Water and heat in the fuel-cell balance

Researchers from the National Renewable Energy Laboratory, Millennium Cell, and DaimlerChrysler are working on a sodium borohydride system that has the potential to meet FreedomCAR's weight-percent hydrogen-storage targets.

Approaches to storing hydrogen onboard fuel cell vehicles include compressed gas, liquid hydrogen, metal hydrides, chemical hydrides, and carbon nanotubes. Millennium Cell has developed a process for storing hydrogen chemically in a sodium borohydride (NaBH₄) solution and then liberating the hydrogen from the NaBH₄ for delivery to a fuel cell. Called Hydrogen On Demand (HOD), it is being evaluated by automotive manufacturers such as DaimlerChrysler. The system is said to offer higher hydrogen volumetric and gravimetric density than some other hydrogen-storage options.

Researchers from the National Renewable Energy Laboratory, Millennium Cell, and DaimlerChrysler have evaluated the NaBH₄ storage/processor system's potential to meet the FreedomCAR program technical target of 6 wt% (percent by weight) hydrogen for hydrogen storage technologies. They presented their findings at the SAE Future Transportation Technology Conference in June.