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 A

ABSORPTANCE -- The ratio of the radiation absorbed by a surface to the total energy falling on that surface described as a percentage.

ACCESS CHARGE -- A charge paid by all market participants withdrawing energy from the ISO controlled grid. The access charge will recover the portion of a utility's transmission revenue requirement not recovered through the variable usage charge.

ACTIVE SOLAR ENERGY -- Solar radiation used by special equipment to provide space heating, hot water or electricity.

ACTIVE SOLAR ENERGY SYSTEM -- A system designed to convert solar radiation into usable energy for space, water heating, or other uses. It requires a mechanical device, usually a pump or fan, to collect the sun's energy.

ACOP (Adjusted Coefficient of Performance) -- A standard rating term that was used to rate the efficiency of heat pumps in California. ACOP was replaced by Heating Seasonal Performance Factor (HSPF) in 1988.

ADDITION -- An alteration to an existing building that increases conditioned space.

ADJUSTMENT BID -- A bid that is used by the ISO to adjust supply or demand when congestion is anticipated.

ADVANCED METERING INFRASTRUCTURE - Refers to the full measurement and collection system that includes meters at the customer site, communication networks between the customer and a service provider, such as electric, gas, or water utility, and data reception and management systems that make the information available to the service provider (Source: Electric Power Research Institute [EPRI]).

ADVERSE HYDRO -- Water conditions limiting the production of hydroelectric power. In years having below-normal levels of rain and snow, and in seasons having less-than-usual runoff from mountain snow pack, there is then less water available for hydro energy production.

AFTER-MARKET -- broad term that applies to any change after the original purchase, such as adding equipment not a part of the original purchase. As applied to alternative fuel vehicles, it refers to conversion devices or kits for conventional fuel vehicles.

AGGREGATOR -- An entity responsible for planning, scheduling, accounting, billing, and settlement for energy deliveries from the aggregator's portfolio of sellers and/or buyers. Aggregators seek to bring together customers or generators so they can buy or sell power in bulk, making a profit on the transaction.

AIR CHANGE -- The replacement of a quantity of air in a space within a given period of time, typically expressed as air changes per hour. If a building has one air change per hour, this is equivalent to all of the air in the building being replaced in a one-hour period.

AIR CONDITIONER -- An assembly of equipment for air treatment consisting of a means for ventilation, air circulation, air cleaning, and heat transfer (either heating or cooling). The unit usually consists of an evaporator or cooling coil, and an electrically-driven compressor and condenser combination.

AIR FILM -- A layer of still air adjacent to a surface which provides some thermal resistance.

AIR FILM COEFFICIENT -- A measure of the heat transfer through an air film. [See ASHRAE Table 1, ASHRAE Handbook, 1985 Fundamentals]

AIR-TO-AIR HEAT EXCHANGER -- A device with separate air chambers that transfers heat between the conditioned air being exhausted and the outside air being supplied to a building.

AIR POLLUTION -- Unwanted particles, mist or gases put into the atmosphere as a result of motor vehicle exhaust, the operation of industrial facilities or other human activity.

ALTERATION -- Any change or modification to a building's construction. [See Addition].

AMBIENT AIR TEMPERATURE -- Surrounding temperature, such as the outdoor air temperature around a building.

ALCOHOL FUELS -- A class of liquid chemicals that have certain combinations of hydrogen, carbon and oxygen, and that are capable of being used as fuel.

ALTERNATING CURRENT -- (AC) Flow of electricity that constantly changes direction between positive and negative sides. Almost all power produced by electric utilities in the United States moves in current that shifts direction at a rate of 60 times per second.

ALTERNATIVE ENERGY SOURCES -- See RENEWABLE ENERGY.

ALTERNATIVE (transportation) FUELS -- as defined by the National Energy Policy Act (EPAct) the fuels are: methanol, denatured ethanol and other alcohols, separately or in mixtures of 85 percent by volume or more (or other percentage not less than 70 percent as determined by U.S. Department of Energy rule) with gasoline or other fuels; CNG; LNG; LPG; hydrogen; "coal-derived liquid fuels;" fuels "other than alcohols" derived from "biological materials;" electricity, or any other fuel determined to be "substantially not petroleum" and yielding "substantial energy security benefits and substantial environmental benefits."

ALTERNATIVE FUEL VEHICLE (AFV) -- motor vehicles that run on fuels other than petroleum-based fuels. As defined by the National Energy Policy Act (EPAct), this excludes reformulated gasoline as an alternative fuel.

ALTERNATIVE AND RENEWABLE FUELS AND VEHICLE TECHNOLOGY PROGRAM -- Created by Assembly Bill 118 (Nunez, Chapter 750, Statutes of 2007), the program with an annual budget of about $100 million supports projects that develop and improve alternative and renewable low-carbon fuels, improve alternative and renewable fuels for existing and developing engine technologies, expand transit and transportation infrastructures, and establishing workforce training programs, conduct public education and promotion, and create technology centers, among other tasks.

AMBIENT -- The surrounding atmosphere; encompassing on all sides; the environment surrounding a body but undisturbed or unaffected by it.

AMERICAN NATIONAL STANDARDS INSTITUTE - The institute oversees the creation, distribution, and use of thousands of norms and guidelines that directly affect businesses in nearly every sector from acoustical devices and construction equipment to dairy and livestock production and energy distribution. (Source: ANSI)

AMERICAN RECOVERY AND REINVESTMENT ACT OF 2009 (ARRA) -- U.S. Congress passed the American Recovery and Reinvestment Act of 2009 on February 13, 2009, at the urging of President Obama, who signed it into law four days later. A direct response to the economic crisis, the Recovery Act strives to create new jobs and save existing ones, spur economic activity and invest in long-term grown, and foster unprecedented levels of accountability and transparency in government spending. Among its objectives, the act makes $275 billion available for federal contracts, grants, and loans.

ANAEROBIC DIGESTION -- A biological process in which biodegradable organic matters are broken down by bacteria into biogas, which consists of methane (CH4), carbon dioxide (CO2), and other trace amount of gases. The biogas can be used to generate heat and electricity.

ANCILLARY SERVICES -- The services other than scheduled energy that are required to maintain system reliability and meet WSCC/NERC operating criteria. Such services include spinning, non-spinning, and replacement reserves, voltage control, and black start capability.

AMPERE (Amp) -- The unit of measure that tells how much electricity flows through a conductor. It is like using cubic feet per second to measure the flow of water. For example, a 1,200 watt, 120-volt hair dryer pulls 10 amperes of electric current (watts divided by volts).

ANGLE OF INCIDENCE -- The angle that the sun's rays make with a line perpendicular to a surface. The angle of incidence determines the percentage of direct sunshine intercepted by a surface.

ANNUAL MAXIMUM DEMAND -- The greatest of all demands of the electrical load which occurred during a prescribed interval in a calendar year.

ANIMAL WASTE CONVERSION -- Process of obtaining energy from animal wastes. This is a type of biomass energy.

AFUE (Annual Fuel Utilization Efficiency) -- A measure of heating efficiency, in consistent units, determined by applying the federal test method for furnaces. This value is intended to represent the ratio of heat transferred to the conditioned space by the fuel energy supplied over one year. [See California Code of Regulations, Title 20, Section 1602(d)(1)]

ANTHRACITE -- Hard coal, found deep in the earth. It burns very hot, with little flame. It usually has a heating value of 12,000-15,000 British thermal units (Btus) per pound.

APPLIANCE EFFICIENCY STANDARDS -- California Code of Regulations, Title 20, Chapter 2, Subchapter 4: Energy Conservation, Article 4: Appliance Efficiency Standards. Appliance Efficiency Standards regulate the minimum performance requirements for appliances sold in California and apply to refrigerators, freezers, room air conditioners, central air conditioners, gas space heaters, water heaters, plumbing fittings, fluorescent lamp ballasts and luminaires, and ignition devices for gas cooking appliances and gas pool heaters. New National Appliance Standards are in place for some of these appliances and will become effective for others at a future date.

APPLIANCE SATURATION -- A percentage telling what proportion of all households in a given geographical area have a certain appliance.

APPLICANT -- Applicant means any person who submits an application for certification pursuant to the provisions of this division, including, but not limited to, any person who explores for or develops geothermal resources.

APPLICATION -- Application means any request for certification of any site and related facility filed in accordance with the procedures established pursuant to this division. An applicant for a geothermal power-plant and related facilities may propose more than one site and related geothermal facilities in the same application.

AREA LOAD -- The total amount of electricity being used at a given point in time by all consumers in a utility's service territory.

ASHRAE -- Acronym for American Society of Heating, Refrigerating and Air- Conditioning Engineers.

ASH -- Non-organic, non-flammable substance left over after combustible material has been completely burned.

ASSOCIATED GAS -- Natural gas that can be developed for commercial use, and which is found in contact with oil in naturally occurring underground formations.

ATGAS -- Synthetic gas produced by dissolving coal in a bath of molten iron. The process was developed by Applied Technology, Inc. Synthetic gas may be used as a substitute for natural gas in industrial and home uses.

ATOM --The smallest unit of an element consisting of a dense positively charged nucleus (of protons and neutrons) orbited by negatively charged electrons.

ATOMIC ENERGY COMMISSION --The independent civilian agency of the federal government with statutory responsibility to supervise and promote use of nuclear energy. Functions were taken over in 1974 by the Energy Research and Development Administration (now part of the U.S. Department of Energy) and the Nuclear Regulatory Commission.

ATOMIC NUCLEUS -- The positively charged core of an atom.

AUTOMATIC METER READING - Technology used in utility meters for collecting the data that's needed for billing. AMR, which works by translating the movement of the mechanical dials on a meter into a digital signal, does not require physical access or visual inspection. The data can be transmitted from the meter to the utility company by telephone, power line, satellite, cable, or radio frequency. (Source: Whatis [dot] com.)

AUXILIARY ENERGY SUBSYSTEM -- Equipment using conventional fuel to supplement the energy output of a solar system. This might be, for example, an oil- fueled generator that adds to the electrical output of a substitutes for the solar system during long overcast periods when there is not enough sunlight.

AUXILIARY EQUIPMENT -- Extra machinery needed to support the operation of a power plant or other large facility.

AVERAGE COST -- The revenue requirement of a utility divided by the utility's sales. Average cost typically includes the costs of existing power plants, transmission, and distribution lines, and other facilities used by a utility to serve its customers. It also included operating and maintenance, tax, and fuel expenses.

AVERAGE DEMAND -- The energy demand in a given geographical area over a period of time. For example, the number of kilowatt-hours used in a 24-hour period, divided by 24, tells the average demand for that period.

AVERAGE HYDRO -- Rain, snow and runoff conditions that provide water for hydroelectric generation equal to the most commonly occurring levels. Average hydro usually is a mean indicating the levels experienced most often in a 104-year period.

AVOIDED COST -- (Regulatory) The amount of money that an electric utility would need to spend for the next increment of electric generation to produce or purchase elsewhere the power that it instead buys from a co-generator or small-power producer. Federal law establishes broad guidelines for determining how much a qualifying facility (QF) gets paid for power sold to the utility.

AVOIDED COST -- The cost the utility would incur but for the existence of an independent generator or other energy service option. Avoided cost rates have been used as the power purchase price utilities offer independent suppliers (see Qualifying Facilities).

AZIMUTH--The angular distance between true south and the point on the horizon directly below the sun. Typically used as an input for opaque surfaces and windows in computer programs for calculating the energy performance of buildings.

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

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