Power Trip

July 1, 2007
Sophisticated electronics drive the need for plentiful power on the battlefield

Sophisticated electronics drive the need for plentiful power on the battlefield

By Courtney E. Howard

The modern battlefield is an intricate network of sophisticated electronics systems enabling increasing communications, information exchange, situational awareness, and other advanced capabilities. All these systems, which contribute to the realization of the U.S. Department of Defense’s (DOD’s) vision of a network-centric battlefield, drive the military’s need for ever-increasing amounts of efficient and reliable power. This need shows no sign of subsiding, given an increased reliance on electronics systems and the technologies that power them.

The DOD is the largest energy customer in the United States, with an annual facility energy bill of roughly $3 billion, according to the Army Energy Management Plan. The U.S. Army spends more than $1 billion on energy annually. Deployed soldiers consume a wealth of portable power; the U.S. Marines alone used 3,000 batteries a day during the second Persian Gulf War of 2003, says Franklin Holcomb, project leader, Fuel Cell Team, at the U.S. Army Corps of Engineers Engineer Research and Development Center (ERDC) in Champaign, Ill.

Other indications of the global military market’s widespread use of batteries are large, multiyear contract awards. Saft America Inc. in Valdese, N.C., for example, will provide batteries to the U.S. Army, Navy, Air Force, and Marine Corps over the next two years, according to a $31 million contract awarded by the U.S. Defense Supply Center in Richmond, Va. Lithium-ion battery technologies, in particular, currently power various deployed systems, including manned and unmanned underwater vehicles.

Li-on in the lead?

Personnel at the U.S. Special Operations Command (USSOCOM) at MacDill Air Force Base, Fla., and the Crane division of the Naval Surface Warfare Center (NSWC Crane) in Crane, Ind., selected Saft’s lithium ion (li-ion) technology to replace the current silver zinc (AgZn) battery system in the SEAL delivery vehicle (SDV), an underwater submersible that transports U.S. Navy SEALs and their equipment on long-distance missions.

The $1.4 million contract is part of the Defense Acquisition Challenge (DAC) program, which pays for the test and evaluation of technologies to improve current systems. Navy personnel sought a new system that enabled SDVs to increase covert range and state of charge, as well as to provide charge-in-place capability. Saft’s li-ion technology not only offers a service life up to 17 times longer than the existing AgZn technology, but also recharges in less time.

Saft engineers customized a high-energy, li-ion system with two batteries that serves as the sole power-source for the SDV. One 185-volt battery drives all vehicle propulsions, whereas a 35-volt unit powers the vehicle’s electronic systems.

Brig. Gen. Roger A. Nadeau, commander, U.S. Research, Development, and Engineering Command, speaks at the unveiling of the Army’s first fuel-cell-powered truck, able to travel 125 miles, carry up to 1,600 pounds, and accelerate from 0 to 60 mph in 19 seconds. (Photo courtesy General Motors/Max Schulte)
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Similarly, Saft engineers have been contracted by the Groupe d’Etudes Sous Marines de l’Atlantique (GESMA) in Brest, France, to develop a rechargeable li-ion battery system to boost the performances and payload capacity of the Redermor, an autonomous unmanned underwater vehicle (UUV). GESMA studies underwater areas of the Atlantic Ocean.

The free-swimming Redermor-designed to carry large, 1-ton payloads, such as sonar or sensors-is about 20 feet long, roughly 3.3 feet in diameter, and weighs between 2.7 and 3.2 tons. Eight electric thrusters enable the Redermor to travel at speeds up to 10 knots at depths of 660 feet.

The new li-ion battery system is designed to provide the Redermor with as much as five hours of power for its electric thrusters and onboard electronics. The Redermor-3 battery system, incorporating Saft’s VL45E li-ion cells, is scheduled for delivery to the GESMA in September.

Advanced li-on

The li-ion battery is known for its low maintenance, high energy density, light weight, and low self-discharge rate (roughly half that of NiCd and NiMH batteries). The li-on battery, however, is typically fragile, requires a protection circuit to maintain safe operation, and does not age well.

A paradigm shift in lithium-based battery technology has occurred, notes Jeffrey Vanzwol, marketing director at Micro Power Electronics Inc. in Beaverton, Ore. The company’s engineers design and develop custom battery packs for military and aerospace systems integrators that embed them in missiles, handheld radios, and other power-sensitive devices and systems.

A few technology companies have unveiled a new type of battery, called the high-power lithium cell, which supports applications and devices requiring a high pulse. “The typical cell today can support roughly a 20-amp pulse, whereas these new cells can support a 300-amp pulse,” Vanzwol explains. “It’s an exponential improvement in capabilities. These lithium cells have applications in the military space.”

A123 Systems in Watertown, Mass., for example, delivers high-power lithium cells for such applications as nonlethal electric weapons, electric-drive and hybrid-propulsion systems, silent- or stealth-drive applications, unmanned-vehicle drive systems, distributed jamming systems, as well as space, aerial, sea, and ground-based directed-energy weapons.

Mil-aero applications

Many technology firms and industry players consider battery-based systems to have a bright future in military and aerospace environments, especially that of the deployed warfighter.

The soldier of today and tomorrow is essentially “a remote node on a larger network, giving him a lot of data and voice connectivity capabilities,” Vanzwol says. “What that means from a product perspective is that soldiers have new variations of radios, GPS tracking devices, handheld computers, night-vision goggles, and other devices which are predominately battery powered.”

Micro Power has made custom battery packs and custom battery chargers for the Single-Channel Ground and Airborne Radio System (SINCGARS) and multiband inter/intra team radio (MBITR). Other potential uses include a ruggedized personal digital assistant or wearable wireless transceiver, a portable device capable of transmitting data in the field from a portable PC.

“Many customers come to us with mutually exclusive requirements,” Vanzwol chuckles. “They are looking for longer run time in a smaller form factor and less weight. If you look at current technology trends, what you are getting is more and more energy density in a similar form factor, equating to longer run time in the same size and weight.”

The reconnaissance, surveillance, and targeting vehicle (RST-V) is a 4x4 hybrid electric-drive vehicle equipped with integrated precision geo location, communication, and reconnaissance, surveillance, and targeting sensor subsystems. (Photo courtesy U.S. Navy)
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With the DOD leaders vying to infuse the warfighter with advanced electronics devices, and thereby comprehensive digital capabilities, the need for portable power is growing and gaining the attentions of myriad energy providers.

“There’s always competition between batteries and fuel cells as a source of portable power,” Vanzwol admits. “The military is dabbling with and testing fuel cells, but the most interesting thing is some of the accomplishments of battery cell vendors, by adding higher-power or higher-capacity cells, are pushing out the adoption of fuel cells in the ruggedized environment to a certain extent.”

Fuel-cell company executives and other advocates disagree, arguing that standard batteries can only be used once and are logistically difficult, given their large size and weight. Moreover, rechargeable batteries are thought to take too long to recharge and require a person-portable recharge method, which does not yet exist.

Fuel-cell feasibility

“Many of the driving forces for military fuel-cell development (and the use of hydrogen) are similar to those in civilian life: lower noise or emissions, longer run times and, potentially, lower running cost are all relevant,” explains Alexandra Baker and David Jollie in Fuel Cell Today’s “Fuel Cell Market Survey: Military Applications.”

In general, fuel cells offer a 61 percent reduction in weight and 57 percent reduction in volume over traditional batteries. Fuel cells, though more expensive, provide low or zero emissions, high efficiency and reliability, quiet operation, worldwide availability, and renewable, high-quality energy.

“A standard comparison for military power sources is a hypothetical 72-hour mission requiring an average 20 watts per hour of power,” says W. Bruce Pharr, vice president of marketing at UltraCell Corp. in Livermore, Calif. “For this scenario, a soldier would need eight BA-5590 batteries, occupying more than 7 liters of space and weighing 18 pounds, or the UltraCell XX25 fuel cell and eight fuel cartridges, occupying less than 3.5 liters of space and weighing 8.9 pounds, for a 50 percent reduction in space and weight. An empty fuel cartridge weighs 0.29 pounds, 85 percent lighter than a discharged BA-5590 battery. The battery should be disposed of as hazardous waste, while methanol is renewable and biodegradable, and the cartridge materials can all be recycled.”

The U.S. Army Communications - Electronics Command (CECOM) displays a military HUMVEE using an IdaTech fuel-cell system as a mounted auxiliary power source.
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Fuel cells are safer than batteries by design. “Unlike a battery, where all reactants are in close proximity, fuel is contained separately from the processor in the UltraCell XX25 fuel cell, for example,” Pharr offers.

Another among the most important benefits of fuel cells is increased military capability. “Fuel cells can provide a higher energy density than current technologies,” continue Baker and Jollie. “For instance, unmanned vehicles can be designed to perform better. Perhaps the most popular area is in researching and developing fuel cells for portable use. It will allow soldiers to carry a greater amount of energy for these devices and operate for longer with less physical effort. In essence, the use of a fuel cell allows the Army to do things that it could not otherwise.”

Fuel-cell forays

Fuel-cell technologies are being used and evaluated for various military applications, including portable soldier power systems, battlefield vehicles, weapons systems, communications, air traffic control, electricity, heat, and propulsion of submarines, unmanned vehicles, and other platforms. Additionally, fuel-cell systems will power submarines in Germany, Italy, Spain, and Canada; small boats in Iceland, Germany, Finland, and the U.S.; and military aircraft in U.S.

“If you can think of an attribute of a fuel cell, there is a military use for it,” Baker and Jollie say. “A low heat signature makes detection by the enemy more difficult, as does low noise; fuel cells produce water as a byproduct, useful in many cases; fuel cells can be placed in several different locations in marine craft, making them harder to disable. Over the long term, it is safe to say that the uses for which fuel cells are being examined will only continue to increase in number to include ones we have not even imagined yet.”

The U.S. Navy’s SEAL delivery vehicle (SDV), previously powered by a silver zinc battery system, now takes advantage of Saft’s lithium ion technology. (U.S. Navy photo by Journalist 3rd Class Davis J. Anderson)
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Engineers at Sandia National Laboratories, a U.S. Department of Energy National Nuclear Security Administration (NNSA) laboratory in Livermore, Calif., and Boeing in Everett, Wash., are investigating the feasibility of using hydrogen-powered fuel cells as backup power in aircraft.

Military aircraft use a variety of techniques-such as an auxiliary power unit, a ram air turbine, or other technologies-for providing backup electrical power to critical subsystems during emergencies. This joint project focuses on the use of a polymer electrolyte membrane (PEM) fuel cell for backup power.

“Fuel-cell technology represents a straightforward and innovative approach to gaining experience with alternative energy sources for airplane electrical power,” says Joe Breit, project manager and an associate technical fellow at the Boeing Systems Concept Center.

Battlefield evac

Another partnership of interest is that of Millennium Cell Inc. in Eatontown, N.J., and Jadoo Power in Folsom, Calif. The companies won a contract with the U.S. Air Force Research Laboratory (AFRL) on Kirtland Air Force Base in N.M. to develop a 300 W power system to provide 12 hours of power for U.S. Air Force aeromedical evacuation flights.

“This mission-critical requirement effectively illustrates an application for which fuel-cell systems deliver a significant value,” Adam Briggs, president of Millennium Cell, notes. “The system has the potential to save lives by extending the mobile medical capabilities of the U.S. military.”

The program culminates late this year with a demonstration of a fuel cell system powering the Air Force’s Patient Support Pallet, designed to improve the survivability of soldiers being evacuated from the battlefield to advanced medical facilities.

Silent systems

Fuel-cell systems can also contribute to lives saved and successful missions, thanks to their noiseless operation and negligible heat signature, both of which are undetectable on the battlefield. The U.S. Army Tank Automotive Research, Development and Engineering Center (TARDEC) in Warren, Mich., is working on various hydrogen initiatives.

One such project employs a multi-service-regenerative fuel-cell auxiliary power unit (MREF-APU) on the Stryker armored combat vehicle. The MREF-APU enables the vehicle to meet low emissions-acoustic, thermal, pollutants, and more-requirements for Silent Watch, which occurs when the vehicle engine is shut off and reconnaissance equipment is activated.

When the Stryker engine is running, the alternator feeds an electrolyzer to create low-pressure hydrogen fuel, which is stored in metal-hydride form. When auxiliary power is needed for Silent Watch, the system is switched from Electrolyzer Mode to Fuel Cell Mode, providing power to the reconnaissance equipment.

The Stryker light-armored-vehicle employs a multi-service-regenerative fuel-cell auxiliary power unit (MREF-APU), which enables a Silent Watch mode.
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Another initiative involved a fuel-cell-powered, 7,603-pound Chevrolet Silverado pickup-the first fuel-cell-powered military truck, borne out of a partnership between General Motors Corp. in Detroit and the U.S. Army Research, Development, and Engineering Command (RDECOM) in Fort Belvoir, Va. The vehicle, capable of a 93-mile-per-hour top speed, is equipped with two 94-kilowatt fuel-cell stacks and fueled by compressed hydrogen gas.

“It’s an important advance incorporating advanced fuel-cell technology and introducing the military to the flexibility and security of fuel-cell power,” says Elizabeth Lowery, GM vice president of Environment and Energy.

“This technology is going to come in better and faster, and will have an incredible impact on us in our civilian lives,” notes U.S. Army Brig Gen. Roger A. Nadeau, commander of the Army Research, Development and Engineering Command. “I know what this is going to do for our military forces. My excitement today in not about this truck, but what is under the hood of this truck,” Nadeau says. “Technology in all our services is changing very rapidly, and it all requires power . . . and batteries are killing us. So my excitement on this is boundless.”

Fuel for the future

The power needs of today’s military and aerospace applications are many and varied. To date, no single power source is sufficient to meet all these needs. Batteries and fuel cells will likely coexist on military bases and battle spaces for the foreseeable future. Nonetheless, research into advanced and alternative power sources, energy-storage technologies, and energy-saving devices will continue indefinitely.

Researchers at Darnell Group in Corona, Calif., predict energy harvesting will be “the next big thing in power,” according to the report, “Energy Harvesting, Micro Batteries, and Power Management ICs: Market Forces and Demand Characteristics.” Energy harvesting will enable next-generation, low-power electronic devices and systems for homeland security, military, and other applications. “The first markets for these new technologies have been applications where batteries are problematic, such as military and avionic devices,” report Darnell Group representatives.

At the same time, personnel at the Office of Clean Energy Systems in the Department of Energy’s (DOE’s) Office of Fossil Energy in Washington have entered into a multiyear, $2 million interagency agreement with engineers at the U.S. Army Corps of Engineers’ Engineer Research and Development Center, Construction Engineering Research Lab (ERDC-CERL). The agreement covers three areas of energy research: energy conversion, energy storage, and power conditioning. These areas are of interest to the DOE and ERDC-CERL for stateside and warfighter base-camp facilities.

Considering research and development investments being made by the DOD, industry organizations, and various technology firms, the future looks bright-and powerful.

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