The Army is channeling the majority of its investments in fuel-efficient technology into the Future Combat Systems. But that program is still years away from fielding, and energy savings may take a long time to materialize.
Army leaders have touted FCS as the Army’s first major opportunity to introduce hybrid-electric engines into the fleet. Not only would hybrid-electric engines help to save fuel, but they would also serve as electricity generators that would power many of the devices that currently require bulky batteries and custom generators.
FCS is a $160 billion project to build a family of manned and unmanned ground and air systems, and sensors connected by a common network.
For the Army, trying to cut its fuel use to significantly lower levels is simply not possible with its current fleet. Its old, gas-guzzling engines can be tweaked, but real fuel economy requires a shift to hybrid-electric technology, experts said.
The FCS combat vehicles that are currently in development are in slated to arrive in 2015. They are being outfitted with “series” diesel-hybrid engines, which differs from what commercial hybrids use. A diesel engine on board turns a generator, which in turn charges batteries and powers electric motors that drive the tracks. The entire vehicle is electrically powered.
The Toyota Prius, by contrast, has a “parallel” gas-hybrid system, which is a more mature technology. Its computer gauges whether it is more efficient to use the batteries or the engine.
The FCS engine was custom designed to move a hefty vehicle that is expected to weigh at least 26 tons.
Both the FCS and the Prius use “regenerative breaking.” When the driver hits the breaks, a mechanism is activated that converts some of the vehicle’s kinetic energy into power that recharges the batteries.
The FCS non-line-of-sight cannon, a 155mm howitzer, already has the hybrid system embedded in its eight prototypes. It is now undergoing road testing, said Army spokesman Paul Mehney.
The diesel engine is removable. If the Army decides in the future to switch to a fuel cell or another engine, the transition should be simple, Mehney said.
There are no available statistics for how much fuel savings the entire FCS fleet will achieve once it arrives. The Army estimates that an FCS heavy brigade combat team will consume 29 percent less fuel than its current counterpart, Mehney said.
During a 1,864 mile mission lasting several days, a current heavy brigade combat team consumes an estimated 1.3 million gallons of fuel. But an FCS brigade would only consume 942,000 gallons, according to a simulation study conducted by Sandia National Laboratories.
On a paved road, the FCS heavy tracked vehicle travels 1.66 miles per gallon. By comparison, the Abrams tank can go 0.52 miles per gallon.
The goal is to reduce the amount of fuel deliveries that convoys have to make to war zones. A Defense Department study noted that trucking a gallon of fuel to conflict zones costs hundreds of dollars. Delivering it also puts troops in harm’s way.
Legislation passed by Congress last year requires the Defense Department to make fuel conservation a priority when developing new vehicles.
Exportable electricity is another benefit of the hybrid-electric engine. Soldiers can plug in their electronics or lighting equipment without having to haul gas-guzzling generators to the front lines, said Don Christian, director of electrical engineering and ground systems at BAE Systems Land and Armaments.
The Army’s goal is for the device is to provide 350 kilowatts of electricity. That amount of energy could power an entire village, Christian said. But FCS engineers have not yet reached that objective.
Other “power management” features promise to improve fuel efficiency just by shutting off systems when they are not needed. Switching off unused electronics and computers will enable vehicles to operate more quietly in “silent mode.”
FCS vehicles will also have lamps that require less electricity, Christian added.
Even though the FCS vehicles are expected to achieve some fuel efficiency, they may not save as much as the military would like. The weight of the vehicles is higher than what was originally planned, said Nate Hughes, a military analyst at Stratfor. Additional weight increases fuel consumption. “You see this most clearly with the move to more heavily armored humvees and mine-resistant ambush-protected vehicles (MRAP),” said Hughes. “A fully armored humvee is supposed to be outfitted with a larger engine in order to handle the increased weight of the armor.”
In 2007, FCS manned ground vehicles were still seven to nine tons over the preferred weight of 20 tons. The Government Accountability Office said that armor was the main reason for this. FCS has now increased its baseline weight to 30 tons.
Experts generally agree that the Army should not expect FCS to produce immediate fuel savings.
A dramatic reduction in fuel demand will not be achieved overnight, said Lou Infante, vice president of vehicle engineering at Ricardo Inc., a consulting firm.
While the Army waits for FCS to arrive, it has tapped a couple of companies to help it improve fuel economy in the current fleet.
Ricardo is engaged in a project to develop and identify technologies that can reduce fuel consumption. In October, the company won a $4 million contract to conduct a study that would identify the best combinations of technologies for achieving fuel savings for military ground vehicles, Infante said. The contract is for the first year of a three-year study. The project is part of the “fuel-efficient ground vehicle demonstrator program,” which is overseen by the U.S. Army Tank-Automotive Research, Development and Engineering Center.
Fuel-saving technologies could be applied to the humvee, as well as the MRAPs, Infante said.
General Dynamics Land Systems, meanwhile, has designed a model to help eliminate the “waste energy” in vehicles such as the Abrams tank. This includes the engine-generated heat that simply dissipates into the atmosphere. The project seeks to put such energy to use, said Rich Dinges, director of technology developments and innovation for General Dynamics Land Systems.
The company is also conducting a study on the Abrams, and aims to lower the tank’s fuel consumption by 50 percent. It is looking at power management systems that automatically turn off unused functions. Such a system might involve dual power packs in which one would be turned off when it is not needed, Dinges said.
The next step is to build a prototype. That is about a year away, Dinges said. “[Fuel savings] don’t come in just the efficiencies of each little component but rather in the way the whole vehicle is used and designed,” he said.
At the moment, that project is still in its early stages. “But it is changing our mindset and hopefully it will migrate into our other products,” Dinges said.
Achieving fuel savings from the current fleet should be a pressing priority for the Army, analysts said, particularly as FCS faces significant budgetary and political hurdles.
Defense Secretary Robert Gates has expressed concerns about the cost and technical scope of FCS, although he vowed to support the program for the time being. Several members of Congress also have voiced discontent about FCS’ complexity and huge price tag.
“A lot of this is dependent on the understanding by the new administration of how tactically important this is, and how it is going to fit into a budget discussion,” Infante said.
The uncertainty surrounding the future of FCS could slow down the Army’s drive toward a greener fleet.
“While FCS may begin to be fielded over the course of the next decade, it will be MRAPs and Abrams… that will continue to guzzle fuel,” Hughes said.