It is our intent to become a major player in the field of Thermoelectric POWER GENERATION using the SEEBECK EFFECT. Incredible interest is building in this novel field. Estimates are that thermoelectric POWER technology will become more competitive than solar or wind technologies even with these technologies having a head start as far as deployment and technological advances. The pay back on thermoelectric power/watt is more economical presently, than both wind and solar, even with the smaller efficiencies that presently are available with today’s materials. (Based on large project deployment) The quoted cost recently at a Department Of Energy funded workshop Sept. 30/2009 was 50 cents per watt based on a Delta Temperature ( DT) of 100°C exempt of assembly materials and installation when large volume pricing is used.

The draw back to the TEG POWER technology is also it’s strength. Because the power densities are very large, small units can be manufactured. For example a 300 watt TEG assembly can fit in an about a twentieth of the space required for an equivalent solar array. As well, the output is 24 hours per day as long as there is a heat source and a cold side. So, actual power output could be 6 -7 times what a 300 watt solar array could produce. What is needed to make the technology cheap to operate is waste heat, which by the definition is free. The key words being “WASTE HEAT”. To extract the most efficiency and thermoelectric power from the present state of the art semiconductor materials. It is advisable to have a temperature of 150 to 250°C (302-482°F) hot side, with a Delta Temperature (DT) of at least 100°C. Some applications can work on low grade heat in the 100°C (212°F) range, if the volume of waste heat is high and ample cold side water or air is available. Presently, Bi2Te3 is the most efficient at room temperature. Material such as PbTe, and CMO’s have also been used in temperatures of 500 to 600° C (932-1112°F). Both Bi2Te3 and PbTe are mature material.Their characteristics and performance are well documented and have been used extensively in commercial application. PbTe however, is almost impossible to purchase commercially by itself in module form. It is being used at present by a number of manufacturers. It’s properties are better suited to temperatures above 500°C. It is much less efficient than BiTe which to date is the most efficient commercially available semiconductor material. We carry CMO’s which work at very high temperatures 700°C to 800°C and come in both single module construction and also Cascaded (stacked) with Bi2Te3 on the cold side to take advantage of lower temperatures ranges after the higher heat has passed through the CMO material. These Cascades result in an overall efficiency of ~6 to 7 %. Europe restricts the use of Pb (lead), but an exemption on PbTe material is in place. But like Cd(Cadmium) used by First Solar for flat panel CdTe solar panels this exemption is expected to expire by 2018.

Therefore, Bi2Te3 (Bismuth Telluride) and our CMO materials are the only thermoelectric material widely available in thermoelectric power module form.

There are other Thermoelectric TEG power materials using the SEEBECK EFFECT that hold promise in the thermoelectric generation field. These include but not limited to:

  • CMO’s – Calcium/Manganese Oxide (CMO) up to 800°C TEG Modules and Cascade High Temperature (CMO) available!
  • CMO’s are the first material commercially available Thermoelectric Material in 20 years! And the first Cascade commercially available ever!
  • Mg2Si –N-type
  • Mn2Si –P-type
  • Skutterudites
  • ZnSb — N-type
  • ZnSb –P-type

The seven Thermoelectric power materials above are of particular interest as they are fairly abundant materials and less expensive compared to Te (Telluride) based semiconductors and have equal or Greater SEEBECK EFFECT Traits . An additional major factor is toxicity. The material above in RED signify benign or exhibit little or no toxicity. Some of these materials can be discussed on thermoelectric TEG module BLOGS located on the instructables wed site. We supply thermoelectric TEG module and generators. At this point we supply four different thermoelectric based modules. BiTe up to 320°C hot side, Hybrid PbTe–BiTe up to 340°C, Cascade CMO with BiTe up to 600°C which,  is a 2 stage device and CMO Oxide which can sustain up to 800 °C.

A typical product that most people are familiar with that using the BiTe material is the Ecofan. This generator sits on top of a wood burning stove and turns a simple fan using the different temperature (DT) between the wood stove tops temperature and the cooling fins on the top of the aluminum assembly. The thermoelectric module is sandwiched in between the hot side and finned cold side.

References