Ground Delivery Goes Green

Transportation is particularly difficult to make environmentally friendly. Electricity can be generated from dams, windmills, or solar cells instead of fossil fuels, but vehicles need a power source they can carry with them. And while charged batteries are suitable for lightweight, short-haul travel, they would be impractically heavy for larger vehicles or longer routes.

Fortunately, there’s a promising middle ground: fuel cells. Fuel cells are essentially batteries that are refueled rather than recharged, and the fuel is clean-burning hydrogen. Los Alamos has been on the forefront of fuel-cell development since 1977, and that investment—widely recognized for its potential to replace hydrocarbon-fuel engines entirely—is paying great dividends. Already, high-efficiency fuel-cell vehicles are driving on the nation’s roadways, mostly in California, where virtually all of America’s 50 or so hydrogen refilling stations reside.

“Every fuel-cell vehicle in existence or under development depends on technology invented at Los Alamos,” says Laboratory scientist and fuel-cells program manager Rod Borup. The key lies in specialized, reaction-catalyzing materials for the fuel cell’s electrodes: the anode and cathode. Unlike a conventional battery, whose electrodes are relatively simple conductors with the energy stored in an ion-carrying electrolyte sandwiched between them, a fuel cell depends on porous electrodes to convey inflowing hydrogen (fuel) and oxygen (to react with) into controlled contact with the electrode catalysts and the electrolyte, while managing the outflow of the cell’s one and only waste product, water. The anode catalyzes the dissociation of H₂ molecules into electrons (which are sent along the circuit path to power the vehicle) and H⁺ ions (which are routed through the chemical electrolyte). These two paths reconverge at the cathode, which catalyzes the process of making water from the hydrogen ions, oxygen, and the electrons arriving after completing the circuit.

President Biden has set a goal for the United States to reach net-zero greenhouse gas emissions by 2050 and at least a 50-percent reduction from 2005 levels by 2030. Doing this will require a substantial ramp-up of many green technologies, and Borup and his colleagues at Los Alamos and other Department of Energy (DOE) sites have teamed up to jumpstart the fuel-cell aspect. Success will require a massive investment in infrastructure for hydrogen production, transportation, and refilling stations comparable to existing gasoline-based infrastructure. How does one obtain a toehold on such a grand undertaking?

“With trucks, no question,” says Borup. “Semi-trucks have limited routes compared to passenger vehicles yet account for about a third of transportation-based emissions. So we can have a huge impact with a comparatively modest, truck-only initial investment. Besides, long-haul, heavy-duty transportation is where fuel cells really shine.” Los Alamos is contributing to the DOE’s Million Mile Fuel Cell Truck consortium to enable hydrogen fuel-cell technology to be dramatically scaled up beyond its current limited application in California, with ongoing research aimed at improving cost effectiveness and durability.

How impactful will success be, for emissions from trucks and subsequent fuel-cell vehicles, which might one day include ships and aircraft as well? Enormously impactful, it turns out. If the hydrogen is sourced using renewable power, it will cut greenhouse gas emissions to essentially zero—and this in the eco-resistant transportation sector! If the hydrogen is initially sourced from natural gas—widely recognized as a transition fuel to renewable power—the reduction would still be about 50 percent.

“If we’re serious about rising to the challenge of climate change, this is necessarily a big part of how we do it,” says Borup. “Nothing short of our future is at stake.”