Featured Research

from universities, journals, and other organizations

New reactor paves the way for efficiently producing fuel from sunlight

Date:
January 19, 2011
Source:
California Institute of Technology
Summary:
Using a common metal most famously found in self-cleaning ovens, Sossina Haile hopes to change our energy future. The metal is cerium oxide -- or ceria -- and it is the centerpiece of a promising new technology developed by Haile and her colleagues that concentrates solar energy and uses it to efficiently convert carbon dioxide and water into fuels.

Sossina Haile and William Chueh stand next to the benchtop thermochemical reactor used to screen materials for implementation on the solar reactor.
Credit: Courtesy of Caltech

Using a common metal most famously found in self-cleaning ovens, Sossina Haile hopes to change our energy future. The metal is cerium oxide -- or ceria -- and it is the centerpiece of a promising new technology developed by Haile and her colleagues that concentrates solar energy and uses it to efficiently convert carbon dioxide and water into fuels.

Solar energy has long been touted as the solution to our energy woes, but while it is plentiful and free, it can't be bottled up and transported from sunny locations to the drearier -- but more energy-hungry -- parts of the world. The process developed by Haile -- a professor of materials science and chemical engineering at the California Institute of Technology (Caltech) -- and her colleagues could make that possible.

The researchers designed and built a two-foot-tall prototype reactor that has a quartz window and a cavity that absorbs concentrated sunlight. The concentrator works "like the magnifying glass you used as a kid" to focus the sun's rays, says Haile.

At the heart of the reactor is a cylindrical lining of ceria. Ceria -- a metal oxide that is commonly embedded in the walls of self-cleaning ovens, where it catalyzes reactions that decompose food and other stuck-on gunk -- propels the solar-driven reactions. The reactor takes advantage of ceria's ability to "exhale" oxygen from its crystalline framework at very high temperatures and then "inhale" oxygen back in at lower temperatures.

"What is special about the material is that it doesn't release all of the oxygen. That helps to leave the framework of the material intact as oxygen leaves," Haile explains. "When we cool it back down, the material's thermodynamically preferred state is to pull oxygen back into the structure."

Specifically, the inhaled oxygen is stripped off of carbon dioxide (CO2) and/or water (H2O) gas molecules that are pumped into the reactor, producing carbon monoxide (CO) and/or hydrogen gas (H2). H2 can be used to fuel hydrogen fuel cells; CO, combined with H2, can be used to create synthetic gas, or "syngas," which is the precursor to liquid hydrocarbon fuels. Adding other catalysts to the gas mixture, meanwhile, produces methane. And once the ceria is oxygenated to full capacity, it can be heated back up again, and the cycle can begin anew.

For all of this to work, the temperatures in the reactor have to be very high -- nearly 3,000 degrees Fahrenheit. At Caltech, Haile and her students achieved such temperatures using electrical furnaces. But for a real-world test, she says, "we needed to use photons, so we went to Switzerland." At the Paul Scherrer Institute's High-Flux Solar Simulator, the researchers and their collaborators -- led by Aldo Steinfeld of the institute's Solar Technology Laboratory -- installed the reactor on a large solar simulator capable of delivering the heat of 1,500 suns.

In experiments conducted last spring, Haile and her colleagues achieved the best rates for CO2 dissociation ever achieved, "by orders of magnitude," she says. The efficiency of the reactor was uncommonly high for CO2 splitting, in part, she says, "because we're using the whole solar spectrum, and not just particular wavelengths." And unlike in electrolysis, the rate is not limited by the low solubility of CO2 in water. Furthermore, Haile says, the high operating temperatures of the reactor mean that fast catalysis is possible, without the need for expensive and rare metal catalysts (cerium, in fact, is the most common of the rare earth metals -- about as abundant as copper).

In the short term, Haile and her colleagues plan to tinker with the ceria formulation so that the reaction temperature can be lowered, and to re-engineer the reactor, to improve its efficiency. Currently, the system harnesses less than 1% of the solar energy it receives, with most of the energy lost as heat through the reactor's walls or by re-radiation through the quartz window. "When we designed the reactor, we didn't do much to control these losses," says Haile. Thermodynamic modeling by lead author and former Caltech graduate student William Chueh suggests that efficiencies of 15% or higher are possible.

Ultimately, Haile says, the process could be adopted in large-scale energy plants, allowing solar-derived power to be reliably available during the day and night. The CO2 emitted by vehicles could be collected and converted to fuel, "but that is difficult," she says. A more realistic scenario might be to take the CO2 emissions from coal-powered electric plants and convert them to transportation fuels. "You'd effectively be using the carbon twice," Haile explains. Alternatively, she says, the reactor could be used in a "zero CO2 emissions" cycle: H2O and CO2 would be converted to methane, would fuel electricity-producing power plants that generate more CO2 and H2O, to keep the process going.

The work was funded by the National Science Foundation, the State of Minnesota Initiative for Renewable Energy and the Environment, and the Swiss National Science Foundation.


Story Source:

The above story is based on materials provided by California Institute of Technology. The original article was written by Kathy Svitil. Note: Materials may be edited for content and length.


Journal Reference:

  1. W. C. Chueh, C. Falter, M. Abbott, D. Scipio, P. Furler, S. M. Haile, A. Steinfeld. High-Flux Solar-Driven Thermochemical Dissociation of CO2 and H2O Using Nonstoichiometric Ceria. Science, 2010; 330 (6012): 1797 DOI: 10.1126/science.1197834

Cite This Page:

California Institute of Technology. "New reactor paves the way for efficiently producing fuel from sunlight." ScienceDaily. ScienceDaily, 19 January 2011. <www.sciencedaily.com/releases/2011/01/110119102746.htm>.
California Institute of Technology. (2011, January 19). New reactor paves the way for efficiently producing fuel from sunlight. ScienceDaily. Retrieved October 23, 2014 from www.sciencedaily.com/releases/2011/01/110119102746.htm
California Institute of Technology. "New reactor paves the way for efficiently producing fuel from sunlight." ScienceDaily. www.sciencedaily.com/releases/2011/01/110119102746.htm (accessed October 23, 2014).

Share This



More Matter & Energy News

Thursday, October 23, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Chameleon Camouflage to Give Tanks Cloaking Capabilities

Chameleon Camouflage to Give Tanks Cloaking Capabilities

Reuters - Innovations Video Online (Oct. 22, 2014) — Inspired by the way a chameleon changes its colour to disguise itself; scientists in Poland want to replace traditional camouflage paint with thousands of electrochromic plates that will continuously change colour to blend with its surroundings. The first PL-01 concept tank prototype will be tested within a few years, with scientists predicting that a similar technology could even be woven into the fabric of a soldiers' clothing making them virtually invisible to the naked eye. Matthew Stock reports. Video provided by Reuters
Powered by NewsLook.com
Jet Sales Lift Boeing Profit 18 Pct.

Jet Sales Lift Boeing Profit 18 Pct.

Reuters - Business Video Online (Oct. 22, 2014) — Strong jet demand has pushed Boeing to raise its profit forecast for the third time, but analysts were disappointed by its small cash flow. Fred Katayama reports. Video provided by Reuters
Powered by NewsLook.com
Internet of Things Aims to Smarten Your Life

Internet of Things Aims to Smarten Your Life

AP (Oct. 22, 2014) — As more and more Bluetooth-enabled devices are reaching consumers, developers are busy connecting them together as part of the Internet of Things. (Oct. 22) Video provided by AP
Powered by NewsLook.com
What Is Magic Leap, And Why Is It Worth $500M?

What Is Magic Leap, And Why Is It Worth $500M?

Newsy (Oct. 22, 2014) — Magic Leap isn't publicizing much more than a description of its product, but it’s been enough for Google and others to invest more than $500M. Video provided by Newsy
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
 
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:  

Breaking News:

Strange & Offbeat Stories

 

Space & Time

Matter & Energy

Computers & Math

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:  

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile iPhone Android Web
Follow Facebook Twitter Google+
Subscribe RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins