AAA’s 12-month chart of the average price of a gallon of regular unleaded looks like a treadmill display from hell: The line just goes up and up and up.

With gas prices on the rise, so too is interest in alternative-fuel vehicles. Ethanol and other biodiesel cars and trucks have gained a foothold already, and a mass market of plug-in hybrids and hydrogen vehicles is seemingly right around the corner.

But before any of this stuff can really go mainstream, there has to be an abundance of stations where consumers can fill up. The Department of Energy has a new Web tool that shows exactly where to find these alternative-fuel stations.

The Alternative Fuels and Advanced Vehicles Data Center shows, as of 7/8/08, 5,701 stations in the U.S. that offer alternative fuel for vehicles. The AFDC counts more than a dozen such alternative fuels, including the seven commercially available: biodiesel, electricity, ethanol, hydrogen, methanol, natural gas and propane.

Looking over the map of stations, one thing is clear: We’re far from critical mass. In many areas, you’re hard pressed to find any alternative-fuel stations. To wit:

-- Four E85 stations in all of New England
-- One E85 station within 90 miles of Boston
-- Eight hydrogen stations in all of the Eastern U.S.
-- Nearly all -- 370 of 436 -- electric stations are in Calif.; 36 states have zero electric stations

California is by far the king, home to 15% of the nation’s alternative-fuel stations. It’s also the only state where Honda’s FCX Clarity hydrogen-powered fuel cell vehicles will be available for the foreseeable future.

GM’s Project Driveway shares the wealth a bit, though, by offering fuel-cell vehicles not only in Calif., but in NYC and D.C. too. BMW is another auto company developing fuel-cell vehicles.

So the future looks promising, but for now, the choices are limited. Here’s a list of the Captivate markets with stations within 10 miles that offer electric, ethanol, biodiesel, or hydrogen fuel (totals in parentheses):

-- Atlanta (9)
-- Austin (25)
-- Boston (10)
-- Chicago (11)
-- Columbia (15)
-- Dallas (4)
-- Denver (12)
-- Hartford (4)
-- Houston (4)
-- Los Angeles (63)
-- Memphis (1)
-- Miami (2)
-- Minneapolis (26)
-- New York City (4)
-- Philadelphia (2)
-- Phoenix (14)
-- San Diego (11)
-- San Francisco (23)
-- San Jose (8)
-- Seattle (14)
-- Washington, D.C. (13)

Let us know what you think of the choices for alternative-fuel vehicles. Any Captivate viewers already driving around in one?