Fuels: A Quick Reference Fact Sheet

Comparison of Alternative Vehicle Fuels Fact Sheet
There are a number of fuels that are being advocated as replacements for gasoline and diesel in transportation applications. These include: biodiesel, electricity, ethanol, LPG (propane), methanol and natural gas (both compressed and liquefied). The following is a brief discussion of the advantages and disadvantages of each of these alternative fuels.


Biodiesel
Biodiesel is a domestically produced, renewable liquid fuel that can be manufactured from vegetable oils (e.g., soy oil), animal fats, or recycled restaurant greases. It is used in compression ignition (diesel-cycle) engines. Blends of 20% biodiesel with 80% petroleum diesel (called B20) can generally be used in unmodified diesel engines. Biodiesel can also be used in its pure form (B100), but this requires engine modifications to avoid significant maintenance and performance problems.

Advantages:

Environmental: When blended with current diesel fuel (i.e., diesel fuel with an average sulfur content of 350 ppm) and used in older diesel engines, biodiesel reduces particulate emissions, carbon dioxide and some air toxics.
Energy Security: Every gallon of biodiesel used displaces one gallon of petroleum (although if the energy used in producing the biodiesel is taken into account – including the energy used in producing the crops from which the biodiesel is made, the net displacement is much less).
Vehicle Cost: Since biodiesel blends (B20 or less) can be used in any diesel engine, there is no incremental cost for the vehicle.
Other: Biodiesel is safe and biodegradable.

Disadvantages:

Environmental: Biodiesel use increases the production of nitrogen oxides (NOx) somewhat. Given that most areas not in attainment with National Ambient Air Quality Standards (NAAQS) are not in attainment because of NOx levels, biodiesel use exacerbates their problems. In addition, beginning in 2006, refiners will be required to produce and sell lower sulfur diesel, and, beginning in 2007, heavy-duty engine manufacturers must meet tighter emission standards. It is unclear whether biodiesel use will produce any emission benefits when used with the lower sulfur fuel in these new engines.
Energy Security: While vehicles that run on B20 displace some petroleum, they are still 100 dependent on diesel fuel to operate.
Operating Cost: Without government incentives, biodiesel is significantly more expensive than diesel fuel.
Driving Range: Because there is less energy in a gallon of biodiesel than in a gallon of petroleum diesel, the driving range of vehicles operating on biodiesel blends is less.
Other: Even as B20, biodiesel use could void some OEM and engine warranties. With the diesel engines that meet the tighter 2007 emission standards, it is unclear whether the engine manufacturers will warrantee these engines if used with any biodiesel blend.


Electricity
As the term historically has been used, electric vehicles are vehicles that operate solely on electricity that is produced off the vehicle and stored on the vehicle in batteries. The term electric vehicle also is now sometimes (confusingly) applied to hybrid-electric vehicles and hydrogen fuel cell vehicles.

Advantages:

Environmental: Since there is no combustion of fuel on the vehicle, there is no pollution produced by the vehicle. In addition, since electric vehicles are indifferent to the source of electricity, electric vehicles can be powered by electricity produced from renewable fuels (e.g., wind, solar).
Energy Security: Electric vehicles operating on electricity produced from fuels other than petroleum displace the use of foreign oil.
Operating Cost: Depending on the local cost of electricity, operating costs can be less than gasoline.
Other: The vehicles operate very quietly.

Disadvantages:

Environmental: Depending on the fuel used to produce the electricity to power the vehicle, total pollution can be much greater than even gasoline and diesel vehicles. In addition, the vehicle’s batteries must be replaced every few years. Disposal of those batteries imposes a hazardous waste disposal problem.
Vehicle and Maintenance Costs: When the automakers (original equipment manufacturers or OEMs) were producing them, the vehicles were very expensive to purchase. In addition, the replacement batteries are expensive. The combination of these two factors makes electric vehicles commercially uneconomic.
Refueling: Despite significant research, no one has developed batteries (or other electricity storage technologies) that recharge in a time comparable refueling a gasoline vehicle. Battery recharging takes hours.
Driving Range: The driving range of electric vehicles is very limited (about 100 miles on a charge.) Aggressive driving and use of accessories (heater, air conditioner, radio) further reduces the driving range.
Vehicle Availability: Because of cost and performance issues, the major OEMs (Ford, GM, DaimlerChrysler) have discontinued their electric vehicle programs. Only a few specialty manufacturers still make electric vehicles.


Ethanol
Ethanol is an alcohol-based liquid fuel produced by fermenting and distilling starch crops that have been converted into simple sugars. The primary feedstock for ethanol today in the U.S. is corn. Other feedstocks include barley and wheat. Ethanol can also be produced from "cellulosic biomass" such as trees and grasses and is called bioethanol. Ethanol is most commonly used as a blend fuel (e.g., 1-3 percent) to increase octane and improve the emissions quality of gasoline. In some areas of the United States, ethanol is blended with gasoline to form an E10 blend or gasohol (10% ethanol and 90% gasoline), but it can be used in higher concentrations such as E85 or E95. OEMs produce flexible-fuel vehicles that can run on E85 or any other combination of ethanol and gasoline. Because of performance and safety problems, 100 percent ethanol (E100) is not used.

Advantages:

Environmental: Ethanol blends reduce emissions of some pollutants (e.g., carbon monoxide, and volatile organic compounds).
Energy Security: Ethanol is produced domestically from renewable crops (see disadvantages below).
Vehicle Cost: No modifications need to be made to gasoline vehicles to allow them to operate on E10 (or lesser) ethanol blends. For greater blends (e.g., E85), OEMs need to make only minor (and inexpensive) modifications to their vehicles.
Other: Since flexible-fuel vehicles can operate on 100 percent gasoline, they provide the flexibility to owners to travel to and from areas where there are no ethanol stations.

Disadvantages:

Environmental: Use of ethanol blends does not reduce NOx emissions and increases significantly the emissions of aldehydes.
Energy Security: This continues to be a disputed issue. Ethanol proponents argue that ethanol use displaces petroleum use. There have been a number of studies, however, that demonstrate that more energy (including petroleum and natural gas) is used in the production of the ethanol than there is in the ethanol.
Driving Range: Because there is less energy in a gallon of ethanol than in a gallon of gasoline, the driving range of vehicles operating on ethanol blends is less.
Operating Cost: Ethanol producers currently receive a federal tax credit of 82 cents per gasoline gallon equivalent. A number of farm states provide additional financial incentives per gallon. Without government incentives, ethanol is significantly more expensive than gasoline.
Fueling: The number of public fueling stations that sell E85 is quite small and geographically limited. This fact, plus the greater cost of E85 over gasoline, has resulted in most flexible fuel vehicles operating solely on gasoline.


LPG (Propane)
Liquefied petroleum gas (LPG) consists mainly of propane, propylene, butane, and butylene in various mixtures. However, in the United States, the mixture is mainly propane. It is produced as a by-product of natural gas processing and petroleum refining. The components of LPG are gases at normal temperatures and pressures. However, they become liquid under moderate pressure. Therefore, LPG is stored on vehicles as a liquid in pressurized tanks.

Advantages:

Environmental: Propane vehicles produce less of virtually all tailpipe pollutants than comparable gasoline or diesel vehicles.
Energy Security: Most propane used in the U.S. today is domestically produced.
Operating Cost: Propane costs less per gallon than gasoline and diesel fuel.
Fueling: A national infrastructure of pipelines, processing facilities, and storage already exists for the efficient distribution of propane.

Disadvantages:

Energy Security: Propane production in the U.S. is limited. If the demand for propane were to increase significantly, the additional propane would have to be imported.
Operating Cost: Propane costs vary considerable throughout the year – usually peaking in the winter when demand for residential heating is greatest. Unless a user enters into an annual contract with a propane provider, this severely complicates fuel cost budgeting.
Vehicle Cost: Primarily because of the cost of on-board storage tanks, the cost of propane vehicles is greater than for comparable gasoline and diesel vehicles.
Driving Range: Because there is less energy in a gallon of propane than in a gallon of gasoline or diesel, the driving range of vehicles operating on propane is less.
Fueling: Compared to gasoline and diesel fuel, the number of propane fueling stations is limited.
Vehicle Availability: Only a couple of propane vehicles are still being manufactured by OEMs. Most propane vehicles produced today are aftermarket conversions.


Methanol
Methanol (CH3OH) is an alcohol fuel. Today, most of the world's methanol is produced by a process using natural gas as a feedstock. However, the ability to produce methanol from non-petroleum feedstocks such as coal or biomass is of interest for reducing petroleum imports.
When methanol was being used as a vehicle fuel, it was used in a blend of 85 percent methanol and 15 percent gasoline (M-85). Vehicles can operate on neat methanol (M-100), but because of performance and safety issues (e.g., M-100 burns with an invisible flame), M-100 is not used for on-road vehicles. Methanol internal combustion engine vehicles were at one time viewed as the primary alternative to petroleum. Because of performance and other problems, this is no longer the case. No commercially available methanol vehicles are available today.

Advantages:

Environmental: Vehicles operating on methanol blends produce fewer NOx, VOCs and CO emissions than comparable gasoline vehicles.
Energy Security: Methanol is made primarily from natural gas, 85 percent of which is produced in the U.S., with virtually all the rest produced in Canada.
Vehicle Cost: If OEMs were to produce M85-capable vehicles, they would need to make only minor (and inexpensive) modifications to their vehicles.

Disadvantages:
Environmental: Methanol vehicles produce a significant amount of formaldehyde.
Safety: Methanol is highly corrosive and toxic when ingested or absorbed through the skin. Public refueling would be very problematic.
Fueling: There virtually are no public methanol fueling stations.
Vehicle Availability: No one now manufactures methanol-powered vehicles.
Operating Cost: Today, methanol is made primarily from natural gas. Because of the energy losses in the conversion process and the cost of domestic natural gas, M85 is much more expensive than gasoline.
Maintenance Cost: Because of methanol’s corrosive qualities, engine parts needed to be frequently replaced.
Energy Security: Even with the greater shipping cost, it is much less expensive to produce methanol at sites around the world where the price of natural gas is much less than to produce the methanol in the U.S. If methanol were to be become a significant transportation fuel, most of it would be imported.
Driving Range: Because there is less energy in a gallon of M85 than in a gallon of gasoline, the driving range of vehicles operating on M85 is less.


Natural Gas (Compressed or Liquefied)
Natural gas consists mostly of methane and is drawn from gas wells or in conjunction with crude oil production. Compressed natural gas (CNG) vehicles store natural gas in high-pressure fuel cylinders at 3,000 to 3,600 pounds per square inch. Since natural gas is colorless, odorless and tasteless, an odorant is normally added to CNG for safety reasons. Liquefied natural gas (LNG) vehicles store natural gas as a cryogenic liquid.

Advantages:

Environmental: CNG vehicles produce far less of all regulated pollutants that compar-able gasoline or diesel vehicles, including NOx and particulate matter. In addition, CNG vehicles produce far less unregulated air toxics and greenhouse gases.
Energy Security: Natural gas is primarily a domestic/North American fuel, 85 percent of which is produced in the U.S., with virtually all the rest produced in Canada.
Operating Cost: Natural gas is cheaper "at the pump" than gasoline and diesel fuel. Prices vary around the country.
Vehicle Availability: There are over 50 natural gas vehicle models available for light-, medium- and heavy-duty applications. This is more than for any alternative fuel.
Distribution Efficiency/Safety: America has a natural gas transmission and distri-bution network of over 1.5 million miles bringing natural gas to every major city in the country. This is the safest and most efficient energy distribution system.
Flexibility: CNG vehicles can be (and are being) produced as dedicated and bi-fuel versions. Dedicated vehicles are most appropriate where vehicles tend to operate in an area where natural gas fueling is available. Bi-fuel vehicles have both natural gas and gasoline storage tanks on board, and can operate on either fuel at the flip of a switch. Bi-fuel vehicles are most appropriate where the driver may need to travel to areas not currently served by natural gas stations.
Home Refueling: The majority of homes in the U.S. are connected to the natural gas transmission and distribution system. Through the use of a "home refueling appliance," homeowners can refuel their CNG vehicles at home.
Transition to Hydrogen: Since hydrogen is a gas, hydrogen-powered vehicles will require changes in a number of areas, including building codes and standards, mechanic/ inspector/user training. NGVs require many of the same changes. Therefore, a growing NGV market today is smoothing the path for a hydrogen vehicle market tomorrow.

Disadvantages:

Fueling: There are only 1,600 natural gas fueling stations in the U.S. (compared to 190,000 gasoline stations). In addition, each station costs significantly more than for a comparable gasoline/diesel dispenser and storage tank system.
Vehicle Cost: Primarily because of (1) low production volumes and (2) the greater cost of fuel storage tanks, NGVs cost more than comparable gasoline or diesel models.
Driving Range: Compared to a volumetric gallon of gasoline or diesel fuel, there is less energy in an energy gallon equivalent of natural gas (both CNG and LNG). Therefore, the driving range of vehicles operating on natural gas is less.
Other: On-board natural gas fuel tanks are larger than comparable gasoline or diesel fuel tanks. Therefore, in some vehicles, some cargo or truck space is lost.

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