The only residue is pure water. It is quiet and smooth on the road, with no shifting needed. Of course, there are issues involved with the creation of a hydrogen fuel manufacturing and delivery infrastructure, and the storage of liquid hydrogen in an automobile at minus 423 degrees centigrade with significant space, weight, and cost problems to solve. One alternative being pursued by Ballard and Dbb is to store methanol in the car's fuel tank and use it to make hydrogen onboard the car. It is an attractive proposition.
Methanol is derived from natural gas, of which there is an abundant supply.
Methanol also can be produced by renewable sources such as biomass or garbage. Extracting hydrogen from methanol produces some undesirable emissions, but only one-tenth of the pollutants from the cleanest automobile on the road today. Dbb uses the PEM proton exchange membrane fuel cells produced by Ballard Power to develop the engines that will power electric cars and buses. Ballard is a publicly-traded firm listed on the Toronto and Nasdaq Stock Exchanges. Ballard and Dbb have partnered with Ford and DaimlerChrysler in a financial and technical arrangement with the goal of developing mass production fuel cell-powered automobile, bus and other applications.