Calorific Value: The maximum amount of energy that is available from burning a substance.
Cambium: The layer of reproducing cells between the inner bark (phloem) and the wood (xylem) of a tree that repeatedly subdivides to form new wood and bark cells.
CAP: Common Agricultural Policy. The system of support for agriculture in the EU. Proposed in 1960, expenditure under CAP represents about 44% of the EU budget, however it is currently under major reform and is being replaced by single farm payments. CAP included import tariffs, minimum prices, and subsidies to farmers.
Capacity: The maximum instantaneous output of an energy conversion device, often expressed in kW or MW.
Capital cost: The total investment needed to complete a project and bring it to an operable status.
Carbohydrate: Organic compounds made up of carbon, hydrogen, and oxygen and having approximately the formula (CH2O)n; includes cellulosics, starches, and sugars.
Carbonaceous: Consisting of, containing, relating to, or yielding carbon.
Carbon burn-out: The end of the combustion process in which all uncombined gaseous and solid carbon is oxidized to carbon dioxide.
Carbon Cycle: The carbon cycle includes the uptake of carbon dioxide by plants through photosynthesis, its ingestion by animals and its release to the atmosphere through respiration and decay of organic materials. Human activities like the burning of fossil fuels contribute to the release of carbon dioxide in the atmosphere.
Carbon dioxide (CO2): A product of combustion that acts as a greenhouse gas in the earth’s atmosphere, trapping heat and contributing to climate change.
Carbonization: The conversion of organic material into carbon or a carbon-containing residue through pyrolysis.
Carbon monoxide (CO): A lethal gas produced by incomplete combustion of carbon-containing fuels in internal combustion engines. It is colorless, odorless, and tasteless.
Carbon Sequestration: The long-term storage of carbon in the terrestrial biosphere, underground, or oceans to reduce the buildup of atmospheric carbon dioxide concentrations.
Carbon sink: A geographical area whose vegetation and/or soil soaks up significant carbon dioxide from atmosphere. Such areas, typically in tropical regions, are increasingly being sacrificed for energy crop production.
Catalyst: A catalyst is a substance that increases the rate of a chemical reaction, without being consumed or produced by the reaction. Enzymes are catalysts for many biochemical reactions.
Catastrophic fire: Uncharacteristically severe stand replacement or high intensity fire that causes damage to ecological and economic assets and values.
Cant: The remaining square section of a log when rounded edges and bark are removed.
CCA: Chromated Copper Arsenate (CCA). A water-borne, combined fungicide and insecticide that includes arsenic for the treatment of wood. It was developed in 1933 and has been used widely in the UK and around the world. The arsenic is carried off in flue gases during combustion if treated wood is burned, and can be volatilized, making it difficult to trap with conventional filters so CCA treated timber must not be burned except in suitable equipment. Modern, less toxic alternatives are now widely available.
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 (see below). 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. Example values are shown below (higher heating value [HHV] at 30°C, dry basis). (Source: Domalski, E.S.; Milne T.A., ed. Thermodynamic Data for Biomass Materials and Waste Components. The ASME Research Committee on Industrial and Municipal Wastes, New York: The American Society of Mechanical Engineers, 1987)
cotton linters: HHV=7497 BTU/LB (4172.0 cal/g, 17426.4 J/g)
wood pulp: HHV=7509.6 BTU/LB (4165.0 cal/g, 17455.6 J/g)
Linear chains of glucose linked by b-Glycosidic bonds comprise cellulose.
Cetane (also called Hexadecane): An alkane hydrocarbon with the chemical formula C16H34. Consists of a chain of 16 carbon atoms, with 3 hydrogen atoms bonded to the 2 end carbon atoms, and 2 hydrogens bonded to each of the 14 other carbon atoms. Cetane is often used as a short-hand for cetane number, a measure of the detonation of diesel fuel. Cetane ignites very easily under compression; for this reason, it is assigned a cetane number of 100, and serves as a reference for other fuel mixtures.
Cetane number (CN): is a measurement of the combustion quality of diesel fuel during compression ignition. It is a significant expression of the quality of a diesel fuel. A number of other measurements determine overall diesel fuel quality - these other measures of diesel fuel quality include density, lubricity, cold-flow properties, and sulfur content.
CFM: Cubic feet per minute (1,000 cfm = 0.472 cubic meters per second, m3/s).
Char reinjector: A device that collects unburned char at certain locations in large boilers and injects it back into the primary combustion zone, both to keep it from going up the stack and to capture its energy through recombustion.
Chemical oxygen demand (COD): The amount of dissolved oxygen required to combine with chemicals in wastewater. A measure of the oxygen equivalent of that portion of organic matter that is susceptible to oxidation by a strong chemical oxidizing agent.
Chip-n-saw: A cutting method used in cutting lumber from trees that measure between 6 and 14 inches diameter at breast height. The process chips off the rounded outer layer of a log before sawing the remaining cant or rectangular inside section into lumber. Chip-n-saw mills provide a market for trees larger than pulpwood and smaller than sawtimber.
Chipper: A large mechanized device that reduces logs, whole trees, slab wood, or lumber to chips of more or less uniform size. Stationary chippers are used in sawmills, while trailer-mounted whole-tree chippers are used in the woods.
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.
Chip Van: Enclosed box trailers, generally 8 to 8.5 ft in width, designed to be less than 12.50 ft high when pulled by a road tractor. The difference between the box trailers seen on most highways and vans hauling harvesting products (bulk vans) is that most box trailers are built for containerized cargo (commodities in boxes or on pallets)
Clean Chips: Chipped wood free of bark, needles, leaves, and soil contamination.
Cleaning: Release treatment made in forest stand not past the sapling stage to free the favored trees from less desirable vegetation that currently or soon will overtop them.
Clearcutting: Regeneration or harvesting method that removes essentially all woody vegetation that would otherwise compete with future crop trees in a single harvesting operation.
Close-coupled gasifier: A biomass combustion burner that produces combustible gases under controlled conditions in the primary combustion chamber or combustor, and burns the gases to produce heat in an adjacent chamber.
Closed-loop biomass: Crops grown, in a sustainable manner, for the purpose of optimizing their value for bioenergy and bioproduct uses. This includes annual crops such as maize and wheat, and perennial crops such as trees, shrubs, and grasses such as switch grass.
Cloud point: The temperature at which paraffin wax or other solid substances begin to crystallize or separate from the solution, imparting a cloudy appearance to the oil when the oil is chilled under prescribed conditions.
Coarse materials: Wood residues suitable for chipping, such as slabs, edgings, and trimmings.
Co-firing: The use of a mixture of two fuels within the same combustion chamber.
Coking: A thermal method used in refineries for the conversion of bitumen and residua to volatile products and coke (See “Delayed coking” and “Fluid coking”).
Co-generation: The technology of producing electric energy and another form of useful energy (usually thermal) for industrial, commercial, or domestic heating or cooling purposes through the sequential use of the energy source.
Combustible gas: A gas that burns, including the fuel gases, hydrogen, hydrocarbon, carbon monoxide, or a mixture of these.
Combustion (direct firing, burning): The burning of biomass in air or oxygen to convert the chemical energy stored in biomass into heat, mechanical power, or electricity using various items of process equipment, e.g. stoves, furnaces, boilers, steam turbines, turbo-generators, etc. Combustion of biomass produces hot gases at temperatures around 800–1000 oC.
Commercial forest land: Forested land which is capable of producing new growth at a minimum rate of 20 cubic feet per acre per year, excluding lands withdrawn from timber production by statute or administrative regulation.
Commercial species: Tree species suitable for industrial wood products.
Comminution: Chopping up material, such as biomass, into small fragments
Commissioning: The process of verifying that a new heating plant meets the performance specifications called for in the installation contract.
Condensing turbine: A turbine used for electrical power generation from a minimum amount of steam. To increase plant efficiency, these units can have multiple uncontrolled extraction openings for feed-water heating.
Conifer: A tree, usually evergreen, with cones and needle-shaped or scale like leaves, producing wood known commercially as softwood.
Conservation reserve program: CRP provides farm owners or operators with an annual per-acre rental payment and half the cost of establishing a permanent land cover in exchange for retiring environmentally sensitive cropland from production for 10 to 15 years. In 1996, Congress reauthorized CRP for an additional round of contracts, limiting enrollment to 36.4 million acres at any time. The 2002 Farm Act increased the enrollment limit to 39 million acres. Producers can offer land for competitive bidding based on an Environmental Benefits Index (EBI) during periodic signups, or can automatically enroll more limited acreages in practices such as riparian buffers, field windbreaks, and grass strips on a continuous basis. CRP is funded through the Commodity Credit Corporation (CCC).
Construction and Demolition (C&D) Debris: Building materials and solid waste from construction, deconstruction, remodeling, repair, cleanup or demolition operations.
Contaminants: An impurity, any substance or material that enters a system–the environment, human body, food, etc. where it is not normally found.
Continuous fermentation: A steady-state fermentation system in which substrate is continuously added to a fermenter while products and residues are removed at a steady rate.
Conventional crude oil (conventional petroleum): Crude oil that is pumped from the ground and recovered using the energy inherent in the reservoir; also recoverable by application of secondary recovery techniques.
Conventional pyrolysis (carbonization, destructive distillation, dry distillation, retorting): consists of the slow, irreversible, thermal degradation of the organic components in biomass, most of which are lignocellulosic polymers, in the absence of oxygen. Slow pyrolysis has traditionally been used for the production of charcoal. See Pyrolysis. see Pyrolysis.
Coppice regeneration: The ability of certain hardwood species to regenerate by producing multiple new shoots from a stump left after harvest.
Coppicing: A traditional method of woodland management, by which young tree stems are cut down to a low level, or sometimes right down to the ground. In subsequent growth years, many new shoots will grow up, and after a number of years the cycle begins again and the coppiced tree or stool is ready to be harvested again. Typically a coppice woodland is harvested in sections, on a rotation. In this way each year a crop is available.
Co-products: The resulting substances and materials that accompany the production of a fuel product such as ethanol.
Cord: A stack of wood comprising 128 ft3 (3.62 m3); standard dimensions are 4 × 4 × 8 ft, including air space and bark. One cord contains approximately 1.2 U. S. tons (oven-dry) =2400 lb =1089kg.
Corn Distillers Dried Grains (DDG): Obtained after the removal of ethanol by distillation from the yeast fermentation of a grain or a grain mixture by separating the resultant coarse grain fraction of the whole stillage and drying it by methods employed in the grain distilling industry.
Corn stover: The refuse of a corn crop after the grain is harvested.
Course Woody Debris: Any piece(s) of dead woody material (includes trunks, branches, and roots) on the ground in forest stands or streams with the large end diameter often greater than 5 inches.
Cracking: A reduction of molecular weight by breaking bonds, which may be done by thermal, catalytic, or hydrocracking. Heavy hydrocarbons, such as fuel oils, are broken up into lighter hydrocarbons such as gasoline.
Cropland: Total cropland includes five components: cropland harvested, crop failure, cultivated summer fallow, cropland used only for pasture, and idle cropland.
Cropland pasture: Land used for long-term crop rotation. However, some cropland pasture is marginal for crop uses and may remain in pasture indefinitely. This category also includes land that was used for pasture before crops reached maturity and some land used for pasture that could have been cropped without additional improvement.
Cropland used for crops: Cropland used for crops includes cropland harvested, crop failure, and cultivated summer fallow. Cropland harvested includes row crops and closely sown crops; hay and silage crops; tree fruits, small fruits, berries, and tree nuts; vegetables and melons; and miscellaneous other minor crops. In recent years, farmers have double-cropped about 4 percent of this acreage. Crop failure consists mainly of the acreage on which crops failed because of weather, insects, and diseases, but includes some land not harvested due to lack of labor, low market prices, or other factors. The acreage planted to cover and soil improvement crops not intended for harvest is excluded from crop failure and is considered idle. Cultivated summer fallow refers to cropland in sub-humid regions of the West cultivated for one or more seasons to control weeds and accumulate moisture before small grains are planted. This practice is optional in some areas, but it is a requirement for crop production in the drier cropland areas of the West. Other types of fallow, such as cropland planted with soil improvement crops but not harvested and cropland left idle all year, are not included in cultivated summer fallow but are included as idle cropland.
Crop Tree: Any tree selected to grow to final harvest or to a selected size. Crop trees are selected for quality, species, size, timber potential, or wildlife value.
Crown Thinning: Removal of trees from the upper level in the canopy in order to favor desired crop trees whose crowns are at a lower position in the canopy.
Cull tree: A live tree, 5.0 in in diameter at breast height (d. b. h.) or larger that is nonmerchantable for saw logs now or prospectively because of rot, roughness, or species.
Cultivar: A race or variety of a plant that has been created or selected intentionally and maintained through cultivation.
Cultivated summer fallow: Cropland cultivated for one or more seasons to control weeds and accumulate moisture before small grains are planted.
Cut-to-Length: A harvest system in which trees are felled, delimbed, and cut to various log lengths at the stump.
Cyclone separator: A flue gas particulate removal device, which creates a vortex that separates solid particles from the hot gas stream.