Learn More: Alternative Fuels

Biodiesel is a renewable fuel that is predominantly domestically produced. It can come from various sources including animal fats, new and use vegetable oil, soybean oil, and restaurant grease. While biodiesel has many similar characteristics to petroleum diesel, it burns much cleaner, is biodegradable and non-toxic, making it overall safer for the environment and human health. The burning of biodiesel creates fewer emissions of CO2 particulates, and other polluting compounds in comparison to regular diesel fuel. In addition, because it is both biodegradable and non-toxic, there is no possibility of it contaminating the soil or water as normal diesel can.

Biodiesel can be utilized in vehicles in either its pure form or as a blend with petroleum diesel. Pure biodiesel, 100% biodiesel fuel, is referred to as B100 where as a blend of 20% biodiesel and 80% petroleum diesel is labeled as B20. B20 is the most common biodiesel blend in the United States; other common blends include B5.

Blends up to B20 may be used in any diesel engine manufactured after 1993 with little impact on performance. Most original equipment manufacturers (OEMs) approve the use of biofuel blends up to B5 in their vehicles without voiding parts or workmanship warrantees. Please check your OEM’s website or contact your dealer to determine what types of biofuels should or should not be used in your vehicle.


For more information:
Clean Cities Fact Sheet
DOE Alt. Fuels Data Center, Biodiesel
National Biodiesel Board
Vermont Biodiesel Association

Vehicles that have the capability to be fueled by electricity are referred to as electric drive vehicles. These vehicles use electricity from a battery, either as their primary power source or as a supplementary source to improve fuel efficiency. These batteries can be recharged by being plugged into the electric grid or by electric generated features in the car such as regenerative braking.

The Department of Energy categorizes electric drive vehicles into three categories based on how electricity is utilized and regenerated: hybrid electric vehicles (HEVs); plug-in hybrid electric vehicles (PHEVs); and all-electric vehicles (EVs). HEVs, such as the Toyota Prius, are powered by traditional petroleum or alternative fuels but they also store electricity in their batteries that can be regenerated through their braking system or their internal combustion engine. You cannot plug in and charge HEVs. PHEVs like the Chevy Volt are powered by both conventional fuels and electricity that is stored within the vehicle in a battery. While these vehicles can be plugged in to be charged they also use regenerative braking and the internal combustion. All-Electronic Vehicles are powered completely by electricity through a battery stored on board, as seen in the Nissan Leaf. The batteries are charged by plugging the car into a power source.

For the most part, electric drive vehicles produce fewer emissions than traditional petroleum fueled vehicles. HEVs produce tailpipe emissions but in general have much higher fuel economy levels than conventional vehicles and thus produce fewer emissions. PHEVs produce emissions when they are running off their engines and none when they operate off their batteries, while all-electric vehicles produce no tailpipe emissions. When evaluating emissions from any type of electric drive vehicle it is important to consider the electricity’s source.

For more information:
DOE Alt. Fuels Data Center, electric
Clean Cities Fact Sheet Hyrbid and Plug-in Vehicles
Plug in America
Vermont Biodiesel Association

Fuel cell vehicles are powered by fuel cells which generate power from hydrogen. These vehicles have the potential to be an extremely efficient and environmentally-sound alternative to traditional vehicles. In general, fuel cells are similar to batteries; however, they do not need recharging and will continue to produce energy as long as it is being supplied.

If it is produced through an emission free process, hydrogen has the potential to be a truly emission-free fuel. Pure hydrogen is extremely rare in the earth’s surface and thus it must be produced by being separated from other compounds such as water.

There are many current barriers to producing fuel cell vehicles powered by hydrogen. First, hydrogen and fuel cell vehicles have been expensive to produce. Plus, because hydrogen carries much less energy than gasoline or diesel, it has been difficult to make the vehicles travel as far or as fast as gasoline vehicles. As a result of these difficulties, the availability of these cars is limited and the ones that have been developed are too expensive for the average consumer.

For more information:
DOE hydrogen page
DOE Alt. Fuels Data Center, Hydrogen
Fuel Cells 2000

According to the Department of Energy, national gas currently fuels over 100,000 vehicles in the United States. Natural gas offers many environmental and energy security benefits in comparison to traditional petroleum as a vehicle fuel. It produces significantly lower amounts of emissions compared to gasoline and diesel. It is widely produced within the United States, thereby reducing our dependence on foreign oil.

The majority of natural gas is produced in the United States from other sources such as gas or oil wells. In order to be utilized in a vehicle, natural gas must be stored onboard as either compressed gas or in a liquefied state. These two types of natural gas are known as Compressed Natural Gas (CNG) or Liquefied Natural Gas (LNG). CNG is optimal for use in light, medium and heavy vehicles while LNG is mostly only used in heavy-duty vehicles. Renewable natural gas (RNG) can be produced from renewable sources such as decaying organic material found in livestock manure, landfills, and waste water. Anaerobic digestion and a treatment process can convert these gases into vehicle-grade RNG.

Natural gas vehicles (NGVs) have been around for more than 60 years and today there are many NGVs on the market. There are three categories of NGV’s including: dedicated, which only runs on NG; bifuels, which can run on both NG or gasoline; and dual-fuels, which can run on both diesel and NG. Generally speaking, NG is less expensive and more stable than diesel or petroleum making NGV particularly attractive to fleets who consume high amounts of fuel.

For more information:
DOE Atl. Fuel Data Center, Natural Gas
Clean Cities Fact Sheet, Natural Gas

Currently, about 190,000 vehicles are powered by propane in the Unites States. Propane, also known as liquefied petroleum gas (LPG) or autogas (when used in vehicles) is a byproduct of natural gas processing and crude oil refining. Propane is odorless, non-toxic, and colorless. At normal pressures and temperatures it is a gas. However, when it is pressurized it becomes a liquid. Ninety seven percent of the propane consumed in the United States is produced within North America.

Environmentally speaking, propane has many benefits similar to natural gas (NG). It is one of the cleanest burning fossil fuels. The emissions from propane vehicles of carbon monoxide, nitrogen oxide, hydrocarbon, greenhouse gas emissions, and particulate matter are much lower than those from gasoline and diesel vehicles.

Propane vehicles operate and are similar to petroleum fueled vehicles in regards to their power and speed capabilities. The fuel economy of propane vehicles is slightly lower than traditionally fueled cars, however, the maintenance costs of a propane vehicle is much lower because it burns so cleanly. Furthermore, while propane vehicles can be more expensive than comparable petroleum vehicles, there are many federal tax credits available to offset their extra costs.

For more information:
DOE Atl. Fuels Data Center, Propane
Clean Cities Fact Sheet, Propane

Ethanol is an alcohol fuel that can be produced from a variety of plant materials referred to as “biomass.” These materials can include starchy feed stocks including corn or sugar cane, or cellulosic feed stocks including perennial grassed or even municipal waste. Ethanol is most commonly made in the United States from fermented and distilled grain crops, mainly corn.

Ethanol is very compatible with traditional internal combustion engines, and is currently used in almost half of the gasoline sold in the U.S. to reduce emissions and to oxygenate the fuel. Ethanol is also available in various blends such as E10, which is 10% ethanol and 90% gasoline, and E85. E85 has grown in popularity in most part due to its use in flex-fuel vehicles (FFVs). FFVs operate very similarly to comparable vehicles in power and acceleration.

For more information:
Clean Cities Fact Sheet, Ethanol –from 2008
DOE Alt. Fuels Data Center, Ethanol
Ethanol Myths and Facts, DOE biomass program