Glossary

Learn terms and definitions related to the green truck industry.

A | B | C | D | E | F | G | H | I | J | K | L | M N | O | P | Q | R | S | T U | V | W | X | Y | Z

21st Century Truck
A DOE Vehicle Technologies Program partnership aimed at developing technologies for the nation’s trucks and buses that could safely and cost-effectively move larger volumes of freight and greater numbers of passengers while emitting little or no pollution and dramatically reducing dependence on foreign oil. Visit www1.eere.energy.gov/vehiclesandfuels/about/partnerships/21centurytruck to learn more. See also Department of Energy (DOE)

A
Accessory Load Electrification
The conversion of common vehicle accessory loads (power steering, power brakes, air conditioning, air compressor, etc.) from being engine-driven (belts or gearing) to being driven by electric motors. Electrically driven systems can be optimized to operate at a fixed speed, thereby increasing efficiency and making them compatible with hybrid vehicle propulsion systems.

Accumulator (Hydraulic)
An energy storage device in which a volume of non-compressible hydraulic fluid is held under pressure by an external source. Compressed gas is the most common external source used in vocational truck applications.

Active Telematics
Systems that are typically capable of interfacing with a vehicle on a real-time basis. See also Telematics

Aerodynamics
Refers to the motion of air and other gaseous fluids and with the forces acting on bodies in motion relative to such fluids. With regard to trucks, wind resistance contributes to drag which can increase fuel costs by as much as 15%-20%. Examples of components that promote proper aerodynamics include roof-mounted air deflectors and side fairings on trailers, and under-cab step and fuel tank skirts on Class 6-8 straight trucks. Components such as aerodynamic mirrors, low-drag hood configurations and aero bumpers are also becoming prevalent.

Alternative Drive Systems
Any vehicle drive (propulsion) system other than a conventional internal combustion/mechanical transmission system. The most common systems are straight electric, hybrid electric and hybrid hydraulic drives.

Alternative Fuel
Any non-conventional fuel used to power a vehicle. In North America, conventional vehicle fuels are normally defined as gasoline and petroleum-based diesel. Alternative fuels currently in use or under development include:

  • B-10 — A blend of 10% biodiesel and 90% petroleum-based diesel fuel.
  • B-20 — A blend of 20% biodiesel and 80% petroleum diesel. B-20 is the most common biodiesel blend in the U.S. It provides substantial benefits but avoids many of the cold-weather performance and material compatibility concerns associated with B-100 (pure biodiesel).
  • Biodiesel — A liquid fuel composed of fatty acid alkyl esters, fatty acid methyl esters or long-chain mono alkyl esters. It is produced from renewable sources such as new and used vegetable oils and animal fats, and is a cleaner-burning replacement for petroleum-based diesel fuel. It is normally blended with conventional petroleum-based diesel fuel for use. 
  • Compressed Natural Gas (CNG) — Natural gas is a mixture of hydrocarbons; predominantly methane (CH4). When used as transportation fuel, it is typically stored onboard a vehicle in tanks at high pressure (up to 3,600 PSI).
  • E-85 — A blend of 85% ethanol and 15% gasoline that is used to fuel E85-capable flexible fuel vehicles (FFVs), which are available in a variety of models from U.S. and foreign automakers.
  • Electricity — Electricity used to power pure electric vehicles (as opposed to electric hybrids) is generally provided by the electricity grid and stored in a vehicle’s battery. Fuel cells are being considered as a way to use electricity generated onboard the vehicle to power electric motors. Unlike batteries, fuel cells convert chemical energy from hydrogen to electricity (see Electric Drive Vehicle).
  • Hydrogen —The simplest and most abundant element in the universe. The interest in hydrogen as an alternative transportation fuel stems from its clean-burning qualities, its potential for domestic production and the fuel cell’s potential for high efficiency (two to three times more efficient than gasoline vehicles).
  • Liquefied Natural Gas (LNG) — Natural gas can be liquefied to store more energy onboard a vehicle in a smaller volume. To produce LNG, natural gas is purified and condensed into liquid by cooling to –260°F (–162°C). Since it must be kept at such cold temperatures, LNG is stored in double-wall, vacuum-insulated pressure vessels. LNG fuel systems are typically only used with heavy-duty vehicles.
  • Propane — A three-carbon alkane gas (C3H8), also known as liquefied petroleum gas (autogas in Europe). Propane turns into a colorless, odorless liquid when stored under pressure inside a tank. As pressure is released, the liquid propane vaporizes and turns into gas that is used for combustion or that can be injected, under pressure, as a liquid fuel. An odorant, ethyl mercaptan, is added for leak detection. 

Auxiliary Engine
A small internal combustion engine carried on a vehicle to for purposes other than direct power. Typical uses include operation of refrigerator units, electric generators and welders, and vehicle-mounted equipment, such as cranes and aerial devices.

B
B-10

A blend of 10% biodiesel and 90% petroleum-based diesel fuel. See also Alternative Fuel 

B-20
A blend of 20% biodiesel and 80% petroleum diesel. B-20 is the most common biodiesel blend in the U.S. It provides substantial benefits but avoids many of the cold-weather performance and material compatibility concerns associated with B-100 (pure biodiesel). See also Alternative Fuel

Battery
A combination of one or more electrochemical cells used to convert stored chemical energy into electrical energy. Batteries are normally described by their mode of operation (primary cell, which is non-rechargeable, or secondary cell, which is rechargeable); their construction (wet or dry cell); and their construction materials. See also Energy Storage Media (Electric) 

Biodiesel
A liquid fuel composed of fatty acid alkyl esters, fatty acid methyl esters or long-chain mono alkyl esters. It is produced from renewable sources such as new and used vegetable oils and animal fats, and is a cleaner-burning replacement for petroleum-based diesel fuel. It is normally blended with conventional petroleum-based diesel fuel for use. See also Alternative Fuel

C
CALSTART
North America’s leading advanced technologies consortium that has led the way in the development and implementation of clean, efficient transportation solutions for businesses, fleets and governments for more than 17 years. Based in Pasadena, CA, CALSTART is a member-supported organization of more than 140 firms, fleets and agencies worldwide dedicated to supporting a growing clean transportation industry. Visit www.calstart.org to learn more. 

Carbon Footprint
The total amount of greenhouse gases produced by an activity, usually expressed in equivalent metric tons (1,000 kilograms) of carbon dioxide (CO2).

Clean Cities
A government-industry partnership sponsored by the DOE’s Vehicle Technologies Program. With nearly 90 local coalitions and more than 6,500 stakeholders, Clean Cities’ mission is to reduce petroleum consumption in the transportation sector. Visit www1.eere.energy.gov/cleancities to learn more. See also Department of Energy (DOE)

Compressed Natural Gas (CNG)
Natural gas is a mixture of hydrocarbons; predominantly methane (CH4). When used as transportation fuel, it is typically stored onboard a vehicle in tanks at high pressure (up to 3,600 PSI). See also Alternative Fuel

D
Department of Energy (DOE)
A governmental department charged with advancing the national, economic and energy security of the U.S.; promoting scientific and technological innovation; and ensuring the environmental cleanup of the national nuclear weapons complex. Visit www.energy.gov to learn more.

  • 21st Century Truck — A DOE Vehicle Technologies Program partnership aimed at developing technologies for the nation’s trucks and buses that could safely and cost-effectively move larger volumes of freight and greater numbers of passengers while emitting little or no pollution and dramatically reducing dependence on foreign oil. Visit www1.eere.energy.gov/vehiclesandfuels/about/partnerships/21centurytruck to learn more.
  • Clean Cities — A government-industry partnership sponsored by the DOE’s Vehicle Technologies Program. With nearly 90 local coalitions and more than 6,500 stakeholders, Clean Cities’ mission is to reduce petroleum consumption in the transportation sector. Visit www1.eere.energy.gov/cleancities to learn more.
  • National Renewable Energy Laboratory (NREL) — A DOE facility dedicated to the research, development, commercialization and deployment of renewable energy and energy efficiency technologies. Visit www.nrel.gov to learn more

Drive Cycle
A series of data points (usually presented as a simple line graph) that plot vehicle speed versus time. In some cases, engine RPM is also incorporated to account for conditions such as stationary power take-off operation, off-road operation and operation of power equipment at low road speeds.

E
E-85

A blend of 85% ethanol and 15% gasoline that is used to fuel E85-capable flexible fuel vehicles (FFVs), which are available in a variety of models from U.S. and foreign automakers. See also Alternative Fuel

Electric Drive Vehicle
In an electric drive vehicle, torque is supplied to the wheels by an electric motor that is powered solely by a battery; an internal combustion engine using hydrogen, gasoline or diesel; or by a fuel cell.

Electric Hybrid
A hybrid drive system that uses one or more electric motors, in parallel or series configuration, as the alternative drive system. Electric hybrids typically use batteries or ultracapacitors to store energy which is generated onboard the vehicle by the conventional engine and through regenerative braking. See also Hybrid (Work Truck)  

Electric Power Take-off (E-PTO)
An electric auxiliary drive used to power vehicle-mounted equipment instead of using power from the vehicle’s primary engine.

Electricity
Electricity used to power pure electric vehicles (as opposed to electric hybrids) is generally provided by the electricity grid and stored in a vehicle’s battery. Fuel cells are being considered as a way to use electricity generated onboard the vehicle to power electric motors. Unlike batteries, fuel cells convert chemical energy from hydrogen to electricity (see Electric Drive Vehicle). See also Alternative Fuel

Energy Storage Media (Electric)
Electrochemical devices utilized to store and release electric energy used for operating electric drive vehicles. Types of electric energy storage media include:

  • Battery — A combination of one or more electrochemical cells used to convert stored chemical energy into electrical energy. Batteries are normally described by their mode of operation (primary cell, which is non-rechargeable, or secondary cell, which is rechargeable); their construction (wet or dry cell); and their construction materials.
  • Lead Acid — A form of rechargeable battery (secondary wet cell) that uses lead and lead dioxide for the electrodes (charged state) and a dilute solution of sulfuric acid as an electrolyte. Lead acid batteries have a low energy-to-weight ratio but are low-cost and have the ability to supply high surge currents without being damaged. 
  • Lithium Ion (Li-ion Battery) — A type of rechargeable dry cell battery (secondary cell) in which the cathode (positive electrode) contains lithium. The anode (negative electrode) is generally made of a type of porous carbon. The non-aqueous electrolytes used in lithium ion batteries are typically based on patented formulations containing manganese or cobalt salts. Lithium ion batteries have a high energy density; are lighter than other energy-equivalent secondary batteries; and have a low self-discharge rate.
  • Nickel-Metal Hydride (NiMH) — Nickel-metal hydride batteries (secondary cells) are related to sealed nickel-cadmium batteries. The only difference is that instead of cadmium, hydrogen is used as the active element at a hydrogen-absorbing negative electrode (anode). This electrode is made from a metal hydride (usually alloys of lanthanum and rare earths) that serves as a solid source of reduced hydrogen that can be oxidized to form protons. The electrolyte is alkaline potassium hydroxide. The energy density of NiMH batteries is more than double that of lead acid.
  • Ultracapacitors (UltraCaps) — High-capacity electrochemical double-layer capacitors consisting of two electrodes immersed into an electrolyte. The electrodes are typically made of activated carbon which has a high, specific surface area of about 2,000 m2/g. UltraCaps have an unusually high energy density when compared to common capacitors, typically thousands of times greater than a high-capacity electrolytic capacitor.  

Environmental Defense Fund
A leading national nonprofit organization founded in 1967 that links science, economics and law to create innovative, equitable and cost-effective solutions to the nation’s most urgent environmental problems. Visit www.edf.org to learn more.

Environmental Protection Agency (EPA)
A U.S. government agency established in 1970 to consolidate a variety of federal research, monitoring, standard-setting and enforcement activities to ensure environmental protection. The EPA’s mission is to protect human health and to safeguard the natural environment. Visit www.epa.gov to learn more.

  • SmartWay Transport — A collaboration between the EPA and the freight sector designed to improve energy efficiency, reduce greenhouse gas and air pollutant emissions, and improve energy security. Visit http://epa.gov/smartway/ to learn more 

F
Fuel Cell
A device that generates electricity via a chemical reaction between a fuel (typically hydrogen) and oxygen. Every fuel cell has two electrodes, the anode (positive) and the cathode (negative). The reactions that produce electricity occur at the electrodes. Every fuel cell also has an electrolyte, which carries electrically charged particles from one electrode to the other, and a catalyst, which speeds the reactions at the electrodes.  

G
Green Manufacturing
A method of manufacturing that minimizes the use of non-renewable energy and resources as well as reduces the production of waste and pollution.  

Green Truck
A "green truck" is any truck that:

  • When operated, significantly reduces the production of waste, pollutants and greenhouse gases
  • Increases productivity, resulting in a total reduction in fuel use to accomplish a given amount of work
  • Has been manufactured using green materials and processes.

Greenhouse Gas
A gas in an atmosphere that absorbs and emits radiation with the thermal infrared range. Earth’s primary greenhouse gases include water vapor, carbon dioxide, methane, nitrous oxide and ozone. 

H
Hotel Loads
Power demands (loads) placed on a vehicle to help maintain cab environmental conditions, such as heating, cooling, lighting and accessories (e.g., radios). 

Hybrid (Work Truck)
The combination of two different drive systems (conventional and alternative) to increase efficiency and reduce fuel consumption. Types of hybrids include:

  • Electric Hybrid — A hybrid drive system that uses one or more electric motors, in parallel or series configuration, as the alternative drive system. Electric hybrids typically use batteries or ultracapacitors to store energy which is generated onboard the vehicle by the conventional engine and through regenerative braking.
  • Hydraulic Hybrid — A hybrid drive system that uses one or more hydraulic motors, in parallel or series configuration, as the alternative drive system. Hydraulic hybrids typically use accumulators to store energy which is generated onboard the vehicle by the conventional engine and through regenerative braking.
  • Hydraulic Launch Assist™ (HLA) — A hydraulic hybrid regenerative braking system introduced by Eaton Corporation. The HLA system recycles energy by converting kinetic energy into potential energy during deceleration via hydraulics, storing the energy at high pressure in an accumulator and returning it to the vehicle during subsequent acceleration. This process reduces the amount of work performed by the internal combustion engine.
  • Parallel Hybrid — A hybrid drive designed so that either system can propel the vehicle independently or in unison.
  • Plug-in Electric Hybrid (PHEV) — A variation of an electric hybrid that can charge the onboard energy storage system by plugging into the electric grid when the vehicle is not in use. Plug-in hybrids typically have greater onboard electric storage capacity than regular electric hybrids.
  • Series Hybrid — A hybrid drive system designed so that only one system (normally the alternative) provides power to propel a vehicle. The conventional power source is used to provide energy to the alternative drive.

Hydraulic Hybrid
A hybrid drive system that uses one or more hydraulic motors, in parallel or series configuration, as the alternative drive system. Hydraulic hybrids typically use accumulators to store energy which is generated onboard the vehicle by the conventional engine and through regenerative braking. See also Hybrid (Work Truck)

Hydraulic Launch Assist™ (HLA)
A hydraulic hybrid regenerative braking system introduced by Eaton Corporation. The HLA system recycles energy by converting kinetic energy into potential energy during deceleration via hydraulics, storing the energy at high pressure in an accumulator and returning it to the vehicle during subsequent acceleration. This process reduces the amount of work performed by the internal combustion engine. See also Hybrid (Work Truck)

Hydrogen
The simplest and most abundant element in the universe. The interest in hydrogen as an alternative transportation fuel stems from its clean-burning qualities, its potential for domestic production and the fuel cell’s potential for high efficiency (two to three times more efficient than gasoline vehicles). See also Alternative Fuel

I
Idle Reduction

Refers to technology or equipment used to reduce the energy wasted by idling trucks. One such example is automated engine shut-off for when the engine is not being used to move the vehicle, simultaneously paired with continued electrical supply to power the vehicle’s accessories and lighting.

L
Lead Acid

A form of rechargeable battery (secondary wet cell) that uses lead and lead dioxide for the electrodes (charged state) and a dilute solution of sulfuric acid as an electrolyte. Lead acid batteries have a low energy-to-weight ratio but are low-cost and have the ability to supply high surge currents without being damaged. See also Energy Storage Media (Electric)

Liquefied Natural Gas (LNG)
Natural gas can be liquefied to store more energy onboard a vehicle in a smaller volume. To produce LNG, natural gas is purified and condensed into liquid by cooling to –260°F (–162°C). Since it must be kept at such cold temperatures, LNG is stored in double-wall, vacuum-insulated pressure vessels. LNG fuel systems are typically only used with heavy-duty vehicles. See also Alternative Fuel

Lithium Ion (Li-ion Battery)
A type of rechargeable dry cell battery (secondary cell) in which the cathode (positive electrode) contains lithium. The anode (negative electrode) is generally made of a type of porous carbon. The non-aqueous electrolytes used in lithium ion batteries are typically based on patented formulations containing manganese or cobalt salts. Lithium ion batteries have a high energy density; are lighter than other energy-equivalent secondary batteries; and have a low self-discharge rate. See also Energy Storage Media (Electric)

M
Manufacturing Extension Partnership (MEP)

A national network with more than 400 locations and thousands of specialists who understand the needs of manufacturers. The MEP provides companies with services and access to public and private resources that enhance growth, improve productivity and expand capacity. Visit http://www.nist.gov/mep/ to learn more.

Multiplexing  
The process of transmitting several different signals or information streams via a single carrier. This occurs by combining the signals into one common signal that efficiently moves through the carrier.

N
National Alternative Fuels Training Consortium (NAFTC)
A government-funded, nationwide alternative fuel vehicle (AFV) and advanced technology vehicle training organization tasked with providing the training infrastructure required for implementing widespread use of alternative fuels, AFVs and advanced technology vehicles. Visit www.naftc.wvu.edu to learn more.

National Renewable Energy Laboratory (NREL)
A DOE facility dedicated to the research, development, commercialization and deployment of renewable energy and energy efficiency technologies. Visit www.nrel.gov to learn more. See also Department of Energy (DOE)

Nickel-Metal Hydride (NiMH)
Nickel-metal hydride batteries (secondary cells) are related to sealed nickel-cadmium batteries. The only difference is that instead of cadmium, hydrogen is used as the active element at a hydrogen-absorbing negative electrode (anode). This electrode is made from a metal hydride (usually alloys of lanthanum and rare earths) that serves as a solid source of reduced hydrogen that can be oxidized to form protons. The electrolyte is alkaline potassium hydroxide. The energy density of NiMH batteries is more than double that of lead acid. See also Energy Storage Media (Electric) 

NTEA
Established in 1964, the NTEA is the leading association for the work truck industry, offering expert knowledge, technical support, strategic resources and business opportunities. The Association represents nearly 1,600 companies that manufacture, distribute, install, buy, sell and repair commercial trucks, truck bodies, truck equipment, trailers and accessories. Many buyers of work trucks (fleets) and the major commercial truck chassis manufacturers also belong to the NTEA. Visit www.ntea.com to learn more.

P
Parallel Hybrid

A hybrid drive designed so that either system can propel the vehicle independently or in unison. See also Hybrid (Work Truck)

Passive Telematics
Systems that may send or receive information but cannot actively interface with a vehicle. See also Telematics

Plug-in Electric Hybrid (PHEV)
A variation of an electric hybrid that can charge the onboard energy storage system by plugging into the electric grid when the vehicle is not in use. Plug-in hybrids typically have greater onboard electric storage capacity than regular electric hybrids. See also Hybrid (Work Truck)

Propane
A three-carbon alkane gas (C3H8), also known as liquefied petroleum gas (autogas in Europe). Propane turns into a colorless, odorless liquid when stored under pressure inside a tank. As pressure is released, the liquid propane vaporizes and turns into gas that is used for combustion or that can be injected, under pressure, as a liquid fuel. An odorant, ethyl mercaptan, is added for leak detection. See alsoAlternative Fuel

S
Self Regeneration System
An onboard system that converts a hybrid vehicle’s kinetic energy (energy of motion) into potential energy (stored electricity or high-pressure hydraulic fluid) during deceleration or braking (regenerative braking). This energy is then returned to the drive system during subsequent operations. 

Series Hybrid
A hybrid drive system designed so that only one system (normally the alternative) provides power to propel a vehicle. The conventional power source is used to provide energy to the alternative drive. See also Hybrid (Work Truck)

SmartWay Transport
A collaboration between the EPA and the freight sector designed to improve energy efficiency, reduce greenhouse gas and air pollutant emissions, and improve energy security. Visit www.epa.gov/smartway/ to learn more. See also Environmental Protection Agency (EPA) 

Stationary Lighting Loads
Vehicle electrical loads that provide lighting on stationary vehicles for work area protection or safety (e.g., flashers and strobe lights) and interior and exterior work area lighting.

Sustainability
The use of methods, systems and materials that minimize or avoid resource depletion and harm to natural cycles. Alternative definition: The satisfaction of basic economic, social and security needs now and in the future without undermining the natural resource base and environmental quality on which life depends. 

T
Telematics 
The integrated use of telecommunications and informatics, also known as Information and Communications Technology (ICT). More specifically, telematics is the science of sending, receiving and storing information via telecommunication devices, including cellular communications and satellite systems.  

  • Active Telematics — Systems that are typically capable of interfacing with a vehicle on a real-time basis.
  • Passive Telematics — Systems that may send or receive information but cannot actively interface with a vehicle.

U
Ultracapacitors (UltraCaps)

High-capacity electrochemical double-layer capacitors consisting of two electrodes immersed into an electrolyte. The electrodes are typically made of activated carbon which has a high, specific surface area of about 2,000 m2/g. UltraCaps have an unusually high energy density when compared to common capacitors, typically thousands of times greater than a high-capacity electrolytic capacitor. See also Energy Storage Media (Electric)

W
Weight Reduction

Refers to a wide range of solutions that result in a vehicle having decreased weight and the same functionalities as its heavier predecessor. Lighter vehicles require less tractive effort for acceleration and less rolling resistance from tires and are, therefore, more fuel efficient (according to the EPA, every 10 percent drop in truck weight reduces fuel use between 5 and 10 percent). One such example of weight reduction is the use of lighter metals in a vehicle component.