SANTA ANA - First a technician attached a cable to the hydrogen car's tailpipe to prevent sparks. Then he snapped a thin, pressurized hose into place where the gasoline-pump nozzle would normally go. A switch was flicked, cameras clicked, and Santa Ana became the latest way station on California's "hydrogen highway."

The city opened its first hydrogen refueling station Thursday, one of five in Southern California that will service fleets of city vehicles that run on compressed hydrogen gas.

The cars emit almost no pollution - only a tiny amount of nitrogen oxides - aand the five-city program, sponsored by the South Coast Air Quality Management District, is meant to encourage the development of a hydrogen-powered economy.

"Hydrogen is now a real possibility," said David Freeman, president of the Port of Los Angeles.

But despite the gradual spread of hydrogen refueling stations around California - this is the state's 18th, and the second in Orange County - experts say we have a long way to go before hydrogen pushes gasoline aside.

Gov. Arnold Schwarzenegger has popularized the notion of a "hydrogen highway" stretching across the state, a broad network of refueling stations. And there are now clusters of such stations in Northern and Southern California.

The problem is getting cars on the road that could make use of them.

Santa Ana's fleet of five new Toyota Priuses relies on the same internal-combustion engines found in conventional cars, only with hydrogen in the tank instead of gasoline.

Such cars could sharply reduce air pollution, assuming pollution is controlled during the fuel-production process as well. Right now, hydrogen fuel is created typically with natural gas or electricity, although demonstration solar-powered or wind-powered systems have been developed.

Carmakers also have created prototypes of hydrogen fuel-cell cars. Instead of using internal-combustion engines, these run on electricity generated when hydrogen is mixed with oxygen, producing an electrochemical reaction.

They produce no pollution at all.

But neither type of hydrogen car is available yet to consumers. Carmakers have so far shown little interest in mass-producing internal-combustion hydrogen cars, and their fuel-cell versions would be far too expensive to place on the market.

None of that muted the enthusiasm of the public officials, regulators and technology company representatives who came to watch Santa Ana's hydrogen fleet gas up Thursday.

Mayor Miguel Pulido took reporters on a spin around the block in one of the cars. He said he would let officials in other cities drive Santa Ana's cars for days or weeks at a time to get a feel for what he hopes will be the hydrogen future.

"You've got to start somewhere," he said. "This is a good place to start."