BALLARD Power Systems Inc, the world's biggest maker of automotive fuel cells, agreed to provide as many as 20 of the power sources for a Shanghai trial of vehicles that use the clean-air technology.

Ballard said it will supply the fuel cells to Shanghai Fuel Cell Vehicle Powertrain Co and help develop the vehicles. Two of the cells will be for use in vehicles this year and the rest in 2007, Burnaby, British Columbia-based Ballard said yesterday in a statement.

The Canadian company, partly owned by DaimlerChrysler AG and Ford Motor Co, thinks "China could be a key market driving the commercialization of automotive fuel-cell technology," Vice President Noordin Nanji said in the statement. Ballard said it also has supplied three fuel-cell engines for Mercedes-Benz buses in a Beijing project that began in November.

Fuel cells generate electricity in a chemical reaction that combines hydrogen and oxygen and emits only water vapor as a byproduct. The Shanghai agreement is part of a program by the municipal government to put 100 fuel-cell vehicles on the road by the end of next year, Ballard said.