The power of the fuel cell is the fuel. It is zero emissions hydrogen but it could power a fuel cell or a regular internal combustion engine and the BMW Hydrogen 7 operated on the same principles as a the propane powered vehicles except with hydrogen fuel. It also had a regular gasoline fuel tank to power the one internal combustion engine. You have the technology. You are already using it and a fuel system conversion to propane on any existing internal combustion engine is just $2000.00 which is almost the same cost as GPS navigation on some brand new vehicles. Think of a Brand new Mustang running on hydrogen or propane fuel. Choose your Heaven with zero emissions!