In a PEM cell the membrane is coated with a catalyst that strips electrons from the fuel, usually hydrogen.

FORBES: Magazine Article

There are two dominant flavors of fuel cell: proton-exchange membrane (PEM) and solid oxide.

FORBES: Magazine Article

The authors believe their system could combine the advantages of methanol as a hydrogen carrier and of proton-exchange membrane (PEM) fuel cells for efficient energy production.

BBC: Hydrogen's energy promise improves

It also develops its own PEM (proton exchange membrane) fuel cell generators and has a growing business in China, where it will power the buses for the 2008 Beijing Olympics.

FORBES: Fueling Speculation