Wiithin two years, some Californians will be able to lease or buy a hydrogen fuel-cell vehicle from at least three well-known carmakers: Honda, Hyundai, and Toyota.

Their state is working hard to ensure that those drivers will have sites at which they can fuel those vehicles.

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California's plans for opening hydrogen fueling stations were detailed yesterday by Bob Carter, Toyota's senior vice president for automotive operations.

"By the end of 2015, 20 refueling stations are scheduled to be opened throughout California," Carter told a Deutsche Bank conference after the Detroit Auto Show, "with 28 additional stations set to come online by the end of 2016."

That will bring the near-term number of hydrogen fueling sites to 48 in California. 

2016 Toyota Mirai hydrogen fuel-cell car, Newport Beach, CA, Nov 2014

2016 Toyota Mirai hydrogen fuel-cell car, Newport Beach, CA, Nov 2014

Those stations are jointly funded by the state and by both Toyota and Honda, which have announced loans to First Element Fuel and other providers to set up hydrogen stations in California and the Northeast.

Carter also noted that Toyota will offer free licenses for more than 5,000 patents on hydrogen vehicles and fueling. While fees will kick in for licenses on vehicle technology after 2020, the 70 patents for fuel production and supply will remain free in perpetuity.

That's an indication that Toyota wants to encourage fast deployment of the fueling infrastructure as its 2016 Toyota Mirai launches later this year.

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But how many vehicles can 48 California stations--or an expanded plan for 63 to 75 fueling sites by 2020--really serve?

In a roundtable at the Detroit Show with Robert Bienenfeld, Honda North America's senior manager for environment & energy strategy, he and his colleagues laid out the math.

Bienenfeld said funds were now in place for a total of 51 hydrogen stations in California, well on the way to a total build-out of 63 to 75 such stations by 2020.

Honda FCV Concept live photos, 2015 Detroit Auto Show

Honda FCV Concept live photos, 2015 Detroit Auto Show

That puts half of the likely buyers of hydrogen fuel-cell vehicles within 6 minutes' drive of a fueling station, he said, because alternative-fuel vehicle buyers tend to cluster in certain neighborhoods.

That's true for owners of hybrid, plug-in electric, and even natural-gas vehicles, Bienenfeld said, and Honda expects the same will apply to hydrogen fuel-cell vehicle buyers as well.

Those 75 stations will be able to serve a total on-road population of 17,000 to 24,000 hydrogen-fueled vehicles, he said.

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Assuming three car companies sell hydrogen vehicles for six years (2015 through 2020), that gives a rough sales rate of 2,000 hydrogen vehicles a year from each carmaker.

Bienenfeld said Honda is confident that the fueling infrastructure can serve those 24,000 vehicles with waits that are no longer than those at a typical gas station.

Tactics will include boosting all current hydrogen stations to a 10,000-psi fill rate, he said, and adding additional hydrogen nozzles to existing compressors as required.

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