Hybrid PV and TE

An article on hybrid photovoltaic and thermoelectric systems - featured in New Scientist this week (mostly focussed on the work of Gang Chen at MIT)

http://smart-grid.tmcnet.com/news/2011/11/24/5952916.htm

Recent IEEE spectrum post highlight potential of thermoelectric

A recent article by IEEE spectrum reports on the Energy innovation summit, we mentionned in a previous blog.

Application example: Intel-led Team Demonstrates Chip-Scale Thermoelectric Refrigerator

Following Moore’s Law, semiconductor transistor density double roughly

every 18 months to follow increasing performance demands. Growing

complexity and performance have led to highly non-uniform on-chip

power distribution. The resulting localized high heat flux or “hot spots” are a

major difficulty as they degrade microprocessor performance and

reduce significantly chip reliability. In a 2009 Nature nanotechnology paper, an Intel-led team demonstrated a potential solution based on on-chip cooling using thermoelectric materials. Lowering thermal contact resistance by an order of magnitude is one of the technical hurdles that must be overcome before a commercial device appears on the market. But Maryland’s Bar-Cohen, an IEEE Fellow, who was not involved in the research, imagines thermoelectrics someday being essential for chips in diminutive portable devices, like multitasking smart phones that must handle simultaneous data-intensive processing tasks.

Thermoelectric to power 10'000 years clock

In a good illustration of the reliability of thermoelectric generators, they will be used to power a clock designed to work for ten thousand years. The clock will be powered by the thermoelectric generator drawing electricity from the temperature difference between the hot exterior and the cool interior of the cave.

Panasonic develops thermoelectric generator for geothermal energy generation

The Japan based maker of electronic products for consumer, business and industrial use has developed thermoelectric tubes that the company says can be used for geothermal electricity generation and waste heat recovery. According to the company: "The tubular shape enables direct and efficient heat transfer without additional heat exchangers, yielding high density of generated power. Panasonic's thermoelectric tube with simple, compact, and efficient features is an ideal solution for capturing unused or wasted heat from hot springs and factory."

Self-powered sensors developed for monitoring aircraft integrity

A joint research project of EADS Germany and the Vienna University of Technology has developed thermoelectric generators to power sensors network to monitor airplane structural integrity. More details can be found here.

A nice view of one of NASA Thermoelectric generator

New images of the Curiosity Mars Rover have been released by NASA. The Curiosity rover will help assess whether Mars was, or is an environment able to support microbial life. The thermoelectric generator can be seen on the left side of the image. More information on NASA thermoelectric generators can be found here

Thermoelectric harvesters for Wireless Sensor Network

Nextreme Thermal Solutions Inc., a maker of thermoelectric modules has teamed up with Arkansas Power Electronics International Inc. to develop TEG harvesting system for wireless sensor network. In particular the WSN is designed to monitor the health of bearings in turbine engines.

Waste heat is ... hot

An interesting post on investment and VC activities in the waste heat recovery market in the US. Cost is still around$2 to $2.5 a watt:

“If you are looking at an average cost of power at six cents per kilowatt hour, the payback is approaching three years on a simple payback analysis without taking advantage of energy tax credits. If you are looking at a coastal state where the cost of power is 10 to12 cents, the payback is less than two years.”

A series of companies are developing new thermoelectric generators with a target cost of $1 per watt, at that price renewable energy is competitive with conventional forms of electricity. Note that the US DOE has recently launch a new $27 million initiative to bring solar energy at this level by 2017!

Arpa-e funds $1.7M to develop Economically Printed Flexible Nanostructured Stacked Thermoelectric Junctions

The University of Illinois received funding through ARPA-E’s 37 Projects Selected From Funding Opportunity Announcement #1 to develop an economic and highly scalable approach to fabricate flexible thermoelectric junctions based on silicon nanotubes and optimize the energy conversion efficiency. The end of phase deliverable is a 1 square inch flexible thermoelectric module with effective ZT>1.2. Publish Post

NY Times list new thermoelectric company among the 10 to watch out of ARPA-E

Early-stage, high-risk, US government-supported and potentially game changing are the common features of these 10 companies. Phononic Devices is an ARPA-E awardee commercializing advanced materials nano-engineered to recapture waste heat and convert it into electric power, or conversely, to provide highly efficient refrigeration and cooling. Phononic Devices is one of only 37 companies selected by ARPA-E in their inaugural solicitation for funding to pursue "transformational" energy breakthroughs and is based on research done atOklahoma University. More detail can be found arpa-e website.

New Swiss startup will launch flexible thermoelectric generators in 2012

GreenTEG ’s team and technology comes from the famous ETH Zurich. The startup has 11 employees and plans its market launch in 2012. The company claims :

• Low specific cost
• Process fully scalable to large area and high volume production
• High output power due to optimised TEG design (no number though!)
• Low specific weight and volume
• Device flexibility (mechanical)

BMW, Ford and GM to test prototype cars with thermoelectric generator by the end of the summer.

Technology Review reports on recent progress at BSST, a thermoelectric-device maker in California and at the GM's research labs in Michigan. GM's project is getting out of the lab and into a Chevy Suburban this summer. GM's thermoelectric research has centered on skutterudites, cobalt arsenide minerals doped with rare earth elements like ytterbium. Other prototype will be tested by BMW and Ford this year.

To manufacture such equipment in large quantities at affordable prices will still took about four years according to the companies. The crucial challenge is to make good electrical and thermal contacts.

Organic thermoelectric

The ideal thermoelectric material must have high electrical conductivity, low thermal conductivity and a high power factor. This naturally raises the question of conductive polymers which have good electrical conductivity and intrinsically poor thermally conductivity. However, organic materials usually have a relatively poor Seebeck coefficient. In a recent paper published on May the 1 in Nature materials, a team from Linkoeping University lead by Xavier Crispin was able to optimize the electrical conductivity of a conducting polymer (PEDOT) through careful chemical modification, without affecting its low thermal conductivity. The thermoelectric efficiency of their material approaches ZT=0.25.

Flat-panel solar thermoelectric generators raise the roof

In a paper published on May 1 in Nature materials, Gang Chen's group at MIT describes a new radical concept to turn the sun's heat into electricity

While solar thermal electricity is not a new idea, typical existing systems rely on arrays of movable mirrors that track the sun and focus heat on a small area. The new approach uses flat stationary panels. The system achieved a already quite impressive peak efficiency of 4.6% under AM1.5G (1 kWm-2) condition.

The performance is enabled by the use of nanostructured thermoelectric materials and spectrally-selective solar absorbers in an innovative flat design.

The device can be integrated into solar hot water systems and could be a relatively unexpensive addition.

NPL talk Energy Harvesting at the Institute of Physics

On 6th April 2011, Dr. Alexandre Cuenat will present NPL's thermoelectric research at a workshop entitled Thermoelectric Energy Solutions, to be held at the Institute of Physics, London. The event aims to explore emerging technologies and opportunities in the development of next generation thermoelectric and thermionic devices.

Alexandre will speak on Efficiency Measurements of Thermoelectric Generators (TEGs)

Other speakers include representatives from Jaguar Land Rover and the University of Cardiff. This worshop is organised by the UK NanoKTN in partnership with Johnson Matthey and Royal Holloway, University of London

Gains in Thermoelectric Performance for Bulk Semiconductor Material

"Researchers from Boston College, MIT, Clemson University and the University of Virginia have used nanotechnology to achieve a 60-90 percent increase in the thermoelectric figure of merit of p-type half-Heusler, a common bulk semiconductor compound. "

This is an example of one approach to improve thermoelectric materials by decreasing the thermal conductivity, while keeping the electrical conductivity relatively unchanged. Usually, the thermopower is also relatively constant, but in this instance the Seebeck coefficient increased. This suggest that grain boundaries may be trapping electrons, leading to increased holes in the sample and energy filtering effect. This may also be due to the involuntary introduction of dopants!

The measurement were done using standard commercial equipments and the uncertainties (without justification) were around 11% for ZT.

An other case for measurement of these quantities at the nanoscale and with reduced uncertainties!

Not that the grain size of the hot-pressed sample is around 200 nm compare to 5-10 nm for the precursors. "Preserving the size of the precursors remains an issue"

The paper can be found here: http://pubs.acs.org/doi/pdfplus/10.1021/nl104138t