Power Generation from Waste Heat
While much of the recent attention given to thermoelectrics has focused on their ability to cool and heat, thermoelectrics can also be applied to generate power from a specific heat source. This application has tremendous potential, as there is a wide range of sources of waste heat in the world today that could be utilized to generate useable electrical power. These sources range from, but are not limited to, automotive engine exhausts, waste processing plants, chemical and industrial manufacturing operations, steam generation systems in naval propulsion systems, and many more. Additionally, thermoelectric technology has the potential to replace the current electricity generation systems as a primary power source in many environments as the technology’s efficiency and cost continue to improve.
In many cases, the value of generating power from waste heat is the potential to either provide additional power to a power-hungry system where none was available before, or to replace heavier, noisier, less efficient mechanical power generation equipment with more effective, efficient, lighter, less costly thermoelectric equipment. Augmenting vehicle power, or replacing the power generation system now used with thermoelectrics are examples of where this aspect of the technology could be deployed.
BSST is actively pursuing the advancement of power generation from waste heat utilizing thermoelectrics as a key portion of its advanced development program. BSST is currently leading a multi-company team, including BMW of North America, Ford Motor Company, Visteon, the National Renewable Energy Laboratory (NREL), California Institute of Technology and the Jet Propulsion Laboratory (JPL), in a U.S. Department of Energy (DOE) program to improve automotive fuel economy by up to 10% using thermoelectric power generation technology. The first phase began in 2004, and the team has successfully completed three phases of the program. Phase 4 of the program is underway to test a thermoelectric generator (TEG) with BMW's six cylinder engine at NREL in Q2 2010 and in Phase 5 later this year TEGs will be installed in both BMW and Ford vehicles and evaluated over a range of driving conditions.
BSST has been or is currently involved in several other thermoelectric power generation projects, including two primary power generation projects with the U.S. Department of Defense and one DOE project where thermoelectrics are combined with a stationary Solid Oxide Fuel Cell (SOFC) to generate electricity at a combined 60% efficiency.
A BSST experimental device is shown below. The copper bars sandwich TE elements between them (left). Several of these are then attached together to make a larger assembly (center). The heat source is introduced in the hole of the central hexagonal bar and the flat surfaces are attached to cold side heat exchangers (right). Electrical current runs straight through the copper bars from either right to left or left to right.
Development programs addressing thermoelectric power generation focus on many of the same performance areas that drive thermoelectric temperature control capabilities. This creates strong synergy across BSST's efforts to continue extending the performance of its technology.
For more information on BSST power generation technology, see the following papers:
- Bell, L. E., "Alternative Thermoelectric Thermodynamic Cycles with Improved Power Generation Efficiencies," Proceedings of the 22nd International Conference on Thermoelectrics, Hérault, France, August 2003.
- Diller, R. W., Bell, L. E., "Experimental Results Confirming Improved Efficiency of Thermoelectric Power Generation Systems with Alternate Thermodynamic Cycles," Proceedings of the 22nd International Conference on Thermoelectrics, Hérault, France, August 2003.
- Crane, D. T., Bell, L. E., "Progress Towards Maximizing the Performance of a Thermoelectric Power Generator," Proceedings of the 25th International Conference on Thermoelectrics, Vienna, Austria, August 2006.
- LaGrandeur, J., et al., "Vehicle Fuel Economy Improvement through Thermoelectric Waste Heat Recovery," Proceedings of the 11th Diesel Engine Emissions Reduction (DEER) Conference, Chicago, Illinois, August 2005.
- LaGrandeur, J., et al., "Automotive Waste Heat Conversion to Electric Power Using Skutterudite, TAGs, PbTe, and BiTe," Proceedings of the 25th International Conference on Thermoelectrics, Vienna, Austria, August 2006.