Featured Research

from universities, journals, and other organizations

A new way to harness waste heat: Electrochemical approach has potential to efficiently turn low-grade heat to electricity

Date:
May 21, 2014
Source:
Massachusetts Institute of Technology
Summary:
Vast amounts of excess heat are generated by industrial processes and by electric power plants; researchers around the world have spent decades seeking ways to harness some of this wasted energy. Now researchers have found a new alternative for low-temperature waste-heat conversion into electricity.

Scientists have found a new alternative for low-temperature waste-heat conversion into electricity.
Credit: Jose-Luis Olivares/MIT

Vast amounts of excess heat are generated by industrial processes and by electric power plants; researchers around the world have spent decades seeking ways to harness some of this wasted energy. Most such efforts have focused on thermoelectric devices, solid-state materials that can produce electricity from a temperature gradient, but the efficiency of such devices is limited by the availability of materials.

Related Articles


Now researchers at MIT and Stanford University have found a new alternative for low-temperature waste-heat conversion into electricity -- that is, in cases where temperature differences are less than 100 degrees Celsius.

The new approach, based on a phenomenon called the thermogalvanic effect, is described in a paper published in the journal Nature Communications by postdoc Yuan Yang and professor Gang Chen at MIT, postdoc Seok Woo Lee and professor Yi Cui at Stanford, and three others.

Since the voltage of rechargeable batteries depends on temperature, the new system combines the charging-discharging cycles of these batteries with heating and cooling, so that the discharge voltage is higher than charge voltage. The system can efficiently harness even relatively small temperature differences, such as a 50 degrees Celsius difference.

To begin, the uncharged battery is heated by the waste heat. Then, while at the higher temperature, the battery is charged; once fully charged, it is allowed to cool. Because the charging voltage is lower at high temperatures than at low temperatures, once it has cooled the battery can actually deliver more electricity than what was used to charge it. That extra energy, of course, doesn't just appear from nowhere: It comes from the heat that was added to the system.

The system aims at harvesting heat of less than 100 degrees Celsius, which accounts for a large proportion of potentially harvestable waste heat. In a demonstration with waste heat of 60 degrees Celsius the new system has an estimated efficiency of 5.7 percent.

The basic concept for this approach was initially proposed in the 1950s, Chen says, but "a key advance is using material that was not around at that time" for the battery electrodes, as well as advances in engineering the system.

That earlier work was based on temperatures of 500 degrees Celsius or more, Yang adds; most current heat-recovery systems work best with higher temperature differences.

While the new system has a significant advantage in energy-conversion efficiency, for now it has a much lower power density -- the amount of power that can be delivered for a given weight -- than thermoelectrics. It also will require further research to assure reliability over a long period of use, and to improve the speed of battery charging and discharging, Chen says. "It will require a lot of work to take the next step," he cautions.

Chen, the Carl Richard Soderberg Professor of Power Engineering and head of MIT's Department of Mechanical Engineering, says there's currently no good technology that can make effective use of the relatively low-temperature differences this system can harness. "This has an efficiency we think is quite attractive," he says. "There is so much of this low-temperature waste heat, if a technology can be created and deployed to use it."

Cui says, "Virtually all power plants and manufacturing processes, like steelmaking and refining, release tremendous amounts of low-grade heat to ambient temperatures. Our new battery technology is designed to take advantage of this temperature gradient at the industrial scale."

Lee adds, "This technology has the additional advantage of using low-cost, abundant materials and manufacturing process that are already widely used in the battery industry."

Peidong Yang, a professor of chemistry at the University of California at Berkeley who was not involved in this work, says, "By exploring the thermogalvanic effect, [the MIT and Stanford researchers] were able to convert low-grade heat to electricity with decent efficiency. It is a very promising technology. … This is a clever idea, and low-grade waste heat is everywhere."

MIT's Yang underscores that point: "One-third of all energy consumption in the United States ends up as low-grade heat."

The MIT work was partially funded by the U.S. Department of Energy, in part through the Solid-State Solar-Thermal Energy Conversion Center, and the U.S. Air Force. The work at Stanford was partially funded by the DOE, the SLAC National Accelerator Laboratory, and National Research Foundation of Korea.


Story Source:

The above story is based on materials provided by Massachusetts Institute of Technology. The original article was written by David L. Chandler. Note: Materials may be edited for content and length.


Journal Reference:

  1. Seok Woo Lee, Yuan Yang, Hyun-Wook Lee, Hadi Ghasemi, Daniel Kraemer, Gang Chen, Yi Cui. An electrochemical system for efficiently harvesting low-grade heat energy. Nature Communications, 2014; 5 DOI: 10.1038/ncomms4942

Cite This Page:

Massachusetts Institute of Technology. "A new way to harness waste heat: Electrochemical approach has potential to efficiently turn low-grade heat to electricity." ScienceDaily. ScienceDaily, 21 May 2014. <www.sciencedaily.com/releases/2014/05/140521133611.htm>.
Massachusetts Institute of Technology. (2014, May 21). A new way to harness waste heat: Electrochemical approach has potential to efficiently turn low-grade heat to electricity. ScienceDaily. Retrieved December 18, 2014 from www.sciencedaily.com/releases/2014/05/140521133611.htm
Massachusetts Institute of Technology. "A new way to harness waste heat: Electrochemical approach has potential to efficiently turn low-grade heat to electricity." ScienceDaily. www.sciencedaily.com/releases/2014/05/140521133611.htm (accessed December 18, 2014).

Share This


More From ScienceDaily



More Matter & Energy News

Thursday, December 18, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Navy Unveils Robot Fish

Navy Unveils Robot Fish

Reuters - Light News Video Online (Dec. 18, 2014) The U.S. Navy unveils an underwater device that mimics the movement of a fish. Tara Cleary reports. Video provided by Reuters
Powered by NewsLook.com
3D Printed Cookies Just in Time for Christmas

3D Printed Cookies Just in Time for Christmas

Reuters - Innovations Video Online (Dec. 18, 2014) A tech company in Spain have combined technology with cuisine to develop the 'Foodini', a 3D printer designed to print the perfect cookie for Santa. Ben Gruber reports. Video provided by Reuters
Powered by NewsLook.com
Ford Expands Air Bag Recall Nationwide

Ford Expands Air Bag Recall Nationwide

Newsy (Dec. 18, 2014) The automaker added 447,000 vehicles to its recall list, bringing the total to more than 502,000. Video provided by Newsy
Powered by NewsLook.com
How Sony Hopes To Make Any Glasses 'Smart'

How Sony Hopes To Make Any Glasses 'Smart'

Newsy (Dec. 17, 2014) Sony's glasses module attaches to the temples of various eye- and sunglasses to add a display and wireless connectivity. 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