th, 2016

The intermediates in a chemical reaction photographed 'red-handed' Researchers at the UPV/EHU-University of the Basque Country have for the first time succeeded in imaging all the steps in a complex organic reaction and have resolved the mechanisms that explain it May 4th, 2016

New tool allows scientists to visualize 'nanoscale' processes May 4th, 2016

FEI Launches Apreo – Industry-Leading Versatile, High-Performance SEM: The Apreo SEM provides high-resolution surface information with excellent contrast, and the flexibility to accommodate a large range of samples, applications and conditions May 4th, 2016

Discoveries

The intermediates in a chemical reaction photographed 'red-handed' Researchers at the UPV/EHU-University of the Basque Country have for the first time succeeded in imaging all the steps in a complex organic reaction and have resolved the mechanisms that explain it May 4th, 2016

New tool allows scientists to visualize 'nanoscale' processes May 4th, 2016

A compact, efficient single photon source that operates at ambient temperatures on a chip: Highly directional single photon source concept is expected to lead to a significant progress in producing compact, cheap, and efficient sources of quantum information bits for future appls May 3rd, 2016

Nuclear pores captured on film: Using an ultra fast-scanning atomic force microscope, researchers from the University of Basel have filmed 'living' nuclear pore complexes at work for the first time May 3rd, 2016

Materials/Metamaterials

Clay nanotube-biopolymer composite scaffolds for tissue engineering May 1st, 2016

Exploring phosphorene, a promising new material April 29th, 2016

Hybrid nanoantennas -- next-generation platform for ultradense data recording April 28th, 2016

Atomic magnets using hydrogen and graphene April 27th, 2016

Announcements

Oxford Instruments Asylum Research and McGill University Announce the McGill AFM Summer School and Workshop, May 12-13, 2016 May 4th, 2016

The intermediates in a chemical reaction photographed 'red-handed' Researchers at the UPV/EHU-University of the Basque Country have for the first time succeeded in imaging all the steps in a complex organic reaction and have resolved the mechanisms that explain it May 4th, 2016

New tool allows scientists to visualize 'nanoscale' processes May 4th, 2016

FEI Launches Apreo – Industry-Leading Versatile, High-Performance SEM: The Apreo SEM provides high-resolution surface information with excellent contrast, and the flexibility to accommodate a large range of samples, applications and conditions May 4th, 2016

Interviews/Book Reviews/Essays/Reports/Podcasts/Journals/White papers

The intermediates in a chemical reaction photographed 'red-handed' Researchers at the UPV/EHU-University of the Basque Country have for the first time succeeded in imaging all the steps in a complex organic reaction and have resolved the mechanisms that explain it May 4th, 2016

New tool allows scientists to visualize 'nanoscale' processes May 4th, 2016

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

Energy

Nanoparticles present sustainable way to grow food crops May 1st, 2016

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

Researchers create artificial protein to control assembly of buckyballs April 27th, 2016

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

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