California's long awaited "hydrogen highway" raced toward reality this week, as the state announced plans to double the number of fueling stations -- a move environmentalists hail as a milestone toward efforts to promote alternative-fuel vehicles.

Stations--usually add-ons to existing gas stations--are planned for many Bay Area communities, including Palo Alto, Woodside, Saratoga, San Jose, Redwood City and Oakland. The stations are expected to open by October 2015.

"It's a very important announcement because it says very clearly that California is on a path to put enough stations out there so cars can get refueled," said Joan Ogden, a professor at the Institute of Transportation Studies at the University of California, Davis.

The Energy Commission plans to contribute $46.6 million to construct 28 new hydrogen-fueling stations by 2015, according to a statement released this week. The stations will be primarily clustered in so-called "early adopter" communities in the Bay Area and Southern California.

Energy Commission Chairman Robert Weisenmiller called the financing a "phenomenal" advancement toward solving the "chicken-and-egg" problem posed by unveiling a new form of transportation.

"Suddenly we're getting close to the threshold" of 100 stations needed to support a system based on hydrogen fuel, Weisenmiller said.

California currently has nine hydrogen refueling stations, including one in Northern California -- at the Alameda-Contra Costa Transit District in Emeryville.

Currently, about 230 fuel cell cars are on the road in California, with many available through trial programs or leasing agreements.

Many more are expected in the next few years, fuel cell experts said. Honda, Hyundai and Toyota are among companies planning to begin marketing cars in California within two years, said Keith Malone, a spokesman for the California Fuel Cell Partnership, a coalition formed in 1999 to bring together car companies, state, local and federal public agencies, academics and other organizations to plan California hydrogen future.

Companies are staying mum about how much the vehicles will cost, although initial estimates hover around $50,000.

Skeptics point out that the "hydrogen highway" promised by former Gov. Arnold Schwarzenegger in 2004 has yet to materialize. The state flubbed several previous attempts to kick start the effort. Oil companies did not voluntarily agree to construct stations--as proposed by Schwarzenegger--nor did they want to be forced by regulations--as proposed by Gov. Jerry Brown--to build the stations.

A compromise of sorts was reached last year. Now, average folks pay for the project with an add-on to their existing vehicle registration fees. The Energy Commission program distributes about $20 million annually to build hydrogen stations.

The hydrogen program is part of Brown's drive to put one million zero-emission vehicles on the road by 2020, Weisenmiller said. That includes a variety of vehicles including plug-in electrics.

Fuel cell cars are considered zero-emission vehicles, which release only water vapor and heat while driving. Hydrogen, a pressurized gas, can be derived from natural gas or it can be produced from renewable sources including landfill methane emissions. One-third of the hydrogen provided must stem from renewable sources, according to Energy Commission.

Some electric vehicle devotees, including San Francisco resident Marc Geller, who heads Plug In America, are dubious about the state's plans.

California should promote electric vehicles "rather than be gambling on a technology that's been promised for decades and has yet to deliver a car for sale," Geller said.

Yet fuel cell experts say the cars have many benefits not offered by traditional electric vehicles. Fuel cells can support larger vehicles such as SUVs and support drives as long as 300 miles, Ogden said.

They also require only minutes to refuel, unlike plug-in electric vehicles that need several hours.

Ogden said filling up with a tank of hydrogen, measured generally in kilograms, is expected to cost the same as filling up with traditional gasoline.

Weisenmiller said the state plans to continue investing in hydrogen stations.

Catherine Dunwoody, executive director of the California Fuel Cell Partnership, said she regularly drives a fuel cell vehicle.

"It has that high acceleration and very smooth operation. It's quiet," Dunwoody said. "I think customers will really like that."

Contact Becky Bach at 408-920-5862. Follow Becky Bach at Twitter.com/troutbach.