Aug 22, 2007
U.S. Department of Energy lab developing solid pellets for hydrogen storage
Richland, Washington – Researchers at the Pacific Northwest National Laboratory, one of the U.S. Department of Energy’s ten national laboratories, have announced they are developing pellets of solid ammonia borane. The small pellets are capable of storing relatively large quantities of hydrogen in a very small volume, which the researchers say “holds promise in meeting long-term targets for transportation use”.
Each millilitre of ammonia borane (AB) weighs about three-quarters of a gram, and holds up to 1.8 litres of hydrogen. Researchers expect that a fuel system using small AB pellets will occupy less space and be lighter in weight than systems using pressurized hydrogen gas, enabling fuel cell vehicles to have room, range and performance comparable to conventional automobiles.
The researchers are learning to manipulate the release of hydrogen from AB at predictable rates; by varying temperature and manipulating AB feed rates to a reactor, they envision controlling the production of hydrogen and thus fuel cell power, much like a throttle pedal regulates fuel to a car’s combustion engine.
“Once hydrogen from the storage material is depleted, the AB pellets must be safely and efficiently regenerated by way of chemical processing,” says researcher Don Camaioni. “This ‘refuelling’ method requires chemically digesting or breaking down the solid spent fuel into chemicals that can be recycled back to AB with hydrogen.”