General Motors is turning a Chevrolet Colorado pickup truck chassis into a three-ton rolling testbed for hydrogen fuel cell propulsion for the military. Unveiled Monday in Washington at the Army of the USA (AUSA) conference, this one-off vehicle will be used to determine how much the Army likes a vehicle that produces no engine noise, has no heat signature, can go on or off-road, and provides 25-50 kilowatts of electric power.
General Motors over the years has invested more than $3 billion in fuel-cell research and development. It believes there’s room for fuel cells in an era when there’s more focus on electric vehicles and hybrids. Other automakers, including Honda, Hyundai, and Toyota, are also pursuing fuel cell propulsion. The fuel cell converts hydrogen stored on board with the oxygen in the air, producing electricity (lots) and water (a couple gallons an hour).
The vehicle is the Chevrolet Colorado ZH2, where H2 stands for hydrogen. Ignore that there once as a vehicle called the Hummer H2 and General Motors for a time owned Hummer. Still, this is a husky vehicle that has been resize and reinforced: It measures 211 inches long, 85 inches wide, and 80 inches tall, with 12 inches of ground clearance and weighing 6038 pounds, or 7338 pounds fully loaded. A stock Chevrolet Colorado midsize pickup measures 212 or 225 inches long (depending on cab configuration) and weighs 4000 to 4700 pounds.
Inside, there are four custom Recaro seats, each with a multi-point harness as on race cars or military aircraft. The front looks like a stock Colorado. The back seat is snug, especially with a bar installed just behind the front seats at shoulder height to secure the front harnesses. Instead of a rear window, there’s a rear-facing camera along with traditional side mirrors. Development was a joint project between GM and TARDEC, the US Army’s Army Tank Automotive Research, Development and Engineering Center. TARDEC is the country’s testing lab for advanced automotive technology used by the military, including tanks and other armored vehicles.
According to Paul Rogers, director of TARDEC, “Fuel cells have the potential to expand the capabilities of Army vehicles significantly through quiet operation, exportable power and solid torque performance.” The Army envisions a vehicle that could be used for “silent watch” patrols with no engine noise and no heat signature from the exhaust. The Colorado prototype is not, however, a direct replacement for the military’s Humvee; that will be the Oshkosh Joint Light Tactical Vehicle, which is significantly larger than the ZH2 and the Humvee.
The electric drive delivers its maximum torque (power) at 0 mph, an advantage in low speed operation. That is an attribute of any kind of electric drive, whether it’s powered by a storage battery, a generator, or a fuel cell. A minor plus for the fuel cell Colorado is that the process of turning hydrogen plus oxygen in the air into electricity is that it produces about 2 gallons of pure water per hour that could be used by the crew for drinking.
A bigger plus is the power inverter in the cargo bay. It produces 25,000 watts continuously and can peak at 50,000 watts (50 kW). It could power an encampment without the noise or heat signature of a diesel generator. But at the full 25-kW load, the fuel cell would only provide two hours of power before refueling the vehicle. At a reduced output of 5 kW (two 20-amp 120-volt circuits), it would run 8.4 hours. A thousand-dollar gasoline generator could also provide 5 kW, albeit with a lot of noise and shutdowns to refuel every 4-6 hours.
GM notes the refueling a fuel cell vehicle takes roughly as long as a petroleum based vehicle — a couple minutes, whereas EVs take hours to recharge.
Three tanks containing 4 kilos of gaseous hydrogen are under the cargo bay. The tanks are wrapped in multiple layers of carbon fiber and can withstand the impact of a .50-cal round, says Rogers. The fuel cell that converts the hydrogen to electrons plus water fills up much of the engine bay. Newer versions would be smaller.
The electric motor driving the wheels sits where the transmission would be on a combustion engine vehicle. It drives all four wheels. There is also a 16-kWh lithium ion battery on board, about the size of the battery on the plug-in hybrid Chevrolet Volt. It provides extra acceleration and should have the ability to propel the ZH2 20 miles or so without invoking fuel cell power.
For the past 25 years, virtually all American vehicles used in tactical combat situations burn a single fuel called JP-8 (JP for jet propellant): tanks, helicopters, transport vehicles. JP-8 is effectively the same as kerosene, diesel, jet fuel, or home heating oil, plus some added icing and corrosion inhibitors. It doesn’t catch fire as easily as gasoline, has about 10% more energy content, and simplifies logistics. A helicopter, a tank, and an Army field stove can be topped off from the same fuel bladder or fuel truck.
If the GM fuel cell project is to succeed, it will have to prove that its attributes, particularly silent operation and no heat signature, are worth the logistics of storing and transporting hydrogen under high pressure, or bringing into the field reformers – the systems that strip hydrogen from (typically) natural gas into natural hydrogen that is then compressed. The feedstock to produce hydrogen could also be ethanol, propane, gasoline, or even JP-8. It could also be something environmentally friendly such as biomass. The reforming process consumes energy, which has been a drawback when proposed as a large scale solution, such as for moving the country’s automobile fleet to fuel cells. There is considerable discussion about the end-to-end efficiency (carbon neutrality) of fuel cells as long as the hydrogen is produced from carbon-based stock such as natural gas.
GM says the test vehicle would get a bit less than 200 miles of driving range from the fuel cell. But over time, with newer fuel cells, the range could double. Some of the Colorado gear GM is using isn’t the absolute latest technology, but that’s intentional, because it has already been certified and GM wants to spend the next year testing, not waiting for approvals then hasty testing.
According to GM, it will work on calibration testing into early 2017 at its Milford (MI) proving ground, then turn it over to the Army for a year of field testing. GM and TARDEC have fuel cell development labs 20 miles apart in Michigan. Charlie Freese, executive director of GM Global Fuel Cell Activities, said, “Over the next year, we expect to learn from the Army the limits of what a fuel cell propulsion system can do when really put to the test.”