Other Alternative Fuels

The auto industry has explored a variety of options over the years in search of more environmentally conscious solutions and higher fuel economy. Gasoline/electric hybrids are by far the most successful of these forays, but there have been others.

Auto manufacturers experimented with battery-electric vehicles in the mid- to late-1990s, but no full-function battery-electric vehicle models remain on the market. High-profile examples include the Dodge EPIC, Ford Ranger EV, GM EV-1, Honda EV Plus and other electric models from major automakers.

Methanol flexible-fuel vehicles also came and went before their early use in corporate vehicle fleets transitioned to consumer sales. Methanol, a combustible alcohol fuel that’s typically made from natural gas, has fallen out of favor as the industry focuses new efforts on ethanol, an alcohol fuel made from the fermentation of various sugars from carbohydrates found in agricultural crops or wood residues.

The Honda Civic GX is the only passenger vehicle on the market that runs on compressed natural gas. Pictured here is the refueling nozzle.

Natural gas is an abundant domestic fuel. Vehicles that run on compressed natural gas (CNG), such as the Honda Civic GX, drive just like a traditional gasoline-powered vehicle but are cleaner in terms of exhaust emissions. Presently, the Civic GX is the only passenger vehicle sold that runs on CNG. After seven years of fleet sales to government agencies, large corporations and businesses of all types that either had to comply with federal alternative-fuel-vehicle requirements or wanted to make an environmental statement, the Civic GX is now being sold to consumers with an optional home CNG refueling appliance, starting in California. If successful there, Honda will consider selling the Civic GX in other states.

GM sells Chevrolet Silverado and GMC Sierra pickups that run on CNG primarily to corporate fleets. Some third-party companies, such as Quantum Technologies, can also convert new vehicles to run on CNG or propane.

More than 20 popular vehicles — from the Chevrolet Avalanche to the Dodge Caravan — are capable of operating on E85 ethanol, or gasoline, or a mixture of the two. Many of these models with special engines, often called flex-fuel or flexible-fuel vehicles, are E85-ethanol-capable as a matter of course, the result of automakers earning additional credits toward their federal Corporate Average Fuel Economy requirements for each of these alternative-fuel vehicles sold.

Saab's 9-5 BioPower 2.0t runs on a blend of E85 ethanol and gasoline. It's currently only sold in Europe.

The challenge is that just over 400 stations in the U.S. dispense E85 ethanol fuel, so those who do own these vehicles almost always operate them on gasoline. That’s too bad, because ethanol is a domestically sourced fuel made from renewable agricultural resources such as corn, woody grasses and various forms of agricultural waste products like corn husks. Using such raw materials is increasingly important as a way to offset dependence on non-renewable fossil fuels, whether imported or produced domestically.

Biodiesel is an alternative fuel that's growing in popularity because it burns considerably cleaner than conventional diesel fuel with no soot or aromatics. In the U.S., it's typically made from soybeans and can be used in regular diesel vehicles with little or no modification. Various mixtures of biodiesel can be used from B5 (5 percent biodiesel and 95 percent petrodiesel) to 100 percent pure biodiesel, although a diesel vehicle's warranty may not cover engine problems if it's determined they're caused by off-specification biodiesel fuel.

Jeep and Volkswagen are now allowing their warranties to cover vehicles running on the lower B5-biodiesel blend. Biodiesel fueling opportunities are limited to about 400 stations nationwide, although momentum has picked up and many more biodiesel pumps are coming.

Biodiesel can be produced from used cooking oil by companies like Pacific Biodiesel in the Hawaiian Islands, or by home-brewers using at-home biodiesel kits. Vehicles running on biodiesel sourced from recycled vegetable oil are being driven by activists and some Hollywood celebrities like Daryl Hannah, and they’re also being driven by commercial fleets and everyday drivers committed to the cause.