| Earth | Refers to physically connecting a part of an electrical system to the ground, done as a safety measure, by means of a conductor embedded in suitable soil. Synonymous with “ground.” |
| Earth-Leakage Circuit Breaker (ELCB) | A device used to prevent electrical shock hazards in mains voltage power systems, including independent power systems. Also known as residual current devices (RCD’s). |
| Earthquake | the vibration or movement of the ground caused by a sudden shift along faults (cracks) in the earth’s crust; most earthquakes occur at the places where tectonic plates edges meet. |
| Ecology | The study of interrelationships of animals and plants to one another and to their environment. |
| Economic Efficiency | A term that refers to the optimal production and consumption of goods and services. This generally occurs when prices of products and services reflect their marginal costs. Economic efficiency gains can be achieved through cost reduction, but it is better to think of the concept as actions that promote an increase in overall net value (which includes, but is not limited to, cost reductions). |
| Economies Of Sale | Economies of scale exist where the industry exhibits decreasing average long-run costs with size. |
| Economizer Air | A ducting arrangement and automatic control system that allows a heating, ventilation and air conditioning (HVAC) system to supply up to 100 percent outside air to satisfy cooling demands, even if additional mechanical cooling is required. |
| Economizer Water | A system which uses either direct evaporative cooling, or a secondary evaporatively cooled water loop and cooling coil to satisfy cooling loads, even if additional mechanical cooling is required. |
| Economy Energy (Electricity Utility) | Electricity purchased by one utility from another to take the place of electricity that would have cost more to produce on the utility’s own system. |
| Ecosystem | The interacting system of biological community and its nonliving environment. |
| Edge-Defined Film-Fed Growth (Efg) | A method for making sheets of polycrystalline silicon for photovoltaic devices in which molten silicon is drawn upward by capillary action through a mold. |
| Edison, Thomas Alva | The "father" of the American energy industry, Thomas Edison was an American inventor who was born in 1847 and died in 1931. He patented a total of 1,093 inventions |
| EEI | Edison Electric Institute. An association of electric companies formed in 1933 "to exchange information on industry developments and to act as an advocate for utilities on subjects of national interest." |
| EER | (Energy Efficiency Ratio) the ratio of cooling capacity of an air conditioning unit in Btus per hour to the total electrical input in watts under specified test conditions. |
| EER (Energy Efficiency Ratio) | The ratio of cooling capacity of an air conditioning unit in Btus per hour to the total electrical input in watts under specified test conditions. |
| Efficacy, Lighting | The ratio of light from a lamp to the electrical power consumed, including ballast losses, expressed as lumens per watt. |
| Efficiency | Found in electrical energy. It is the amount of a utility’s power generation process that is efficiently used to produce power. However some power can be lost in the transmission process. |
| Efficiency (PV Modules) | The ratio of power output of a photovoltaic cell to the incident power from the sun or simulated sun sources under specified standard insolation conditions. A solar cell that converts 1/10 of the sun’s energy that strikes its surface to electricity has an efficiency of 10 percent. |
| Electric Circuit | Path followed by electrons from a power source (generator or battery) through an external line (including devices that use the electricity) and returning through another line to the source. |
| Electric Current | The rate at which electrons flow through an electrical conductor, usually measured in amperes (amps). |
| Electric Generator | A device that converts a heat, chemical or mechanical energy into electricity. |
| Electric Radiant Heating | A heating system in which electric resistance is used to produce heat which radiates to nearby surfaces. There is no fan component to a radiant heating system. |
| Electric Resistance Heater | A device that produces heat through electric resistance. For example, an electric current is run through a wire coil with a relatively high electric resistance, thereby converting the electric energy into heat which can be transferred to the space by fans. |
| Electric Utility | Any person or state agency with a monopoly franchise (including any municipality), which sells electric energy to end-use customers; this term includes the Tennessee valley Authority, but does not include other Federal power marketing agency (from EPAct). |
| Electrical Energy | energy of electric charges or electric currents. |
| Electrical Grid | An integrated system of electricity distribution, usually covering a large area. |
| Electrical Potential | Same as VOLTAGE. |
| Electricity | The movement of electrons (a sub-atomic particle), produced by a voltage, through a conductor. |
| Electricity Generation | The process of producing electricity by transforming other forms or sources of energy into electrical energy. Electricity is measured in kilowatt hours (kWh). |
| Electrochemical Cell | A device containing two conducting electrodes, one positive and the other negative, made of dissimilar materials (usually metals) that are immersed in a chemical solution (electrolyte) that transmits positive ions from the negative to the positive electrode and thus forms an electrical charge. One or more cells constitute a battery. |
| Electrode | An electrically conductive material, forming part of an electrical device, often used to lead current into or out of a liquid or gas. In a battery, the electrodes are also known as plates. |
| Electrodeposition | Electrolytic process in which a metal is deposited at the cathode from a solution of its ions. |
| Electrolysis | The production of chemical energy by passing an electric current through a liquid called an electrolyte. |
| Electrolyte | The medium that provides ionic transport between the electrodes of a battery. All common batteries contain an electrolyte, such as the sulfuric acid used in lead-acid batteries. |
| Electromagnet | A magnet created from wire coils that produces a magnetic field when electricity flows through the coils |
| Electromagnetic | Objects made magnetic by an electric current. |
| Electromagnetic Fields (Emf) | Ordinary every day use of electricity produces magnetic and electric fields. These 60 Hertz fields (fields that go back and forth 60 times a second) are associated with electrical appliances, power lines and wiring in buildings. |
| Electromagnetic Radiation (Emr) | Magnetic radiation produced by a changing electrical current, such as alternating current (AC). |
| Electron | A negatively charged particle. The movement of electrons in an electrical conductor constitutes an electric current. |
| Electron Volt (Ev) | The amount of kinetic energy gained by an electron when accelerated through an electric potential difference of 1 Volt; equivalent to 1.603 x 10^-19; a unit of energy or work. |
| Element | A substance consisting entirely of atoms of the same atomic number. |
| Elephanta | The violent windstorms that occur at the beginning and the end of the monsoon season in India. |
| Elevation | 1) The height above sea level (altitude); 2) A geometrical projection, such as a building, on a plane perpendicular to the horizon. |
| Embodied Energy | The energy consumed by all of the processes associated with the production of a material. This includes the energy required in mining, transport, manufacturing, administration, use, disposal, etc. |
| Emergency Core Cooling System (Eccs) | Equipment designed to cool the core of a nuclear reactor in the event of a complete loss of the coolant. |
| Emission | A substance or pollutant emitted as a result of a process. |
| Emission Standard | The maximum amount of a pollutant legally permitted to be discharged from a single source. |
| Emissivity | The property of emitting radiation; possessed by all materials to a varying extent. |
| Emittance | The emissivity of a material, expressed as a fraction. Emittance values range from 0.05 for brightly polished metals to 0.96 for flat black paint. |
| Energy | Power consumed multiplied by the duration of use. For example, 1000 Watts used for four hours is 4000 Watt hours. |
| Energy Audit | A survey that shows how much energy used in a home, which helps find ways to use less energy. |
| Energy Budget | A requirement in the Building Energy Efficiency Standards that a proposed building be designed to consume no more than a specified number of British thermal units (Btus) per year per square foot of conditioned floor area. |
| Energy Charge | The amount of money owed by an electric customer for kilowatt-hours consumed. |
| Energy Consumption | The amount of energy consumed in the form in which it is acquired by the user. The term excludes electrical generation and distribution losses. |
| Energy Contribution Potential | Recombination occurring in the emitter region of a photovoltaic cell. |
| Energy Conversion | The Changing Of Energy From One Form To Another. One Of The Many Examples Are Heat Energy Being Converted Into Mechanical Energy, And Then Mechanical Energy Into Electrical Energy, As Is Done In Steam-Driven Electric Power Plants. |
| Energy Density | A ratio of a battery or cell’s capacity to either its volume or weight. Volumetric energy density is expressed in watt-hours per cubic inch. Weight energy density is expressed in watt-hours per pound. |
| Energy Efficiency | the measure of the amount of energy which any technology can convert to useful work; technology with a higher energy efficiency will require less energy to do the same amount of work. |
| Energy Levels | The energy represented by an electron in the band model of a substance. |
| Energy Management System | A control system (often computerized) designed to regulate the energy consumption of a building by controlling the operation of energy consuming systems, such as the heating, ventilation and air conditioning (HVAC), lighting and water heating systems. |
| Energy Payback Time | The time required for any energy producing system or device to produce as much energy as was required in its manufacture. For solar electric panels, this is normally in the range 6-36 months. |
| Energy Reserves | The portion of total energy resources that is known and can be recovered with presently available technology at an affordable cost. |
| Energy Resource | a source of useable power which can be drawn on when needed. Energy resources are often classified as renewable or non-renewable. |
| Energy Resources | Everything that could be used by society as a source of energy. |
| Energy Security/Fuel Security | policy that considers the risk of dependence on fuel sources located in remote and unstable regions of the world and the benefits of domestic and diverse fuel sources. |
| Energy Storage | The process of storing or converting energy from one form to another for later use. An example of a storage device is a battery. |
| Energy/Fuel Diversity | policy that encourages the development of energy technologies to diversify energy supply sources, thus reducing reliance on conventional (petroleum) fuels; applies to all energy sectors. |
| Engine | A machine that converts energy into mechanical force or motion. Sources of energy include heat, chemical reaction, potential energy of elevated water, etc. |
| Enthalpy | The quantity of heat necessary to raise the temperature of a substance from one point to a higher temperature. The quantity of heat includes both latent and sensible. |
| Entitlement | Electric energy or generating capacity that a utility has a right to access under power exchange or sales agreements. |
| Environment | All the natural and living things around us. The earth, air, weather, plants, and animals all make up our environment. |
| Environmental Protection Agency (EPA) |
Federal government agency that makes and enforces standards for pollution control; designed to protect the environment. |
| Epact | The Environmental Protection Agency. A federal agency charged with protecting the environment. |
| EPACT | The Energy Policy Act of 1992 addresses a wide variety of energy issues. The legislation creates a new class of power generators, exempt wholesale generators (EWGs), that are exempt from the provisions of the Public Utilities Holding Company Act of 1935 and grants the authority to FERC to order and condition access by eligible parties to the interconnected transmission grid. |
| Epitaxial Growth | The growth of one crystal on the surface of another crystal. The growth of the deposited crystal is oriented by the lattice structure of the original crystal. |
| Equalization | The process of restoring all cells in a battery to an equal state-of-charge. For lead-acid batteries, this is a charging process designed to bring all cells to 100 percent state-of-charge. |
| Equalization Charge | The process of mixing the electrolyte in batteries by periodically overcharging the batteries for a short time. |
| Equalizing Charge | A continuation of normal battery charging, at a voltage level slightly higher than the normal end-of-charge voltage, in order to provide cell equalization within a battery. |
| Equinox | The two times of the year when the sun crosses the equator and night and day are of equal length; usually occurs on March 21st (spring equinox) and September 23 (fall equinox). |
| Equinox (Spring & Fall) | The time when the sun crosses the plane of the earth’s equator, making night and day of equal length all over the earth, occurring about March 21st and September 21st. |
| Eruption | the explosive discharge of material such as molten rock and gases, or hot water (as from volcanoes or geysers). |
| Esco (Efficiency Service Company) | A company that offers to reduce a client’s electricity consumption with the cost savings being split with the client. |
| Ethanol (Also Know As Ethyl Alcohol Or Grain Alcohol, Ch3ch2oh) |
a liquid that is produced chemically from ethylene or biologically from the fermentation of various sugars from carbohydrates found in agricultural crops and cellulosic residues from crops or wood. Used in the United States as a gasoline octane enhancer and oxygenate, it increases octane 2.5 to 3.0 numbers at 10 percent concentration. Ethanol can also be used in higher concentration (E85) in vehicles optimized for its use. |
| Ethyl Tertiary Butyl Ether (Etbe) | an aliphatic ether similar to MTBE. This fuel oxygenate is manufactured by reacting isobutylene with ethanol. Having high octane and low volatility characteristics, ETBE can be added to gasoline up to a level of approximately 17 percent by volume. ETBE is used as an oxygenate in some reformulated gasolines. |
| Ethylene | A colorless gas that burns and is an oil refinery product. |
| Eurus | The East Wind in Greek mythology. (The same word is used in Latin.) |
| EV (Electric Vehicle) | a vehicle powered by electricity, usually provided by batteries but may also be provided by photovoltaic (solar) cells or a fuel cell. |
| EVA (Ethylene Vinyl Acetate) | An encapsulant used between the glass cover and the solar cells in PV modules. It is durable, transparent, resistant to corrosion, and flame retardant. |
| Evaporation | The process of a liquid changing its state into a gas when heat is added. In the most common occurrence on earth, water evaporation requires 970 btus per pound (pint). |
| Evaporative Cooling | Cooling by exchange of latent heat from water sprays, jets of water, or wetted material. |
| Exchange (Electric Utility) | Agreements between utilities providing for purchase, sale and trading of power. Usually relates to capacity (kilowatts) but sometimes energy (kilowatt-hours). |
| Exempt Wholesale Generator (Ewg) | Created under the 1992 Energy Policy Act, these wholesale generators are exempt from certain financial and legal restrictions stipulated in the Public Utilities Holding Company Act of 1935. |
| Exfiltration | Air flow outward through a wall, building envelope, etc. |
| Exhaust | Air removed deliberately from a space, by a fan or other means, usually to remove contaminants from a location near their source. |
| Exports (Electric Utility) | Power capacity or energy that a utility is required by contract to supply outside of its own service area and not covered by general rate schedules. |
| Extra High Voltage (Ehv) | Voltage levels higher than those normally used on transmission lines. Generally EHV is considered to be 345,000 volts or higher. |
| Extrinsic Semiconductor | The product of doping a pure semiconductor. |
