Where's the Juice? Army Explores Alternative Ways to Add Power on Battlefields
Magnuson, Stew, National Defense
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. …