Where the heck are our hydrogen-powered cars?

In the new issue of mental_floss magazine, Ethan Trex answers The Biggest Questions of 2009. All this week, he'll be answering additional questions of various sizes here on the blog.

As climate-saving plans go, few sound quite as appealing as cars powered by hydrogen fuel cells. They don't need any petroleum! They're low on emissions! They're"¦not in our garages. Why not?

Although most of us might not have seen one, there are hydrogen-powered cars out there. There just aren't very many of them. Honda began production of its FCX Clarity in 2008. The little car runs on hydrogen fuel cells and can travel up to 270 miles on a full tank of hydrogen. The car can get from 0 to 60 in 9.2 seconds—about the same as Honda's Accord. Sounds perfect, but there are a few hitches.

First, the hand-assembled car is tricky to put together; Honda can only crank out 200 of them in the first three years of production, and mass-production probably can't start until 2018. On top of that, fuel-cell cars are mind-numbingly expensive, and not just by the standards of Honda's Accord-buying public. According to Honda, just building a single 134-horsepower FCX Clarity costs several hundred thousand dollars, which is part of why the company only leases the cars instead of selling them.

Finally, there's the problem of our lack of hydrogen fueling infrastructure. (When was the last time you saw a hydrogen station as you cruised down the highway?) Until there's a nationwide effort to build an infrastructure for producing, distributing, and retailing hydrogen, the cars might be little more than a pleasant daydream. When Honda announced its plans to start leasing the Clarity in 2008, only Southern California residents were eligible to drive one home, and even they had to live near one of three existing hydrogen fueling stations in the area.

Although GM, BMW, and Hyundai hope to have hydrogen fuel-cell vehicles of their own in showrooms within the next five years, some experts estimate that it will take decades before the American fleet can convert to hydrogen. If hydrogen cars can't really take off in significant numbers until 2050, it might be too late for the technology to make a meaningful impact on how we drive.

Bonus Question: Why are there different types of gas (premium, regular, and super) but it seems like there is only one gas tanker?

You can't judge a tanker truck by its shiny metallic covering. Although from the outside these trucks look like one gigantic tank, they're actually divided into a series of compartments. Each compartment contains a certain grade of gas so one truck can stock a station for all three grades of fuel.

You can pick up mental_floss wherever brilliant/lots of magazines are sold. Or you could just subscribe.

* * * * *