Using Nanowire Silicon Thermoelectrics to Capture Waste Heat
January 21, 2008 3:17 AM
comment(s) - last by
Professor Peidong Yang led the University of California, Berkley team who discovered silicon nanowire's thermoelectric properties.
(Source: University of California, Berkley)
A scanning electron microscope image of a thin silicon nanowire stretching between two heating pads, one as a heat source, the other as a sensor.
(Source: A. Hochbaum)
Silicon heat capture could allow cheap refrigeration and energy saving
Among the many valuable properties of silicon is its ability to
capture solar energy
to create electricity via its photoelectric character. Now scientists are discovering that silicon, when properly prepared, can form a very good thermoelectric as well. This opens the door to a plethora of uses, including refrigeration, solar heat power generation, and power generation from other heat sources, such as computer waste heat or car heat.
has two basic modes of operation. When a thermoelectric is placed over a heat gradient, it generates an electric current. The other mode is the reverse; when a thermoelectric is exposed to an electric current, it creates a heat difference, cooling one side of it, and warming the other side. Thus thermoelectrics are applicable to power generation, refrigeration and heating.
Traditional thermoelectrics, which have been around since the 1960s, rely on either bismuth telluride or lead telluride. These materials are relatively expensive due to scarcity and lack of a large manufacturing infrastructure. They are also bulky and require more material, which further increaese their cost. While thermoelectric coolers have achieved modest commercial usage in seat coolers and picnic coolers, they have yet to realize their full potential.
may change that. Professor Peidong Yang and his colleagues at the University of California, Berkley published in last week's
journal the results of years of research into using silicon as thermoelectrics. Their results show that silicon can be a viable thermoelectric.
The key is in the preparation. The researchers prepared thin nanowires of silicon. When these wires are exposed to a temperature difference, they generate electricity. Standard silicon is a poor thermoelectric, but according to Dr. Yang, "the performance of the nanowires is already comparable to the best existing thermoelectric material."
A good thermoelectric needs to have two key properties -- good electrical conduction, and poor heat conduction. Silicon typically conducts both very well, but by producing 50 nm nanowires, the heat conduction of silicon is reduced to one hundreth of its normal levels, while electrical conduction remains unchanged. The material is comparable to commercial thermoelectrics.
Two possible uses of the technology are to generate electricity from waste heat of car engines. Current thermoelectrics are too expensive and large to make this a practical possibility. Nanowire silicon layers, though could provide a means to recapture some of the energy lost to heat during the conversion to mechanical energy in a car engine. This extra savings could be stored in batteries, to give next generation electric vehicles, such as
the Chevrolet Volt
, even better efficiency.
It could also find a home in solar power cells. By coupling it with traditional photoelectric cells, much higher efficiencies could possibly be reached. Yet another application is to put the materials in computers to provide energy savings, which would be particularly valuable to mobile computing. Further, it could be used in refrigeration applications, as well.
Much work needs to be done before the process is perfected. The physics behind why nanowires of silicon lose their heat conduction is not understood, which stands in the way of refining the efficiency of this class of devices. Further creating a thermoelectric on the macroscopic scale, by creating a network of nanowires, has yet to be accomplished. Still, the discovery of these properties in silicon promise a way to eventually use replace current less ideal thermoelectrics with an abundant material with a large processing infrastructure.
This article is over a month old, voting and posting comments is disabled
1/22/2008 9:04:19 AM
You bring up an excellent point. However, there are two issues I have with your assertion:
1) In a public forum, the same mistakes tend not to be dealt with in multiplicity, save for the cases where they are simultaneously addressed. Additionally, the more eyes, the better.
2) Since Jason Mick has provided this story in a public forum, then Jason must also accept the responsibility of public scrutiny for either premise or presentation.
It's evident that Daily Tech doesn't have an editorial staff; if it does, it's certainly not a traditional one where style guides, proofreading and grammatical analysis are part and parcel of such responsibilities. That doesn't mean such responsibilities are unimportant or unnecessary; it probably means that Daily Tech simply can't afford to hire someone to fill that role.
I like Jason Mick's articles. I look forward to more from him, and wish him well in his endeavors here at Daily Tech.
"There is a single light of science, and to brighten it anywhere is to brighten it everywhere." -- Isaac Asimov
GM Adds Wiggle Room to 2010 Volt Deadline
January 4, 2008, 11:18 AM
Promise of Thermoelectric Materials on the Rebound
November 27, 2007, 2:32 PM
Sharp Readying Thin Solar Cell Output For 2008
November 4, 2007, 10:58 AM
U.S. Air Force F-35 Lightning II, F-22 Raptor Team Up for “Integration Training”
November 19, 2014, 9:15 AM
U.S. Marshals Using Fake, Airplane-based Cell Towers to Scan Cell Phones of Americans
November 14, 2014, 9:05 AM
Ford Enlists Wind Energy Corp. to Provide Wind, Solar Energy to Four U.S. Dealerships
November 10, 2014, 10:58 AM
Disney Reveals Star Wars Ep. VII Title -- "The Force Awakens"
November 6, 2014, 3:45 PM
U.S. Navy Lockheed F-35C Completes First Carrier Landing
November 4, 2014, 12:44 PM
Microsoft Co-founder Paul Allen Donates $100M to Fight Raging Ebola Epidemic
October 23, 2014, 6:05 PM
Most Popular Articles
Uber Exec Threatens to "Spend Millions" to Stalk Female Reporter and Her Family
November 19, 2014, 12:31 PM
Apple Replaces “FREE” Label with “GET” on App Downloads in iTunes App Store
November 19, 2014, 5:38 PM
Rand Paul Casts Crucial "No" Vote on Obama-Backed PATRIOT Act Renewal Bill
November 19, 2014, 5:15 PM
FTC Announces Crackdown on Computer Speedup/Tech Support Scams
November 20, 2014, 1:40 PM
Wal-Mart: Miss Thanksgiving, Get Xbox One + Master Chief Collection for $299
November 17, 2014, 9:40 PM
Latest Blog Posts
Costco Gives Employees Thanksgiving Off; Wal-Mart Leads "Black Thursday" Charge
Oct 29, 2014, 9:57 PM
"Bear Selfies" Fad Could Turn Deadly, Warn Nevada Wildlife Officials
Oct 28, 2014, 12:00 PM
The Surface Mini That Was Never Released Gets "Hands On" Treatment
Sep 26, 2014, 8:22 AM
ISIS Imposes Ban on Teaching Evolution in Iraq
Sep 17, 2014, 5:22 PM
Space Terrorism is a Looming Threat For the United States
Apr 23, 2014, 7:47 PM
More Blog Posts
Copyright 2014 DailyTech LLC. -
Terms, Conditions & Privacy Information