Thermoelectric energy harvesting is used in many military applications. In addition, it is used in the related area of generating energy on space vehicles in deep space where thermoelectric are ineffective, this being done by converting the heat of a radioactive material - the Radioisotope Thermoelectric Generator RTG.
Source Caltech
This is not energy harvesting because it does not use ambient energy but rather something deliberately put there. Some examples are shown below:
Tellurex tells the story of how the U.S. military had been searching for a company that could build a new missile guidance system tester. They had not been able to locate a thermoelectric company that could design and develop a test system capable of achieving 500 watts, a high ramp rate and high heat load (acceleration from runway level to sub-space altitudes). Tellurex was able to create an innovative thermoelectric solution that successfully achieved those challenging specs. Its military solutions are aimed at:
- Military avionics
- Infrared detectors
- Thermal viewers
- Black body references
- Space telescope cameras
- Body cooling systems
- Missile testing systems
Thermo Life Corporation says that its thermoelectric modules can power all kinds of low-power electronic devices in situations where battery power is limited, needs recharging, is not feasible or is not desirable continuous, renewable power for decades without maintenance or human intervention of any kind.
- Wireless personal area networks
- Ammunition safety sensors
- Space science
- Building environmental control and security
JPL Thermoelectrics is involved in military thermoelectric as is NXtreme with its thin-film superlattice material made from a semiconductor alloy, which emerged from RTI's work with the U.S. Department of Defense. The Office of Naval Research (ONR) and the Defense Advance Research Projects Agency (DARPA) have provided funding since 1993 for the company's development of the new materials and devices. Marlow Industries is serving the military with thermoelectric devices and its cataog power generation module is designed for low-to-medium temperature applications (<225°C). Built with high efficiency bismuth telluride alloys and special high temperature solders, these modules are said to be " ideal for converting waste heat streams into useful DC power. Typical applications include: fans and lights for wood stoves, furnaces and mosquito catchers. "
Temperature Controllers
Source Marlow Industries
Although the focus of the above work is the USA, the Europeans are active too. Wireless Sensor Networks are of great interest to the military and others and, in 2009, Micropelt GmbH, Freiburg, Germany-based specialist in thin film thermoelectrics, announced immediate commercial availability of "the world`s first thermo-powered wireless sensor system, the TE-Power NODE." Micropelt`s built-in chip thermogenerator takes a few degrees of temperature differential and harvests that thermal energy to operate the wireless sensor node, enabling unlimited battery-free operation.
"Micropelt`s battery-free thermal energy harvesting technology can be used to power our ultra-low-power microcontrollers and RF transceivers, enabling endless possibilities in the wireless sensor market," says Volker Prueller, EMEA marketing manager, Catalogue MCU and Low-Power RF at Texas Instruments. "With increased interest for wireless sensor systems across many markets, Micropelt`s solution offers a renewable source of power and freedom from traditional batteries."
Burkhard Habbe, VP Business Development, adds, "We wanted to prove to our customers that thermoharvesters right now represent a viable energy supply for many applications including most IEEE 802.15.4 based systems. Even a few hundred microwatts supplied continuously can easily outperform a good set of batteries. Our new TE-Power NODE lets customers easily verify that batteries have better alternatives." As motivation for more potential users and system integrators to explore its technologies, Micropelt has lowered its prices for evaluation kits significantly. Quotes are still supplied based on clear application specifications. Mass production of devices is scheduled to start in 2010.
Some of the military thermoelectric work involves cooling by the Peltier effect for components and refrigerators but all of these companies are involved in energy harvesting using the Seebeck effect.
