No wonder the Army is so excited about thermoelectric technology, it’s the perfect energy scavenging system for those new surveillance drones you’ve been reading so much about. With a high power density and freedom from maintenance due to their lack of moving parts, thermoelectric systems are lightweight, durable, miniaturizable and above all, silent. As for matching the technology with the temperature extremes that lend themselves to thermoelectric conversion, Army surveillance drones are perfect for that, too. Come to think of it, just about any kind of drone is. Run for the hills!
The Thermoelectric Angle
When exposed to heat on one side and cold on the other, certain materials create an electrical charge, and that’s the basic idea behind thermoelectric systems.
In the context of President Obama’s climate speech earlier this week, thermoelectricity could play a huge role in the transition to advanced energy systems. In addition to lending itself to harvesting waste energy from moving vehicle tailpipes, thermoelectricity can be used to recapture energy from stationary sources such as factory equipment, power generating facilities and elevator motors. There are numerous potential applications in outer space as well.
The Obama Administration is already all over thermoelectric research with the launch of a massive, sprawling initiative involving several federal laboratories and academic research institutes.
Another big player in the thermoelectric game is GM, which is working on a system that will enable cars to “eat” their own exhaust. Another one is the company Gentherm, which last year won $1.55 million in contract modifications from the Department of Energy to adapt its light-vehicle thermoelectric system to heavy vehicles.
The Army has been right up there with the front-runners, having already successfully tested a thermoelectric system on an Abrams tank in partnership with Research Triangle Institute International, General Dynamics Land Systems and Creare, Inc.
Army Surveillance Drones And Thermoelectricity
With an eye to applying its thermoelectricity elsewhere, the Army took a “systems engineering” approach to the Abrams tank project, and that brings us to the use of thermoelectric systems in drones.
Drones fit the bill perfectly for thermoelectric waste heat capture, partly because of their exposure to temperature extremes. The Army’s drone of choice for the demonstration is the Shadow Tactical Unmanned Aircraft System manufactured by the company AAI. According to the Army, while the Shadow coasts along at frigid altitudes, the internal tailpipe temperature often exceeds 2,000 degrees Fahrenheit.
In an article published last year, The Army Research Laboratory (ARL), which is spearheading the project, also had this to say about adaptation of ground vehicle thermoelectric systems to drones:
“Thermoelectric power generation is preferred because it directly and simply converts heat to electrical power in a form factor that can be highly miniaturized and made extremely covert…As a matter of fact, applying thermoelectric power generators along the exhaust train of the Shadow will also reduce its infrared signature, and therefore reduce its detect-ability from adversaries.”
As a first step in the project, the ARL team calculated the amount of waste heat available from the drone and applied it to a model thermoelectric system. The results showed enough promise to continue on to the next steps, miniaturization and customization.
In terms of customization, one promising avenue is the use of curved exhaust ducting that optimizes the generation of heat from air inside the duct.
Stay tuned for the next step – or run for the hills!
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