With the imminent unveiling of the Toyota Fuel Cell Vehicle, and the Hyundai Tucson Fuel Cell already on sale, you can expect to hear a lot more about hydrogen fuel-cell vehicles in the coming months.

Initially they will be offered only in very low numbers, and restricted to Southern California, where the state and the carmakers are jointly funding the installation of several dozen hydrogen fueling stations.

2015 Hyundai Tucson Fuel Cell at hydrogen fueling station, Fountain Valley, CA

Cars that use hydrogen as fuel to produce electricity in a fuel cell are, by definition, zero-emission vehicles: Their only exhaust is water vapor.

As such they have tended to be posed against battery-electric vehicles, the other (and more common) ZEV now on the market.

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But electric-car advocate Chelsea Sexton suggests a different framing.

The quotes below are excerpted and edited from a longer conversation about where hydrogen-powered vehicles fit into the U.S. market.

"I don't think battery-electric cars are the main competition for fuel-cell vehicles, and they never were," she said.

"Plug-in hybrids, on the other hand, absolutely are--especially if you think about longer-range plug-in hybrids and range-extended vehicles like the Chevy Volt and BMW i3 REx."

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"The entire sales pitch for fuel-cell cars can be summed up as 'long range, fast fueling'."

"Yes, electric cars can achieve long range at a price, and 'fast fueling' depending on how you define that, and proper infrastructure. Today, there's far more fast charging than there is hydrogen infrastructure--but that's missing the point."

BMW X5 e-Drive plug-in hybrid prototype, test drive, Woodcliff Lake, NJ, April 2014

"A decently electrified plug-in hybrid or range-extended electric car is already both long-range and fast-fueling, with no infrastructure issues at all. Off the lot, today. And far less expensive than any fuel-cell vehicle will be in the next 5 to 10 years."

"Assuming a category of plug-in hybrids that basically meets most folks' daily commute--not an 11-mile Prius, maybe 19-mile Fords, but certainly a 38-mile Volt or a 72-mile BMW i3 REx, they're already driving in zero-emission mode for 70 to 80 percent of the time--based on Department of Transportation data and what's been said publicly by carmakers themselves."

First 2015 Hyundai Tucson Fuel Cell delivered to lessee at Tustin Hyundai, June 2014

"If we spend enough money on infrastructure, fuel-cell vehicles might turn those last 20 to 30 percent of gasoline miles into zero-emission miles. And since the carmakers aren't generally interested in funding much hydrogen fueling infrastructure, the 'we' will be us, the public, through tax money."

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"And for longer-distance trips, pervasive hydrogen infrastructure will be just as much of an issue as DC fast-charging infrastructure is for battery-electric cars today--and probably more, due to its cost."

Chelsea Sexton

"So the question becomes, what's the incremental return on that 20 to 30 percent of overall mileage versus the investment in vehicle technology, fueling infrastructure, and so forth--environmentally, financially, and otherwise?"

"If we accept that much of the concern about road trips is more psychological than based in reality, how much do fuel-cell vehicles actually deliver that plug-in hybrids can't?"

"Finally, plug-in hybrids also present the 'inconvenient truth' (for purists) of being compatible, politically and technologically, with just about any other alternative fuel out there. Today, they use gasoline as the second fuel. But they could just as easily use natural gas, biofuels--or even hydrogen--if or when each becomes viable or available."

"You could easily deploy plug-in hybrids using different fuels on a regional basis, depending on what's available in a given area. They'd still likely be as capable of long-distance trips in that region as hydrogen vehicles will be for the next decade or more.".

AND FINALLY: Why Green Car Reports Writes About Hydrogen Fuel-Cell Cars

Sexton's thoughts neatly crystallize one side of a debate that's likely to take place as hydrogen vehicles roll out: How much should society spend on fueling for new vehicles types--and what is the return on that investment?

Expect many more such analyses as battery-electric cars sell in greater numbers, but face zero-emission competition both at dealers and in the public eye over the next decade.

It promises to be a fascinating discussion.

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