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Calorie: Any of several approximately equal values of heat, each measured as the quantity of heat require to raise the temperature of 1 gram of water by 1 degree Celsius from a standard initial temperature, esp. from 3.98 degrees Celsius. 14.5 degrees Celsius, or 19.5 degrees Celsius, at 1 atmosphere pressure. A calorie is the unit of heat equal to 4.184 joules. It takes 500,000 calories of energy to boil a pot of coffee. One food calorie equals 1,000 energy calories.

Capability: The maximum load that a generating unit, generating station or other electrical apparatus can carry under specified conditions for a given period of time without exceeding approved limits of temperature and stress.

Capacity: The full–load continuous rating of a generator, prime mover, or other electric equipment under specified conditions as designated by the manufacturer. It is usually indicated on a nameplate attached to the equipment.

Capacity factor: The capacity factor of a generating unit is the ratio of the actual output of the generating unit over a period of time and its output if it had operated at full capacity during that time period. The capacity factor is calculated by totaling the energy the generating unit produced and dividing it by the energy it would have produced at full capacity.

Captive Customer: A customer who does not have realistic alternatives to buying power from the local utility, even if that customer had the legal right to buy from competitors.

Carbon Dioxide: A colorless, odorless, non–poisonous gas that is a normal part of the air. Carbon dioxide, also called CO2, is exhaled by humans and animals and is absorbed by green growing things and by the sea.

Carbon Monoxide (CO): A colorless, odorless, highly poisonous gas made up of carbon and oxygen molecules formed by the incomplete combustion of carbon or carbonaceous material, including gasoline. It is a major air pollutant on the basis of weight.

Carbon Sink: A reservoir that absorbs or takes up released carbon. Vegetation and soils are common carbon sinks.

Carcinogens: Potential cancer–causing agents in the environment. They include among others: industrial chemical compounds found in food additives, pesticides and fertilizers, drugs, toy, household cleaners, toiletries and paints. Naturally occurring ultraviolet solar radiation is also a carcinogen.

Casinghead (Oil Well) Gas: Wet gas which is usually used to run the equipment or is flared (burned off).

Catalytic Cracking: A refinery process that converts a high–boiling range fraction of petroleum (gas oil) to gasoline, olefin feed for alkylation, distillate, fuel oil and fuel gas by use of a catalyst and heat.

Caulking: Material used to make an air–tight seal by filling in cracks, such as those around windows and doors.

ccf: One hundred cubic feet. See Cubic Foot

Celsius: A temperature scale based on the freezing (0 degrees) and boiling (100 degrees) points of water. Abbreviated as C in second and subsequent references in text. Formerly known as Centigrade. To convert Celsius to Fahrenheit, multiply the number by 9, divide by 5, and add 32. For example:

CFCs (Chlorofluorocarbons or Chlorinated Fluorocarbons): A family of artificially produced chemicals receiving much attention for their role in stratospheric ozone depletion. On a per molecule basis, these chemicals are several thousand times more effective as greenhouse gases than carbon dioxide. Since they were introduced in the mid–1930s, CFCs have been used as refrigerants, solvents and in the production of foam material. The 1987 Montreal protocol on CFCs seeks to reduce their production by one–half by the year 1998.

Chained Dollars: A measure used to express real prices. Real prices are those that have been adjusted to remove the effect of changes in the purchasing power of the dollar; they usually reflect buying power relative to a reference year. Prior to 1996, real prices were expressed in constant dollars, a measure based on the weights of goods and services in a single year, usually a recent year. In 1996, the U.S. Department of Commerce introduced the chained–dollar measure. The new measure is based on the average weights of goods and services in successive pairs of years. It is "chained" because the second year in each pair, with its weights, becomes the first year of the next pair. The advantage of using the chained–dollar measure is that it is more closely related to any given period covered and is therefore subject to less distortion over time.

Chemical Energy: The energy generated when a chemical compound combusts, decomposes, or transforms to produce new compounds.

Chiller: A device that cools water, usually to between 40 and 50 degrees Fahrenheit for eventual use in cooling air.

Circuit: One complete run of a set of electric conductors from a power source to various electrical devices (appliances, lights, etc.) and back to the same power source.

City Gate Price: Price of natural gas at the point it is transferred from a pipeline to a local distribution company.

Clerestory: A wall with windows that is between two different (roof) levels. The windows are used to provide natural light into a building.

Coal: Black or brown rock, formed under pressure from organic fossils in prehistoric times, that is mined and burned to produce heat energy.

Coal Conversion: Changing coal into synthetic gas or liquid fuels. See Gasification.

Coal Oil: Oil that can be obtained by distilling bituminous coal.

Coal Seam: A mass of coal, occurring naturally at a particular location, that can be commercially mined.

Coal Slurry Pipeline: A pipe system that transports pulverized coal suspended in water.

Coefficient of Performance (COP): Used to rate the performance of a heat pump, the COP is the ratio of the rate of useful heat output delivered by the complete heat pump unit (exclusive of supplementary heating) to the corresponding rate of energy input, in consistent units and under specific conditions.

Cogeneration: Cogeneration means the sequential use of energy for the production of electrical and useful thermal energy. The sequence can be thermal use followed by power production or the reverse.

Cogenerator: Cogenerators use the waste heat created by one process, for example during manufacturing, to produce steam which is used, in turn, to spin a turbine and generate electricity.

Coke: A porous solid left over after the incomplete burning of coal or of crude oil.

Coke Oven Gas: Gas given off by coke ovens. Coke oven gas is interchangeable with goal gas.

Coker: A coker is used to crack straight-run fuel oil to produce distillates.

Combination Burning: Rapid oxidation, with the release of energy in the form of heat and light.

Combined Cycle Plant: An electric generating station that uses waste heat from its gas turbines to produce steam for conventional steam turbines.

Combined Heat and Power (CHP) Plant: A plant designed to produce both heat and electricity from a single heat source. Note: This term is being used in place of the term "cogenerator" that was used by the Energy Information Administration in the past. CHP is a better description of the facilities because some of the plants included do not produce heat and power in a sequential fashion and, as a result, do not meet the legal definition of cogeneration specified in the Public Utility Regulatory Policy Act (PURPA).

Combined Hydronic Space/Water Heating: a system in which both space heating and domestic water heating are provided by the same water heater(s).

Comfort Conditioning: The process of treating air to simultaneously control its temperature, humidity, cleanliness, and distribution to meet the comfort requirements of the occupants of the conditioned space.

Comfort Zone: The range of temperatures over which the majority of persons feel comfortable (neither too hot nor too cold).

Commercial Sector: Nonmanufacturing business establishments, including hotels, motels, restaurants, wholesale businesses, retail stores, laundries and other service enterprises; health, social and educational institutions; and federal, state and local governments. Street lights, pumps, bridges and public services are also included.

Community Solar Farm:A solar farm funded in part by community members, sometimes through shares in the power.

Compressed Natural Gas (CNG): Natural gas that has been compressed under high pressure, typically between 2,000 and 3,600 pounds per square inch, held in a container. The gas expands when released for use as a fuel.

Condensate: Liquid fuel obtained by burning gas or vapor produced from oil and gas wells.

Condenser: A heat exchanger in which the refrigerant, compressed to a hot gas, is condensed to liquid by rejecting heat.

Conditioned Floor Area: The floor area of enclosed conditioned spaces on all floors measured from the interior surfaces of exterior partitions for nonresidential buildings and from the exterior surfaces of exterior partitions for residential buildings.

Conditioned Space: Enclosed space that is either directly conditioned space or indirectly conditioned space.

Conductance: The quantity of heat, in British thermal units, that will flow through one square foot of material in one hour, when there is a 1 degree F temperature difference between both surfaces. Conductance values are given for a specific thickness of material, not per inch thickness.

Conduction: The transfer of heat energy through a material (solid, liquid or gas) by the motion of adjacent atoms and molecules without gross displacement of the particles.

Conductivity (k): The quantity of heat that will flow through one square foot of homogeneous material, one inch thick, in one hour, when there is a temperature difference of one degree Fahrenheit between its surfaces.

Congestion (Electric Utility): A condition that occurs when insufficient transfer capacity is available to implement all of the preferred schedules simultaneously.

Conservation: Steps taken to cause less energy to be used than would otherwise be the case. These steps may involve improved efficiency, avoidance of waste, reduced consumption, etc. They may involve installing equipment (such as a computer to ensure efficient energy use), modifying equipment (such as making a boiler more efficient), adding insulation, changing behavior patterns, or other such actions.

Contango: The condition where longer term futures contracts carry a higher price than shorter term contracts. This condition encourages inventory builds if the contango exceeds the costs of carrying the commodity for future delivery. In other words, prices are low now but people believe prices will go up so they carry as much inventory as possible. Backwardation is the situation with opposite circumstances from contango.

Continental Shelf: The portion of the sea bottom that slopes gradually from the edge of a continent. Usually defined as areas where water is less than 200 meters or 600 feet deep.

Convection: Transferring heat by moving air, or transferring heat by means of upward motion of particles of liquid or gas heat from beneath. Heat transfer by the movement of fluid.

Conventional Gas: Natural gas occurring in nature, as opposed to synthetic gas.

Conversion: Device or kit by which a conventional fuel vehicle is changed to an alternative fuel vehicle.

Conversion Factor: A number that translates units of one system of measure into corresponding values of another system of measure.

Converted Vehicle: A vehicle originally designed to operate on gasoline that has been modified or altered to run on an alternative fuel.

Converter: Any technology that changes the potential energy in a fuel into a different from of energy such as heat or motion. The term also is used to mean an apparatus that changes the quantity or quality of electrical energy.

Cooling Capacity, Latent: Available refrigerating capacity of an air conditioning unit for removing latent heat from the space to be conditioned.

Cooling Capacity, Sensible: Available refrigerating capacity of an air conditioning unit for removing sensible heat from the space to be conditioned.

Cooling Capacity, Total: Available refrigerating capacity of an air conditioner for removing sensible heat and latent heat from the space to be conditioned.

Cooling Degree Day (CDD): A measure of how warm a location is over a period of time relative to a base temperature, most commonly specified as 65 degrees Fahrenheit. The measure is computed for each day by subtracting the base temperature (65 degrees) from the average of the day's high and low temperatures, with negative values set equal to zero. Each day's cooling degree–days are summed to create a cooling degree day measure for a specified reference period. Cooling degree days are used in energy analysis as an indicator of air conditioning energy requirements or use.

Cooling Load: The rate at which heat must be extracted from a space in order to maintain the desired temperature within the space.

Cooling Load Temperature Difference (CLTD): A value used in cooling load calculations for the effective temperature difference (delta T) across a wall or ceiling, which accounts for the effect of radiant heat as well as the temperature difference.

Cooling Tower: A device for evaporatively cooling water by contact with air.

CO–OP: This is the commonly used term for a rural electric cooperative. Rural electric cooperatives generate and purchase wholesale power, arrange for the transmission of that power, and then distribute the power to serve the demand of rural customers. Co–ops typically become involved in ancillary services such as energy conservation, load management and other demand–side management programs in order to serve their customers at least cost.

Cooperative (Electric Utility): A joint venture organized by consumers to make electric utility service available in their area.

Cord: A measure of volume, 4 by 4 by 8 feet, used to define amounts of stacked wood available for use as fuel. Burned, a cord of wood produces about 5 million calories of energy.

Corporate Average Fuel Economy (CAFE): A sales–weighted average fuel mileage calculation, in terms of miles per gallon, based on city and highway fuel economy measurements performed as part of the federal emissions test procedures. CAFE requirements were instituted by the Energy Policy and Conservation Act of 1975 (89 Statute. 902) and modified by the Automobile Fuel Efficiency Act of 1980 (94 Statute. 1821). For major manufacturers, CAFE levels in 1996 are 27.5 miles per gallon for light–duty automobiles. CAFE standards also apply to some light trucks. The Alternative Motor Fuels Act of 1988 allows for an adjusted calculation of the fuel economy of vehicles that can use alternative fuels, including fuel–flexible and dual–fuel vehicles.

Crude Oil: Petroleum as found in the earth, before it is refined into oil products. Also called CRUDE. A mixture of hydrocarbons that existed in liquid phase in underground reservoirs and remains liquid at atmospheric pressure after passing through surface separating facilities.

Crude Oil (Including Lease Condensate): A mixture of hydrocarbons that exists in liquid phase in underground reservoirs and remains liquid at atmospheric pressure after passing through surface separating facilities. Included are lease condensate and liquid hydrocarbons produced from tar sands, gilsonite, and oil shale. Drip gases are also included, but topped crude oil (residual oil) and other unfinished oils are excluded. Where identifiable, liquids produced at natural gas processing plants and mixed with crude oil are likewise excluded.

Crude Oil Used Directly: Crude oil consumed as fuel by crude oil pipelines and on crude oil leases.

Crude Oil Stocks: Stocks held at refineries and at pipeline terminals. Does not include stocks held on leases (storage facilities adjacent to the wells).

Cubic Foot: The most common unit of measurement of natural gas volume. It equals the amount of gas required to fill a volume of one cubic foot under stated conditions of temperature, pressure and water vapor. One cubic foot of natural gas has an energy content of approximately 1,000 British thermal units (Btu). One hundred (100) cubic feet equals one therm (100 ft3 = 1 therm).

Cubic Feet per Minute (CFM): A measure of flow rate.

Curie: A measure of radioactivity.