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Solid State Power Breakthrough

Thermoelectrics Revisited — Again

The bytes were barely dry on the 14 Oct UFTO Note about thermoelectrics (“There is a tantalizing hope that someday someone will come up with a real breakthrough in direct heat-to-electricity conversion.”), and the following day, just such a possible breakthrough came to my attention in an item in EV Progress. (www.EVProgress.com)

The article talked about dramatic claims made at the September Global Powertrain Congress in Ann Arbor, Michigan for a “Power Chip” that would recover from 10-70 KW of the waste heat of a car’s engine as electric power. The technology is a new variant on direct thermal conversion.

Here is a portion the Power Chip’s own press release:
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“Power Chips are discs comprising two electrodes separated by a gap of less than 20 nanometers, through which the hottest (most energetic) electrons tunnel to create an electrical current. Power Chips are silent, nonpolluting, solid-state devices that are scalable as arrays to meet any size power load. They can generate electricity from heat produced by any primary energy source……

They are projected to operate at 70% of the maximum theoretical [Carnot] efficiency for energy conversion, even when converting low-grade waste heat. The only other technology capable of converting such heat directly to electrical output is thermoelectric (Peltier) devices, but the efficiency of production thermoelectric systems is only 5-8%.

Power Chips™ are protected by an extensive patent portfolio covering general theory and specific techniques for quantum thermotunneling and thermal energy conversion. More details are available on the Power Chips plc Website http://www.powerchips.gi, including the full text of issued patents and photographs of prototype Power Chips.

Power Chips™ were invented and are being developed and licensed by Power Chips plc, a majority-owned subsidiary of Borealis Exploration Limited (BOREF). Both companies are incorporated in Gibraltar. Borealis’ business is reinventing the core technologies used by basic industries, including electrical power generation, cooling and thermal management, electric motors, and steel production.”
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Not mentioned was the obvious point that if you could do that, you wouldn’t bother with the IC engine in the first place. The company is in discussions with GM, who invited them to participate in the Powertrain conference.

I contacted the company, executed an NDA, and learned a great deal more about it through extensive conversations with management. Actually, the first product is going to be for cooling. (As with thermoelectrics, this process can be used either as a heat pump or a power generator.) It has attracted serious attention of major defense contractors for cooling of critical electronic components.
(See: http://www.boeing.com/news/releases/2001/q4/nr_011130a.html)

The parent company is Borealis, an unusual company with a colorful history dating back to an oil company founded in 1924.. There are over 100 employees scattered all over the world, and they draw on many additional institutions and people. The CoolChips subsidiary is already public (COLCF), and PowerChips and other subsidiaries are poised to go public as well. The long technology development has mostly been funded privately by private/family money of the principals, however they now recognize the need to broaden the base of support and involvement. A private offering memorandum is available from the company.

A great deal of technical and business information is available in various areas of the companies’ interlinked websites, powerchips.gi, coolchips.gi, and borealis.gi. The cooling technology was presented at the recent Long Beach 21st International Conference on Thermoelectrics, and another paper is being given today at the “Thermal Management” conference in Dallas. (Both events were cited in the 14 Oct UFTO Note).

Note in particular a new version of their technical overview dated Oct-28 (this is what is being presented in Dallas). Two nanotechnology milestones were reached recently: the fabrication of large conformal pairs of electrodes, and electrodes with excellent local smoothness. The document includes new detailed electron microscope data of the surfaces.
(http://www.coolchips.gi/technology/coolchipstech28Oct02v2.pdf)

The quantum tunneling theory is described in a paper by a group of Stanford materials researchers (I have the pdf if anyone would like to see it–it’s not easy reading unless you’re a quantum physicist–and even then it’s no walk in the park):

“Refrigeration by Combined Tunneling and Thermionic Emission in Vacuum: Use of Nanometer Scale Design”, Y. Hishinuma, T. H. Geballe, and B. Y. Moyzhes, Applied Physics Letters, Vol 78, No. 17, 23 April 2001.

According to their calculations, the basic tunneling process is ideally capable of delivering 95% of Carnot efficiency. The technical overview then goes through detailed analysis of losses, and comes up with a final figure of 70-80% of Carnot overall.

The physics theory is one thing; making a device is another. The company says it has developed reliable means to build such devices — with the unheard-of narrow gaps. Two small production lines are being debugged and ramped up currently.

First deliveries of the initial product are anticipated in a matter of months. It will be a several watt cooling chip, which will be offered for sale at a very high price. The device is said to be capable of delivering temperature differences of over 400 deg K, cooling down to 150 deg K with a hot side of 250 deg C.

If these claims bear out, even partially, it would truly be a game changer. If the devices can be made reliably and cheaply, then little would stand in the path, in every arena of refrigeration, power production and transportation, not to mention electronics. Time will tell.

JTEC New Solid State Heat to Electricity

The Johnson Thermo-Electric Conversion (JTEC) system is a solid state, thermodynamic, energy conversion device that operates on the Ericsson cycle, which is equivalent to the Carnot cycle. It can be configured to operate as either a heat engine (for power production) or a heat pump (for cooling). As a heat engine, the JTEC can use any source of heat, e.g. combustible fuels (external combustion), solar energy, or waste heat. Several proof of concept, component level experiments have been successfully conducted to establish its feasibility.

The JTEC employs fuel cell technology, however, is not a fuel cell. Hydrogen is the working fluid, not the fuel. As a sealed solid state system that generates electricity from heat, it is better compared to thermoelectric converters, but with significantly higher efficiency.

JTEC is at an early development stage, however there is reason to believe progress could be relatively rapid. The company has laid out a multi-year plan, with working prototypes “soon”.. Details are closely guarded — I have executed an NDA and visited the company — the concept appears to be quite solid.

Texaco has funded the company to do a brief study of commercialization prospects. The company is looking for investors and strategic development partners.

Johnson Electro-Mechanical Systems, LLC (JEMS), is a spinoff of Johnson Research & Development, Atlanta GA, a technology development company involved in a number of areas. Another spinoff, Excellatron, has a licensed lithium thin film battery technology from Oak Ridge National Lab. The founder, Lonnie Johnson, followed a distinguished career in aerospace with the development of the SuperSoaker, one of the best selling toys of all time.

Contact: Lonnie Johnson 770-438-2201
http://www.johnsonrd.com

Magnetic Refrigeration

Ames Lab and Astronautics Corporation of America, are making considerable progress towards a commercially viable refrigeration technology based on the magnetocaloric effect present in certain rare earth materials .

Magnetic refrigeration has been around for a long time, and was used principally to reach ultra low temperatures in cryogenics research. Developments on two fronts are mutually moving the technology towards room temperature and commercial application. One is the refrigeration cycle itself–new approaches have been developed, which are reaching performance at room temperature that is very competitive with vapor compression. A laboratory scale magnetic refrigerator built by Astronautics produces 600 watts of cooling power, achieves temperature span of 28 degrees K near room temperature with the lowest temperature being just above the freezing point of water, efficiencies up to 60% of Carnot, and a COPs of five to eight. It has been in continuous operation since December ’96. This work used traditional gadolinium spheres as the magnetic refrigerant.

The other key ingredient is the magnetic material. Ames Lab, a leader in the field of rare earth metals research, announced a breakthrough this summer of a giant magnetocaloric effect in new alloys of gadolinium, silicon and germanium. Magnetocaloric effect in these materials is 2 to 7 times larger than in other prototype refrigerant materials. Also, the operating temperature (the Curie point) can be tuned from -400 degrees F to 65 degrees F, by adjusting the ratio of silicon to germanium.

Magnetic refrigeration operates by magnetizing and demagnetizing the material, analogous to compression and expansion in a vapor cycle. However, magnetizing and demagnetizing losses are much less compared to friction losses during compression and expansion. Two ÒbedsÓ filled with magnetic material are pushed in and out of a magnetic field. As a bed enters high magnetic field space, it heats up (magnetocaloric effect) and the heat is picked up by a flow of heat transfer fluid (which is water in this laboratory scale magnetic refrigerator) and is dissipated into the surroundings. When a bed is pulled out of magnetic field, it cools down due to the reverse magnetocaloric effect, cooling the water.

The use of solid refrigerant material (gadolinium) and water as a heat transfer fluid offer another advantage compared to conventional vapor cycle refrigerators: it is the absence of harmful chemicals as liquid refrigerants that present serious environmental hazard .

Strong magnetic fields are needed, currently produced by superconducting magnets. However, the team is finding ways to lower the field required, while new developments in permanent magnets (materials, fabrication, and expiration of key patents) offer the possibility of simpler and less expensive systems. Also, high temperature superconductors are coming into their own, which likewise could change things dramatically.

The need for a strong field puts the economics in favor of larger systems, however smaller scale devices are also anticipated. The key differentiating features are:

1. Higher efficiency (which can be highly significant when power is limited–e.g. in an electric vehicle).
2. None of the environmental issues associated with
conventional liquid refrigerants.
3. Ability to cool continuously over a range of temperatures (e.g. in chilling a fluid stream) which is thermodynamically
more efficient.
4. Ability to scale down without significant losses of cooling efficiency, which is to the contrary of conventional vapor cycle refrigeration.

Initial applications will probably be in industrial and commercial (e.g. supermarkets) refrigeration, cooling and air conditioning. Other possibilities of interest to utilities are cooling of inlet air for combustion turbines, and district cooling.

The technology is at least five years from a practical commercial reality, however Ames and Astronautics are already fielding numerous inquiries from interested parties and potential partners. The developers are opened to the possibility of teaming with other companies who may do the manufacturing and marketing of actual products.

A number of technical and popular articles and other information are available from Ames.

Contacts:
Carl Zimm, Astronautics (principal investigator) Madison WI,
608-221-9001, zimm@astronautics.keafott.com
Karl Gschneidner, Ames Lab (principal investigator)
515-294-7931, cagey@ameslab.gov
Vitalij Pecharsky, Ames Lab (principal investigator)
515-294-8220 , vitkp@ameslab.gov
Alan Paau, Iowa State Univ. (intellectual property)
515-294-4740
Todd Zdorkowski, Ames Lab (tech transfer)
515-294-5640, zdorkowski@ameslab.gov