Army Exploring New Tech to Charge Up Troops on the Go

iStock, Defense Dept. photo-illustration

The Army is looking at new technology that harvests energy from a variety of sources — from the heat generated by a soldier’s body to the fuel already widely used in the service — to power troops on the go.

The Army envisions a future where soldiers will be carrying even more high-tech equipment that will require batteries or other power sources.

At the same time, the service is preparing to transition from large logistical footprints to operating in more distributed formations, said Lt. Col. Jon Villasenor, the lead and concepts director for the Army’s operational energy strategy, which is being drafted by Army Futures Command.

Based on the capabilities being developed by potential rivals, the Army needs to break apart larger groups of soldiers and deconsolidate big equipment that will be easy targets and likely to be destroyed, Villasenor said.

“When I break that apart, there’s a lot of things we’ll have to modernize as well,” Villasenor added. “My sustainment infrastructure has to be able to adapt to that ability to support what I would consider a giant spider web, where units are operating very small and I still have to get them … supplies.”

How to power the individual soldier will be addressed in the operational energy strategy — slated for release by the end of 2022 — along with a slew of additional actions that aim to optimize the service’s power usage with more efficient, diverse and sustainable sources, he said.

In the meantime, industry is making strides in next-generation energy harvesting and power generation methods. Companies are working with the Defense Department and independently to mature their technologies and turn them into products useful to the soldier.

Members of industry gathered in April at the Army’s VERTEX Energy conference in Austin, Texas to discuss their innovative technologies with service leaders tackling soldier power.

One potential opportunity for the Army is thermoelectric power, said Douglas Tham, chief technology officer of Silicon Valley-based MATRIX Industries.

Thermoelectric generators can convert the difference in temperature between two points into electricity. When the generator is placed on something warm — like the engine of an M1 Abrams or the skin of a soldier — electrons move from the hot to the cold side of the device to create an electric current.

The company has developed technology that uses small temperature differences to create self-sustaining thermal energy and power electronics, he said.

“That’s one big vertical that we’re really targeting — to take the latest and greatest in sensor technologies and algorithms which are really low power … and reduce the power consumption to the point where even small amounts of energy harvesting can sustain,” he said.

This technology could boost current Army efforts to improve the lifespan of batteries used to power equipment. On average, a soldier will be carrying five to eight different batteries during missions, Villasenor said.

“If you’re talking about redundancies for extended operations, he’s carrying mass batteries so you’re also talking about a lot of weight,” he added. According to an Army press release, a 72-hour mission could require a soldier to carry 20 pounds of batteries.

But if the service were to use thermoelectric generators to harvest energy from a continuous heat source, like the body heat of a soldier, “we can either get rid of the battery entirely or shrink it to such a small extent that it’s essentially just a capacitor to mitigate some of the spikes in consumption,” Tham said.

The technology has already entered the commercial sector, but the company is working with the Army, Navy and Marine Corps to make it usable for warfighters needing power on the go, he noted.

However, there are still hurdles industry must cross before a self-sustained soldier on the battlefield becomes a reality, said Giri Joshi, senior scientist at Nanohmics Inc. of Austin, Texas.

“The main challenge is when you see the body temperature and the outside temperature, it is a big gap, but our skin is not conductive,” Joshi explained. As a result, wearable devices rarely find a large enough temperature difference to create sufficient power, he said.

Another problem will be increasing the efficiency of wearable thermoelectric generators. In future operating environments, soldiers will likely rely on multiple electronic devices that need continuous power, including communication systems, night-vision devices, weapons and situational awareness devices like the Nett Warrior system or upcoming Integrated Visual Augmentation System, according to the service.

“Right now, we’re seeing less than 5 watts on a soldier. That will still provide you the capability to draw out insights from hundreds of sensors,” said Josh Seagroves, the chief technology officer at Austin, Texas-based company Parasanti. He noted there’s also been progress made in reducing the power consumption of the next-generation devices used by soldiers.

With a wearable device at maximum efficiency, a single soldier could harvest about 100 watts. However, the technology’s efficiency isn’t there yet, Joshi said.

Tham echoed Joshi, also noting that efficiency will never come close to 100 watts.

To address this, MATRIX Industries has condensed the sensor systems it uses to harvest energy down to be able to consume microwatts and milliwatts, he said.

“That’s where you can actually start to make a difference in the lifetime of your sensory system,” he said.
Joshi said to turn thermoelectric generators into wearable power sources, more studies should be done beyond system-level engineering.

“Thermoelectric technology is a pretty mature technology. The only thing not well studied is how to [best] design the system,” he said.

Specifically, the efficiency of thermoelectric generators can be improved by working on the engineering materials of the devices at the nanoscopic level, said Shannon Sentell, chief operating officer of Stealth Power, a hybrid energy supplier in Austin, Texas.

“That’s where I think we can, as industry, pool our resources … together and make that leap,” Sentell said. “If we can make that [difference in temperatures] better between two materials, then you’re going to see the amount of [heat flow] go up that you’re able to pull out of these devices.”

That doesn’t mean the thermoelectric devices can’t use other heat sources to harvest energy for other applications.
MATRIX Industries is also using its energy harvesting technology to detect the variations in temperatures in topsoil during the day and night.

The power produced from that temperature difference can be used to power unattended, remote monitoring systems that detect vibrations of people, animals or vehicles crossing an area, Tham said.

Like with wearables, the thermoelectric generator would allow the monitoring system to power itself and remove the need for soldiers traveling to replace batteries, he added.

Joshi added that thermoelectric devices can also be used to power localized, autonomous sensors, but batteries may still be needed to compensate for the fluctuations in temperature gradients. Still, it would extend the battery’s life much longer, he added.

While wearable thermoelectric technology matures, other members of industry are focusing their efforts on using fuel sources in the Army’s current logistics chain to provide the service with portable power.

Veronika Stelmakh, the chief executive officer at Massachusetts-based Mesodyne, said the Army has been looking at solutions to expand soldier power for years — from solar and wind energy to optimizing fuel cells.

At Mesodyne, they have created a small, portable generator called the LightCell that leverages thermophotovoltaics, which converts heat emitted from light into electricity.

The generator takes any type of fuel and uses it to heat a material, which begins to glow. The light emitted from the material is then converted into electricity by a photovoltaic cell, Stelmakh said.

The result is energy that is 10 times more dense than standard batteries used for small systems, including those carried by soldiers or ones powering unmanned aircraft and surface vessels, she said.

Extremely lightweight and about the size of a water bottle, the LightCell would help lessen the burden of equipment carried by troops, Stelmakh said.

The LightCell is also able to use any type of fuel to begin the energy conversion process, including the Jet Propellant-8 fuel universally used by the U.S. military. Stelmakh said using a fuel already on the battlefield is a huge advantage.

The company was originally funded by the Army, and has received more than $5 million in grants from the Air Force, the Defense Advanced Research Projects Agency, the Department of Energy and the National Science Foundation for research and development of the technology.

Stelmakh said they have recently partnered with a large defense prime to continue work on making the LightCell a viable product for the warfighter. One of the biggest concerns now is reducing the heat the generator produces during the conversion process.

Similarly, Modern Electronics is developing a device called a thermionic converter. The device is also able to produce electricity using fuel, but harnesses power using the heat it emits rather than light, said Max Mankin, the company’s chief technology officer.

“You can envision taking one of these heat-to-power devices that can accept heat from any fuel as long as it’s hot, and deploying it in a small box … and bringing that with you out in the field, using it to recharge batteries, using it to power up some remote equipment — whatever is needed,” he said.

The company is working to to both lower the operating temperature and increase the power density and efficiency of the device.

As Modern Electrics tries to break into the defense sector, however, supply constraints on key materials for its converter have challenged the small company, Mankin said.

“The majority of battery manufacturing infrastructure and mineral processing infrastructure exists outside the United States,” he said. “Most of those parts, if we’re ever going to make them cost effectively, have to get machined or stamped offshore.”

Tham agreed that supply chain issues can cause serious problems with development, and that it’s difficult to come up with alternatives to offshore suppliers when for decades the industry’s main supply center has been China.

One solution could be to continue allowing production of key materials overseas, but to move the product’s final assembly to the United States, he said.

“There’s a lot of stuff that happens in the final assembly,” Tham explained. “Bringing it onshore at least allows you to have that final bit of control.”

Although energy harvesting technology and power generation won’t be available to the Army in the near future, Tham encouraged the service to continue having open conversations with industry about limitations of the batteries of today and what the Army wants to see in the future.

“Let us in industry try to be your eyes and ears and try to help you see connections and overlaps between our commercial paths and your longer-term goals,” he said. “If we can find a path to map our commercial technology trees with yours, then I think it’s a win-win.”

Topics: Energy, Army News