SAN FRANCISCO (KPIX) — The city of San Francisco’s environment chief doesn’t have many kind words to say about cars or what comes out of their tailpipes.

“Forty percent of our emissions — our CO2 emissions — are coming from vehicles,” said Debbie Raphel director of the S.F. Department of the Environment.

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But Raphel was all smiles Thursday when when she got behind the wheel of the new Toyota Mirai — the first major-brand production automobile powered by hydrogen fuel cells.

To “fill ‘er up” you fill a couple of scuba-size tanks with compressed hydrogen gas.

“And then it uses that (hydrogen), combines with oxygen in the atmosphere to generate electricity,” explained Jay Turmell, a product-training specialist with Toyota.

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Because it operates using a chemical reaction rather than combustion, the only thing expelled water. The Mirai gets about 300 miles on a gas recharge — but there lies a problem.

“Right now, infrastructure is probably the one thing that’s holding it back a little bit. Because, we made the car and now we need a few more stations to make it work,” Turmell said.

There are only about 20 refueling stations in the entire state and none outside California. Lawmakers have given San Francisco a $250,000 grant to help Bay Area communities work with private industry to build more. The stations would create hydrogen on-site by burning natural gas to create steam.

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As we learned from the Hindenburg dirigible disaster, hydrogen is not without its dangers. But so is every current gasoline station for that matter. Backers of fuel-cell cars say the technology is here now to create safe, zero-emission vehicles. But, like all new technology, it takes some effort to get the idea off the ground.