+- Report from ECT2007 in Odessa

Eighty Nine thermoelectricians from 21 countries gathered at Black Sea port of Odessa, Ukraine to enjoy ECT2007, the 5th European Conference on Thermoelectrics.  Attendees represented countries including Russia (17), France (12), Germany and USA (7 each), Italy, Poland, Ukraine (6 each), Japan (3) and Korea (2).   Everyone was treated to a banquet, a walking tour of Odessa and an evening excursion by boat on the Black Sea.  The center city of Odessa offered an excellent and inviting location for ECT2007.

On Sunday prior to the conference the European Thermoelectric Society held their business meeting.  See the notes below for announcements from that meeting.

Through a remarkable effort, a bound Proceedings containing 57 manuscripts (9 invited, 21 oral and 27 poster) was printed and distributed to attendees on the final day.  And I’m pleased to announce that all those papers, plus two more, are available for immediate download on the conference website:

    http://ect2007.thermion-company.com/proc-contents

All in all, a really remarkable effort on the part of Vladimir Semenyuk and the ECT2007 local organizing committee.  Well done!

In the following section I’ll briefly highlight some of the papers that caught my attention.  As usual, I apologize in advance for omissions and errors.  I shall cite papers by refering to the pdf file number on the conference website.  For example, [21.pdf] refers to the paper:

Diffusion Protection of Thermoelectric Cooler Junctions as a Means of Increasing its Reliability
by V. Semenyuk, A. Antonenko.. [21.pdf]

which is available online via:

http://ect2007.thermion-company.com/system/files/u1/pdf/21.pdf


HIGHLIGHTS


Activities and Future Vision of Komatsu Thermo modules

Hachiuma of Komatsu presented a paper discussing the history and future vision for Komatsu Electronics [01.pdf].  Komatsu initiated thermoelectric research in 1957 and formed Komatsu Electronics in 1966.   Once dominated by defense applications, consumer applications dominate today and continue to grow. The paper includes rare public estimates of the thermoelectric cooling market size (US$200M) and distribution (35% consumer, 15% telecom, 14% automotive).  Hachiuma included a nice figure showing the number of thermoelectric patents vs. year, which unfortunately does not appear in the manuscript.

My own presentation [02.pdf] summarizes selected developments in the past 15 years and points out the greatest challenge facing thermoelectrics today is what role, if any, TE technology can play in the coming struggle with climate change.

Rowe’s study of ‘Economic Thermoelectric Recovery of Low Temperature Heat’ [03.pdf] is a case study and cost analysis of low grade waste heat. Both naturally occurring and waste heat are discussed.  Some comparison is made Rankine engines, perhaps the main alternative conversion technology for these applications.  Organic Rankine cycle engines are significantly more efficient than thermoelectrics and used in commercial geothermal plants throughout the world today.

Anatychuk summarized developments at his Institute of Thermoelectricity in Chernivsti, Ukraine in his paper ‘Current Status and Some Prospects of Thermoelectricity’ [04.pdf].  Trends and prospects for growth ZT and a number of novel technologies nearly unique to the Institute are presented.  One A figure indicates more than a 5 fold growth in the number of thermoelectric patents awarded annually since 1990.

A paper by Pustavolov [05.pdf] reviews the use of Plutonium-238 RTGs for planetary exploration.  Both Russian and US technologies are discussed.    In the oral presentation Pustavolov indicated more than 1000 pacemakers based on Pu-238 have been implanted in people.  [It is my understanding this practice has long since been abandoned in the west due to inconveniences in recovering the Pu-238 sources after the patients no longer need them, but I don’t know about Russian practices.]  My primary reason for mentioning this paper is a brief remark, not found in the manuscript, that they are negotiating to develop RTGs for the  Chinese moon program.

A theoretical paper by Zianni, ‘Thermoelectric Coefficients for Electron Tunneling through a Nanocrystal’, [14.pdf] concerns tunneling between two reservoirs at different voltages and temperatures.  The situation is of some theoretical interest but also may have some application in understanding quantum dot superlattices where tunneling between dots may be important.  The Wiedemann-Franz law is discussed.

A paper by Fluerial from the Jet Propulsion Laboratory titled "Advanced Bulk Materials for High Temperature Power Generation Applications".  The paper includes 19 authors and summarizes NASA-funded work at JPL to achieve (ZT)_average = 2, 19% efficiency from 300-1275 K and 8-13 Watts/kg for space nuclear power RTGs.  Sadly, this paper (as well as some others of interest) did not make it into the Proceedings.  Progress reported included a p-type Zintl compound (Yb_14MnSb_11) with ZT_max = 1.8 and thermal conductivity of 0.4 W/m-K.  An n-type lanthanum telluride with ZT~1.5 at 1275 K was also reported.  Perhaps most interesting was a ZT~0.7 at high temperatures in ‘nano-bulk’ silicon.  Generally germanium alloying has been thought essential to a low thermal conductivity, but in this case nano processing seems to produce similar results but without the germanium.

At the last minute John Fairbanks of the US Department of Energy was unable to attend due to family health reasons.  He did manage to send along his powerpoint presentation ‘Thermoelectrics Applications Review’ [10.pdf] and I was enlisted, with interpretive support from Jean-Pierre Fleurial, to attempt to deliver John’s paper.  The paper summarizes extensive US DoE efforts to use TE technology to improve transportation efficiency, primarily cars and trucks.  As proof that content trumps presentation style, several people have asked for copies of the presentation in spite of my mangling of John’s message.  A pdf version of John’s powerpoint presentation is available on the conference website [10.pdf].

Shakouri describes their work on ErAs nanoparticles embedded in InGaAlAs with a ZT~1 at 600 K in his paper ‘Thermal, electrical and thermoelectric transport in nanostructured ErAs:InAlAs materials’ [11.pdf].  Notably, an actual thin-film power generation module was manufactured using n- and p-type variations of the base material and actual power output measurements are reported.  While discussing whether the transport should be described as ‘thermionic’ or ‘thermoelectric’ equations, Shakouri produced one of the best quotes of the conference:  "electrons don’t know which equations you use".  Exactly so.

Finally, I’d like to note three papers presented by Leonov on ‘Thermoelectric Generators on Living Beings’ [09.pdf], ‘Small-Size BiTe Thermopiles and a Thermoelectric Generator for Wearable Sensor Nodes’ [18.pdf] and ‘Thermal Matching of a Thermoelectric Energy Scavenger with the Ambience’ [31.pdf].  Generally these papers discuss principles and practice of using thermoelectric devices to extract electrical power from living things.  Included are estimates of the heat flux, and the maximum useful heat flux, available from various parts of the human body.  Leonov, who clearly loves his work, gives a very animated and enthusiastic presentation

Obviously there are many more fine papers which will be of interest, but these few left some particular impression on me.