Biodiesel and Ethanol Glossary For Biofuels

Acid - Any of a class of substances whose aqueous solutions are characterized by a sour taste, the ability to turn blue litmus red, and the ability to react with bases and certain metals to form salts. A substance that yields hydrogen ions when dissolved in water. A substance that can act as a proton donor.

Acid Detergent Fiber (ADF) - Organic matter that is not solubilized after 1 hour of refluxing in an acid detergent of cetyltrimethylammonium bromide in 1N sulfuric acid. ADF includes cellulose and lignin. This analytical method is commonly used in the feed and fiber industries.

Acid Hydrolysis - A chemical process in which acid is used to convert cellulose or starch to sugar.

Acid Insoluble Lignin - Lignin is mostly insoluble in mineral acids, and therefore can be analyzed gravimetrically after hydrolyzing the cellulose and hemicellulose fractions of the biomass with sulfuric acid. ASTM E-1721-95 describes the standard method for determining acid insoluble lignin in biomass.

Acid Soluble Lignin - A small fraction of the lignin in a biomass sample is solubilized during the hydrolysis process of the acid insoluble lignin method. This lignin fraction is referred to as acid soluble lignin and may be quantified by ultraviolet spectroscopy. See lignin and acid insoluble lignin.

AGE 85 - Aviation Grade Ethanol used in piston engine aircraft. This fuel contains 85 percent ethanol along with light hydrocarbons and biodiesel fuel.

Agitator - A device such as a stirrer that provides complete mixing and uniform dispersion of all components in a mixture. Agitators are generally used continuously during the cooking process and intermittently during fermentation.

Agricultural Residue - Agricultural crop residues are the plant parts, primarily stalks and leaves, not removed from the fields with the primary food or fiber product. Examples include corn stover (stalks, leaves, husks, and cobs); wheat straw; and rice straw.

Air Quality Maintenance Area - Specific populated area where air quality is a problem for one or more pollutants.

Alcohol - A general class of hydrocarbons that contain a hydroxyl group (OH). The term "alcohol" is often used interchangeably with the term "ethanol," even though there are many types of alcohol. (See Butanol, Ethanol, Methanol.)

Aldoses - Occur when the carbonyl group of a monosaccharide is an aldehyde.

Aliphatic - Any non-aromatic organic compound having an open chain structure.

Alkali - A soluble mineral salt.

Alkali Lignin - Lignin obtained by acidification of an alkaline extract of wood.

Alloy - Any large number of substances having metallic properties and consisting of two or more elements; with few exceptions, the components are usually metallic elements.

Alternative Fuel - As defined in the Energy Policy Act of 1992 (EPACT): Methanol, denatured ethanol and other alcohols, separately or in blends of at least 10 percent by volume with gasoline or other fuels; compressed natural gas; liquefied natural gas, liquefied propane gas, hydrogen, coal derived liquid fuels, fuels other than alcohols derived from biological materials, electricity, biodiesel, and any other fuel deemed to be substantially not petroleum and yielding potential energy security benefits and substantial environmental benefits.

Ambient Air Quality - The condition of the air in the surrounding environment.

American Society for Testing and Materials (ASTM) - An international voluntary standards organization that develops and produces technical standards for materials, products, systems and services.

Anaerobic - Life or biological processes that occur in the absence of oxygen.

Anaerobic Digestion - A biochemical process by which organic matter is decomposed by bacteria in the absence of oxygen, producing methane and other byproducts.

Anhydrous - A compound that does not contain water.

Aquatic Plants - The wide variety of aquatic biomass resources, such as algae, giant kelp, other seaweed, and water hyacinth. Certain microalgae can produce hydrogen and oxygen while others manufacture hydrocarbons and a host of other products. Microalgae examples include Chlorella, Dunaliella, and Euglena.

Arabinan - The polymer of arabinose with a repeating unit of C5H804. Can be hydrolyzed to arabinose.

Arabinose - A five-carbon sugar C5H1005. A product of hydrolysis of arabinan found in the hemicellulose fraction of biomass.

Aromatic - Any organic compound containing de-localized electrons in a ring structure - e.g. benzene and benzoic acid. Aromatics have strong, characteristic odors.

Atmospheric Pressure - Pressure of the air and atmosphere surrounding us which changes from day to day. It is equal to 14.7 psia.

Attainment Area - A geographic region where the concentration of a specific air pollutant does not exceed federal standards.

Auger - A rotating, screw-type device that moves material through a cylinder.

Available Production Capacity - The biodiesel production capacity of refining facilities that are not specifically designed to produce biodiesel.

Average Megawatt (MWa or aMW) - One megawatt of capacity produced continuously over a period of one year. 1 aMW = 1 MW x 8760 hours/year = 8,760 MWh = 8,760,000 kWh.

B100 - B100 indicates that the biodiesel is pure biodiesel since it is 100% biodiesel. See “Biodiesel Blend” for explanation of “B” and “100”.

Background Level - The average amount of a substance present in the environment. Originally referring to naturally occurring phenomena. Used in toxic substance monitoring.

Backup Rate - A utility charge for providing occasional electricity service to replace on-site generation.

Backup Electricity - Power or services needed occasionally; for example, when on-site generation equipment fails.

Baffle Chamber - In incinerator design, a chamber designed to settle fly ash and coarse particulate matter by changing the direction and reducing the velocity of the combustion gases.

Bark - The outer protective layer of a tree outside the cambium comprising the inner bark and the outer bark. The inner bark is a layer of living bark that separates the outer bark from the cambium and in a living tree is generally soft and moist. The outer bark is a layer of dead bark that forms the exterior surface of the tree stem. The outer bark is frequently dry and corky.

Barrel of Oil Equivalent - A unit of energy equal to the amount of energy contained in a barrel of crude oil. Approximately 5.78 million Btu or 1,700 kWh. One barrel equals 5.6 cubic feet or .159 cubic meters; for crude oil, one barrel is about .136 metric tons, .134 long tons, and .150 short tons. A barrel is a liquid measure equal to 42 gallons or about 306 pounds.

Base - A classification of substances which when combined with an acid will form a salt plus water, usually producing hydroxide ions when dissolved.

Baseload Capacity - The power output that generating equipment can continuously produce.

Baseload Demand - The minimum demand experienced by an electric utility, usually 30-40 percent of the utility´s peak demand.

Batch Distillation - A process in which the liquid feed is placed in a single container and the entire volume is heated, in contrast to continuous distillation in which the liquid is fed continuously through the still.

Batch Fermentation - Fermentation conducted from start to finish in a single vessel.

Batch Process - Unit operation where one cycle of feedstock preparation, cooking, fermentation and distillation is completed before the next cycle is started.

Beer - A general term for all fermented malt beverages flavored with hops. A low level (6 to 12 percent) alcohol solution derived from the fermentation of mash by microorganisms.

Beer Still - The stripping section of a distillation column for concentrating ethanol.

Benzene - A toxic, six-carbon aromatic component of gasoline. A known carcinogen.

Biochemical Conversion Process - The use of living organisms or their products to convert organic material to fuels, chemicals or other products.

Biochemical Oxygen Demand (BOD) - A standard means of estimating the degree of water pollution, especially of water bodies that receive contamination from sewage and industrial waste. BOD is the amount of oxygen needed by bacteria and other microorganisms to decompose organic matter in water. The greater the BOD, the greater the degree of pollution. Biochemical oxygen demand is a process that occurs over a period of time and is commonly measured for a five-day period, referred to as BOD5.

Bioconcentration (Bioaccumulation) - The accumulation of a chemical in tissues of an organism to levels greater than in the environment in which the organism lives.

Biodegradable - Capable of decomposing rapidly under natural conditions.

Biodiesel - Refers to a diesel-equivalent, processed fuel derived from biological sources. Though derived from biological sources, it is a processed fuel that can be readily used in diesel engined vehicles, which distinguishes biodiesel from the straight vegetable oils (SVO) or waste vegetable oils (WVO) used as fuels in some modified diesel vehicles.

Biodiesel Blend - Blend of biodiesel and diesel fuels. The blend can be with Diesel #1, Diesel #2, or JP8. One standard blend that meets the minimum requirements of the federal EPA Clean Air Act criteria is B20. The number after "B" indicates the percentage of biodiesel included in the blend. In B20, there would be 20 percent biodiesel and 80 percent diesel in the fuel blend. A biodiesel blend can come in any mixture percentage, i.e., B2, B5, B50, B85, and so on.

Bioenergy - Renewable energy produced from organic matter. The conversion of the complex carbohydrates in organic matter to energy. Organic matter may either be used directly as a fuel or processed into liquids or gases.

Biofuel - Alcohols, esters, ethers, and other chemicals (biodiesel, ethanol, and methane) made from cellulosic biomass sources or organic matter (herbaceous and woody plants, animal fats, agricultural and forest waste, or municipal solid and industrial waste) within an active carbon cycle. Production and combustion of biofuels take and replenish the CO² in a circular, sustainable fashion. These fuels are used for stationary and mobile applications, i.e., electricity and transportation. Two commonly used biofuels are ethanol and biodiesel.

Biogas - A combustible gas derived from decomposing biological waste. Biogas normally consists of 50 to 60 percent methane.

Bioheat - A name sometimes applied to biodiesel when its application is for heating purposes.

Biological Assessment - A specific process required as part of an environmental assessment. An evaluation of potential effects of a proposed project on proposed, endangered, threatened and sensitive animal and plant species and their habitats.

Biological Oxidation - Decomposition of organic materials by microorganisms.

Biomass - Renewable organic matter such as agricultural crops and residue, wood and wood waste, animal waste, aquatic plants and organic components of municipal and industrial wastes.

Biomass Fuel - Liquid, solid or gaseous fuel produced by conversion of biomass.

Biomass Processing Residues - Byproducts from processing all forms of biomass that have significant energy potential. For example, making solid wood products and pulp from logs produces bark, shavings and sawdust, and spent pulping liquors. Because these residues are already collected at the point of processing, they can be convenient and relatively inexpensive sources of biomass for energy.

Bio-Naphtha - A term used in some eastern European nations for biodiesel.

Biosphere - The portion of the Earth and its atmosphere that can support life.

Biotechnology - Technology that use living organisms to produce products such as medicines, to improve plants or animals, or to produce microorganisms for bioremediation.

Biotic - Pertaining to life or living organisms.

BOD5 - The amount of dissolved oxygen consumed in five days by biological processes breaking down organic matter. See biochemical oxygen demand.

Boiler - Any device used to burn biomass fuel to heat water for generating steam.

Boiler Horsepower - A measure of the maximum rate of heat energy output of a steam generator. One boiler horsepower equals 33,480 Btu/hr output in steam.

Brewing - Generically, the entire beer-making process, but technically only the part of the process during which the beer wort is cooked in a brew kettle and during which time the hops are added. After brewing the beer is fermented.

British Thermal Unit (BTUs) - A quantitative measure of heat equivalent to the amount of heat required to raise 1 pound of water by 1 degree Fahrenheit.

Brown Grease - Waste grease that is the least expensive of the various grades of waste grease.

Bubble-Cap Trays - Cross flow trays usually installed in rectifying columns handling liquids free of suspended solids. The bubble caps consist of circular cups inverted over small vapor pipes. The vapor from the tray below passes through the vapor pipes into the caps and curves downward to escape below the rim into the liquid. The rim of each cap is slotted or serrated to break up the escaping vapor into small bubbles, thereby increasing the surface area of the vapor as it passes through the liquid.

Bubble Wash - A method of final washing of biodiesel through air agitation. Biodiesel floats above a quantity of water. Bubbles from an aquarium air pump and air stone are injected into the water causing the bubbles to rise. At the water/biodiesel interface, the air bubbles carry water up through the biodiesel by surface tension. Simple diffusion causes water soluble impurities in the biodiesel to be extracted into the water. As the bubble reaches the surface and breaks, the water is freed and percolates back down through the biodiesel again.

Bulk Density - Weight per unit of volume, usually specified in pounds per cubic foot.

Bureau of Alcohol, Tobacco, and Firearms (BATF) - under the U.S. Department of Treasury. Responsible for the issuance of permits, both experimental and commercial, for the production of alcohol.

Butane - A gas derived from natural gas. Used as a component of gasoline. Used in liquefied petroleum gas (LPG) for domestic and industrial applications.

Butanol or Butyl Alcohol - An alcohol with the chemical formula CH3(CH2)3OH. It is formed during anaerobic fermentation using bacteria to convert the sugars to butanol and carbon dioxide.

Capacity - The maximum power that a machine or system can produce or carry safely. The maximum instantaneous output of a resource under specified conditions. The capacity of generating equipment is generally expressed in kilowatts or megawatts.

Capacity Factor - The amount of energy that a power plant actually generates compared to its maximum rated output, expressed as a percentage.

Capital Cost - The total investment needed to complete a project and bring it to a commercially operable status. The cost of construction of a new plant. The expenditures for the purchase or acquisition of existing facilities.

Carbohydrate - A chemical compound made up of carbon, hydrogen, and oxygen. Includes sugars, cellulose, and starches.

Carbon Chain - The atomic structure of hydrocarbons in which a series of carbon atoms, saturated by hydrogen atoms, form a chain. Volatile oils have shorter chains. Fats have longer chain lengths, and waxes have extremely long chains.

Carbon Dioxide (CO2) - A product of combustion. The most common greenhouse gas.

Carbon Monoxide (CO) - A colorless, odorless gas produced by incomplete combustion. Carbon monoxide is poisonous if inhaled.

Carbon Sequestration - The absorption and storage of carbon dioxide from the atmosphere. Naturally-occurring in plants.

Carboxyl - The univalent radical, COOH, the functional group characteristic of all organic acids.

Catalyst - A substance which without itself undergoing any permanent chemical change, facilitates or enables a reaction between other substances.

Cellulase - Enzymes that act to degrade cellulose. Cellulases are produced commonly by fungal and microbial organisms.

Cellulose - The carbohydrate that is the principal constituent of wood and other biomass and forms the structural framework of the wood cells. It is a polymer of glucose with a repeating unit of C6H10O5 strung together by ß-glycosidic linkages. The ß-linkages in cellulose form linear chains that are highly stable and resistant to chemical attack because of the high degree of hydrogen bonding that can occur between chains of cellulose. Hydrogen bonding between cellulose chains makes the polymers more rigid, inhibiting the flexing of the molecules that must occur in the hydrolytic breaking of the glycosidic linkages. Hydrolysis can reduce cellulose to a cellobiose repeating unit, C12H22O11, and ultimately to glucose, C6H12O6. Heating values for cellulose may be slightly different based upon the feedstock.

Cetane Number - Measure of fuel ignition characteristics. Like the octane number used for gasoline, the higher the value, the better the fuel performance. A higher cetane number correlates with improved combustion, improved cold starting, reduced noise, white smoke, hydrocarbons, carbon monoxide and particulate emissions particularly during early warm-up phase. The EPA uses this parameter as a measure of aromatic content in fuel.

CFM - Cubic Feet per Minute.

Chips - Small fragments of wood chopped or broken by mechanical equipment. Total tree chips include wood, bark, and foliage. Pulp chips or clean chips are free of bark and foliage.

Chlorofluorocarbon - A family of chemicals composed primarily of carbon, hydrogen, chlorine, and fluorine. Used principally as refrigerants and industrial cleansers. Chlorofluorocarbons have the tendency to destroy the Earth’s protective ozone layer.

Clarifier - A tank used to remove solids by gravity, to remove colloidal solids by coagulation, and to remove floating oil and scum through skimming.

Class I Area - Any area designated for the most stringent protection from air quality degradation.

Class II Area - Any area where air is cleaner than required by federal air quality standards and designated for a moderate degree of protection from air quality degradation. Moderate increases in new pollution may be permitted in Class II areas.

Clean Air Act (CAA) - National law establishing ambient air quality emission standards to be implemented by participating states. Originally enacted in 1963, the CAA has been amended several times, most recently in 1990. The CAA includes vehicle emission standards regulating the emission of criteria pollutants (lead, ozone, carbon monoxide, sulfur dioxide, nitrogen oxides and particulate matter). The 1990 amendments added reformulated gasoline (RFG) requirements and oxygenated gasoline provisions.

Clean Fuels - Fuels such as E-10 Unleaded that burn cleaner and produce fewer harmful emissions compared to ordinary gasoline.

Cloud Point - The temperature at which the first wax crystals appear and a standardized ASTM test protocol is used to determine this temperature.

Code of Federal Regulations (CFR) - Federal regulations published by the Office of the Federal Registrar, National Archives, and Records Service of the General Services Administration.

Cogeneration - The sequential production of electricity and useful thermal energy from a common fuel source.

Coking – The formation of harmful carbon deposits on internal components of diesel engines.

Column - A vertical, cylindrical vessel used to increase the degree of separation of liquid mixtures by distillation or extraction.

Colloid - A stable system of small particles dispersed in something else. A multi-phase system in which one dimension of a dispersed phase is of colloidal size. Colloids are the liquid and solid forms of aerosols, foams, emulsions, and suspensions within the colloidal size class. Milk and smoke are both colloids. Colloidal size is typically.001 micron to 1 micron in any dimension. Dispersions where the particle size is in this range are referred to as colloidal aerosols, colloidal emulsions, colloidal foams, or colloidal suspensions.

Colza - Eurasian plant cultivated for its seed and as a forage crop.

Combustion Burning - The transformation of biomass fuel into heat, chemicals, and gases through chemical combination of hydrogen and carbon in the fuel with oxygen in the air.

Combustion Gases - The gases released from a combustion process.

Compound - A chemical term denoting a combination of two or more distinct elements.

Compressed Natural Gas (CNG) - Natural gas that has been compressed under high pressure (typically 2000 to 3600 psi).

Compression-Ignition Engine - An engine in which the fuel is ignited by high temperature caused by extreme pressure in the cylinder, rather than by a spark from a spark plug. Diesel engines are compression-ignition engines.

Concentration - The ratio of mass or volume of solute present in a solution to the amount of solvent. The quantity of ethyl alcohol (or sugar) present in a known quantity of water.

Condenser - A heat-transfer device that reduces a fluid from a vapor phase to a liquid phase.

Conditional Use Permit - A permit, with conditions, allowing an approved use on a site outside the appropriate zoning class.

Conservation - Efficiency of energy use, production, transmission, or distribution that results in a decrease of energy consumption while providing the same level of service.

Continuous Fermentation - A steady state fermentation system that operates without interruption; each stage of fermentation occurs in a separate section of the fermenter, and flow rates are set to correspond with required residence times.

Continuous-Flow Process - A general term for any number of biodiesel production processes that involves the continuous addition of ingredients to produce biodiesel on a continual, round-the-clock basis, as opposed to the batch process.

Conversion Efficiency - A comparison of the useful energy output to the potential energy contained in the fuel. The efficiency calculation relates to the form of energy produced. A direct comparison of the efficiency of different conversion processes can be made only when the processes produce the same form of energy output.

Cooker - A tank or vessel designed to cook a liquid or extract or digest solids in suspension; the cooker usually contains a source of heat; and is fitted with an agitator.

Cooking - The process that breaks down the starch granules in the grain. This process makes the starch available for the liquefaction and saccharification steps.

Co-Products - The resulting substances and materials that accompany the production of ethanol by fermentation process. Depending on the type of ethanol facility, co-products can include livestock feed, corn sweeteners, corn oil, carbon dioxide and other value-added products.

Corn Stover - Residue materials from harvesting corn consisting of the cob, leaves and stalk.

Council on Environmental Quality (CEQ) - An advisory council to the President established by the National Environmental Policy Act of 1969. The CEQ reviews federal programs for their effect on the environment, conducts environmental studies, and advises the President on environmental matters.

Cross Flow Trays - Liquid flows across the tray and over a weir to a downcomer that carries it to the next lower tray. Vapors rise from the bottom of the column to the top passing through the tray openings and the pools of cross flowing liquid.

Deaeration - Removal of gases from a liquid.

Dedicated Production - The biodiesel production capabilities of refining facilities that are specifically designed to produce biodiesel.

Denatured - Ethanol that has had a substance added to make it unfit for human consumption.

Dewatering - To remove the free water from a solid substance.

Diesel #1 and Diesel #2 - Diesel #1 is also called kerosene and is not generally used as a fuel oil in diesel vehicles. Diesel #1 has a lower viscosity (it is thinner) than Diesel #2. Diesel #2 is the typical diesel vehicle fuel. Biodiesel replaces Diesel #2 or a percentage.

Diester - The French term for biodiesel, from the contraction of the words diesel and ester.

Digester - An airtight vessel or enclosure in which bacteria decomposes biomass in water to produce biogas.

Dioxin - A family of compounds, some of which are hazardous, that result from combustion of carbon materials. The most toxic of these compounds is 2, 3, 7, 8-tetrachlorodibenzo-p-dioxin.

Direct-Injection Engine - A diesel engine in which the fuel is injected directly into the cylinder. Most new diesel engines have direct injection (DI).

Dispersion - A stable or unstable system of fine particles, larger than colloidal size, evenly distributed in a medium.

Distillate Oil - Any distilled product of crude oil. A light petroleum product used for home heating and most machinery.

Distillation - The process to separate the components of a liquid mixture by boiling the liquid and then recondensing the resulting vapor.

Distillers´ Dried Grains (DDG) - The dried byproduct of the grain fermentation process. Typically used as a high-protein animal feed.

Distribution - The transfer of electricity from the transmission network to the consumer.

Draft Environmental Impact Statement (DEIS) - A draft statement of environmental effects. Section 102 of the National Environmental Policy Act requires a DEIS for all major federal actions. The DEIS is released to the public and other agencies for comment and review.

Dried Distillers Grains (DDG) - A co-product of dry mill ethanol production that is fed to livestock. May also be referred to as DDGS (dried distillers grains with solubles or even distillers’ dried grains).

Dry Mill - An ethanol production process in which the entire corn kernel is first ground into flour before processing. In addition to ethanol, dry mills also produce dried distillers grains with solubles (DDGS) which is fed to livestock; and carbon dioxide which is used in food processing and bottling. Most new ethanol plants are dry mill facilities.

Dry Ton - 2,000 pounds of material dried to a constant weight.

E10 Unleaded - Ordinary unleaded gasoline enhanced with ethanol, which is blended at a rate of ten percent. E-10 Unleaded is approved for use by every major automaker in the world.

E85 - A blend of 15 percent gasoline and 85 percent denatured ethanol by volume.

Ecology - The study of the interrelationships between organisms and their environment. From the Greek word “oikos”, meaning “house”.

E Diesel - A blend of ethanol and diesel fuel plus other additives designed to reduce air pollution from heavy equipment, city buses and other vehicles that operate on diesel engines.

Effluent - The treated waste water discharged by sewage treatment plants.

Electricity - Electric current used as a power source.

Elemental Analysis - The determination of carbon, hydrogen, nitrogen, oxygen, sulfur, chlorine and ash in a sample.

Emission Offset - A reduction in the air pollution emissions of existing sources to compensate for emissions from new sources.

Emissions - Waste substances released into the air or water.

Emulsion - A usually unstable dispersion of two liquids which do not normally mix (they are immiscible). Emulsions can be formed either by mechanical agitation, or by chemical processes. Unstable emulsions will separate over time or temperature, stable emulsions will not separate.

Energy Crops - Crops grown specifically for their fuel value. These include food crops such as corn and sugarcane and nonfood crops such as poplar trees and switchgrass. Currently, two energy crops are under development in the United States: short-rotation woody crops, which are fast-growing hardwood trees harvested in 5 to 8 years, and herbaceous energy crops, such as perennial grasses, which are harvested annually after taking 2 to 3 years to reach full productivity.

Energy Efficiency Ratio – A numerical figure that represents the energy stored in a fuel compared to the total energy required to produce, manufacture, transport, and distribute it.

Environment - The external conditions that affect organisms and influence their development and survival.

Environmental Assessment (EA) - A public document that analyzes a proposed federal action for the possibility of significant environmental impacts. The analysis is required by the National Environmental Policy Act. If the environmental impacts will be significant, the federal agency must then prepare an environmental impact statement.

Environmental Impact Statement (EIS) - A statement of the environmental effects of a proposed action and of alternative actions. Section 102 of the National Environmental Policy Act requires an EIS for all major federal actions.

Enzymatic Hydrolysis - A process by which enzymes (biological catalysts) are used to break down starch or cellulose into sugar.

EP Toxicity - A test defined by the federal Environmental Protection Agency to check a substance for the presence of arsenic, barium, cadmium, chromium, lead, mercury, selenium, or silver. 40 CFR 261.24 defines the concentrations constituting hazardous waste and the test procedure.

Ester - A classification of organic compounds occurring naturally as oils and fats, produced by replacing the hydrogen of an acid by an alkyl, aryl, radical. A compound of an organic acid bonded via an ester bond to an alcohol. Any of a large group of organic compounds formed when an acid and alcohol is mixed. CH3COOCH3 (Methyl acetate) is the simplest ester.

Ethanol - Ethyl alcohol produced by fermentation and distillation. An alcohol compound with the chemical formula CH3CH20H formed during sugar fermentation by yeast. Grain alcohol.

Ethyl Ester - Biodiesel that is made with the use of ethanol in its production process.

Ethyl Tertiary Butyl Ether (ETBE) - An ether similar to MTBE. ETBE is manufactured by reacting ethanol with isobutylene. ETBE has high octane and low volatility characteristics. Used as an oxygenate.

Evaporation - The conversion of a liquid to the vapor state by the addition of latent heat or vaporization.

Extractives - Any number of different compounds in biomass that are not an integral part of the cellular structure. The compounds can be extracted from wood by means of polar and non-polar solvents including hot or cold water, ether, benzene, methanol, or other solvents that do not degrade the biomass structure. The types of extractives found in biomass samples are entirely dependent upon the sample itself.

Fast Pyrolysis - Thermal conversion of biomass by rapid heating to between 842 degrees to 1,112 degrees Fahrenheit (450 degrees to 600 degrees Celsius) in the absence of oxygen.

Fat - A classification of natural esters of glycerol, and fatty acids existing as solids at room temperature.

Fatty Acid - A carboxylic acid (or organic acid), often with a long aliphatic tail (long chains), either saturated or unsaturated.

Fatty Acid Alkyl Ester (FAAE) - A term for biodiesel made from any alcohol during its production process.

Fatty Acid Methyl Ester (FAME) - A term for biodiesel made from methanol during its production process.

Federal Water Pollution Control Act - A federal regulatory law administered by the states. The act created the National Pollution Discharge Elimination System.

Feedstock - Any material that can be converted to another form of fuel or energy product.

Fermentation - The biological conversion of biomass by yeast or sugar. The products of fermentation are carbon dioxide and alcohol.

Finding of No Significant Impact (FONSI) - A document describing the reasons why the impacts of a proposed federal action are not significant. Required by the National Environmental Policy Act after an environmental assessment when a federal agency is not preparing an environmental impact statement.

Fischer-Tropsch Fuels - Liquid hydrocarbon fuels produced by a process that combines carbon monoxide and hydrogen. The process is used to convert coal, natural gas and low-value refinery products into a high-value diesel substitute fuel.

Fixed Carbon - The carbon remaining after heating in a prescribed manner to decompose thermally unstable components and to distill volatiles. Part of the proximate analysis group.

Flashpoint - The lowest temperature at which a liquid will produce enough vapor to ignite, if the vapor is flammable.

Flexible-Fuel Vehicle - A vehicle with a single fuel tank designed to run on varying blends of unleaded gasoline with either ethanol or methanol.

Flow Rate - The amount of fluid that moves through an area (usually pipe) in a given period of time.

Fluidized-Bed Boiler - A large, refractory-lined vessel with an air distribution member or plate in the bottom, a hot gas outlet in or near the top, and some provisions for introducing fuel. The fluidized bed is formed by blowing air up through a layer of inert particles (such as sand or limestone) at a rate that causes the particles to go into suspension and continuous motion. The super-hot bed material increased combustion efficiency by its direct contact with the fuel.

Fluorinated Polyethylene/Polypropylene - Two types of plastic that have been specially modified to withstand certain chemicals, including biodiesel.

Forestry Residues - Includes tops, limbs, and other woody material not removed in forest harvesting operations in commercial hardwood and softwood stands, as well as woody material resulting from forest management operations such as pre-commercial thinning and removal of dead and dying trees.

Fossil fuel - Solid, liquid or gaseous fuels formed in the ground after millions of years by chemical and physical changes in plant and animal residues under high temperature and pressure. Oil, natural gas and coal are fossil fuels.

Free Fatty Acids - Fatty acid hydrocarbon chains detached from other molecules.

Fuel - Any material that can be converted to energy.

Fuel Cycle - The series of steps required to produce electricity. The fuel cycle includes mining or otherwise acquiring the raw fuel source, processing and cleaning the fuel, transport, electricity generation, waste management and plant decommissioning.

Galactan - The polymer of galactose with a repeating unit of C6H10O5. Found in hemicellulose it can be hydrolyzed to galactose.

Galactose - A six-carbon sugar with the formula C6H1206. A product of hydrolysis of galactan found in the hemicellulose fraction of biomass.

Gas Engine - A piston engine that uses natural gas rather than gasoline. Fuel and air are mixed before they enter cylinders; ignition occurs with a spark.

Gaseous Emissions - Substances discharged into the air during combustion, typically including carbon dioxide, carbon monoxide, water vapor, and hydrocarbons.

Gas Shift Process - A process in which carbon monoxide and hydrogen react in the presence of a catalyst to form methane and water.

Gas Turbine - (combustion turbine) A turbine that converts the energy of hot compressed gases (produced by burning fuel in compressed air) into mechanical power. Often fired by natural gas or fuel oil.

Gasification - A chemical or heat process to convert a solid fuel to a gaseous form.

Gasifier - A device for converting solid fuel into gaseous fuel. In biomass systems, the process is also referred to as pyrolitic distillation.

Gasohol - A motor vehicle fuel which is a blend of 90 percent unleaded gasoline with 10 percent ethanol (by volume). This term was used in the late 1970s.

Gasoline - A volatile, flammable liquid obtained from petroleum that has a boiling range of approximately 86-428 degrees Fahrenheit (30-220 degrees Celsius) and is used for fuel for spark-ignition internal combustion engines.

Gel Point - The point at which a liquid fuel gels (changes to the consistency of petroleum jelly) due to extremely low temperature.

Generator - A machine used for converting rotating mechanical energy to electrical energy.

Glucan - The polymer of glucose with a repeating unit of C6H10O5. Cellulose is a form of glucan. Can be hydrolyzed to glucose.

Glucose - A simple six-carbon sugar C6H12O6. A product of hydrolysis of glucan found in cellulose and starch. A sweet, colorless sugar that is the most common sugar in nature and the sugar most commonly fermented to ethanol.

Glycerin (Glycerol) - A sweet syrupy trihydroxy alcohol obtained by saponification of fats and oils

Greenhouse Effect - A warming of the Earth and its atmosphere caused by greenhouse gases and water vapor trapping heat from the sun.

Greenhouse Gases - Gases that trap the heat of the sun in the Earth´s atmosphere, producing the greenhouse effect. The two major greenhouse gases are water vapor and carbon dioxide. Other greenhouse gases include methane, ozone, chlorofluorocarbons, and nitrous oxide.

Grid - An electric utility´s system for distributing power.

Grid Connection - Joining a plant that generates electric power to a utility system so that electricity can flow in either direction between the utility system and the plant.

Gross Heating Value (GHV) - The maximum potential energy in the fuel as received, considering moisture content (MC). It reflects the heat used to evaporate moisture.

Guaiacyl - A chemical component of lignin. It has a six-carbon aromatic ring with one methoxyl group attached. It is the predominant aromatic structure in softwood lignins.

Gum Number - The measure of the tendency of a fuel to form gums via oxidation.

Hardwood - One of the botanical groups of dicotyledonous trees that have broad leaves in contrast to the conifers or softwoods. The term has no reference to the actual hardness of the wood. The botanical name for hardwoods is angiosperms. Short-rotation, fast growing hardwood trees are being developed as future energy crops. They are uniquely developed for harvest from 5 - 8 years after planting. Examples include: Hybrid poplars (Populus sp.), Hybrid willows (Salix sp.), Silver maple (Acer saccharinum), and Black locust (Robinia pseudoacacia).

Heat Exchanger - A unit that transfers heat from one liquid (or vapor) to another without mixing the fluids. A condenser is one type of heat exchanger.

Heat Rate - The amount of fuel energy required by a power plant to produce one kilowatt-hour of electrical output. A measure of generating station thermal efficiency, generally expressed in Btu per net kWh. It is computed by dividing the total Btu content of fuel burned for electric generation by the resulting net kWh generation.

Heating Value - Higher heating value (HHV) is the potential combustion energy when water vapor from combustion is condensed to recover the latent heat of vaporization. Lower heating value (LHV) is the potential combustion energy when water vapor from combustion is not condensed.

Hectare - An area equal to 2.47 acres. There are 100 hectares in 1 square kilometer.

Hemicellulose - Hemicellulose consists of short, highly branched chains of sugars. In contrast to cellulose, which is a polymer of only glucose, a hemicellulose is a polymer of five different sugars. It contains five-carbon sugars (usually D-xylose and L-arabinose) and six-carbon sugars (D-galactose, D-glucose, and D-mannose) and uronic acid. The sugars are highly substituted with acetic acid. The branched nature of hemicellulose renders it amorphous and relatively easy to hydrolyze to its constituent sugars compared to cellulose. When hydrolyzed, the hemicellulose from hardwoods releases products high in xylose (a five-carbon sugar). The hemicellulose contained in softwoods, by contrast, yields more six-carbon sugars.

Herbaceous Energy Crops - Perennial non-woody crops that are harvested annually, though they may take 2 to 3 years to reach full productivity. Examples include: Switchgrass (Panicum virgatum), Reed canarygrass (Phalaris arundinacea), Miscanthus (Miscanthus x giganteus), and Giant reed (Arundo donax).

Herbaceous Plants - Non-woody species of vegetation, usually of low lignin content such as grasses.

Hexose - Any of various simple sugars that have six carbon atoms per molecule (e.g. glucose, mannose, and galactose.)

High Compression Ignition Engine - Also known as a Diesel engine. Unlike gasoline engines which use a spark plug to ignite the fuel, there is no external ignition spark in a high compression engine. Air is compressed, driving its temperature up to a point that it ignites fuel which has been injected into the chamber.

Holocellulose - The total carbohydrate fraction of wood — cellulose plus hemicellulose.

Hops - The dried blossom of the female hop plant which is a climbing herb (Humulus lupulus).

Horsepower (electrical horsepower; hp) - A unit for measuring the rate of mechanical energy output. The term is usually applied to engines or electric motors to describe maximum output. 1 hp = 745.7 Watts = 0.746 kW = 2,545 Btu/hr.

Hydraulic Load - Amount of liquid going into a system.

Hydrocarbon - Any chemical compound containing hydrogen, oxygen, and carbon.

Hydrogenation - Chemical reaction of a substance with molecular hydrogen, usually in the presence of a catalyst. A common hydrogenation is the hardening of animal fats or vegetable oils to make them solid at room temperature and improve their stability. Hydrogen is added (in the presence of a nickel catalyst) to carbon-carbon double bonds in the unsaturated fatty acid portion of the fat or oil molecule:

Hygroscopic - The tendency of something to absorb water (usually from humidity in the air).

Hydrolysis - A process of breaking chemical bonds of a compound by adding water to the bonds.

Incremental Energy Costs - The cost of producing and transporting the next available unit of electrical energy. Short Run Incremental Costs (SRIC) include only incremental operating costs. Long Run Incremental Costs (LRIC) include the capital cost of new resources or capital equipment.

Independent Power Producer - A power production facility that is not part of a regulated utility.

Indicator - A substance which changes color at a given stage in or as a result of a chemical reaction. Phenolphthalein is commonly used in titrations measuring the acidity of vegetable.

Indirect-Injection Engine - A diesel engine in which the fuel is injected into a prechamber, where it is partly combusted, before it enters the cylinder.

Indirect Liquefaction - Conversion of biomass to a liquid fuel through a synthesis gas intermediate step.

Infiltration - Leakage of ground water into a sewage collection system.

Inorganic Compounds - Those compounds lacking carbon but including carbonates and cyanides. Compounds not having the organized anatomical structure of animal or vegetable life.

Interconnection - A connection or link between power systems that enables them to draw on one another’s reserve in time of need.

Interruptible Load - Loads that can be curtailed at the supplier’s discretion or in accordance with a contractual agreement.

Investment Tax Credit - A specified percentage of the dollar amount of certain new investments that a company can deduct as a credit against its income tax bill.

Investor-Owned Utility (IOU) - A private power company owned by and responsible to its shareholders.

Iodine # - The iodine number (or "iodine adsorption number" or "iodine value") in chemistry is the mass of iodine in grams that is consumed by 100 grams of a chemical substance. One application of the iodine number is the determination of saturation of fatty acids as double bonds in fatty acids also react with iodine compounds.

Jet Propellant #8 (JP-8) - A jet fuel, specified in 1990 by the U.S. government. It is kerosene-based.

Kerosene - Dodecane (Kerosene) (C12H26) - Commonly used mineral fuel oil used as aviation fuel and central heating consisting of many hydrocarbons containing molecules with about 10 to 16 carbon atoms.

Kilowatt (kW) - A measure of electrical power equal to 1,000 Watts. 1 kW = 3,413 Btu/hr = 1.341 horsepower.

Kilowatt Hour (kWh) - A measure of energy equivalent to the expenditure of one kilowatt for one hour. For example, 1 kWh will light a 100-watt light bulb for 10 hours. 1 kWh = 3,413 Btu.

Klason Lignin - Lignin obtained from wood after the non-lignin components of the wood have been removed with a prescribed sulfuric acid treatment. A specific type of acid-insoluble lignin analysis.

KOH - (Potassium Hydroxide) - A caustic white solid used as a bleach and in the manufacture of soaps, dyes, alkaline batteries, and many potassium compounds. Also called caustic potash, potash, and lye.

Landfill Gas - Gas that is generated by decomposition of organic material at landfill disposal sites. Landfill gas is approximately 50 percent methane.

Lautering - The process of straining wort in a lauter tun before it is cooled in the brew kettle.

Lauter Tun - The vessel used in brewing between the mash tun and the brew kettle. It separates the barley husks from the clear liquid wort. The barley husks themselves help provide a natural filter bed through which the wort is strained.

LH2O - The heat (Btu) needed to vaporize and superheat one pound of water.

Life-Cycle Analysis - A total valuation of a process, in which all the inputs and outcomes of a reaction are fully considered.

Life-Cycle Costing - A method of comparing costs of equipment or buildings based on original costs plus all operating and maintenance costs over the useful life of the equipment. Future costs are discounted.

Lignin - The major noncarbohydrate, polypenolic structural constituent of wood and other native plant material that encrusts the cell walls and cements the cells together.

Lignin Ratio of MeO to C9 - Lignin empirical formulae are based on ratios of methoxy groups to phenylpropanoid groups (MeO:C9). The general empirical formula for lignin monomers is C9H10O2 (OCH3)n, where n is the ratio of MeO to C9 groups. Where no experimental ratios have been found, they are estimated as follows: 0.94 for softwoods; 1.18 for grasses; 1.4 for hardwoods. These are averages of the lignin ratios found in the literature. Paper products, which are produced primarily from softwoods, are estimated to have an MeO:C9 ratio of 0.94.

Lignin Pseudo-Molecule for Modeling - The n Lignin ratio of methoxy groups to phenylpropanoid groups (MeO:C9) is used to calculate an ultimate analysis for the lignin pseudo-molecule and then this ultimate analysis is used to estimate other properties of the molecule, such as its higher and lower heating values.

Lignocellulose - Refers to plant materials made up primarily of lignin, cellulose, and hemicellulose.

Lipid - Any of a group of organic compounds, including the fats, oils, waxes, sterols, and triglycerides, that are insoluble in water but soluble in nonpolar organic solvents, are oily to the touch, and together with carbohydrates and proteins constitute the principal structural material of living cells.

Liquefaction - The process of converting biomass from a solid to a liquid. The conversion process is a chemical change that takes place at elevated temperatures and pressures.

Liquid Hydrocarbon - One of a very large group of chemical compounds composed only of carbon and hydrogen. The largest source of hydrocarbons is petroleum.

Liquefied Natural Gas (LNG) - Natural gas that has been condensed to a liquid by cooling the gas.

Load Factor - Load factor is the ratio of average demand to maximum demand or to capacity.

Load - The amount of electrical power required at a given point on a system. The average demand on electrical equipment or on an electric system.

Load Management - Any method or device that evens out electric power demand by eliminating uses during peak periods or shifting usage from peak time to off-peak time.

Long Ton (shipping ton) - 2,240 pounds. Commonly used in Great Britain.

Lower Heating Value (LLV also known as Net Heat of Combustion) - The heat produced by combustion of one unit of a substance, at atmospheric pressure under conditions such that all water in the products remains in the form of vapor. The net heat of combustion is calculated from the gross heat of combustion at 68 degrees Fahrenheit (20 degrees Celsius) by subtracting 572 cal/g (1030 Btu/lb) of water derived from one unit mass of sample, including both the water originally present as moisture and that formed by combustion. This subtracted amount is not equal to the latent heat of vaporization of water because the calculation also reduces the data from the gross value at constant volume to the net value at constant pressure. The appropriate factor for this reduction is 572 cal/g.

Lowest Achievable Emissions Rate (LAER) - Used to describe air emissions control technology. A rate of emissions defined by the permitting agency. LAER sets emission limits for non-attainment areas.

Lubricity - The "smoothness" of a fuel which affects wear-and-tear on the engine. The higher the lubricity, the easier a fuel can move through an engine, resulting in longer engine life. Lubricity is measured as "kinetic viscosity." Biodiesel is known for its lubricity.

Major Source - A source that emits, or has the potential to emit, a pollutant regulated under the Clean Air Act in excess of a specified rate in a non-attainment area.

Mannan - The polymer of mannose with a repeating unit of C6H10O5. Can be hydrolyzed to mannose.

Mannose - A six-carbon sugar C6H1206. A product of hydrolysis of mannan found in the hemicellulose fraction of biomass.

Mash - A mixture, consisting of crushed grains and water, which can be fermented to produce ethyl alcohol.

Mass Closure (%) - The percent by weight of the total samples extracted from the biomass sample compared to the weight of the original sample. It is a sum of the weight percent of moisture, extractives, ash, protein, total lignin, acetic acid, uronic acids, arabinan, xylan, mannan, galactan, glucan, and starch. This is a good indicator of the accuracy of a complete biomass compositional analysis.

Mashing - The process by which barley malt is mixed with water and cooked to turn soluble starch into fermentable sugar. Other cereal grains, such as corn and rice, may also be added. After mashing in a mash tun, the mash is filtered through a lauter tun, where upon it becomes known as wort.

Megawatt (MW) - The electrical unit of power that equals one million Watts (1,000 kW).

Methane - An odorless, colorless, flammable gas with the formula CH4 that is the primary constituent of natural gas.

Methanogen - A methane-producing organism.

Methanol - Methyl alcohol having the chemical formula CH30H. Methanol is usually produced by chemical conversion at high temperatures and pressures. Wood alcohol. Although usually produced from natural gas, methanol can be produced from gasified biomass (syngas).

Methoxide - In organic chemistry, the methoxide ion has a formula of CH3O- and is the conjugate base of methyl alcohol.

Methyl Ester - Biodiesel made with methanol during its production process.

Methyl Tertiary Butyl Ether (MTBE) - An ether manufactured by reacting methanol and isobutylene. MTBE has high octane and low volatility. Used as a fuel oxygenate.

Metric Ton (or Ton) - 1000 kilograms. 1 metric ton = 2,204.62 lb = 1.023 short tons.

mg/l - Milligrams per liter.

MGD - Million Gallons Per Day.

Microalgae - Unicellular, photosynthetic aquatic plants.

Micron - One thousandth of a millimeter.

Mill/kWh - A common method of pricing electricity. Tenths of a cent per kilowatt hour.

Mill - A tenth of a cent ($0.001).

Mitigation - Steps taken to avoid or minimize negative environmental impacts. Mitigation can include: avoiding the impact by not taking a certain action; minimizing impacts by limiting the degree or magnitude of the action; rectifying the impact by repairing or restoring the affected environment; reducing the impact by protective steps required with the action; and compensating for the impact by replacing or providing substitute resources.

MMBtu - One million British thermal units.

Moisture - This is a measure of the amount of water and other components that are volatilized at 221 degrees Fahrenheit (105 degrees Celsius) present in the biomass sample.

Moisture Free Basis - Biomass composition and chemical analysis data is typically reported on a moisture free or dry weight basis. Moisture (and some volatile matter) is removed prior to analytical testing by heating the sample at 221 degrees Fahrenheit (105 degrees Celsius) to constant weight. By definition, samples dried in this manner are considered moisture free.

Monosaccharide - A simple sugar such as a five-carbon sugar (xylose, arabinose) or six-carbon sugar (glucose, fructose). Sucrose, on the other hand is a disaccharide, composed of a combination of two simple sugar units, glucose and fructose.

Multifeedstock - Term used to describe a biodiesel process technology that is capable of using a wide variety of feedstock types as inputs.

Municipal Wastes - Residential, commercial, and institutional post-consumer wastes contain a significant proportion of plant-derived organic material that constitutes a renewable energy resource. Waste paper, cardboard, construction and demolition wood waste, and yard wastes are examples of biomass resources in municipal wastes.

Mutagenicity - The property of chemical or physical agents inducing changes in genetic material that are transmitted during cell division.

NaOH - Sodium Hydroxide, lye, caustic soda. A metallic base. Strongly alkaline and extremely corrosive.

National Ambient Air Quality Standards (NAAQS) - Federal standards established by the Clean Air Act.

National Environmental Policy Act (NEPA) - Federal law enacted in 1969 that requires all federal agencies to consider and analyze the environmental impacts of any proposed action. NEPA requires an environmental impact statement for major federal actions significantly affecting the quality of the environment. NEPA requires federal agencies to inform and involve the public in the agency´s decision making process and to consider the environmental impacts of the agency´s decision.

National Emissions Standards for Hazardous Pollutants (NESHAPS) - Federal standards that control pollutants considered toxic to humans.

National Renewable Energy Laboratory (NREL) -.Government agency which is responsible for our government's alternative fuel research.

Native Lignin - The lignin as it exists in the lignocellulosic complex before separation.

Natural Gas - A mixture of gaseous hydrocarbons, primarily methane, occurs naturally in the earth. Used as fuel.

Neat Biodiesel - Pure biodiesel or B100.

Neat Fuel - Fuel that is free from admixture or dilution with other fuels.

Net Energy Balance - The difference between the energy produced and the energy it takes to produce it. Research has shown that ethanol has a net energy balance of 1.67 to 1, meaning that for every 100 BTUs of energy used to make ethanol, 167 BTUs of ethanol are produced.

Net Heating Value (NHV) - The potential energy available in the fuel as received, taking into account the energy loss in evaporating and superheating the water in the sample. NVH = (HHV x (1- MC / 100)) - (LH(2)O x MC / 100)

Net Present Value - The sum of the costs and benefits of a project or activity. Future benefits and costs are discounted to account for interest costs.

Neutral Detergent Fiber (NDF) - Organic matter that is not solubilized after one hour of refluxing in a neutral detergent consisting of sodium lauryl sulfate and EDTA at pH 7. NDF includes hemicellulose, cellulose, and lignin.

New Source Performance Standards - (NSPS) Federal standards for very large new sources of air pollution.

Nitrile - A low grade rubber common in older vehicles' fuel systems. Also called "Buna-N."

Nitrogen Oxides - (NOx) Regulated air pollutants, primarily NO and NO2. Nitrogen oxides are precursors to the formation of smog and contribute to the formation of acid rain.

Non-Attainment Area (NAA) - Geographic area in which air quality is worse than that allowed by federal air pollution standards.

Octane Enhancer - Any substance that is added to gasoline to increase octane.

Octane Rating - The octane rating of a fuel is indicated on the pump - using numbers such as 87, 90, 91, etc. The higher the number, the greater the octane rating of the gasoline. The octane rating represents the "antiknock" properties of the fuel. The higher the number, the slower the fuel burns-and the less likely your engine will knock. Ethanol typically adds two to three octane numbers when blended with ordinary gasoline-making it a cost-effective octane-enhancer.

Oleochemicals - Chemicals derived from biological oils or fats.

OEM - Original Equipment Manufacturer.

Opacity - The degree to which smoke or particles emitted into the air reduce the transmission of light and obscure the view of an object in the background.

OPEC - Oil Producing & Exporting Countries

Organic - Derived from living organisms.

Organic Compounds - Chemical compounds based on carbon chains or rings and also containing hydrogen, with or without oxygen, nitrogen, and other elements.

Oxidation - Any chemical reaction in which a material gives up electrons, as when the material combines with oxygen. Burning is an example of rapid oxidation; rusting is an example of slow oxidation.

Oxygenate - A gasoline fuel additive containing hydrogen, carbon and oxygen. The oxygen content promotes more complete combustion of gasoline, which reduces tailpipe emissions of carbon monoxide.

Oxygenated Fuels - Ethanol is an oxygenate, meaning that it adds oxygen to the fuel mixture. More oxygen helps the fuel burn more completely—reducing the amount of harmful emissions from the tailpipe. A fuel such as ethanol-blended gasoline that contains a high oxygen content is called "oxygenated."

Oxygenated Gasoline - Gasoline containing an oxygenate.

Ozone - Much like cholesterol, there is "good" ozone and "bad" ozone. The good ozone (atmospheric) lies in the upper reaches of the atmosphere, helping protect us from ultraviolet radiation from the sun. However, when ground level ozone (tropospheric) is in the air we breathe, it's not healthy. What we commonly call "smog" is really ozone build-up in the air. The use of ethanol-blended gasoline has been shown to help reduce tropospheric ozone levels.

Particulate - A small, discrete mass of solid or liquid matter that remains individually dispersed in gas or liquid emissions. Particulates take the form of aerosol, dust, fume, mist, smoke or spray. Each of these forms has different properties.

Particulate Emissions - Fine liquid or solid particles discharged with exhaust gases. Usually measured as grains per cubic foot or pounds per million Btu input.

Passive Solar Energy System - Solar heating or cooling that uses natural energy flows to transfer heat.

PCB’s (Polychlorinated biphenyls) - A group of organic compounds. PCB’s are highly toxic to aquatic life. They persist in the environment for long periods of time, and they are bioaccumulants.

Petrodiesel - Petroleum-based diesel fuel, usually referred to simply as diesel.

pH - A measure of acidity or alkalinity. A pH of 7 represents neutrality. Acid substances have lower pH. Basic substances have higher pH.

Photosynthesis - a process by which plants and other organisms use light to convert carbon dioxide and water into a simple sugar. Photosynthesis provides the basic energy source for almost all organisms.

Pilot Scale - The size of a system between the small laboratory model size (bench scale) and a full-size system.

PM2.5 - Particulate that is less than 2.5 microns in diameter.

PM10 - Particulate that is less than 10 microns in diameter. These particulates are present in the smoke created by burning wood.

Polysaccharide - A long-chain carbohydrate containing at least three molecules of simple anhydrosugars linked together. Examples include cellulose and starch.

Pot - A hollow vessel more deep than broad.

Pound - Pound mass (sometimes abbreviated lb(m)). A unit of mass equal to 0.454 kilograms.

Pound of Steam - One pound mass of water converted to steam.

Pour Point - The lowest temperature at which oils or other liquids will pour under given conditions.

Pressure Vessel - A metal container generally cylindrical or spheroid, capable of withstanding various loadings.

Process Heat - Heat used in an industrial process rather than for space heating or other housekeeping purposes.

Producer Gas - Fuel gas high in carbon monoxide (CO) and hydrogen (H2), produced by burning a solid fuel with insufficient air or by passing a mixture of air and steam through a burning bed of solid fuel.

Productive Machine Hours - That portion of scheduled operating hours during which a machine performs its designated functions, excluding time to transport the machine and operational or mechanical delays.

Products of Combustions - Substances formed during combustion. The products of complete fuel combustion are carbon monoxide and water. Products of incomplete combustion can include carbon monoxide, hydrocarbons, soot, tars, and other substances.

Proof - A measure of ethanol content. 1 percent ethanol content equals 2 proof.

Protein - A protein molecule is a chain of up to several hundred amino acids and is folded into a more or less compact structure. Because about 20 different amino acids are used by living matter in making proteins, the variety of protein types is enormous. In their biologically active states, proteins function as catalysts in metabolism and to some extent as structural elements of cells and tissues. Protein content in biomass (in mass percentage) can be estimated by multiplying the mass percentage nitrogen of the sample by 6.25.

Proximate Analysis - The determination, by prescribed methods, of moisture, volatile matter, fixed carbon (by difference), and ash. The term proximate analysis does not include determinations of chemical elements or determinations other than those named. The group of analyses is defined in ASTM D 3172.

psi - Pounds force of pressure per square inch.

psia - Pounds force of pressure per square inch absolute (including atmospheric pressure).

psig - Pounds force of pressure per square inch gauge (excluding atmospheric pressure).

Pyrolysis - The thermal decomposition of biomass at high temperatures (greater than 400 degrees Fahrenheit, or 200 degrees Celsius) in the absence of air. Also called destructive distillation. The end product of pyrolysis is a mixture of solids (char), liquids (oxygenated oils), and gases (methane, carbon monoxide, and carbon dioxide) with proportions determined by operating temperature, pressure, oxygen content, and other conditions.

Quad - One quadrillion Btu (1015 Btu). An energy equivalent to approximately 172 million barrels of oil.

Rape Seed Oil - Food grade oil produced from rape seed is called Canola oil. Canola is a name taken from "Canada Oil" due to the fact that much of the development of the oil was performed in Canada. Another early term for this oil is Colza.

Record of Decision (ROD) - The decision document for an environmental impact statement (EIS). Separate from the EIS itself. This document states the decision, states the reasons for the decision, identifies all alternatives, and states compliance with applicable laws.

Rectification - With regard to distillation, the selective increase of the concentration of the lower volatile component in a mixture by successive evaporation and condensation.

Rectifying Column - The portion of a distillation column above the feed tray in which rising vapor is enriched by interaction with a countercurrent falling stream of condensed vapor.

Reformulated Gasoline (RFG) - Gasoline that has altered composition or characteristics to reduce emissions of pollutants from vehicles in accordance with the Clean Air Act.

Reid Vapor Pressure (RVP) - A standard measurement of a liquid’s vapor pressure at 100 degrees Fahrenheit. An indication of the propensity of the liquid to evaporate.

Renewable Energy Source - An energy source that is replenished continuously in nature or that is replaced after use through natural means. Sustainable energy sources and renewable energy sources include the sun, wind, flowing water, biomass and geothermal energy.

Renewable Fuels Standard (RFS) - Part of proposed federal energy legislation that would set a minimum number of gallons of renewable fuels to be used in the nation’s transportation fuel supply each year. The RFS would include fuels such as ethanol and biodiesel (soy diesel).

Residues (Biomass) - Byproducts from processing all forms of biomass that have significant energy potential. For example, making solid wood products and pulp from logs produces bark, shavings and sawdust, and spent pulping liquors. Because these residues are already collected at the point of processing, they can be convenient and relatively inexpensive sources of biomass for energy.

Resource Conservation and Recovery Act (RCRA) - A federal law regulating solid and hazardous waste. RCRA governs the generation, storage, treatment, transport, and disposal of hazardous waste.

Retrofitting - The application of conservation, efficiency, or renewable energy technologies to existing structures.

Return On Investment (ROI) - A performance measure used to evaluate the efficiency of an investment or to compare the efficiency of a number of different investments. To calculate ROI, the benefit (return) of an investment is divided by the cost of the investment; the result is expressed as a percentage or a ratio.

Saccharide - A simple sugar or a more complex compound that can be hydrolyzed to simple sugar units.

Saponification - The reaction of an ester with a metallic base and water. The making of soap.

Saturated - A fat or fatty acid in which there are no double bonds between the carbon atoms of the fatty acid chain. Saturated fats tend to be solid at room temperature. Diets high in saturated fat correlate in some studies with an increased incidence of atherosclerosis and coronary heart disease.

Sewage - The waste water from domestic, commercial and industrial sources carried by sewers.

Short Ton - 2000 pounds. A ton, as commonly used in the U.S. and Canada.

Shower Type Trays - These trays do not have downcomers. The liquid level results from the pressure drop caused by the counter-flowing streams.

Sieve Trays - Sieve trays are usually cross flow type perforated with small holes. Sieve trays are sometimes used for feeds that tend to deposit solids or polimerize in the column.

Sight Gauge - A clear calibrated cylinder through which liquid level can be observed and measured.

Silicon - Fluoropolymer that can withstand high heat, especially useful in replacing older rubber fuel lines.

SIP - See State Implementation Plan.

Smog - A visible haze caused by particulate matter and ground-level ozone.

Sodium Hydroxide (NaOH) - Lye or caustic soda. A metallic base. Strongly alkaline and extremely corrosive.

Softwood - Generally, one of the botanical groups of trees that in most cases have needle-like or scale-like leaves; the conifers; also the wood produced by such trees. The term has no reference to the actual hardness of the wood. The botanical name for softwoods is gymnosperms

Solvent Extraction - A method of separation used to purify vegetable oils.

Source Emission Reduction Plan (SERP) - A contingency plan developed to reduce emissions during an air quality emergency.

Soy - The soybean.

Soy Oil - A vegetable oil pressed from soy beans.

Soydiesel - A term used in the United States for biodiesel made from soybean oil.

Standards and Guidelines - Bounds or constraints within which all practices in a given area will be carried out, in achieving the goals and objectives for that area. Standards and guidelines provide environmental safeguards and also describe constraints prescribed by law.

Starch - A molecule composed of long chains of a-glucose molecules linked together (repeating unit C12H16O5 ). These linkages occur in chains of a-1,4 linkages with branches formed as a result of a-1,6 linkages. This polysaccharide is widely distributed in the vegetable kingdom and is stored in all grains and tubers (swollen underground plant stems). A not-so-obvious consequence of the a linkages in starch is that this polymer is highly amorphous, making it more readily attacked by human and animal enzyme systems and broken down into glucose. Gross heat of combustion: Qv(gross)=7560 Btu/lb (4200 cal/g,17570 J/g).

State Implementation Plan - A state plan required by the Clean Air Act to bring non-attainment areas into compliance with federal ambient air quality standards.

Steam Conversion Factors - (approximations) 1 pound of steam = 1,000 Btu = .3 kW. 10,000 lbs/hr steam = 300 boiler horsepower.

Steam Turbine - A device for converting energy of high-pressure steam (produced in a boiler) into mechanical power which can then be used to generate electricity.

Still - An apparatus for distilling liquids, particularly alcohols; it consists of a vessel in which the liquid is vaporized by heat, and a cooling device in which the vapor is condensed.

Stillage - The grains and liquid effluent remaining after distillation.

Stripping Column - The section of the distillation column in which the alcohol concentration in the starting beer solution is decreased. This section is below the beer injection point.

Stripping Section - The section of a distillation column below the feed in which the condensate is progressively decreased in the fraction of more volatile component by stripping.

Stoichiometric Condition - That condition at which the proportion of the air-to-fuel is such that all combustible products will be completely burned with no oxygen remaining in the combustion air.

Stover - The dried stalks and leaves of a crop remaining after the grain has been harvested.

Structural Chemical Analysis - The composition of biomass reported by the proportions of the major structural components; cellulose, hemicellulose, and lignin. Typical ranges are shown in the table below.

Suspended Solids - Waste particles suspended in water. Suspended solids can harbor harmful microorganisms and toxic chemicals. Suspended solids cloud the water and make disinfection more difficult and costly.

Suspension - A dispersion of a solid in a gas, liquid, or solid.

Straight Vegetable Oil (SVO) - A fuel for diesel engines that can be either pure new vegetable oil or Waste vegetable oil that has been cleaned, although this is normally referred to as WVO.

Sustainable - An ecosystem condition in which biodiversity, renewability, and resource productivity are maintained over time.

Sustained Yield - The maintenance in perpetuity of regular, periodic harvest of resources from land without damaging the productivity of the land.

Syringyl - A component of lignin, normally only found in hardwood lignins. It has a six-carbon aromatic ring with two methoxyl groups attached.

Tallow - One of the harder organic fats derived from animal carcasses, made by rendering the internal body fat found within the abdominal cavity under the backbone and surrounding the kidneys. This material was greatly used in manufacture of soap and candle wax.

Tank - A vessel of large size to contain liquids.

Teflon - Fluoropolymer that can withstand high heat, especially useful in replacing older rubber fuel lines.

Therm - A unit of energy equal to 100,000 British thermal units; used primarily for natural gas.

Thermochemical Conversion Process - Chemical reactions employing heat to produce fuels.

Tipping Fee - A fee for disposal of waste.

Titration - The process, operation, or method of determining the concentration of a substance in solution by adding to it a standard reagent of known concentration in carefully measured amounts until a reaction of definite and known proportion is completed, as shown by a color change or by electrical measurement, and then calculating the unknown concentration.

Ton - 1. A unit of weight equal to 2,000 pounds (0.907 metric ton or 907.18 kilograms). Also called net ton, short ton. 2. A unit of weight equal to 2,240 pounds (1.016 metric tons or 1,016.05 kilograms). Also called long ton.

Total Lignin - The sum of the acid soluble lignin and acid insoluble lignin fractions.

Total Solids - The amount of solids remaining after all volatile matter has been removed from a biomass sample by heating at 221 degrees Fahrenheit (105 degrees Celsius) to constant weight.

Toxic Substances - A chemical or mixture of chemicals that presents a high risk of injury to human health or to the environment.

Transesterification - In organic chemistry, transesterification is the process of exchanging the alkoxy group of an ester compound by another alcohol. These reactions are often catalyzed by the addition of an acid or base.

Triglyceride - Natural fats and oils, composed of glycerin and three fatty acid chains.

Tunnel Cap Trays - Tunnel cap trays are similar to bubble cap trays except that they are rectangular.

Turbidity - The relative clarity of water, which may be affected by material in suspension in the water.

Turnkey System - A system which is built, engineered, and installed to the point of readiness for operation by the owner.

Ultimate Analysis - The determination of the elemental composition of the organic portion of carbonaceous materials, as well as the total ash and moisture. A description of a fuel’s elemental composition as a percentage of the dry fuel weight. Determined by prescribed methods.

Ultra Low Sulphur Diesel (ULSD) - Ultra low sulfur diesel describes a new EPA standard for the sulfur content in diesel fuel sold in the United States beginning in 2006. This applies to all diesel fuel sold for use in roadgoing vehicles. The allowable sulfur content (15 ppm) is much lower than the previous U.S. standard (500 ppm), which not only reduces emissions of sulfur compounds (blamed for acid rain), but also allows advanced emission control systems to be fitted that would otherwise be poisoned by these compounds. These systems can greatly reduce emissions of oxides of nitrogen and particulates.

Uniform Mechanical Code (UMC) - A code sponsored by the International Association of Plumbing and Mechanical Officials and the International Conference of Building Officials. The UMC contains requirements for the installation and maintenance of heating, ventilating, cooling, and refrigeration systems.

Uniform Building Code - (UBC) A building code published by the International Conference of Building Officials. The UBC covers the fire, life and structural safety aspects of all buildings and related structures.

Unsaturated - Of or relating to an organic compound, especially a fatty acid, containing one or more double or triple bonds between the carbon atoms.

Uronic Acid - A simple sugar whose terminal -CH2OH group has been oxidized to an acid, COOH group. The uronic acids occur as branching groups bonded to hemicelluloses such as xylan.

United States Department of Agriculture Forest Service (USFS) - The Forest Service was established in 1905 and is an agency of the U.S. Department of Agriculture. The Forest Service manages public lands in national forests and grasslands, which encompass 193 million acres.

Valve Trays - Valve trays are cross flow trays with large perforations that are covered with flat plates. The cover plates are free to move vertically and thus permit the passage of ascending vapors.

Vapor Lock - An engine performance problem due to high vapor pressure in fuel. While ethanol increases the vapor pressure of fuel, state and federal standards continue to lower vapor pressure levels - virtually eliminating vapor lock problems. Additionally, all major auto manufacturers now use in-tank fuel pumps, which are not subject to the vapor lock problems seen in older in-line fuel pumps.

Vaporization - The process of converting a compound from a liquid or solid state to the gaseous state.

Vessel - A container or structural envelope in which material are processed, treated or stored; for example, pressure vessels, reactor vessels, agitator vessels, and storage vessels (tanks).

Viscosity - Resistance of a fluid to flow. This resistance acts against the motion of any solid object through the fluid and also against motion of the fluid itself past stationary obstacles. Viscosity also acts internally on the fluid between slower and faster moving adjacent layers.

Viton - The most recommended fluoropolymer for replacing nitrile or natural rubber in older vehicles' fuel systems. It is very similar in functionality and appearance to rubber.

Volatile Matter - Those products, exclusive of moisture, given off by a material as a gas or vapor, determined by definite prescribed methods that may vary according to the nature of the material. One definition of volatile matter is part of the proximate analysis group usually determined as described in ASTM D 3175.

Volatile Organic Compounds (VOC) - Non-methane hydrocarbon gases. Released during combustion or evaporation of fuel.

Volatiles - Substances that are readily vaporized.

Volatility - The tendency of a liquid to pass into the vapor state at a given temperature. Vapor pressure.

Volumetric Ethanol Excise Tax Credit (VEETC) - 2004 federal legislation that strengthened the nation’s commitment to renewable fuels by extending tax incentives for ethanol and biodiesel, improving flexibility for petroleum companies to blend ethanol, and ensuring that Highway Trust Fund revenues are not adversely affected by increased ethanol use.

Waste Vegetable Oil (WVO) - Vegetable oil that has become unfit for food preparation.

Watt - The common base unit of power in the metric system. One watt equals one joule per second. It is the power developed in a circuit by a current of one ampere flowing through a potential difference of one volt. One Watt = 3.413 Btu/hr.

Wet Mill - An ethanol production facility in which the corn is first soaked or “steeped” in water before processing. In addition to ethanol, wet mills have the ability to produce co-products such as industrial starch, food starch, high fructose corn syrup, gluten feed and corn oils.

Whole Tree Chips - Wood chips produced by chipping whole trees, usually in the forest. Thus the chips contain both bark and wood. They are frequently produced from the low-quality trees or from tops, limbs, and other logging residues.

Willstatter Lignin - Lignin obtained from the lignocellulosic complex after it has been extracted with fuming hydrochloric acid.

Wood - A solid lignocellulosic material naturally produced in trees and some shrubs, made of up to 40-50 percent cellulose, 20-30 percent hemicellulose, and 20-30 percent lignin.

Wort - An oatmeal-like substance consisting of water and mash barley in which soluble starch has been turned into fermentable sugar during the mashing process. The liquid remaining from a brewing mash preparation following the filtration of fermentable beer.

Xylan - A polymer of xylose with a repeating unit of C5H804, found in the hemicellulose fraction of biomass. Can be hydrolyzed to xylose. Gross heat of combustion: Qv(gross)=17751.9 Jg-1.

Xylose - A five-carbon sugar C5H1005. A product of hydrolysis of xylan found in the hemicellulose fraction of biomass.

Yellow Grease - A term from the rendering industry. It usually means used frying oils from deep fryers and restaurants' grease traps. It can also refer to lower-quality grades of tallow from rendering plants.