But in the short term, researchers are working on reformers which produce hydrogen aboard vehicles by extracting the gas from methanol or other hydrocarbon fuels -- a process that can release pollutants, though at far lower levels than internal combustion engines, Roan said.

CNN: Bus showcases fuel cell technology

The deal for Mariner is even larger with 181M proven barrels of oil equivalent (47 percent are oil or other hydrocarbon liquids), but according to the press release there is the potential of 2B barrels of oil equivalent among their 50 deepwater prospects.

FORBES: Drilling Into Apache And Mariner