Glossary of Energy Terms

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A B C D E F G H I J K L M N O P Q R S T U V W X-Z Acronyms

Note: No entries for Y or Z.

Letter C

CALIFORNIA ENDANGERED SPECIES ACT - The state law originally enacted in 1970, expresses the state's concern over California's threatened wildlife, defined rare and endangered wildlife, and gave authority to the Department of Fish and Game to "identify, conserve, protect, restore, and enhance any endangered species or any threatened species and its habitat in California...." The statute is under the state Fish and Game Code as Chapter 1.5.

CALIFORNIA ENERGY COMMISSION - The state agency established by the Warren-Alquist State Energy Resources Conservation and Development Act in 1974 (Public Resources Code, Sections 25000 et seq.) responsible for energy policy. The Energy Commission's five major areas of responsibilities are:

  1. Forecasting future statewide energy needs
  2. Licensing power plants sufficient to meet those needs
  3. Promoting energy conservation and efficiency measures
  4. Developing renewable and alternative energy resources, including providing assistance to develop clean transportation fuels
  5. Planning for and directing state response to energy emergencies

Funding for the Commission's activities comes from the Energy Resources Program Account, Federal Petroleum Violation Escrow Account and other sources.

CALIFORNIA ENVIRONMENTAL QUALITY ACT (CEQA - pronounced See' quah) Enacted in 1970 and amended through 1983, established state policy to maintain a high-quality environment in California and set up regulations to inhibit degradation of the environment.

CALIFORNIA PUBLIC UTILITIES COMMISSION (CPUC) - A state agency created by constitutional amendment in 1911 to regulate the rates and services of more than 1,500 privately owned utilities and 20,000 transportation companies. The CPUC is an administrative agency that exercises both legislative and judicial powers; its decisions and orders may be appealed only to the California Supreme Court. The major duties of the CPUC are to regulate privately owned utilities, securing adequate service to the public at rates that are just and reasonable both to customers and shareholders of the utilities; including rates, electricity transmission lines and natural gas pipelines. The CPUC also provides electricity and natural gas forecasting, and analysis and planning of energy supply and resources. Its main headquarters are in San Francisco.

CALIFORNIA UTILITY RESEARCH COUNCIL (CURC) - Public Utilities Code, Sections 9201-9203 requires the California Energy Commission, the California Public Utilities Commission, and the investor-owned utilities (Pacific Gas and Electric Company, Southern California Edition, and San Diego Gas & Electric) to coordinate and promote consistency of research, development and demonstration (RD&D) programs with state energy policy. The CURC provides coordination for and sharing of information on energy RD&D in California to avoid duplication of efforts.

CALL-BACK - A provision included in some power sale contracts that lets the supplier stop delivery when the power is needed to meet certain other obligations.

CALORIE (energy calorie - small "c" - as opposed to food Calorie - capital "C") 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.

CAP AND TRADE - Cap and Trade is a market-based policy tool for protecting human health and the environment. A cap and trade program first sets an aggressive cap, or maximum limit, on emissions. Sources covered by the program then receive authorizations to emit in the form of emissions allowances, with the total amount of allowances limited by the cap. Each source can design its own compliance strategy to meet the overall reduction requirement, including sale or purchase of allowances, installation of pollution controls, implementation of efficiency measures, among other options. Individual control requirements are not specified under a cap and trade program, but each emissions source must surrender allowances equal to its actual emissions in order to comply. Sources must also completely and accurately measure and report all emissions in a timely manner to guarantee that the overall cap is achieved. (EPA)

CAPACITY - The amount of electric power for which a generating unit, generating station, or other electrical apparatus is rated either by the user or manufacturer. The term is also used for the total volume of natural gas that can flow through a pipeline over a given amount of time, considering such factors as compression and pipeline size.

There are various types of electricity capacity.:

CAPACITY FACTOR - A percentage that tells how much of a power plant's capacity is used over time. For example, typical plant capacity factors range as high as 80 percent for geothermal and 70 percent for co-generation.

CAPACITY RELEASE - A secondary market for capacity that is contracted by a customer which is not using all of its 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 (CO2) - A colorless, odorless, non-poisonous gas that is a normal part of the air. Carbon dioxide is exhaled by humans and animals and is absorbed by green growing things and by the sea. CO2 is the greenhouse gas whose concentration is being most affected directly by human activities. CO2 also serves as the reference to compare all other greenhouse gases (see carbon dioxide equivalent). The major source of CO2 emissions is fossil fuel combustion. CO2 emissions are also a product of forest clearing, biomass burning, and non-energy production processes such as cement production. Atmospheric concentrations of CO2 have been increasing at a rate of about 0.5% per year and are now about 30% above preindustrial levels. (EPA)

CARBON DIOXIDE EQUIVALENT (CDE). A metric measure used to compare the emissions from various greenhouse gases based upon their global warming potential (GWP). Carbon dioxide equivalents are commonly expressed as "million metric tons of carbon dioxide equivalents (MMTCDE)" or "million short tons of carbon dioxide equivalents (MSTCDE)" The carbon dioxide equivalent for a gas is derived by multiplying the tons of the gas by the associated GWP. MMTCDE= (million metric tons of a gas) * (GWP of the gas) For example, the GWP for methane is 24.5. This means that emissions of one million metric tons of methane is equivalent to emissions of 24.5 million metric tons of carbon dioxide. Carbon may also be used as the reference and other greenhouse gases may be converted to carbon equivalents. To convert carbon to carbon dioxide, multiply the carbon by 44/12 (the ratio of the molecular weight of carbon dioxide to carbon). (EPA)

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 SEQUESTRATION - The uptake and storage of carbon. Trees and plants, for example, absorb carbon dioxide, release the oxygen and store the carbon. Fossil fuels were at one time biomass and continue to store the carbon until burned. (EPA)

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.

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.

CCR - California Code of Regulations.

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:

CERTIFICATION - process by which a motor vehicle, motor vehicle engine, or motor vehicle pollution control device satisfies the criteria adopted by the California Air Resources Board (ARB) for the control of specified air contaminants from vehicular sources (Health & Safety Code, Section 39018). Certification constitutes a guarantee by the manufacturer that the engine will meet certain standards at 50,000 miles; if not, it must be replaced or repaired without change.

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.

CFM (cubic feet per minute) - A measure of flow rate.

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.

CLEAN FUEL VEHICLE - is frequently incorrectly used interchangeably with "alternative fuel vehicle." Generally, refers to vehicles that use low-emission, clean-burning fuels. Public Resources Code Section 25326 defines clean fuels, for purposes of the section only, as fuels designated by ARB for use in LEVs, ULEVs or ZEVs and include, but are not limited to, electricity, ethanol, hydrogen, liquefied petroleum gas, methanol, natural gas, and reformulated gasoline.

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

CLIMATE CHANGE - Also referred to as 'global climate change'. The term 'climate change' is sometimes used to refer to all forms of climatic inconsistency, but because the Earth's climate is never static, the term is more properly used to imply a significant change from one climatic condition to another. In some cases, 'climate change' has been used synonymously with the term, 'global warming'; scientists however, tend to use the term in the wider sense to also include natural changes in climate. See also Enhanced Greenhouse Effect. (EPA)

CLIMATE ZONE - A geographical area is the state that has particular weather patterns. These zones are used to determine the type of building standards that are required by law.

CLUNKERS - also known as gross-polluting or super- emitting vehicles, i.e., vehicles that emit far in excess of the emission standards by which the vehicle was certified when it was new.

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.

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. Cogenerators may also be QFs.

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, subject to the following standards:

(a) At least 5 percent of the cogeneration project's total annual energy output shall be in the form of useful thermal energy.

(b) Where useful thermal energy follows power production, the useful annual power output plus one-half the useful annual thermal energy output equals not less than 42.5 percent of any natural gas and oil energy input.

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.

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 -- Also known as "cogeneration," it is the simultaneous production of electricity and heat from a fuel source such as natural gas, biomass, biogas, coal, waste heat, or oil. Combined heat and power is not a single technology, but an integrated energy system that can be modified depending on the energy user's needs.

COMBINED HYDRONIC SPACE/WATER HEATING - a system in which both space heating and domestic water heating are provided by the same water heater(s).

COMBUSTION Burning - Rapid oxidation, with the release of energy in the form of heat and light.

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).

COMPETITIVE TRANSMISSION CHARGE - A non-bypassable charge that customers pay to a utility for the recovery of its stranded costs.

COMMERCIALIZATION - Programs or activities that increase the value or decrease the cost of integrating new products or services into the electricity sector. (See "Sustained Orderly Development.")

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. [See California Code of Regulations, Title 24, Section 2-5302]

CONDITIONED SPACE - Enclosed space that is either directly conditioned space or indirectly conditioned space. [See California Code of Regulations, Title 24, Section 2-5302]

CONDITIONED SPACE, DIRECTLY -- An enclosed space that is provided with heating equipment that has a capacity exceeding 10 Btus/(hr-ft2), or with cooling equipment that has a capacity exceeding 10 Btus/(hr-ft2). An exception is if the heating and cooling equipment is designed and thermostatically controlled to maintain a process environment temperature less than 65 degrees Fahrenheit or greater than 85 degrees Fahrenheit for the whole space the equipment serves. [See California Code of Regulations, Title 24, Section 2- 5302]

CONDITIONED SPACE, INDIRECTLY --Enclosed space that: (1) has a greater area weighted heat transfer coefficient (u-value) between it and directly conditioned spaces than between it and the outdoors or unconditioned space; (2) has air transferred from directly conditioned space moving through it at a rate exceeding three air changes per hour.

CONDUCTANCE - The quantity of heat, in Btu's, 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 - A condition that occurs when insufficient transfer capacity is available to implement all of the preferred schedules simultaneously.

CONGESTION MANAGEMENT - Alleviation of congestion by the ISO.

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, etc.

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.

CONTINGENCY PLANNING - The Energy Commission's strategy to respond to impending energy emergencies such as curtailment or shortage of fuel or power because of natural disasters or the result of human or political causes, or a clear threat to public health, safety or welfare. The contingency plan specifies state actions to alleviate the impacts of a possible shortage or disruption of petroleum, natural gas or electricity. The plan is reviewed and updated at least every five years, with the last plan being adopted in 1993. Legislative authority for the California Energy Shortage Contingency Plan is found in Public Resources Code, Section 25216.5.

CONTRACT PATH - The most direct physical transmission tie between two interconnected entities. When utility systems interchange power, the transfer is presumed to take place across the "contract path," notwithstanding the electrical fact that power flow in the network will distribute in accordance with network flow conditions. This term can also mean to arrange for power transfer between systems. (See also Parallel path flow)

CONTRACTS FOR DIFFERENCES (CFD) -- A type of bilateral contract where the electric generation seller is paid a fixed amount over time which is a combination of the short-term market price and an adjustment with the purchaser for the difference. For example, a generator may sell a distribution company power for ten years at 6-cents/kilowatt-hour (kWh). That power is bid into Poolco at some low /kWh value (to ensure it is always taken). The seller then gets the market clearing price from the pool and the purchaser pays the producer the difference between the Poolco selling price and 6-cents/kWh (or vice versa if the pool price should go above the contract price).

CONTROL AREA - An electric power system, or a combination of electric power systems, to which a common automatic generation control (AGC) is applied to match the power output of generating units within the area to demand. The control area of the ISO is the state of California.

CONVECTION - Transferring heat by moving air, or transferring heat by means of upward motion of particles of liquid or gas heat from beneath.

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 FUEL FACTOR - A number stating units of one system in corresponding values of another system.

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 - A unit of measure that indicates how heavy the air conditioning needs are under certain weather conditions.

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.

COP (COEFFICIENT OF PERFORMANCE) - - 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. [See California Code of Regulations, Title 24, Section 2-1602(c)(4)]

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.

CRUDE OIL STOCKS - Stocks held at refineries and at pipeline terminals. Does not include stocks held on leases (storage facilities adjacent to the wells). In California, crude oil stocks in 1990 are approximately 18 million barrels on any given day.


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 Btus. One hundred (100) cubic feet equals one therm (100 ft3 = 1 therm).

CURIE - A measure of radioactivity.

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