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Alternative Fuel (AF)
A transportation fuel certified by EPA, which results in higher fuel efficiency and lower exhaust emissions when used in motor vehicles.
Alternative fuels for transportation are defined by the U.S. Energy Policy Act as:
- Biofuels (fuels, other than alcohols, derived from biological materials)
- Methanol, denatured Ethanol, and other alcohols
- Blends containing 85% or more by volume of Methanol, denatured Ethanol, and other alcohols; the remainder volume is gasoline or other fuels
- Compressed Natural Gas
- Liquefied Natural Gas
- Liquefied Petroleum Gas (commonly called propane)
- Hydrogen
- Electricity
- Coal-derived liquid fuels
- P-series
- Other fuel determined to be 'substantially not petroleum' and yielding 'substantial energy security benefits and substantial environmental benefits'
Alternative Fuel Vehicle (AFV)
A dedicated, dual-fuel, or flexible fueled vehicle designed to operate on at least one alternative fuel.
Aromatics
Hydrocarbons based on the ringed six-carbon benzene series of related organic groups. Benzene, toluene and xylene are the principal aromatics, commonly referred to as the BTX group. They represent one of the heaviest fractions of gasoline.
American Society for Testing and Materials (ASTM)
ASTM sets more than 12,000 consensus standards, including transportation fuel standards, making consumer products safer.
B100
100% (neat) biodiesel, defined as an alternative fuel.
B20
A fuel blend of 20% biodiesel and 80% petroleum-based diesel.
Barrel
A unit of volume equal to 42 U.S. gallons.
Benzene
A six-carbon aromatic; common gasoline component identified as being toxic. Benzene is a known carcinogen.
Bi-fuel Vehicle
A motor vehicle with two separate fuel systems designed to run on an alternative fuel, gasoline, or diesel. The vehicle uses one fuel at a time, not a mixture of the fuels. Bi-fuel vehicles are referred to as 'dual-fuel' vehicles in the Clean Air Act and the EPAct.
Biodiesel
A biodegradable transportation fuel produced through transesterification of oils (such as soybeans, rapeseed, or sunflowers) or animal fats. Biodiesel is a domestic, renewable fuel containing no petroleum, and can be used in compression-ignition (diesel) engines with no major modifications. Biodiesel is defined as an alternative fuel.
Technical definition: a fuel comprised of mono-alkyl esters of long chain fatty acids derived from vegetable oils or animal fats, designated B100, and meeting the requirements of ASTM D 6751.
Biodiesel Blend
Biodiesel blended with petroleum-based diesel fuel. Common biodiesel blends are B5 and B20 where the 5 and 20 denote the percentage of biodiesel in the blend.
Biofuel
Liquid fuel produced from biomass feedstocks (plant materials) such as corn or grasses, and organic wastes, such as animal wastes. Corn and soybeans constitute the majority of the crops grown for conversion to biofuels. Common biofuels include ethanol, methanol, biodiesel, and methane. Research is ongoing to improve the conversion of non-grain crops, such as switchgrass and woody crops, to biofuels.
Biomass
Renewable organic matter from plants or animals. Domestic biomass resources include agricultural and forestry residues, perennial grasses, woody energy crops, terrestrial and aquatic crops, and wastes (municipal solid waste, industrial waste, urban wood waste, and food waste). Biomass can be converted into usable forms of energy such as biofuels, making it a renewable or naturally occurring alternative to petroleum.
British Thermal Unit (BTU)
A standard unit for measuring heat energy. 1 Btu is the quantity of heat required to raise the temperature of 1 pound of water at sea level by 1 degree Fahrenheit.
Btu conversion factors:
- Electricity: 3,412 Btu per kilowatt-hour
- Natural Gas: 1,031 Btu per cubic foot
- Fuel Oil No.2: 138,690 Btu per gallon
- LPG (Propane): 91,330 Btu per gallon
Bulk Station
A facility used primarily for the storage and/or marketing of petroleum products, which has a total bulk storage capacity of less than 50,000 barrels and receives its petroleum products by tank car or truck.
Bulk Terminal
A facility used primarily for the storage and/or marketing of petroleum products, which has a total bulk storage capacity of 50,000 barrels or more and receives petroleum products by tanker, barge, or pipeline.
Butane
A gas, easily liquefied, extracted from natural gas. Used in LPG for domestic and industrial applications, used as a raw material for petrochemical synthesis, used as a low-volatility component for gasoline, and processed further for a high-octane gasoline component.
Byproduct
A secondary or additional material produced from converting biomass into biofuel. A biodiesel byproduct is glycerin and an ethanol byproduct is dried distiller's grain with solubles.
Carbon Dioxide (CO2)
A colorless, odorless, non-poisonous gas produced from fossil-fuel combustion, as well as other processes. CO2 does not directly impair human health but is a greenhouse gas that traps the earth's heat and contributes to the potential for global warming.
Carbon Monoxide (CO)
A colorless, odorless gas produced by the incomplete combustion of fuels with a limited oxygen supply as in automobile engines. CO is poisonous if inhaled and can impair exercise capacity, visual perception, manual dexterity, and learning functions.
Carcinogen
Chemicals and other substances known to cause cancer.
Cardlock
Cardlocks are automated, unattended fueling stations open 24 hours a day, 7 days a week and are mainly used by commercial fleet vehicles. At cardlocks, drivers pump their own fuel and pay by inserting a card similar to a credit card into a card reader. Most pumps will prompt the driver with a few questions, such as a PIN, to verify authorization for using the card.
In Oregon, cardlock use is restricted to businesses, government agencies, farms, and nonprofit organizations that have signed for an account. The fuel can only be used in a business vehicle and never for personal use.
In other states, individuals, pending credit approval, can set up accounts and use cardlocks even though they are not businesses.
Many companies offer cardlock accounts, with some requiring a minimum amount of fuel to be purchased per year. Companies providing fuel payment services to fleet managers and owners include:
Stations throughout Oregon and Washington differ on the company chosen to provide cardlock services. Visit the company websites or use the CWCCC alternative fuel locator to find where certain brands of cards are accepted.
Cardlock (no retail)
Cardlock sites accepting cards from drivers having accounts with fuel payment providers, such as CFN, Pacific Pride, and Wright Express. All Oregon cardlocks are cardlock (no retail).
Cardlock (retail)
Cardlock sites accepting personal credit cards such as MasterCard, Visa, and Discover. These types of cardlocks are by law not available in Oregon but are widely available in other states like Washington.
Cellulosic Ethanol
Cellulose is the main component of plant cell walls and is the most common organic compound on earth. Ethanol is typically produced from the starch contained in grains such as corn, but it can also be produced from cellulose. Cellulosic ethanol takes advantage of the "waste" materials such as corn stalks, rice straw, wood chips, or "energy crops" of fast-growing trees and grasses, which are currently disposed of, unused. Cellulose is more difficult to convert into usable sugars for ethanol production, but research is ongoing to develop cellulosic ethanol production technology.
Clean Air Act (CAA)
The original Clean Air Act was signed in 1963 and is enforced by the EPA. The law set emissions standards for stationary sources such as factories and power plants. The Amendments of 1970 introduced motor vehicle emission standards (e.g., automobiles, trucks); criteria pollutants included lead, ozone, CO, SO2, NOx, and PM, as well as air toxics. The Amendments of 1990 set two new gasoline standards to reduce harmful fuel emissions; one standard required gasoline to contain fuel oxygenates such as ethanol, which are cleaner burning additives.
Climate Change
A term used to refer to all forms of climatic inconsistency, but especially to significant change from one prevailing climatic condition to another. In some cases, "climate change" has been used synonymously with the term "global warming"; scientists, however, tend to use the term in a wider sense inclusive of natural changes in climate, including climatic cooling.
Compressed Natural Gas (CNG)
Natural gas that has been compressed under high pressures, typically between 2000 and 3600 psi, and held in special high-pressure containers. The gas expands when released for use as a fuel in natural gas powered vehicles. CNG is defined as an alternative fuel.
Conversion or Converted Vehicle
A vehicle, originally designed to operate on gasoline or diesel, modified or altered to run on an alternative fuel after its initial delivery to an end-user.
Corporate Average Fuel Economy (CAFE)
A law passed in 1975 that set federal fuel economy standards for cars and light trucks. The CAFE values are an average of city and highway fuel economy test results weighted by a manufacturer for either its car or truck fleet. Current CAFE standards for cars are 27.5 mpg and 22.2 mpg for light trucks. Automakers are required to increase the average fuel economy of new cars and trucks to 35 mpg by 2020. Light trucks exceeding 8,500 Gross Vehicle Weight are exempt from CAFE standards.
Dedicated Vehicle
A vehicle operating solely on one fuel, whether conventional gasoline/diesel or alternative fuels. Generally, dedicated vehicles provide superior emissions and performance results because their design has been optimized for operation on only one fuel.
Domestic Fuel
As defined by EPA, domestic fuel is derived from resources within the United States, its possessions and commonwealths, and Canada and Mexico (the two nations in a free-trade agreement with the U.S.).
Dual-fuel Vehicle
EPACT Definition: A vehicle designed to operate on a combination of an alternative fuel and a conventional fuel. This includes: a) vehicles using a mixture of gasoline or diesel and an alternative fuel in one fuel tank (e.g., flexible-fueled vehicles); and b) vehicles capable of operating either on an alternative fuel, a conventional fuel or both, simultaneously using two fuel systems (e.g., bi-fuel vehicles).
CAA Definition: A vehicle with two separate fuel systems designed to run on either an alternative fuel or conventional gasoline, using only one fuel at a time.
E10
A fuel blend of 10% ethanol and 90% unleaded gasoline. Known as gasohol.
E85
A fuel blend of 85% ethanol and 15% unleaded gasoline, defined as an alternative fuel. For use only in flexible fuel vehicles.
E-Diesel
A fuel blend of diesel fuel, up to 15% ethanol, and proprietary additives (which prevent the ethanol and diesel from separating at very low temperatures). E-diesel is currently an experimental fuel that is being tested in farm machinery, buses, and heavy-duty trucks. Demonstrations have shown E-diesel has the potential to reduce harmful emissions from diesel engines, especially particulate matter.
Electric Vehicle (EV)
A vehicle powered by electricity, generally provided by batteries. EVs qualify in the zero emission vehicle (ZEV) category for emissions.
Energy Content
The energy content of fuel, referred to as the heating value, is the amount of heat released when a known quantity of fuel is burned under specific conditions. In the U.S., the heating value is expressed in British thermal units (Btu) per gallon at 60 degrees Fahrenheit. The energy content in each distinct fuel can vary from supplier to supplier or from season to season and is determined by the refining and blending practices.
Energy Policy Act (EPAct)
A broad-ranging act signed into law (P.L. 102-486) in 1992 to reduce our nation's reliance on foreign petroleum and improve air quality. Titles III, IV, V, XV and XIX of EPACT deal with alternative transportation fuels. EPACT accelerates the purchase requirements for AFVs by the federal fleet, and requires fleets in large urban areas to purchase AFVs. EPAct establishes tax incentives for purchasing AFVs, converting conventional gasoline vehicles to operate on alternative fuels, and installing refueling or recharging facilities by the private sector.
Ethanol (CH3CH2OH)
Ethanol (also known as ethyl alcohol, grain alcohol, and EtOH) is a clear, colorless, flammable oxygenated hydrocarbon. Ethanol is water soluble, non-toxic, and biodegradable. Ethanol is typically produced chemically from ethylene, or biologically from fermentation of various sugars from carbohydrates found in agricultural crops and cellulosic residues from crops or wood. It is used in the United States as a gasoline octane enhancer to improve air quality and oxygenate (blended up to 10% concentration). Ethanol is defined as an alternative fuel.
Ethyl Tertiary Butyl Ether (ETBE)
An aliphatic ether similar to MTBE. This fuel oxygenate is manufactured by reacting isobutylene with ethanol. Having high octane and low volatility characteristics, ETBE can be added to gasoline up to a level of approximately 17% by volume. ETBE is not yet commercially available.
Feedstock
Any material converted to another form of fuel or energy product. For example, cornstarch can be used as a feedstock for ethanol production. Biomass feedstock includes all plant and plant-derived material.
Fleet Vehicle
Any motor vehicle a company owns or leases that is in the normal operations of a company. Fleet vehicles include gasoline/diesel powered vehicles and alternative-fuel vehicles.
Flexible Fuel Vehicle (FFV)
A vehicle with a common fuel tank designed to operate on:
- alternative fuels (such as M85 or E85)
- 100-percent petroleum-based fuels
- any mixture of an alternative fuel and a petroleum-based fuel.
Fuel Cell
An electrochemical engine (no moving parts) that converts the chemical energy of a fuel, such as hydrogen, and an oxidant, such as oxygen, directly to electricity. The principal components of a fuel cell are catalytically activated electrodes for the fuel (anode) and the oxidant (cathode) and an electrolyte to conduct ions between the two electrodes. Fuel cells have the potential to replace the internal combustion engine in vehicles because they are energy-efficient, clean, and fuel-flexible.
Fuel economy
The average mileage traveled by an automobile per gallon of gasoline (or equivalent amount of other fuel) consumed as measured in accordance with the testing and evaluation protocol set forth by the EPA.
Gasohol
A fuel blend of 10% ethanol and 90% unleaded gasoline. Also referred to as E10.
Gasoline Gallon Equivalent (GGE)
This tool allows users to compare gallons of different fuels by using a gallon of gasoline as the base gallon and then comparing energy content based on British thermal units..
| Fuel Type |
Unit of Measure |
BTUs per Unit |
Gallon Equivalent |
| Gasoline (regular unleaded) |
Gallon |
114,100 |
1.00 gallon |
| Gasoline (reformulated, 10% MTBE) |
Gallon |
112,000 |
1.02 gallons |
| Diesel |
Gallon |
129,800 |
0.88 gallons |
| Liquefied Natural Gas (LNG) |
Gallon |
75,000 |
1.52 gallons |
| Compressed Natural Gas (CNG) |
Cubic Foot |
900 |
126.67 cu. ft. |
| Liquefied Petroleum Gas (propane) |
Gallon |
84,300 |
1.35 gallons |
| Methanol (M100) |
Gallon |
56,800 |
2.01 gallons |
| Methanol (M85) |
Gallon |
65,400 |
1.74 gallons |
| Ethanol (E100) |
Gallon |
76,100 |
1.50 gallons |
| Ethanol (E85) |
Gallon |
81,800 |
1.40 gallons |
| Biodiesel (B20) |
Gallon |
129,500 |
0.88 gallons |
| Electricity |
Kilowatt hour |
3,400 |
33.53 kwhrs |
Source: National Association of Fleet Administrators, Inc.
Greenhouse Effect
A warming of the earth and its atmosphere as a result of the thermal trapping of solar radiation by CO2, water vapor, methane, NOx, chlorofluorocarbons and other gases, both natural and man-made.
Greenhouse Gas
Chemical compounds that allow sunlight to enter Earth's atmosphere and then capture the infrared radiation (heat) reflected off oceans and land, trapping it in the atmosphere and keeping Earth a constant temperature. Greenhouse gases include water vapor, carbon dioxide, methane, and nitrous oxide.
Hybrid-Electric Vehicle (HEV)
A vehicle powered by two or more energy sources, one of which is electricity. HEVs may combine the engine and fuel system of a conventional vehicle with the batteries and electric motor of an electric vehicle in a single drive train.
Hydrogen (H2)
A colorless, highly flammable gaseous fuel. Hydrogen is the simplest and most abundant element in the universe. It is rarely found alone in nature; instead, it is usually bonded with other elements and is largely locked in water, methane and other organic sources. Hydrogen can be produced from fossil fuels, biomass and electrolyzing water and is defined as an alternative fuel.
Liquefied Natural Gas (LNG)
Natural gas that has been condensed to a liquid typically by cryogenically cooling the gas to -260 degrees Fahrenheit at atmospheric pressure. LNG is defined as an alternative fuel and is primarily used to fuel buses and heavy-duty vehicles.
Liquefied Petroleum Gas (C3H8)
A mixture of hydrocarbons found in natural gas and produced from crude oil, used principally as a feedstock for the chemical industry, home heating fuel, and motor vehicle fuel. For convenience of transportation, it is liquefied through pressurization. Also known as the principal constituent of propane; propane is non-toxic and defined as an alternative fuel.
Methanol (CH3OH):
Also known as methyl alcohol and wood alcohol, methanol is a light, volatile alcohol eligible for gasoline blending, and defined as an alternative fuel. Methanol is a liquid fuel formed by catalytically combining CO with hydrogen in a 1:2 ratio under high temperature and pressure. Commercially, it is typically manufactured by steam reforming natural gas. Also formed in the destructive distillation of wood. Methanol can be used to make the fuel oxygenate MTBE.
Methyl Tertiary Butyl Ether (MTBE)
An ether manufactured by reacting methanol and isobutylene. The resulting ether has high octane and low volatility. MTBE is a fuel oxygenate used as an additive to gasoline to increase octane and reduce engine knock. It is permitted in unleaded gasoline up to a level of 15% by volume. MTBE was initially used to substitute lead as an octane enhancer. Its used has declined as MTBE has been found to be a persistent environmental contaminant when leaked from underground storage tanks and gasoline spills.
National Ambient Air Quality Standards (NAAQS)
Ambient standards for criteria air pollutants specifically regulated under the CAA. These pollutants include ozone, CO, NO2, lead, particulate matter and SOx.
Natural Gas
Natural gas is a mixture of gaseous hydrocarbons, primarily methane, occurring naturally in the earth and used principally as a fuel. Most natural gas is extracted from gas and oil wells. Natural gas has a high octane rating and is non-toxic, non-corrosive, and non-carcinogenic.
Octane
A flammable liquid hydrocarbon found in petroleum. Used as a standard to measure the anti-knock properties of motor fuel.
Off-road Diesel Fuel
Off-road diesel fuel is not subject to federal or state excise taxes; currently, the fuel is allowed to have the sulfur content higher than on-road diesel. Off-road diesel is not allowed for use in any vehicle or machinery using public roads. Typically, off-road diesel is used in farming, construction, and mining equipment and vehicles.
Off-road diesel is dyed red, indicating the fuel was sold tax-free. Anyone found to be using dyed fuel while driving a vehicle on public roads will be fined. The color of the fuel can be seen through the translucent fuel lines to and from the fuel filter.
Through the Clean Air Nonroad Diesel Rule, the Environmental Protection Agency mandates off-road diesel to be low sulfur diesel (500 ppm) by 2007 and ultra-low sulfur diesel (15 ppm) by 2010.
On-road Diesel Fuel
On-road diesel fuel is subject to federal and state excise taxes and is allowed in highway vehicles using public roads. Currently, on-road diesel is held to stricter clean air standards than off-road diesel.
Through the Clean Air Highway Diesel Rule, the Environmental Protection Agency mandates on-road diesel to be ultra-low sulfur diesel. The sulfur content must be 15 parts per million (ppm) or lower.
Original Equipment Manufacturer (OEM)
Oxides of Nitrogen (NOx)
Regulated air pollutants, primarily NO and NO2, but including other substances in minute concentrations. Under the high pressure and temperature conditions in an engine burning petroleum-based fuels, nitrogen and oxygen atoms in the air react to form various NOx. Like hydrocarbons, NOx are precursors to the formation of smog and ozone.
Oxygenate
A term used in the petroleum industry to denote fuel additives containing hydrogen, carbon and oxygen in their molecular structure, which, when added to gasoline, increase the amount of oxygen in the fuel. Oxygenates allow the fuel to burn more thoroughly, decreasing carbon monoxide emissions. Oxygenates include ethers such as MTBE and ETBE and alcohols such as ethanol and methanol.
Ozone
Tropospheric ozone (smog) is formed when volatile organic compounds (VOCs), oxygen and NOx react in the presence of sunlight. This is not to be confused with stratospheric ozone, which is found in the upper atmosphere and protects the earth from the sun's ultraviolet rays. Though beneficial in the upper atmosphere, at ground level, ozone is a respiratory irritant and considered a pollutant.
P-Series Fuels
Fuels designed by the Pure Fuel Corporation to run in flexible fuel vehicles. P-Series fuel is a blend of natural gas liquids (pentanes plus), ethanol, and the biomass-derived co-solvent methyltetrahydrofuran (MeTHF). P-Series is the only fuel to be added to the list of authorized alternative fuels under EPAct. Currently, P-Series is not being produced in large quantities and is not widely used.
Particulate Matter (PM)
A generic term for a broad class of chemically and physically diverse substances that exist as discrete particles (liquid droplets or solids) over a wide range of sizes. These particles become dangerous when they contain heavy metals, nitrogen and sulfur oxides, VOCs, and other elements that are harmful when inhaled. Diesel emissions contain PM and once inhaled, can cause health problems. PM is a NAAQS pollutant.
Propane (C3H8)
A gas whose molecules are co
mposed of three carbon and eight hydrogen atoms. Propane is present in most natural gas in the United States, and is refined from crude petroleum. Propane contains about 2,500 Btu per standard cubic foot. Propane is the principal constituent in LPG. Propane has a high energy density and widespread infrastructure in the U.S.
Reid Vapor Pressure (RVP)
A standard measurement of a liquid's vapor pressure in psi at 100 degrees Fahrenheit. It is an indication of the propensity of the liquid to evaporate.
Renewable Diesel
Also known as hydrogenated-derived renewable diesel (HDRD), it is the product of fats or vegetable oils - alone or blended with petroleum - that has been refined in an existing oil refinery and meets the requirements of ASTM D 975 or D 396. Renewable diesel meets the ASTM standard for diesel, not biodiesel. Renewable diesel has an ultra-low sulfur content and high cetane number.
Renewable Energy Resources
Naturally replenishing, but flow-limited, energy resources. They are virtually inexhaustible in duration but limited in the amount of energy that is available per unit of time. Renewable energy resources include: biomass, hydro, geothermal, solar, wind, ocean thermal, wave action, and tidal action.
Renewable Fuel
Transportation fuel with a naturally replenishing feedstock, such as plant and animal biomass. Renewable fuels form a subcategory within alternative fuels because they do not originate from fossil fuels (coal, petroleum, and natural gas).
Smog
A visible haze caused primarily by particulate matter and ozone.
Sulfur oxides (SOx)
Sulfur is present at various levels of concentration in many fossil fuels. Sulfur oxides are compounds containing sulfur and oxygen, such as sulfur dioxide (SO2) and sulfur trioxide (SO3). Combustion of fossil fuels, such as petroleum, releases sulfur oxides, which contribute to smog formation and are catalysts to the creation of acid rain.
Transesterification
A process in which organically derived oils or fats are combined with alcohol (ethanol or methanol) in the presence of a catalyst to form esters (ethyl or methyl ester) and glycerol (glycerin). This process is used to produce biodiesel.
Ultra-low sulfur Diesel
Diesel fuel containing a maximum 15 parts per million (ppm) sulfur.
Volatile Organic Compound
Reactive gases released during combustion or evaporation of fuel and regulated by EPA. VOCs react with NOx in the presence of sunlight and form ozone.
