DEARBORN (AP) – Ford is joining with Daimler and Renault-Nissan to speed development of cars that run on hydrogen, with hopes of bringing a vehicle to market in as little as four years.

Hydrogen fuel cell vehicles generate electricity after a chemical reaction between hydrogen and oxygen. Hydrogen is stored in special high-pressure tanks, and the only emissions are water vapor and heat.

Many automakers have been testing the hydrogen fuel cell vehicles for years, but so far haven’t been able to bring costs down enough to sell the vehicles in mass markets.

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