Compressed Natural Gas (CNG)Natural gas (methane) that has been compressed to a higher pressure gaseous state by a compressor; used in CNG vehicles.
Concentrating (Solar) CollectorA solar collector that uses reflective surfaces to concentrate sunlight onto a small area, where it is absorbed and converted to heat or, in the case of…
Concentrating solar power (CSP) technologiesAny of a family of solar energy technologies that reflect and concentrate the sun's energy to produce heat that is subsequently used to produce steam to…
ConcentrationAmount of a chemical in a particular volume or weight of air, water, soil, or other medium.
ConcentratorA photovoltaic module, which includes optical components such as lenses (Fresnel lens) to direct and concentrate sunlight onto a solar cell.
CondenserThe device in an air conditioner or heat pump in which the refrigerant condenses from a gas to a liquid when it is depressurized or cooled.
Condensing powerPower generated through a final steam turbine stage where the steam is exhausted into a condenser and cooled to a liquid to be recycled back into a boiler.
Condensing turbineA turbine used for electrical power generation from a minimum amount of steam. To increase plant efficiency, these units can have multiple uncontrolled…
Condensing, controlled extraction turbinesA controlled turbine that bleeds off (condenses) part of the main stream flow at one (single extraction) or two (double extraction) points.
Conditional use permitA permit, with conditions, allowing an approved use on a site outside the appropriate zoning class.
Conditional Use Permit (CUP)In California, this is a permit that is required to be obtained from the county government authority in which a solar energy facility is to be located.
Cone of DepressionA depression in the water table that develops around a pumped well.
Consumptive use(1) Any use of water that permanently removes water from the natural stream system.
continuous fermentationA process in which cells or micro-organisms are maintained in culture in the exponential growth phase by the continuous addition of fresh medium that is…
ContrastThe difference between the brightness of an object compared to that of its immediate background.
Contrast levelA description of the relative amount of visual contrast resulting from a change in the visible landscape.
Control plotA plot in which no vegetation will be cut and natural succession will occur. A control plot serves as a baseline to compare other treatments (Early, Mid…
Conventional forest productsAny commercial roundwood product (boards, dimension lumber, pulp and paper products) except fuelwood.
Conversion EfficiencyThe amount of energy produced as a percentage of the amount of energy consumed.
ConveyorA mechanical apparatus for carrying bulk material from place to place; for example, an endless moving belt or a chain of receptacles.
Coppice regenerationThe ability of certain hardwood species to regenerate by producing multiple new shoots from a stump left after harvest.
CoproductsThe potentially useful byproducts of ethanol fermentation process.
CordA stack of wood consisting of 128 cubic feet. A cord has standard dimensions of 4´ x 4´ x 8´ including air space and bark. One cord contains about 1.
Corn stoverResidue materials from harvesting corn consisting of the cob, leaves and stalk.
Corona dischargeElectrical discharge accompanied by ionization of surrounding atmosphere around high-voltage transmission lines, occurring mostly under wet conditions.
Corona/corona noiseThe electrical breakdown of air into charged particles. The phenomenon appears as a bluish-purple glow on the surface of and adjacent to a conductor when…
Corporate average fuel economy (CAFE)Federal standards enacted in 1975 for fuel economy in motor vehicles. The average of city and highway fuel economy test results weighted by a manufacturer…
CorridorA strip of land through which one or more existing or potential facilities may be located.
coverNatural or manmade objects on the bottom of lakes, rivers, or impoundments, especially those that influence fish behavior.
crackingA reduction of molecular weight by breaking bonds, which may be done by thermal, catalytic, or hydrocracking.
CraterA steep-sided, usually circular depression formed by either explosion or collapse at a volcanic vent.
Creep (rate)Relatively slow movement along a fault. It is sometimes called "seismic creep" to distinguish it from the slumping of rock or soil on slopes (which is…
CrescentsQuarter-moon-shaped (hence crescent) artifacts that may have been in the form of blades, scrapers, or projectile points.
Criteria air pollutantsSix common air pollutants for which National Ambient Air Quality Standards (NAAQS) have been established by the U.S.
Critical habitatThe specific area within the geographical area occupied by the species at the time it is listed as endangered or threatened.
Critical habitat unit (CHU)Under the Endangered Species Act, critical habitat is defined as "the specific areas within the geographic area occupied by a species on which are found…
Crop treeUsually a conifer tree grown to provide wood products.
Crucial winter rangeThe portion of the winter range to which a wildlife species is confined during periods of heaviest snow cover or that portion of the year-long range which…
CrustaceansAquatic animals with hard external skeletons and segmented limbs, belonging to the class Crustacea; include cladocerans, shrimp, crayfish, fairy shrimp…
Crustal spreading centerA linear zone in the Earth's crust whose opposite sides are moving away from one another.
Cryptogamic soil crustsA soil crust dominated by a community of algae, lichens, or mosses. See also Biological soil crusts
CSPA type of tumor found in breast or prostate tissue. It is often large and bulky and grows quickly.
CuestaAn elongated ridge formed by gently tilting sedimentary strata. The landform has a steep slope (escarpment or cliff) where the strata are exposed on their…
CullAny item of production picked out for rejection because it does not meet certain specifications.
Cull sectionA log cut from a tree that is rejected because of defects making it unsuitable for conventional forest products.
Cull treesLive saw-timber and pole-timber size trees which do not contain a merchantable sawlog due to poor form, quality, or undesirable species.
Cultural modificationAny human-caused change in the land form, water form, vegetation, or the addition of a structure which creates a visual contrast in the basic elements (e.
Cultural resourcesArchaeological sites, structures, or features; traditional use areas; and Native American sacred sites or special use areas that provide evidence of the…
Cumulative effectsEffects on the environment resulting from actions that are individually minor but that add up to a greater total effect as they take place over a period…
Cumulative impactsThe impacts assessed in an environmental impact statement that could potentially result from incremental impacts of the action when added to other past…
Cut-and-fillThe process of earth grading by excavating part of a higher area and using the excavated material for fill to raise the surface of an adjacent lower area.
CyanobacteriaBlue-green algae, prokaryotic, photosynthetic organisms that generally have a blue-green tint and lack chloroplasts.
Cyclone separatorA device used to remove particulate matter suspended in exhaust gases.