Army explores alternative ways to add power on battlefields

By Stew Magnuson

ArmyExplores As the Army ponders which direction to go with hybrid vehicles, it still has acute shortages of electrical power on the battlefield.

The Army Tank Automotive Research, Development and Engineering center, TARDEC, is among several military laboratories looking into the promise of fuel cell technology to give soldiers the extra juice they need on the battlefield to operate equipment loaded onto humvees and other vehicles.

“The Army has a big need for electric power on the battlefield,” Herb Dobbs, TARDEC team leader for alternative fuels and fuel cell technology, told National Defense. “Our vehicles for years have suffered from a shortage of electric power volts for use onboard.”

That is coupled with the need to export power from the vehicle for command posts, mobile hospitals and living quarters, Dobbs said. The Army can always haul mobile generators on to battlefields, but that is a logistical burden, he added. A more practical solution is to export the power from vehicles. However, their batteries are already overtaxed.

Furthermore, there is a need for soldiers using such vehicles to operate them in “silent watch.” They may take a position at night where they don’t want the enemy to hear their engines running, or have them drown out the sounds of an approaching foe.

TARDEC recently began a two-year research and development project to find out if hydrogen fuel cells can provide the answer to these problems. It’s spending $11.7 million this fiscal year on the project.

Fuel cell technology has been around for decades, but in the past few years it has become a buzzword in alternative energy circles, with President Bush among those who have touted its potential benefits.

A hydrogen fuel cell is an electrochemical device that combines hydrogen and oxygen to make electricity. Proponents praise the technology as clean, quiet and highly efficient.

Feeding the fuel cell with oxygen is relatively simple. That comes from air. Hydrogen is another matter. It is difficult to distribute and store. Hydrogen can be converted from common fossil fuels like natural gas or propane or alcohol-based fuels like methanol.

To convert these common fuels into hydrogen, there must be a “reformer.” If the reformer lets too many impurities through, it poisons the fuel cell, making it less efficient, or disabling it entirely.

The Army, however, runs on jet fuel. And converting jet fuel to hydrogen will be the most complicated hurdle for TARDEC to overcome, Dobbs said.

“Hydrogen has to be made. Basically, you don’t get it out of the ground,” Dobbs said.

Eric Kallio, TARDEC principal investigator for fuel cell technology, said both diesel and jet fuel are complex compounds with hundreds of chemical ingredients. For example, both have high sulfur content, an impurity that would quickly choke a fuel cell. For logistical purposes, the military will not be transporting propane, methanol or other fuels into the field. The services made a decision in the early 1990s to have one primary fuel to simplify the supply chain, Dobbs said.

The quality of jet fuel is highly variable. The sulfur content depends on where it is bought. The U.S. market may have lower sulfur content, but the military buys its fuel regionally. It will not be, for example, hauling lower sulfur fuel from U.S. refineries halfway around the world to Afghanistan or Iraq, Dobbs said.

Jet fuel refined in the United States may have a sulfur content of 15 parts per million. In the first Gulf War, the military bought fuel from Saudi Arabia with a whopping 3,000 parts per million ratio, Dobbs pointed out.

The military will mostly be on its own in solving the jet fuel-reforming problem, Kallio noted. In the past, much of the military tactical truck technology has derived from research first carried out in the commercial market. But no commercial or government research labs, such as the Department of Energy’s, are working on reforming jet fuel into hydrogen.

“There are two conflicting things here,” said Kallio. “We have to operate on jet fuel, and industry and other government investment is not focusing on jet-fuel derived energy.”

Also, research dollars are being spent to look for ways to propel vehicles with hydrogen. TARDEC does not see that as a possibility, Dobbs said.

“The efficiency argument is overshadowed by the need to make additional power and do it quietly,” said Dobbs. The military would effectively have to bring more energy along than it currently does to power vehicles such as humvees entirely on hydrogen, he said. And there are other ways to obtain fuel efficiency, he added. “Diesel engines are awfully efficient and there’s still room to make them more efficient,” he added. Diesel and jet fuel are chemically close.

Glen Bowling, general manager of Saft America Inc., a leading manufacturer of lithium ion batteries, is among those who are skeptical that fuel cells will ever replace diesel engines.

“A fuel cell is good at running at a single power level for a long time, but it does not do any kind of variation at all,” Bowling said in an interview at Saft’s Cockeysville, Md. plant.

Meanwhile, battery technology has made leaps and bounds over the past decade, he noted.

Lithium ion batteries cycle more efficiently and more slowly than nickel cadmium, lead acid or silver zinc varieties, he said. Lithium ion batteries are being used to power popular commercial products such as cell phones, laptop computers and MP-3 players. The military is slowly switching from silver zinc to lithium ion in many of its systems.

Saft has already supplied lithium ion batteries to military demonstration hybrid vehicle programs such as General Dynamics Land System’s reconnaissance, surveillance and targeting vehicle, as well as the Air Force’s joint strike fighter and the Navy’s SEAL delivery vehicle.

Saft still sees too many technology challenges to enter the fuel cell market. “The only one that can work consistently is a hydrogen fuel cell, and that is expensive.”

“We don’t see the fuel cell business as real,” he added. A fuel cell-powered vehicle can’t provide the power to go up and down hills, he said.

Still, he believed a lithium ion battery could be used in conjunction with a fuel cell-powered vehicle to absorb the peak demands, such as when the truck needs to accelerate.

“It’s not a battle to the death [between the two technologies]. It’s finding the right combination of things to balance,” he said.

Lithium ion is proving itself to be a safe and effective alternative power source on the battlefield, he said. One of the company’s biggest contracts is to supply the power for the improved target acquisition system, the Army’s TOW missile. More than 500 units have been delivered so far.

The main technological hurdle the industry had to overcome is overcharging, which can cause the parts inside the battery to catch fire. Manufacturers such as Saft and its main competitor for the military market, Lithion Inc. of Pawcatuck, Conn., have worked hard to create protection systems to prevent such accidents, Bowling said. While lithium ion batteries have received bad press in the consumer market for safety problems caused by overcharging, Bowling said there is no margin for error in the defense industry when soldiers’ lives are at stake.

“You cannot safely build a lithium ion battery without an electronic protection system in it,” he said.

John Bosma, director of technological scouting for the Reston, Va.-based Synthesis Partners Inc. consulting firm, is also among the hydrogen fuel cell skeptics.

“There’s a lot of fuel cell romanticism out there,” he said. While he doesn’t think it is wrong for TARDEC, or other military branches, to explore hydrogen fuel cell technology for auxiliary power, he doubted they would be ever be practical for vehicle propulsion.

The sulfur issue could be a deal breaker. “Fuel cells are tricky. They are electrochemical nightmares.”

He questioned whether such a system would ever be rugged enough to withstand the rigors the military puts its trucks through. Road shock, potholes, and other impacts would disrupt their use. Although a unit used for auxiliary power could potentially be provided enough insulation and shock absorption to be placed in a truck cabin, he said.

Lithium ion batteries, as long as they are rechargeable and rugged, are also possible for silent watch and auxiliary purposes, Bosma said. They would have a smaller logistical burden than fuel cells, he said.

Furthermore, hydrogen fuel cell systems are wasteful, he said.

Reformers, after they separate the hydrogen out of the fuel, throw away the carbon, which is 50 percent of the fuel value, he said. “Most people don’t realize that hydrogen fuel cells are incredibly wasteful, and nobody will stand up and say it, but that’s the truth,” Bosma said.

In addition, the electrochemical process produces a good deal of “scatter,” meaning they will not put out a consistent amount of power. The scatter can be anywhere from 5 to 10 percent.

Direct carbon fuel cells, which use coal or graphite, might be a better bet for the military, Bosma said. Such fuel cells do not need a reformer.

“There’s been very little discussion of [direct carbon fuel cells] in public … and very little publicity of it,” Bosma said.

The Department of Energy’s Lawrence Livermore National Laboratory, along with a handful of companies, are carrying research on direct carbon fuel cells. As of yet, the technology has not received the billions of dollars in research funds as hydrogen fuel cells.

The conversion efficiency for modern coal power plants is 35 to 40 percent, according to a laboratory statement. Experiments have shown the carbon fuel cells working at rates of up to 80 percent. It creates a pure carbon dioxide byproduct, which is easily captured and could be recycled by industry, thus reducing the amount of greenhouse gasses released into the atmosphere, the lab said.

“You ditch the reformer, and theoretically it should be a much simpler application and design,” Bosma said.

Bosma doesn’t rule out hydrogen fuel cells overcoming the technological hurdles to create an efficient means to propel vehicles, but that may take decades, he said.

As for auxiliary power, Dobbs said the earliest a system could be integrated into a military vehicle would be in about five years.

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