CienegaA perennially wet area supported by a spring or other water source; also called wetland, marsh, or swamp.
Cinder coneA conical hill formed around a volcanic vent by the accumulation of loose cinders and other pyroclastics ejected during a volcanic eruption, normally…
CircuitA device, or system of devices, that allows electrical current to flow through it and allows voltage to occur across positive and negative terminals.
Circuit breakerAfter the stock market crash of 1987, stock and commodities exchanges established a system of trigger-point rules known as circuit breakers.
Circuit LagAs time increases from zero at the terminals of an inductor, the voltage comes to a particular value on the sine function curve ahead of the current.
Circulating Fluidized BedA type of furnace or reactor in which the emission of sulfur compounds is lowered by the addition of crushed limestone in the fluidized bed thus obviating…
City GateGenerally refers to the location at which gas changes ownership or transportation responsibility from a pipeline to a local distribution company or gas…
ClarifierA tank used to remove solids by gravity, to remove colloidal solids by coagulation, and to remove floating oil and scum through skimming.
Class I AreaAny area designated for the most stringent protection from air quality degradation.
Class II AreaAny area where air is cleaner than required by federal air quality standards and designated for a moderate degree of protection from air quality…
Class IVAll other intermittent streams not meeting higher class criteria.
ClayA very fine-grained rock or mineral fragment of any composition that has a diameter of less than 0.002 mm.
Clean Air Act (CAA)The Superfund law incorporates those substances listed as hazardous air pollutants under section 112 of the Clean Air Act (CAA) as CERCLA hazardous…
Clean Air Act Amendments of 1990Amendments to the Clean Air Act of 1970 creating two gasoline standards to reduce vehicle emissions in highly polluted cities by requiring gasoline to…
Clean Power GeneratorA company or other organizational unit that produces electricity from sources that are thought to be environmentally cleaner than traditional sources.
Clean Water Act (CWA)The Superfund law incorporates those substances listed as hazardous water pollutants under section 311 (b)(4) of the Clean Water Act (CWA) as CERCLA…
ClearcutThe removal, in a single cutting, of the entire stand of trees within a designated area.
ClearingThe registration and settlement of a trade that includes provisions for margin requirement and performance guarantee.
Clearing and grubbingCleaning a site to prepare it for construction. Involves removing debris, structures, shrubbery, trees, obstructions, and objectionable and unsuitable…
ClerestoryA window located high in a wall near the eaves that allows daylight into a building interior, and may be used for ventilation and solar heat gain.
ClimateThe prevailing or average weather conditions of a geographic region.
Climate Action PlanA description of the policies and measures that a local government will take to reduce greenhouse gas emissions and achieve its emissions reduction…
Climate ChangeA term used to describe short and long-term affects on the Earth's climate as a result of human activities such as fossil fuel combustion and vegetation…
CloneAn exact genetic replica of a specific gene or an entire organism. See Cloning.
Close CoupledAn energy system in which the fuel production equipment is in close proximity, or connected to, the fuel using equipment.
Closed BasinA basin draining to some depression or a pond within its area, from which water is lost only by evaporation or percolation.
Closed CycleA system in which a working fluid is used over and over without introduction of new fluid, as in a hydronic heating system or mechanical refrigeration…
Closed-Loop BiomassAs defined by the Comprehensive National Energy Act of 1992 (or the Energy Policy Act; EPAct): any organic matter from a plant which is planted for the…
Closed-loop cooling systemAlso known as a wet closed-cycle cooling system, a system that circulates water between a steam condenser and a cooling tower to cool steam condensate at…
Closed-Loop Geothermal Heat Pump SystemsClosed-loop (also known as "indirect") systems circulate a solution of water and antifreeze through a series of sealed loops of piping.
Clovis ComplexCharacteristic of Paleoindian finds located near Clovis, New Mexico, such as specific fluted points.
Cluster DevelopmentA pattern of development in which industrial and commercial facilities, and homes are grouped together on parcels of land in order to leave parts of the…
co-firingThe use of a mixture of two fuels within the same combustion chamber.
co-generationThe technology of producing electric energy and another form of useful energy (usually thermal) for industrial, commercial, or domestic heating or cooling…
Coalbed methaneA methane-rich gas, similar to natural gas, produced from in-situ coal through drilled wells that are typically completed open-hole, as opposed to the…
Coastal Zone Management ActNational law encouraging states to develop coastal management programs. The act establishes a method for the federal government to approve states´ plans…
Coastal Zone Management Act (CZMA)National Oceanographic and Atmospheric Administration (NOAA) provides funding for implementation and sets standards (including prevention of non-point…
CodesLegal documents that regulate construction to protect the health, safety, and welfare of people.
Coefficient of Heat Transmission (U-Value)A value that describes the ability of a material to conduct heat. The number of Btu that flow through 1 square foot of material, in one hour.
Coefficient of Performance (COP)A ratio of the work or useful energy output of a system versus the amount of work or energy inputted into the system as determined by using the same…
Coefficient of Utilization (CU)A term used for lighting appliances; the ratio of lumens received on a flat surface to the light output, in lumens, from a lamp; used to evaluate the…
CofiringThe use of two or more different fuels (e.g. wood and coal) simultaneously in the same combustion chamber of a power plant.
CogenerationThe generation of electricity or shaft power by an energy conversion system and the concurrent use of rejected thermal energy from the conversion system…
CogeneratorA class of energy producer that produces both heat and electricity from a single fuel.
COILAs a component of a heating or cooling appliance, rows of tubing or pipe with fins attached through which a heat transfer fluid is circulated and to…
Coincidence FactorThe ratio of the coincident, maximum demand or two or more loads to the sum of their noncoincident maximum demand for a given period; the reciprocal of…
Coincident DemandThe demand of a consumer of electricity at the time of a power supplier's peak system demand.
Cold Night SkyThe low effective temperature of the sky on a clear night.
Coliform bacteriaBacteria whose presence in waste water is an indicator of pollution and of potentially dangerous contamination.
CollateralAssets that are offered to secure a loan or other credit. For example, if you get a real estate mortgage, the bank's collateral is typically your house.
CollectionThe capture or obtaining of plant or animal specimens. This can include obtaining specimens for scientific study, pets, or illegal trade.
CollectorThe component of a solar energy heating system that collects solar radiation, and that contains components to absorb solar radiation and transfer the heat…
Collector EfficiencyThe ratio of solar radiation captured and transferred to the collector (heat transfer) fluid.
Collector FluidThe fluid, liquid (water or water/antifreeze solution) or air, used to absorb solar energy and transfer it for direct use, indirect heating of interior…
Collector TiltThe angle that a solar collector is positioned from horizontal.
ColluviumA general term to include loose rock and soil material that accumulates at the base of a slope as the result of mass wasting processes.
ColorThe sensible perception of hue, value and saturation characteristics of surfaces of window components.
Color RenditionHow colors appear when illuminated by a light source. Color rendition is generally considered to be a more important lighting quality than color…
Color TemperatureThe color of the light source. By convention, yellow-red colors (like the flames of a fire) are considered warm, and blue-green colors (like light from an…
Combined cycleTwo or more generation processes in series or in parallel, configured to optimize the energy output of the system.
Combined Heat and Power (CHP)Also called cogeneration, CHP is the use of the waste heat generated by an engine or power station to produce useful heat, typically for heating of a…
Combustion turbineA turbine that generates power from the combustion of a fuel.
Comfort ZoneA frequently used room or area that is maintained at a more comfortable level than the rest of the house; also known as a "warm room."
Commercial BuildingA building with more than 50 percent of its floor space used for commercial activities, which include stores, offices, schools, churches, libraries…
Commercial forest landForested 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…
Commercial SectorConsists of businesses that are not engaged in transportation or manufacturing or other types of industrial activities.
CommissioningThe process by which a power plant, apparatus, or building is approved for operation based on observed or measured operation that meets design…
CommunityA political entity that has the authority to adopt and enforce floodplain ordinances for the area under its jurisdiction.
compactAn agreement between states apportioning the water of a river basin to each of the signatory states.
Compact Building DesignRefers to the act of constructing buildings vertically rather than horizontally, and configuring them on a block or neighborhood scale that makes…
Compact FluorescentA smaller version of standard fluorescent lamps which can directly replace standard incandescent lights.
Compact Linear Fresnel Reflector (CLFR)A type of concentrated solar power (CSP) technology similar to a parabolic trough design, where the sun's heat energy is reflected onto a receiver…
CompensationA type of mitigation in which the impacts to a species or habitat are offset by protecting, restoring, or creating suitable habitat elsewhere.
Compensatory mitigation(For purposes of the Clean Water Act Section 404 and Rivers and Harbors Act Section 10 regulatory programs), compensatory mitigation is the restoration…
Complete Mix DigesterA type of anaerobic digester that has a mechanical mixing system and where temperature and volume are controlled to maximize the anaerobic digestion…
Composite noise levelA single noise level summed on an energy basis from many noise sources (e.g., Stirling engine, electric generator, cooling fan, and air compressor for a…
CompostingThe process of degrading organic material (biomass) by microorganisms in aerobic conditions.
Composting ToiletA self-contained toilet that use the process of aerobic decomposition (composting) to break down feces into humus and odorless gases.
Comprehensive PlanRegional, state, or local documents that describe community visions for future growth.
Compressed Air StorageThe storage of compressed air in a container for use to operate a prime mover for electricity generation.
Compressed Natural Gas (CNG)Natural gas (methane) that has been compressed to a higher pressure gaseous state by a compressor; used in CNG vehicles.
Compression ChillerA cooling device that uses mechanical energy to produce chilled water.
CompressorA device used to compress air for mechanical or electrical power production, and in air conditioners, heat pumps, and refrigerators to pressurize the…
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…