Production of H2 fuel cell trucks are years away, but time’s flying

Fuel cells – are they the future powerplants for trucks? Could be. Fuel cells silently make electricity for an electric driveline that might replace the diesel and mechanical transmission in the typical road tractor. That future truck might still have a driveline with an electric motor that turns gears in a normal differential and axles, or motors could be located on axle shafts or wheel hubs. And the cells would be powered by hydrogen.

“Hydrogen fuel is where you get your electric energy from, that’s all,” says Jack Legler, technical director at the American Trucking Associations. “The electrics on the truck are the same as they are with an electric truck. But with a fuel cell, the truck becomes more independent of the power source,” which for a battery-electric truck is plugging into the grid. So the fuel cell is a “range extender,” which in present-day hybrid cars and trucks is a gasoline or diesel engine. Another major component is a battery pack, usually lithium-ion. High weight and hefty prices for batteries have delayed introduction of electric powertrains, but progress is being made to bring down poundage and expense.

The science

Fuel cells can be powered in several ways, but hydrogen is the one environmentalists want. It’s the most abundant element in the universe, but here on earth it doesn’t exist alone in two-molecule form (thus its symbol of H2). It’s always part of a compound.

“Now, 95% of hydrogen comes from steam reforming of methane,” a hydrocarbon compound, explains Kevin Otto, a retired Cummins engineer who’s now a consultant. “If you grab the hydrogen from methane, the leftover carbon goes into the atmosphere, and that’s just as bad as now,” with exhaust emissions from internal combustion engines and the wells that pump petroleum.

Water – H2O – is a familiar hydrogen compound, and will be the source of “clean” hydrogen because the only other product after it’s extracted through electrolysis is oxygen. It’s the same electrolysis you applied to that beaker of water in high school chemistry class, remember? You did it with electricity, then maybe lit the escaping gases and watched them burn. Electrolysis using purified water is how future H2 production will work, says Legler at ATA. That’ll take a lot of electricity, and how it’s generated determines whether it’s clean or dirty. Visionaries want clean electricity generated from wind turbines or solar cells, though building those isn’t all that clean, but that’s another matter.

Fuel cells go back 50 to 60 years, says Otto, who heads an ATA group that’s studying electric powertrains, including fuel cells.

They flew in manned spacecraft during NASA’s glory years. Fuel cells are in Honda Clarity and Toyota Murai cars running in California and Japan. In principle, they’re all the same: A fuel cell generates electric energy by recombining the hydrogen carried in on-board tanks with oxygen from the atmosphere. The two elements join as they pass through an anode and cathode inside the cell, and the result is the electricity – a sort of reverse electrolysis. The electricity then goes into a battery pack that feeds power to the electric motor(s). The byproduct is air and distilled water that can drip harmlessly to the pavement (or that you can capture and sell for 98 cents a gallon, right?).

Practicality?

Transporting, storing and dispensing hydrogen will be costly because it needs to be highly compressed to pack enough energy into the tanks on the truck. Tanks are expensive pressure vessels, like those that carry natural gas on some current trucks. (Natural gas is also supercooled to liquified form, which makes it more dense, but that’s even more costly.) Whereas natural gas is compressed to 4,000 or 5,000 psi, hydrogen might have to go to 10,000 psi, Otto says, and compressing takes costly energy. So fueling stations will likewise be costly and take up real estate at a trucking terminal or truck stop.

“Tanks and fueling stations – the only ones now are in Southern California,” he continues. “You’ll need a network of fueling stations all over the country, and that’s a big hurdle. Another hurdle is that hydrogen is expensive. One kilogram of hydrogen equals one gallon of diesel fuel in energy, and costs $13 to $16 per kilogram. Diesel costs about 3 bucks a gallon, and about 75 cents of that is road tax – that varies by where you are. None of the $13 to $15 for hydrogen is tax … But, if you can get that hydrogen cost down to $2.50, $3, all of a sudden it makes a lot of sense.”

Volume production and high demand will reduce prices, and the federal Department of Energy is investing millions of dollars to encourage hydrogen production and electric generation infrastructure. DOE just announced support for Super Truck 3, the third phase of a demonstration project begun in 2009. Tractor-trailers in the first two phases used advanced diesels and enhanced aerodynamics to achieve high mile-per-gallon levels. This time DOE wants alternative powertrains, including hydrogen fuel cells.

Cummins’ New Power division has developed a 6×4 tractor with a fuel cell and battery pack that powers an electric driveline.

The package could go in any Class 8 truck, like its diesel engines, the company says. Meanwhile, big names in the established automotive business are partnering with familiar heavy truck makers – Toyota with Kenworth and General Motors with International – to develop hydrogen fuel cell rigs. Daimler and Volvo in Europe have formed a joint venture to design hydrogen fuel cells that will be large and powerful enough for heavy trucks. Nikola, the start-up that’s developing fuel-cell and battery-electric trucks, also aims to set up a hydrogen fueling network in the United States.

So-called first adopters are already in line to acquire and run fuel cell-electric trucks. They are big fleets managed by progressive executives who’ll have the resources to test and evaluate them. A few such trucks are now hauling containers out of California seaports, where comparatively short runs allow close monitoring of the trucks’ systems. The trucks cost much more than comparable diesel trucks, so they do not yet make a good business case. For now, federal and state money subsidizes their purchase and operation. When will their prices reach parity with diesels? By 2028-30, the Department of Energy estimates. But time goes fast, and you might be driving one, and maybe buying it, sooner than you think. LL