Propane fuel, also known as liquefied petroleum gas (LPG), is a fossil fuel alternative to gasoline. LPG is often used in light- and medium-duty trucks, buses, vans, taxis and government fleets. Propane is supported by many industry leaders, such as Roush Clean Tech (a division of Roush-Fenway Racing) and Uhaul.
- Propane is one of cleanest burning fossil fuels, releasing fewer toxins and greenhouse gases than gasoline or diesel.
- LPG-fueled vehicles generally have lower maintenance costs and greater engine life than gasoline-powered vehicles.
- Propane is non-toxic and has a narrower range of flammability than other petroleum products.
- Propane fuel has a higher octane rating than gasoline, potentially allowing more horsepower.
- A byproduct of natural gas production and the crude oil refinement process, propane is readily available from domestic sources. This reduces dependence on foreign petroleum and increases energy security.
- Propane has a lower Btu rating than gasoline, reducing the number of miles per tank of fuel.
- There are a limited number of commercially available LPG-powered vehicles, although vehicle conversions are available.
- While propane is often cheaper than gasoline, the price can increase during the winter, when demand for propane is higher.
- Propane fueling infrastructure may be limited in some parts of the country.
Natural gas is a fossil fuel, consisting mostly of methane. Two types of natural gas can be used in vehicles: compressed natural gas (CNG) and liquefied natural gas (LNG). CNG may be used in light-, medium- and heavy-duty vehicles, while LNG is ideal for medium- and heavy-duty vehicles that travel long distances, such as semi-trailers. LNG is not currently available in the Tucson region.
- Natural gas combustion releases fewer smog-producing pollutants and slightly lower greenhouse gas emissions than gasoline. CNG vehicles do not produce evaporative emissions.
- Natural gas fuels are generally less expensive than gasoline.
- There is a wide variety of natural gas vehicle options available for heavy-duty applications.
- A majority of natural gas used in the United States is produced domestically, reducing dependence on foreign petroleum and increasing energy security.
- Vehicle fueling infrastructure may be limited.
- Although CNG is gasoline gallon equivalent (gge), the tanks on CNG vehicles are smaller and carry less fuel, therefore get fewer miles on a full tank. On many light-duty and all heavy-duty vehicles there is an option to add extra tanks, allowing more miles between fueling.
- Manufacturers’ offerings of light-duty natural gas vehicles are limited, but growing.
Ethanol is an alcohol-based fuel, produced domestically from plant material, including corn and sugar cane. A wide variety of other materials, such as sorghum, algae and stover, are being researched and trials are underway. Ethanol is blended with gasoline to make three main formulations – E10, E15 and E85. The gasoline is added to denature the fuel, rendering it no longer consumable.
• E10 contains up to 10 percent ethanol blended with gasoline and accounts for most of the ethanol sold in the United States.
• E15 contains up to 15 percent ethanol blended with gasoline and is only suitable for use in 2001 or newer vehicles and flex fuel vehicles.
• E85 contains from 51% to 85% ethanol blended with gasoline and may only be used in flex-fuel vehicles. Flex-fuel vehicles are capable of running on E85, gasoline or any combination thereof.
• Ethanol combustion results in lower net carbon dioxide emissions than gasoline due to the “recycling” of carbon dioxide when growing new ethanol feedstocks.
• Ethanol combustion produces less carbon dioxide, particulate matter and other air pollutants than gasoline.
• Ethanol is non-toxic, biodegradable, and safe to handle, store and transport.
• Ethanol is produced from renewable plant sources.
• A variety of flex fuel vehicles are widely available from manufacturers.
• Ethanol is domestically produced, reducing dependence on foreign petroleum and increasing energy security.
• Ethanol has a lower energy content than gasoline, resulting in fewer miles to the gallon.
• While E85 is generally cheaper than gasoline, lower mpg may result in a higher cost per mile.
• While fueling infrastructure is growing, E85 fueling stations may be limited in some regions.
Biodiesel is a renewable fuel that may be produced from vegetable oils, animal fats or recycled restaurant grease. Biodiesel is commonly blended with petroleum diesel, producing blends including B2 (2% biodiesel), B5 and B20. In its pure form, biodiesel fuel is referred to as B100. Blends up to B5 are the most commonly approved by vehicle manufacturers for use in diesel engines, while some manufacturers recommend blends up to B20.
• The combustion of biodiesel produces fewer air pollutants (except nitrogen oxides) and lower greenhouse gas emissions than petroleum fuels.
• Biodiesel is domestically produced from renewable sources.
• Blends up to B5 are marketed as approved for use in most diesel engines.
• Biodiesel is non-toxic, biodegradable, and safe to handle, store and transport.
• Biodiesel combustion may produce higher nitrogen oxide (NOx) emissions, depending upon the engine technology. Selective catalytic reduction (SCR) technology can reduce NOx emissions to near zero levels.
• B100 may not be suitable for use in low temperatures.
• High blends of biodiesel are currently more expensive than petroleum diesel in most areas.
Electricity is a domestically produced energy source which can be used to power both plug-in hybrid and all-electric vehicles (EVs). In both types of vehicles, electricity from external power sources is stored on-board in rechargeable batteries. Plug-in hybrid electric vehicles use electricity to power electric-drive systems, which improve fuel economy. EVs run on entirely electric motors, without the use of petroleum-based fuels.
- EVs do not release tailpipe pollutants.
- Plug-in hybrids produce lower tailpipe emissions on average than conventional vehicles, and zero tailpipe emissions in all-electric mode.
- Electricity is produced domestically, reducing reliance on imported petroleum.
- Electric motors are energy-efficient; modern EVs can exceed 100 miles per gallon of gasoline equivalent (mpge)
- Electricity is cheaper than conventional fuels.
- EVs have a lower driving range than conventional vehicles, usually 100-200 miles as opposed to 300+ miles for gasoline-powered vehicles.
- A full battery recharge can take 4 to 8 hours, although quick chargers, which charge up to 80 percent in 30 minutes, are becoming more widely available.
- Battery packs for EVs and plug-in hybrids are expensive to replace, and the large batteries can take up a significant amount of space in the vehicles.
- Emissions from electricity production can vary by region, although plug-in vehicles generally have lower lifetime emissions than comparable conventional vehicles.
Hydrogen is currently being explored as an environmentally friendly fossil fuel alternative. Hydrogen is not currently available in Tucson or most other areas of the United States, but hydrogen fuel cell technology continues to evolve.
- Hydrogen fuel cells produce no air pollutants or greenhouse gases.
- Hydrogen is domestically produced.
- Hydrogen fueling infrastructure is highly limited.
- Vehicles with hydrogen fuel cells are more expensive than conventional vehicles and are not publically available at the moment.
- The energy content per volume of hydrogen is low compared with that of conventional fuels, requiring a larger fuel tank to achieve a comparable driving range.