Hybrid electric vehicles combine the use of gasoline with a rechargeable battery. The battery recharges itself without being plugged into a power source. This technology reduces fuel consumption and emissions because the vehicle uses less gasoline since it can draw power from the rechargeable battery. The engine runs off the battery when idling, which also decreases the emissions. Here are some numbers to consider: 100,000 miles of travel equals 75 tons of carbon dioxide emitted by a large SUV, 40 tons of carbon dioxide emitted by a typical sedan, and 20 tons of carbon dioxide emitted by an electric hybrid sedan.

Plug-in hybrid electric vehicles (PHEVs) can be recharged from the electrical power grid and do not require gasoline for short trips. The Renault Kangoo was the first production model of this design, released in France in 2003.

Solar powered vehicles are based on the same technology as electric vehicles, but instead of plugging your car into an electric source to charge the battery, the needed electricity is generated from the sun. Unfortunately, current solar technologies do not produce enough energy to completely power a traditional vehicle. However, technologies are constantly advancing and solar roofs are now available for the Toyota Prius electric hybrid.

Ethanol (ethyl alcohol, grain alcohol, EtOH) is currently used as an EPA-approved fuel additive in gasoline blends to help gasoline burn more completely and thus reduce air pollution. A blend of 10% ethanol and 90% gasoline is available in many areas across the United States and can be used in any gasoline vehicle manufactured after 1980. E85 is a blend of 85% denatured ethanol and 15% gasoline. E85 cannot be used in a conventional, gasoline-only engine but can be used in fuel vehicles (FFVs) specifically calibrated to run on any fuel from gasoline to E-85. Currently, ethanol is produced almost exclusively from corn although research continues on ways of making ethanol from the non-food portion of crops and other plants. 

There are several important issues to consider when evaluating the sustainability of using corn ethanol as a substitute for gasoline beyond the 10% level required to meet federal air pollution requirements. Three of the most important issues with corn ethanol include: an energy penalty (it takes 1.48 gallons of ethanol to replace the energy content of a gallon of gasoline); the water intensity of ethanol production (current estimates of the consumptive water use from biorefinery facilities are in the range of 4 gallons of water per gallon of ethanol produced (4 gal/gal) (Pate et al., 2007). For perspective, consumptive water use in petroleum refining is about 1.5 gal/gal. The declining availability of corn for human and animal food and resulting increases in food cost and availability in many parts of the world as increasing amounts of corn are dedicated to ethanol production are also concerns.

Visit the National Ethanol Vehicle Coalition for more information about this alternative fuel choice.

Biodiesel is a domestic, renewable fuel for diesel engines derived from natural oils like soybean oil. Biodiesel does not contain petroleum, but it can be blended at any level with petroleum diesel to create a biodiesel blend. Biodiesel is made through a chemical process called transesterification which removes the glycerin from fat or vegetable oil. Biodiesel remains (methyl esters) and the glycerin that was removed is often sold to be used in soaps and other products. Biodiesel has less emissions than regular petroleum diesel and is made from renewable sources such as soy beans.

For more information about biodiesel, visit:

The National Biodiesel Board

The National Biodiesel Board (NBB) is the national trade association representing the biodiesel industry in the United States.

The Sustainable Biodiesel Alliance

Concerns about global warming and the U.S. dependence on foreign oil are driving an historic shift from fossil fuels to biofuels and other types of renewable energy. Now more than ever it is important to focus on the benefits of a sustainable, local model for biodiesel in the United States in order to maintain local energy and economic security.

Compressed Natural Gas (CNG) vehicles use the same gas that many of us already use to heat our homes. The gas is stored on board vehicles under high-pressure (3,000-3,600 pounds per square inch) and operates in a way similar to traditional gasoline vehicles. If your vehicle was not manufactured to use CNG, then it will need to be converted. Many car manufacturers are starting to manufacture CNG vehicles and new technologies allow you to fuel your CNG vehicle at home with your gas hook-up (visit http://www.myphill.com/index.htm).

Visit the Natural Gas Vehicle Coalition (NGV America) for more information about CNG. 

Fuel cell and hydrogen technologies are still being developed, but some models are already available to consumers. Fuel cell vehicles (FCVs) run on electric motors but don’t need to be plugged in because they generate their own electricity. Fuel cells onboard the vehicle creates electricity through a chemical process using hydrogen fuel and oxygen from the air. When FCVs are fueled with pure hydrogen, the only emissions are water and heat. 

Visit http://www.fueleconomy.gov/feg/fuelcell.shtml for more information about fuel cell vehicles.

Additional Resources:

Click here to view a map of alternative fuel stations in the Tucson area (from PAG)

Alternative Fuel Vehicles

U.S. DOE and EPA Fuel Economy website with information about alternative fuel technologies and options.

Alternative Fuel Vehicle Federal Tax Incentives

Visit the South Coast AQMD website to learn about the MPG and carbon footprints of low emissions vehicles.