Advanced Soldier Thermoelectric Power System for Power Generation from Battlefield Heat Sources

Technical Objectives

The U.S. military uses large amounts of fuel during deployments and battlefield operations. Consequently, the U.S. military has a strong need to develop technologies that increase fuel efficiency and minimize fuel requirements all along the logistics trail and in all battlefield operations. There are additional requirements to reduce and minimize the environmental footprint of various military equipment and operations and reduce the need for batteries (non-rechargeable) in battlefield operations.

The tri-agency SERDP (Strategic Environmental Research and Development Program) office is sponsoring a challenging, high-payoff project to develop a lightweight, small form-factor, soldier-portable advanced thermoelectric (TE) generator (TEG) prototype to recover and convert waste heat from a variety of deployed equipment (i.e., diesel generators/engines, incinerators, vehicles and potentially mobile kitchens), with the ultimate purpose of obtaining additional power for soldier battery charging, advanced capacitor charging and other battlefield power applications. The collaborative project with Tellurex Corporation and Michigan State University seeks to achieve power conversion efficiencies of approximately 9-10% (double current commercial TE conversion efficiencies) in a system with near 1.6-kW power output for a spectrum of battlefield power applications.

Results to Date

This work has investigated and developed critical LAST (Lead Antimony Silver Telluride)/LASTT (Lead Antimony Silver Tin Telluride) materials for critical U.S. Army battlefield power generation applications. Various compositions and processing parameters have been discovered that can create tunable temperature-dependent behaviors that can be exploited in designing segmented TE modules in this application. The thermal fatigue and mechanical strength properties of these refined LAST/LASTT materials have been investigated and characterized for the first time.

The Young’s modulus and Poisson’s ratio were used to monitor microcrack generation and growth and thereby characterize thermal fatigue damage within these materials. The elasticity/thermal fatigue testing on n-type LAST and p-type LASTT showed that the Young’s modulus and Poisson’s ratio were relatively insensitive to thermal fatigue cycling. New mechanical strength measurements were also obtained on these materials.

This new property knowledge, along with extensive thermal, thermoelectric and structural analysis work, has enabled and accelerated the first-ever segmented TE module designs using n-type LAST / p-type LASTT segmented with bismuth telluride components (Figure 1).

Structural analysis results (Figure 2, right, with stress units is MPa) were as important in designing and fabricating the TE module design as thermoelectric design considerations. This work has also investigated and developed new high-performance microchannel heat exchanger designs (Figure 3) to integrate with these advanced TE module designs in an advanced thermoelectric power generation system for U.S. Army Tactical Quiet Generators. This work has investigated and quantified various TEG system options that can deliver 1.4-2.9 kW of power output at 8.2-8.9% conversion efficiencies in Model A 30-kW and 60-kW Tactical Quiet Generators and that could be applicable to other Army battlefield heat sources. This project represents a high-challenge, high payoff endeavor to transition LAST/LASTT materials into operating TE modules and an operating TEG system.

Implications

The project is taking on the multi-faceted challenges of:

• Tailoring LAST/LASTT nanocomposite thermoelectric materials for the proper temperature ranges (300K – 700K);
• Fabricating these materials with cost-effective manufacturing processes while maintaining their TE properties;
• Measuring and characterizing their thermal fatigue and structural properties; developing high-volume manufacturing processes for the TE materials and modules;
• Designing and fabricating the necessary microtechnology heat exchangers; and
• Fabricating and testing the final TEG system. Figure 3 is a device designed in furtherance of this objective.

The ultimate goal is to provide an opportunity to deploy these TEG systems in a wide variety of current military equipment (i.e., various Tactical Quiet Generator (TQG) systems) and battlefield operations, so that they can provide the military with a pathway toward energy savings and environmental footprint management through enhanced fuel efficiency and battery recharging.

Partners

• Terry J. Hendricks
• Charles J. Cauchy, Tellurex Corporation
• Tim P. Hogan, Michigan State University
• Eldon D. Case, Michigan State University

Acknowledgments 

This project was sponsored by the Strategic Environmental Research and Development (SERDP) program office, Arlington, VA, a tri-agency office supported by the Department of Defense, Department of Energy, and Environmental Protection Agency. SERDP Program Manager: Dr. John Hall.

For Additional Information

Contact Program Manager Terry J. Hendricks.