Which Biofuels Are Right for Your Car?

Which Biofuels Are Right for Your Car?

If biofuels still seem like a futuristic idea to you, it might be time to start paying a little more attention at the pump. You may not realize it, but a number of different biofuel choices are already available to consumers at gas stations all across the country. To help you understand your options and figure out what’s right for your vehicle, read on for a handy guide to what that label on your gas pump really means.


ethanol powered carE10 is used to designate a fuel blend containing 10 percent ethanol, which is made from plant materials and carries a high octane rating. At the pump, this blend is identified with a label clearly stating “Contains 10% ethanol” (although the exact wording may vary slightly). What this means is that ethanol has been combined with standard petroleum gasoline at a ratio of 10 percent ethanol to 90 percent petroleum gasoline, thus creating a new blend. So can you still use it in a regular car? Absolutely. While ethanol can only be used in conventional vehicles if it is first blended with petroleum fuel, E10 (and any blend up to 10 percent ethanol) is approved for use not only in all vehicles, but also in all of America’s gasoline transportation, storage, and dispensing infrastructure. E10 is currently sold in every state.

While US ethanol production has relied almost exclusively on corn grain as its source since the 1990s, scientists and researchers are on the hunt for alternative ethanol sources that do not compete with food crops. One of the most promising candidates is cellulose, an abundant type of plant fiber found in a wide range of materials such as corn husks and stalks. A number of biorefineries are currently exploring the potential of cellulosic ethanol; once commercial production begins, you can expect to see cellulosic ethanol coming to an E10 gas pump near you.


You may have noticed a separate pump at your gas station with a yellow “E85” marked on it. This is another ethanol blend, but with a much higher ratio—up to 85 percent ethanol to 15 percent petroleum gasoline. E85 is still available nationwide, but not at quite as many locations as E10.

There’s another key difference between E85 and E10: to use E85, you must have a flexible-fuel vehicle (FFV). FFVs, as their name suggests, are designed to be able to run either on standard gasoline or on any blend of up to 85 percent ethanol (some gas stations offer blend pumps that allow you to choose the percentage of ethanol blend you want to use). How do you know if you have an FFV? Look on your car for a yellow gas cap that indicates “flex fuel” or “FFV,” as well as a badge either on the fuel door or on the outside of your car. The US Department of Energy also operates an online database where you can search by type and model year to see if your car is an FFV.

Although ethanol has the benefit of being a fuel octane booster, the fact that present-day FFVs are designed to run on gasoline as well as ethanol blends prevents them from taking full advantage of octane benefits. Researchers from the Vehicle Technologies Office and the Bioenergy Technologies Office are currently investigating how to develop more advanced engines that would be better able to utilize high-octane fuel.


biodieselIf you have a diesel engine, you could choose to fill up with a biodiesel-blend fuel, currently available at many fueling stations. With similar properties to petroleum diesel but produced from vegetable oils and animal fats, biodiesel burns cleaner and emits fewer pollutants. B20 is the most common blend, which is well suited to unmodified diesel engines (diesel engines do not have to be modified to use biodiesel, but they tend to run better when using a blend like B20).

Biodiesel is currently commercially available, and scientists are already working on its next iteration: renewable diesel, which is produced from renewable bioenergy feedstocks such as algae and woody crops. Renewable diesel has the benefit of being chemically identical to petroleum diesel, but it is not produced from food-based oils, as biodiesel is.

“Drop-in” biofuels

While E10, E85, and B20 are all biofuel options you can find at the pump, further research is also exploring the potential of “drop-in” hydrocarbon biofuels. Including such options as algae-based fuels, these innovative fuels could directly replace petroleum fuel in conventional cars altogether. The ultimate goal is to produce more fuel domestically using renewable resources, thus improving energy security in the US and helping the environment.