Alex Keros, a General Motors senior engineer, demonstrates how to fill up a General Motors Chevrolet Equinox fuel cell-electric SUV with hydrogen at California's first hydrogen refueling station.

­AP Photo/Damian Dovarganes

Types of Alternative Fuel Filling Stations

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Makers of alternative fuels want drivers to be able to fuel up easily and conveniently with the type of fuel they provide. Some alternate fuels already enjoy wide availability, with convenient access via fuel pumps. Others are just becoming available to consumers, and only at a few locations. Here's a quick status report on what's out there right now:

Flex-Fuel vehicles run on E85, which is 85 percent ethanol -- a fuel made from renewable organic resources -- and 15 percent gasoline. Filling up with E85 for green driving is achieved in exactly the same manner as with gasoline -- just pull up next to the pump and fill it up.

Biodiesel blends add a green tint to diesel engine fuel efficiency. According to The National Biodiesel Board, the most popular and widely available blend is B20, consisting of 20 percent renewable resource biodiesel and 80 percent fossil fuel diesel. Regionally adjusted biodiesel blends are usually found at dedicated stations, and biodiesel is dispensed in the same manner as other liquid fuels.

Most natural gas vehicles (NGVs) run on compressed natural gas (CNG), but some large trucks use highly pressurized liquefied natural gas (LNG). A special tank is required to hold the natural gas and other special vehicle equipment is necessary, too. "Bi-Fuel" vehicles can actually switch between CNG and gasoline tanks. Natural gas is usually dispensed by attendants at authorized service centers, but self-service pumps are beginning to appear. In selected areas of California and several other states, vehicle owners can legally fuel their NGV at home, through a home fueling station appliance called "Phill" [source: MyPhill.com].

Liquefied petroleum gas (LPG, or propane) is another relatively clean burning fossil fuel. As with CNG, a special high-pressure fuel tank and components must be installed in the vehicle. Although factory LPG-fueled vehicles were last offered in 2004, aftermarket conversions are readily available. LPG is sold in many locations, such as truck and trailer rental stores and RV centers. An attendant typically handles fueling, but some 24/7 self-service LPG stations can be found.

Hydrogen has great promise for eco-friendly driving, yet it presents significant challenges from an infrastructure and distribution standpoint. Most existing hydrogen fueling stations supply commercial fleets and are of restricted access; however, a few stations featuring self-service hydrogen pumps open to the public have been announced recently. Stations located along envisioned "hydrogen highways" might eventually make hydrogen available along established national corridors.

The fuel efficiency of plug-in hybrid and fully electric cars is supported by stand-alone public charging stations located in parking garages or curbside. Of course, virtually any accessible conventional electrical outlet is a potential charging station.

Now, let's roll on to the next page, to discover how to locate alternate fueling stations near you.