Science

High-efficiency solar energy tech turns water into steam

High-efficiency solar energy t...
Rice University graduate student Oara Neumann (left) and scientist Naomi Halas are co-authors of new research on a highly efficient method of turning sunlight into steam
Rice University graduate student Oara Neumann (left) and scientist Naomi Halas are co-authors of new research on a highly efficient method of turning sunlight into steam
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New solar steam technology developed at Rice University is so effective at turning sunlight into heat that it can produce steam from icy-cold water
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New solar steam technology developed at Rice University is so effective at turning sunlight into heat that it can produce steam from icy-cold water
A diagram illustrating how the light-absorbing nanoparticles turn sunlight into steam
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A diagram illustrating how the light-absorbing nanoparticles turn sunlight into steam
The solar steam device developed at Rice University has an overall energy efficiency of 24 percent, far surpassing that of photovoltaic solar panels
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The solar steam device developed at Rice University has an overall energy efficiency of 24 percent, far surpassing that of photovoltaic solar panels
Rice University graduate student Oara Neumann (left) and scientist Naomi Halas are co-authors of new research on a highly efficient method of turning sunlight into steam
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Rice University graduate student Oara Neumann (left) and scientist Naomi Halas are co-authors of new research on a highly efficient method of turning sunlight into steam
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A team of researchers at Rice University has developed a new technology that uses light-absorbing nanoparticles to convert solar energy directly into steam. Even though it is already significantly more efficient than solar panels at producing electricity, the technology will likely find its first applications in low-cost sanitation, water purification and human waste treatment for the developing world.

Approximately 90 percent of the world's electricity is produced from steam turbines. Most industrial steam is produced in large, expensive boilers, but because of its very small footprint and high efficiency, this new development promises to make steam economically viable on a much smaller scale. Sterilizing medical waste and surgical instruments, preparing food and purifying water could soon become within reach of a large chunk of the developing world, that doesn't have access to the electrical grid.

The Rice technology relies on light-absorbing nanoparticles. When they are submerged and then illuminated, these particles can very quickly reach temperatures well above the boiling point of water. At this stage, they quickly dissipate heat through their very small surface area, which almost instantly results in 150°C (300°F) steam generated right at the surface of the particle. The system is so effective that it can even turn icy-cold water directly into vapor with ease.

A diagram illustrating how the light-absorbing nanoparticles turn sunlight into steam
A diagram illustrating how the light-absorbing nanoparticles turn sunlight into steam

The technology converts about 80 percent of the energy coming from the sun into steam. With the current iteration, passing the resulting steam to a turbine would generate electricity with an overall efficiency of 24 percent (compared to a solar panel's typical efficiency of around 15 percent). As the technology is further refined, the researchers say there is still room for improvement on the efficiency front.

Other potential uses could be powering hybrid air-conditioning and heating systems that run off of sunlight during the day and off of electricity at night. The system has also proved very promising in distilling water, with an experiment finding that the technology is about two and a half times more efficient than existing commercially available systems.

The project was awarded a grant from the Bill and Melinda Gates Foundation to create a small-scale system for treating human waste in areas lacking sewer systems or electricity. In the meantime, Rice engineering undergraduates have already created a solar steam-powered autoclave that can sterilize medical and dental instruments in clinics lacking electricity.

An open-access paper detailing the research efforts was published in the journal ACS Nano.

Source: Rice University

The video below illustrates the working principles behind this technology.

Researchers create solar steam using nanoparticles at Rice University

View gallery - 4 images
21 comments
Slowburn
The problem with heating water with a light source is getting the energy to stop in the water. I suggested something similar when I noticed that a glass of cola warms up faster than a glass lemon-lime soda when on a picnic. If getting the radiant heat (as apposed to conducting heat) to stop in the water more efficiently makes the water heat faster adding some soot to the water in a conventional boiler might make it slightly more efficient.
ivan4
This was done in Victorian times and demonstrated at the great exhibition if my reading of the description is correct. OK, that one didn't use nano tech so that is the new thing. There have also been several solar powered AC units built over the years.
abe
Desalianation? Wouldn't the salt particles bind to the nano particles and make them less efficient. I imagine that the water used needs to be pretty clean (filtered...), unless the steam boiled other water, in that case you no longer have 90% efficiency.
Reason
abe, the way I see it desalination and especially human waste treatment would involve a closed loop using pure water - steam - water and a heat exchanger to treat/desalinate.
Scion
What about just solar hot water system that actually works well? Heat the water and pass it to a holding tank. You could use a much smaller collector.
ikarus342000
Great new idea. Desalniation by evaporation is not new, but would be now more efficient. By the way, tell me where I can buy solar panels with an efficiency of 15 % ? You can be happy if the reach 9 %. So this makes this invention even more important.
usugo
The technology seems interesting and cool. However, good commercial photovoltaics have an efficiency of about 20%, not 15%. And I remember a solar concentrator using a stirling engine that had an efficiency of 25-30%. So, either the technology is much cheaper or it will end up like the aforementioned concentrator .... nowhere
Stephen N Russell
Mass produce & use for Temp emergencies or for LT power IE EU, Russia, Iceland, Greenland, Alaska alone can use & Yukon Terr Canada.
Sergey Jivetin
80% efficiency! Amazing!
Fretting Freddy the Ferret pressing the Fret
"At this stage, they quickly dissipate heat through their very small surface area..." It should read as a very high surface area. We're talking about nano-particles, they have a high surface to volume ratio, meaning the particles have more surface access area to quickly dissipate heat to the medium than if the particles were bigger.