Glossary A-M

NOTE: Due to the length of this page, it has been divided into two pages, Glossary A-M and Glossary N-Z.
NOTE: Items marked with the symbol “W” are extracted from the Glossary from the publication Biofuels for Transportation by the Worldwatch Institute; used with permission.
Quick links to sections: 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
acid catalyst
An acid used to accelerate the process of a chemical reaction (to catalyze). The catalyst itself is not consumed by the reaction. Used in the pretreatment of oils or fats for biodiesel production in an esterification process to remove fatty acids. (This definition may need work) (sources: (source:Wikipedia, EPA Technology Matrix)
aerobic process
Organic material decomposing with oxygen.WSU (This definition may need work)
aerobic technologies
advanced biofuels
a term used by organizations advocating “sustainable” or “green” biofuels; “biofuels that are greenhouse gas-reducing, water conserving and wildlife-friendly.”
agrichar is also called biochar, which is a type of charcoal produced from biomass. In some cases, the term is used to distinguish biomass charcoal produced via pyrolysis.
agricultural inputs
All substances or materials used in the production or handling of agricultural products.
agrifuel (also “agri-fuel” or “agrofuel”)
Fuel derived from agricultural products
alcohol / alcohol fuel
See ethanol.
algae reactor
Also known as algae bioreactors. A technology that uses algae to remove CO2 from power plant emissions. The algae can then be converted into various kinds of biofuel using gasification, extraction and transesterification, fermentation, anaerobic digestion or drying to produce biomass. (Source: Green Fuel Technology)
algal biodiesel
Biodiesel produced from algae. (
all-lands approach
An integrated approach to land use management expounded in 2009 by U.S. Department of Agriculture Secretary Tom Vilsack, to include Federal- and state-managed, as well as privately owned forest lands.[1]
alternative fuel
The definition of alternative fuels will vary based on the context the term is used in. It usually means an alternative to petroleum fuels and not necessarily a renewable one.
alternative fuel vehicle (AFV)
Any dedicated, flexible-fueled, or dual-fueled vehicle designed to operate on at least one alternative fuel. (Source: National Energy Policy Act USA)
anaerobic activated sludge process
The anaerobic activated sludge process consists of a bioreactor and clarifier in series. When influent waste is pumped into the bioreactor, bacteria are allowed to digest the waste, and biogas is created. The gas is then collected at the top of the bioreactor in a variety of ways. The effluent waste, often called mixed liquor, is sent to a clarifier where the larger solids are allowed to settle out of solution. A portion of these sediments are returned to the bioreactor in order to maintain an adequate level of biomass in the reactor. The liquid effluent from the clarifier is then ready for disposal. (source: RPI) (This definition may need work)
anaerobic clarigester
The anaerobic clarigester is a form of anaerobic digester. It is regarded as being the ancestor of the UASB anaerobic digester . A clarigester treats dilute biodegradable feedstocks and separates out solid and hydraulic (liquid) retention times. (source:Wikipedia) (This definition may need work)
anaerobic contact process
The anaerobic contact process is a type of anaerobic digester. Here a set of reactors are created in series, often with recycling. This recycled material is pumped up into the bottom of the first reactor, an upflow reactor, which allows the waste to flow up from the bottom and separates the waste into 3 zones. At the very top is the biogas zone where the gas is collected. (source:Wikipedia)
anaerobic digester
An anaerobic digester is an industrial system that harnesses the naturally occurring process of anaerobic decomposition to treat waste, produce biogas that can be used to power electricity generators, provide heat and produce soil improving material. (Source: Wikipedia)
anaerobic digestion
Decomposition of biological wastes by micro-organisms, usually under wet conditions, in the absence of air (oxygen), to produce a gas comprising mostly methane and carbon dioxide. (Source: BFIN)
anaerobic expanded-bed reactor
an expanded bed reactor that is operated anaerobically. An expanded bed reactor is a wastewater treatment process where the wastewater flows upward through a bad of sand or activated carbon.
anaerobic filter
An anaerobic filter (AF) is a form of anaerobic digester, commonly employed in the treatment of waste waters.. The digestion tank contains a filter medium which anaerobic bacterial populations can establish upon. They are used to produce biogas(source:Wikipedia) (This definition may need work)
anaerobic fluidized bed
a system for the treatment of moderate and high strength industrial waste
anaerobic lagoon
A type of anaerobic digester used to treat animal waste and produce biogas. Animal waste is flushed into a pool of water where organisms naturally present in manure and the environment decompose the waste and a cover captures the released biogas. (source:Wikipedia) (This definition may need work)
anaerobic migrating blanket reactor AMBR
A kind of anaerobic digester. It is a continuously fed, compartmentalized reactor that reverses its flow in a horizontal manner. This system is developed without the requirement of elaborate gas-solids-separator and feed-distribution systems. Effluent recycling is not required, but mixing is necessary to obtain a sufficient biomass/substrate contact. (source:freepatentsonline)
anhydrous ethanol
Ethanol that has less than 1 percent volume water content. Most commonly used in the United States for blending with gasoline (e.g., E10, E85); in Brazil, many vehicles are set up to run on hydrated ethanol.W
aquatic biofuels
Aquatic organisms and wastes that can be used to produce biofuels. (See Aquatic Biofuels (PDF file), paper by T. Piccolo.)
ASTM D6751
A U.S. standard for biodiesel that establishes fuel quality requirements such as purity and lubricity characteristics. See CEN 14214 for European specifications.W
auto-thermal reforming (ATR)
A method for extracting hydrogen from hydrocarbons. ATR breaks down hydrocarbon molecules into separate hydrogen and carbon atoms using a catalyst, steam, and oxygen.W
A biodiesel blend of 5% biodiesel, 95% diesel fuel.
Sugar cane processing residues.W
barrel of oil equivalent (boe)
The amount of energy contained in a barrel of crude oil, i.e. approximately 6.1 GJ (5.8 million Btu), equivalent to 1,700 kWh. A “petroleum barrel” is a liquid measure equal to 42 U.S. gallons (35 Imperial gallons or 159 liters); about 7.2 barrels are equivalent to one tonne of oil (metric). (Source: BFIN)
base catalyst
A base used to accelerate the process of a chemical reaction (to catalyze). The catalyst itself is not consumed by the reaction. Base catalysts, like sodium hydroxide or potassium hydroxide, are combined with oils or fats to produce biodiesel. (This definition may need work)
batch system anaerobic digester
An aromatic hydrocarbon with a single six-carbon ring and no alkyl branches. A known carcinogen.W
Methane produced from biomass.
biobased product
A “commercial or industrial product (other than food or feed) that is composed, in whole or in significant part, of biological products or renewable domestic agricultural materials (including plant, animal, and marine materials) or forestry materials.” (Source: Iowa State University Bioeconomy Institute)
butanol produced from biomass.
biochemical conversion
The use of fermentation or anaerobic digestion to produce fuels and chemicals from organic sources. (Source: BFIN)
Charcoal-like product made from biomass. See also biochar.
biocycle (also spelled bio-cycle)
A biocycle is the cycle through which energy and essential substances are transferred among species and between the biotic and abiotic segments of the environment. (source: OECD)
biodiesel (also spelled bio-diesel)
A biofuel used in compression-ignition (diesel) engines containing mono alkyl esters of long chain fatty acids created by transesterifying plant or animal oils with a simple alcohol (typically methanol but sometimes ethanol) and a catalyst. Biofuels for diesel engines can also be produced from lignocellulosic biomass using gasification and synthesis, pyrolysis, or hydrothermal liquefaction; however, the term ‘biodiesel’ typically applies only to those fuels derived from renewable lipid sources. Often produced from soybean oil. Other feedstocks include rapeseed oil, palm oil.W
biodiesel plant
A factory or facility that converts biomass into biodiesel.
According to Wikipedia, “Biodrying is the process by which biodegradable waste is rapidly heated through initial stages of composting to remove moisture from a waste stream and hence reduce its overall weight.” See the Wikipedia entry
productive economic activity based on crops, residues and biomass for production of fuel and other products, such as biopolymers.
Energy produced from organic matter, or biomass. Biomass may either be burned directly or converted into liquids or gaseous fuel.W
A biofuel produced by the fermentation of plants rich in sugar/starch (e.g. sugar cane, corn). (source: European Environmental Agency)
living materials used to increase fertility of soils. Some free-living or symbiotic bacteria and blue-green algae (Cyanobacteria) fix gaseous nitrogen as ammonia and release it increasing the fertility of soil and water. (
Liquid fuels derived from organic matter, or biomass.W
biofuel plantation
A plantation intended to grow plants as feedstocks for biofuel production. Such plantations may include corn, jatropha, palm oil, sugar cane, or other plants.
biofuel reserve program
Biogas typically refers to a (biofuel) gas produced by the anaerobic digestion or fermentation of organic matter including manure, sewage sludge, municipal solid waste, biodegradable waste or any other biodegradable feedstock, under anaerobic conditions. Biogas is comprised primarily of methane and carbon dioxide. (source: Wikipedia)
A synthetic form of gasoline produced from biomass.[2]
bioenergy used as a heating source.
Biomass energy
Energy from biomass, such as wood.
Biomass Energy Conservation (BEC)
biomass ethanol
Ethanol made from biomass. See cellulosic ethanol.
biomass fuel
liquid, solid, or gaseous fuel produced by conversion of biomass. (source:
biomass power and heat
Power and/or heat generation from biomass.W
biomass residues
Residue resulting from the harvesting, processing, and use of biomass. Can be divided into primary residues (generated before and at harvest, e.g. tops and leaves of sugar cane), secondary residues (generated during processing, e.g. sugar cane bagasse, rice husks, black liquor), and tertiary residues (generated during and after product end use, e.g. demolition wood, municipal solid waste).W
biomass-to-liquid (BTL)
Processes, such as gasification and Fischer-Tropsch synthesis, that convert biomass into liquid fuels.W
Organic material from plants or animals, including forest product wastes, agricultural residues and waste, energy crops, animal manures, and the organic component of municipal solid waste and industrial waste.W
A liquid fuel similar to diesel, which is produced by fast pyrolysis of biomass. The Bio-oils currently produced are suitable for use in boilers for electricity generation but not for transportation fuel. (Source: EERE)
(Spelled as “BioOil” as a trade name used by DynaMotive.)
A pesticide in which the active ingredient is a virus, fungus, or bacteria, or a natural product derived from a plant source. A biopesticide’s mechanism of action is based on specific biological effects and not on chemical poisons. (source:
Petroleum made from biomass
Bioplastics are a form of plastics derived from plant sources rather than traditional plastics which are derived from petroleum. Bioplastics are truly biodegradable. (source: Wikipedia)
Long-chain compounds composed of organic molecule subunits, for example plastics, that are synthesized by living organisms. (source: U. of Minnesota)
A bioreactor may refer to any device or system that supports a biologically active environment. In one case, a bioreactor is a vessel in which is carried out a chemical process which involves organisms or biochemically active substances derived from such organisms. This process can either be aerobic or anaerobic. (source: Wikipedia)
A refining facility where biomass is converted into fuel, chemicals, materials, and other uses, all at the same plant.W See also biocycle
The process by which biomass is converted into fuel, chemicals, and/or biomass-based materials.W
Solid or semisolid material obtained from treated wastewater, often used as fertilizer. (source:
black liquor
Solution of lignin-residue and the pulping chemicals used to extract lignin during the manufacture of paper. (Source: BFIN)
See fuel blends.
blender pump
A filling station pump that allows consumers to select the desired blend of gasoline and ethanol.
Blender’s Credit
The “Blender’s Credit” is a U.S. federal government subsidy of $0.51 per gallon paid to companies that blend ethanol with gasoline prior to transferring the resulting fuel blend to gas stations. (adapted from Zfacts)
bottoming cycle
A cogeneration system in which steam is used first for process heat and then for electric power production. (Source: BFIN)
Btu (BTU)
British Thermal Unit. A non-metric unit of heat, still widely used by engineers. One Btu is the heat energy needed to raise the temperature of one pound of water from 60°F to 61°F at one atmosphere pressure. 1 Btu = 1055 joules (1.055 kJ). (Source: BFIN)
highly flammable, colorless, easily liquified gas.
Butanol or butyl alcohol (sometimes also called biobutanol when produced biologically), is an alcohol with a 4 carbon structure and the molecular formula of C4H10O. It is primarily used as a solvent, as an intermediate in chemical synthesis, and as a fuel. There are four isomeric structures for butanol. (source:Wikipedia)
Bxx (where xx is a number, eg. B5, B10, etc.)
Biodiesel blended with petroleum diesel, with biodiesel volume percentage indicated by the number.W
carbon dioxide (CO2)
carbon emissions
see also carbon cycle, net (carbon) emissions
carbon finance
carbon footprint
See carbon neutral.
carbon negative biofuels
carbon neutrality
See carbon neutral.
carbon offset
carbon sequestration
carbon storage
catalytic process
Cellulase is an enzyme complex which breaks down cellulose to beta-glucose. It is produced mainly by symbiotic bacteria in the ruminating chambers of herbivores. Artificially produced cellulose is used in the production of bioethanol from cellulosic biomass. It is used to hydrolyze the cellulose fraction of the biomass. (sources:Wikipedia US Department of Energy)
cellulase production
The artificial production of cellulase for use in producing bioethanol : Ethanol produced from biomass.
A complex carbohydrate that forms the main constituent of the cell wall in most plants and is important in the manufacture of numerous products, such as paper, textiles, pharmaceuticals, and explosives. (chemistry) A polysaccharide containing many glucose units in parallel chains. (source:Wiktionary)
cellulose accessing packages
cellulose hydrolysis
The process of breaking down cellulose into sugar molecules that are then fermented and distilled into ethanol. It can be done either chemically or with enzymes. (source:Wikipedia)
cellulosic biomass
Plant matter composed of linked glucose molecules that strengthen the cell walls of most plants. Next-generation biofuel conversion technologies can convert cellulosic biomass into liquids. W
cellulosic ethanol (cellulose ethanol)
Ethanol produced from cellulose (plant fibers) in biomass. Cellulose is found in grasses and woody plants. Promising feedstocks for cellulosic ethanol may include poplar trees and switchgrass.
CEN 14214
A standard for European biodiesel performance, established by the European Committee for Standardization, that sets fuel quality requirements such as purity and lubricity characteristics. See ASTM D6751 for U.S. standards.
cereal (cereal crop)
See the page for sustainability standards.
Cetane number
An empirical measure of a diesel fuel’s self-ignition quality that indicates the readiness of the fuel to ignite spontaneously under the temperature and pressure conditions in the engine’s combustion chamber. (Higher cetane improves the performance of diesel engines.) W
Also known as biochar. Char is a type of charcoal produced when biomass smoulders in an oxygen-poor environment, rather than burns. It can be used as a soil amendment. Char-rich soil, such as the Amazonian “terra preta”, is extremely fertile and stores a very large amount of carbon, indicating that biochar is a potential tool for carbon sequestration. (sources: (source:Wikipedia
High-carbon content material obtained by heating wood or other organic matter in the absence of oxygen. (source:Wiktionary)
Clean Development Mechanism (CDM)
The CDM is one of the two flexible financing provisions under the Kyoto Protocol. It provides opportunities to promote biofuel development in developing countries.
clean energy
Beneficial results of an action or policy in addition to the main goal sought. For example, actions to preserve forests in order to sequester carbon would likely have the co-benefit of conserving wildlife and biodiversity.
See combined heat and power (CHP).
combined heat and power (CHP)
The use of a power station to simultaneously generate both heat and electricity. It allows for more total use of energy than conventional generation, potentially reaching an efficiency of 70-90 percent, compared with approximately 50 percent for the best conventional plants. Also known as cogeneration. W
A chemical reaction between a compound (fuel) and an oxidizing element (oxygen in air) that releases energy in the forms of heat and light. W
compact biogas plant
compressed natural gas (CNG)
Made from compressing purified natural gas (a fossil fuel composed primarily of methane) for storage in hard containers. It is frequently used to power vehicles and is considered a cleaner alternative to more carbonaceous fuels such as diesel or gasoline. W
compression-ignition engines
Also known as diesel engines. Internal combustion engines in which atomized fuel is injected into highly compressed air. The heat and pressure of the compressed air alone causes the fuel to ignite. W
Conservation Reserve Program (CRP) (United States)
Established in 1985 and reauthorized under the 2002 Farm Security and Rural Investment Act (P.L. 107-171); “allows for the enrollment of up to 39.2 million acres of farmland” through “a voluntary program that allow[s] farmers to retire highly erodible land from production” and supports land conservation methods. Elimination of this program may result in currently conserved land reverting to production, including of biofuel feedstocks.(EESI Press Release)
consolidated bioprocessing (CBP)
A strategy for processing cellulosic biomass that involves consolidating four biologically mediated events into a single step: cellulase production, cellulose hydrolysis, hexose fermentation, and pentose fermentation. This kind of processing is facilitated by microorganisms that can simultaneously hydrolyze plant fibers and starches and ferment the resulting sugars. W
conversion efficiency
A measure of how effectively fuel is transformed into usable energy. Each type of fuel is deemed to have a specific energy-producing potential per unit of weight, but some or most of that potential is lost during production or refining. (
conversion technology
A technology that converts biomass into bioenergy or biofuel.
The other products produced when ethanol, biodiesel or other biofuel is produced.
corn gluten
A powdery by-product of the corn-milling process and ethanol production. It is high in protein and has been used as animal feed and as a natural herbicide. (source:
corn grain
A small, dry, one-seeded fruit of the corn plant, having the fruit and the seed walls united. The fruits the corn plant especially after having been harvested, considered as a group. (
Corporate Average Fuel Economy (CAFE)
A U.S. standard that requires light vehicles to achieve a certain average mileage per gallon (3.8 liters) of gasoline. It has been a market driver for the E85 engine. W
crop rotation
diesel fuel
A fuel processed from petroleum that contains a mix of molecules ranging from 12 to 22 carbon atoms (C-12 to C-22), which is designed to run in diesel internal combustion engines.
diesel engine
See compression-ignition engines.
The solid product of anaerobic digestion, which also produces biogas.
An airtight vessel or enclosure in which bacteria decomposes biomass in water to produce biogas. (Source: BFIN)
Dimethyl Ether (DME)
Sometimes called methyl ether or wood ether. A gaseous ether (CH3OCH3) that can be manufactured as a biofuel and used as a substitute for natural gas. W
distiller’s grains
(also known as distillers grains or distillers dried grains) A co-product of dry-milling operations that produce ethanol, DDG is a fibrous, high-protein residue that can be used as food for animals, especially cattle. W
downdraft Gasifier
A gasifier in which the product gases pass through a combustion zone at the bottom of the gasifier. (Source: BFIN)
dry mill
A type of starch-ethanol mill characterized by the method of milling grains prior to fermentation into ethanol. Dried grains are ground and all parts are introduced into the production process. Proteins and fibers are usually extracted after fermentation. W
A mixture of 10% ethanol and 90% gasoline.
A mixture of 85% ethanol and 15% gasoline. (See the Wikipedia entry on E85)
ecosystem services
The liquid or gas discharged from a process or chemical reactor, usually containing residues from that process. (Source: BFIN)
embodied energy
see gray energy.
enclosed compost
energy balance
When comparing fuel production, energy balance is the difference between the energy produced by a 1 kg of the fuel and the energy necessary to produce it ( extraction (e.g. drilling or cultivation of energetic plants), transportation, refining etc). Other factors affect fuel selection, such as portability. See also net energy gain and EROEI. (Source: Wikipedia)
energy content (of fuel)
energy crop
Crops grown and harvested for use as a feedstock in the production of fuels or other energy products. Energy crops are contrasted with conventional food and feed crops. Examples include perennial grasses and short-rotation forestry species and includes “dedicated energy crops”, such as hybrid poplars, willow, miscanthus and sorghum. W[3]
energy density
In energy storage applications, the energy density relates the mass of an energy store to its stored energy. The higher the energy density, the more energy may be stored or transported for the same amount of mass. In the context of fuel selection, the energy density of a fuel is also called the specific energy of that fuel, though in general an engine using that fuel will yield less energy due to inefficiencies and thermodynamic considerations — hence the specific fuel consumption of an engine will be greater than the reciprocal of the specific energy of the fuel. (Source: Wikipedia)
Enzymes are biomolecules that catalyze (i.e. increase the rates of) chemical reactions.(Source: Wikipedia)
In physics and energy economics, EROEI (energy returned on energy invested), or EROI (energy returned on invested), is the ratio between the amount of energy expended to obtain a resource, compared with the amount of energy obtained from that resource. When the EROEI of a resource becomes equal to or lower than 1, that energy source becomes an energy sink and can no longer be used as a primary source of energy. (Source: Wikipedia)
In chemistry, esters are organic compounds in which an organic group replaces a hydrogen atom (or more than one) in an oxygen acid. (Source: Wikipedia)
Esterification is the general name for a chemical reaction in which two chemicals (typically an alcohol and an acid) form an ester as the reaction product. Esterification is used to reduce the fatty acid content of fats or oils so they can be converted into biodiesel. (Sources: Wikipedia, EPA Technology Matrix) (This definition may need work)
ethanol plant
A factory or facility for the mass production of ethanol from biomass or other sources.
ethanol (ethyl alcohol)
CH3CH2OH. A vehicle fuel typically made from fermenting sugar derived from biomass (typically corn, sugar cane, or wheat) that can replace ordinary gasoline in modest percentages (blends) in spark ignition engines or be used in pure form in specially modified vehicles. Nearly all ethanol is produced by fermenting plant sugars and starches (or hydrolyzed cellulose or hemicellulose in the future); however, it can also be produced from fossil feedstock. The mileage per gallon in vehicles yielded by ethanol is roughly two-thirds that of gasoline. W
ethyl ester
An alkyl ester produced by transesterfying ethanol with esters found in animal, vegetable, and waste oils; used as a biodiesel fuel.
ethyl tertiary butyl ether (ETBE)
(CH3)3COC2H. An oxygenate blend stock formed by the catalytic etherification of isobutylene with ethanol.
Shorthand chemical expression for ethanol.
exajoule (EJ)
A unit of energy equal to 1018 joules.
expanded granular sludge bed digestion (EGSB)
extension (agricultural extension)
The provision of technical assistance and information to farmers and others.
fatty acid
A fatty acid is a carboxylic acid often with a long unbranched aliphatic tail (chain), which is either saturated or unsaturated. A low level of fatty acids is necessary for the production of bio-diesel, so any excess fatty acids need to be removed by pre-treatment. (source:Wikipedia and EPA Technology Matrix) (This definition may need some work)
fatty acid methyl ester (FAME)
Another term for biodiesel. W
feedstock (production feedstock)
A material used as a raw material in an industrial process. W
Fermentation can be simply defined as the conversion of sugar molecules into ethanol and carbon dioxide by yeast. Industrial fermentation more loosely refers to the breakdown of organic substances into simpler substances. (Source:Wikipedia)
first-generation biofuels
Biofuels that are in use at the moment, and come from crops such as sugar beet and oil seed rape. (Source: WWF and the EU Biofuels Communication)
Fischer-Tropsch (F-T) process
A biomass-to-liquid (BTL) method of synthesizing hydrocarbons, specifically gasoline and diesel molecules, from syngas. Passes hydrogen and carbon monoxide over a catalyst, either cobalt or iron, at high temperature and pressure. Named after German chemists Franz Fischer (1877-1948) and Hans Tropsch (1889-1935), the process is most often used to create F-T diesel, a fuel for compression-ignition engines. (Source: W) Resulting products are known as “Fischer-Tropsch liquids.”
flex-fuel vehicle (flexible-fuel vehicle)
A vehicle specially designed to run on straight gasoline or any gasoline-ethanol blend up to E85 in temperate climates, and E96 in tropical climates, from a single tank. W
flue gas
The air coming out of a chimney after combustion in the burner it is venting. It can include nitrogen oxides, carbon oxides, water vapor, sulfur oxides, particles and many chemical pollutants. EPA
food-based biofuels
Biofuels produced from biomass that is also fit for human consumptions, such as corn, sugar cane, or soybeans. Usually contrasted with cellulosic biomass which can not be digested by humans.
forest residues
Forest Stewardship Council (FSC)
See page for the Forest Stewardship Council.
fossil energy
Energy produced from fossil fuels such as oil and coal.
fossil fuel equivalent (FFE)
A measure of energy potential from a given fuel or energy source relative to producing that same amount of energy with fossil fuels. W
fossil fuels
A general term for buried combustible geologic deposits of organic materials, formed from decayed plants and animals that have been converted to crude oil, coal, natural gas, or heavy oils by exposure to heat and pressure in the earth’s crust over hundreds of millions of years. EPA
a substance consumed to provide power, especially for an engine.
fuel additive
Any substance added to a fuel to alter its properties.
fuel atomization
A process by which fuel atomizers, such as injectors or jets, deliver fuel in minute droplets to be mixed with air prior to combustion in an engine or turbine. W
fuel Cell vehicle (FCV)
A vehicle propelled by a fuel cell engine using hydrogen as a fuel. (Note that it is possible that on-board reformers can be used to extract the hydrogen from various fuels, such as methane, gasoline, ethanol, etc.) W
fuel ethanol
A process by which a carburetor, fuel injector, heated vaporizer, or mist generator is used to meter ethanol into a vehicle engine’s air-intake manifold. W
gas turbine (GT)
An engine that passes the products of the combustion of its fuel/air mixture over the blades of a turbine. The turbine drives an air compressor, which in turn provides the air for the combustion process. The energy of the combustion products not taken up by the compressor can be used to provide a jet of exhaust gases, or drive another turbine. Gas turbine combined cycle (GTCC). Gas-powered turbines for generating electricity may combine several components into one system to increase overall efficiency. For example, a unit may use heat from gas turbine exhaust to produce steam to turn a second turbine for two-stage power generation. Other components, such as heat recovery steam generators or peripheral electricity generators, may also be added. W
The process of converting biomass to a mixture of carbon monoxide, carbon dioxide, hydrogen, and methane by heating it in oxygen-starved conditions. The resulting syngas can be used either as a fuel for heat and power production or as a feedstock for the synthesis of liquid fuels (see F-T synthesis). W
Also known as E10, is a fuel mixture of 10% ethanol and 90% gasoline that can be used in the internal combustion engine of most modern automobiles.
A liquid fuel for use in internal combustion engines where the fuel-air mixture is ignited by a spark. It consists of a mixture of volatile hydrocarbons derived from the distillation and cracking of petroleum. It normally contains additives such as lead compounds or benzene to improve performance (the prevention of premature ignition) or rust inhibitors. W
gasoline additive
gasoline oxygenator
gas-to-liquid (GTL)
A route of gaseous fuel processing that results in byproducts that can include liquid fuels such as naphta and diesel. The resulting BTL/GTL diesel can be used as a straight fuel or blended with ordinary diesel or biodiesel. W
a clean-burning non-poisonous biobased fuel used for cooking in specially designed stoves.
General Systems of Preferences (GSP)
A trade policy instrument that gives developing countries preferred access to industrialized country markets, generally through lowered tariffs. W
genetically modified crops
Plants whose genetic makeup has been altered using genetic engineering technology that does not involve natural methods of reproduction. Some biomass crops, including sugar cane and corn, have been genetically modified to improve aspects of plant productivity. W
gigajoule (GJ)
A unit of energy equal to 109 joules. W
gigawatt (GW)
A unit of power-generating capacity equal to 109 watts. Needs confirmation
gigawatt-hour (GWh)
A unit of produced energy equal to 109 watt-hours. Needs confirmation
gigawatt-thermal (GWth)
A unit of heat-supply capacity equal to 109 watts-thermal. Needs confirmation
Glycerine (glycerin, glycerol, propane-1,2,3-triol, 1,2,3-propanetriol, 1,2,3-trihydroxypropane, glyceritol, and glycyl alcohol) is the main by-product of making biodiesel. Pure glycerine is a colorless, odorless, hygroscopic, and sweet-tasting viscous liquid. The by-product of bio-diesel is not pure and contains soaps and lye. (source: journeytoforever, Glycerine Wikipedia) (This definition may need work)
grain ethanol
ethanol derived from grain crops (such as corn), as opposed to cellulosic ethanol.
grass fuel pellets
Compressed pellets of a high-energy grass like switchgrass, which can be burned in a pellet stove or furnace as an alternative heating source to oil, gas or electricity. (source:Wikipedia Pellet Fuels Institute)
gray energy/grey energy
the sum of energy from all inputs required for the production of an item; e.g., the production of biofuels such as corn ethanol requires the gray energy associated with the application of fertilizers, the use of farm machinery, etc. According to Wikipedia, gray energy is synonymous with embodied energy.
green charcoal
compressed and carbonized briquets made from agricultural waste, used as a substitute for charcoal.[4]
green chemistry
green diesel
a term loosely used as a stand-in for biodiesel or a specific type of diesel acquired by hydrogenation of vegetable oils.
green fuel
greenhouse gas emissions
emissions of greenhouse gases.
greenhouse gas (GHG)
Gaseous components of the atmosphere that contribute to the greenhouse effect of gases in the Earth’s atmosphere (where increased amounts of solar heat are trapped in the air). Human activity contributes to the greenhouse effect by releasing GHGs such as carbon dioxide, methane, and others. W
green waste
biodegradable waste such as grass trimmings and fallen leaves that can be composted.
carbohydrate structure present in cellulose cell walls, it has a less regular shape than cellulose and is less resistant to being broken up by hydrolysis. W
higher heating value (HHV)
The amount of heat released per unit mass or unit volume of a substance when the substance is completely burned, including the heat of condensation of water vapor to liquid water. W
hybrid reactor
A hybrid reactor is an anaerobic digester that combines a UASB reactor with an anaerobic filter. This combination is an advanced form enabling improved solid retention time in the treatment of waste water. (source:Wikipedia)
A compound containing atoms of only carbon and hydrogen (Source: Wiktionary). Hydrocarbon energy is energy produced from hydrocarbons.
hydrous ethanol
Ethanol containing approximately 4 percent water by volume. W
Hydrous pyrolysis
A biomass refining process that mimics the zero oxygen, pressurized, hot, and aqueous conditions that created petroleum, though in a much shorter time period. The process removes the oxygen from the biomass and yields a solid mineral layer, gaseous fuels, and a liquid biocrude. W
indoor air pollution (IAP)
Pollution occuring indoors, often caused by the burning of traditional biofuels for heating or cooking.
industrial ecology
Industrial ecology is the shifting of industrial process from linear (open loop) systems, in which resource and capital investments move through the system to become waste, to a closed loop system where wastes become inputs for new processes. (source:Wikipedia)
industrial waste
includes pulp/paper and sludge. [5]
installed capacity (installed electrical capacity)
integrated bioenergy center
Any plant or factory that combines a number of different bioenergy technologies in an integrated loop. For example a dairy farm might provide manure, which is converted into biogas to fuel a power plant. Flue gas from the plant would be cleaned by an algae reactor and then the algae solids fed back to the cows. (This definition may need work)
Internal Combustion Engine Vehicle (ICEV)
A vehicle that uses either a compression-ignition or spark ignition engine for propulsion. W
Internal rate of return (IRR)
A financial measure used to evaluate the return on capital investments. W
A “second-generation biofuel that balances high octane content and low vapor pressure”. (Source: Department of Energy [6])
An oilseed crop that grows well on marginal and semi-arid lands. The bushes can be harvested twice annually, are rarely browsed by livestock, and remain productive for decades. W According to Wikipedia, “Jatropha is a genus of approximately 175 succulents, shrubs and trees (some are deciduous, like Jatropha curcas L.), from the family Euphorbiaceae. Plants from the genus natively occur in Africa, North America, and the Caribbean.”[7] It is a feedstock for production of biodiesel.
Joint Implementation (JI)
A mechanism under the Kyoto Protocol designed to encourage GHG emissions reductions or carbon sequestration projects. The mechanism allows an Annex 1 party to implement such projects in other Annex 1 party territories in exchange for emissions reduction credits. W
Joule (J)
The unit of work of energy. Specifically, it is the work done or energy expended by a force of 1 newton action through a distance of 1 meter. W
Kilowatt-hour (KWh)
The kilowatt-hour (symbolized kWh) is a unit of energy equivalent to one kilowatt (1 kW) of power expended for one hour (1 h) of time. The kilowatt-hour is not a standard unit in any formal system, but it is commonly used in electrical applications.
Kilowatt-thermal (KWth)
A unit of heat-supply capacity used to measure the potential output from a heating plant. It represents an instantaneous heat flow and should not be confused with units of produced heat (i.e., KWh(th), or kilowatt-hours-thermal).
life-cycle accounting (LCA)
(This definition may need work)
life-cycle analysis (LCA)
An analysis that examines the environmental impact of a product or process from its inception to the end of its useful life. W
A complex chemical found in woody plants, which binds with cellulose fibers, creating strong cell walls.
lignocellulosic feedstock (lignocellulose)
Biomass feedstock, such as woody materials, grasses, and agricultural and forestry residues, that contains cellulose, hemicellulose, and lignin. It can be broken down in a number of ways to be used as biofuels. W
liquefied natural gas (LNG)
A fossil fuel composed primarily of methane. Purified natural gas turns to liquid at -160 degrees Celsius and is 1/640th the volume of natural gas at standard temperature and pressure, making it easier to transport in specialized cryogenic tanks. W
liquefied petroleum gas (LPG)
A fossil fuel extracted from crude oil and natural gas, comprised principally of propane (C3H8) and butane (C4H10). LPG turns to liquid under moderate pressure and is roughly 1/250th the volume of its gas form. W
liquid fuel
Liquid fuels are those combustible or energy-generating molecules that can be harnessed to create mechanical energy, usually producing kinetic energy; they also must take the shape of their container. (source:Wikipedia)
A measure of a substance’s lubricating qualities, a property of oiliness or slipperiness. Lubricity is a concern for engine systems using liquid fuels, as many components, such as fuel pumps, depend upon fuel for lubrication. W
See also algae.
Manure is organic matter used as fertilizer in agriculture. Manures contribute to the fertility of the soil by adding organic matter and nutrients, such as nitrogen that is trapped by bacteria in the soil. Manure can be a feedstock for various bioenergy technologies, particularly in the production of biogas. (This definition may need work)(source:Wikipedia)
megawatt (MW)
Equal to 1000KW. A unit of power-generating capacity. It represents an instantaneous power flow. It is distinct from units of produced energy, i.e. megawatt-hours. W
megawatt-hour (MWh)
1000 KWh (See Kilowatt-hour).
megawatt-thermal (MWth)
1000 KWth (See Kilowatt-thermal).W
The simplest hydrocarbon, methane, is a gas (at standard temperature and pressure, STP) with a chemical formula of CH4. Methane is the principal component of natural gas and biogas. (source:Wikipedia)
CH3OH. A simple alkyl also known as methyl alcohol. (W) Also known as wood alcohol.
methyl ester
Another term for biodiesel. W
methyl tertiary butyl ether (MTBE)
A common oxygenate added to gasoline to help combustion and reduce emissions of carbon monoxide and troposheric ozone. MTBE is highly water soluble and has been found to contaminate groundwater. The World Health Organization has identified MTBE as a carcinogen. W
See also algae.
Also known as elephant grass. A tropical and sub-tropical hardy perennial grass species that originated in Asia and Africa. It is a promising source of biomass due to its high rates of growth. W
multi-stakeholder process
A multi-stakeholder process seeks to bring together all the major stakeholders on a certain issue for communication and decision-finding on that issue.
multiple-use crops
Crops that can be used for a variety of purposes, including as human food, animalfeed, material inputs for products, and energy (in the form of heat or electricity, or stored in liquid biofuels). W
modern biofuels
A term used to distinguish processed biofuels like ethanol and biodiesel from ‘traditional biofuels’, like dung or wood, which are usually burned in an unprocessed state to provide heat and energy. (This definition may need work)
modular biomass systems (SMB)
The term SMB refers to a broad range of biopower systems of 1-5 MWe in size. They can use a variety of conversion technologies and feedstocks. Some may be small enough to be portable, while others, though still smaller than a full-scale plant, are fixed. (This definition may need work.)
the practice of growing one crop over a wide area
municipal solid waste (MSW)
Total waste excluding industrial waste, agricultural waste, and sewage sludge, including durable goods, non-durable goods, containers and packaging, food wastes, yard wastes, and miscellaneous inorganic wastes from residential, commercial, institutional, and industrial sources. Waste-to-energy combustion and landfill gas are byproducts of municipal solid waste. W

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