| Landfill Gas | Gas generated by the natural degrading and decomposition of municipal solid waste by anaerobic microorganisms in sanitary landfills. The gases produced, carbon dioxide and methane, can be collected by a series of low-level pressure wells and can be processed into a medium Btu gas that can be burned to generate steam or electricity. |
| Landman | An in-house or independent land management consultant who negotiates terms of land leases with land owners. |
| Landscaping | Features and vegetation on a section of ground for decoration and/or energy conservation. |
| Langley | Unit of solar irradiance, one calorie per square centimeter. 1 L = 41.84 kj/m2. |
| Langley (L) | Unit of solar irradiance. One gram calorie per square centimeter. 1 L = 85.93 kwh/m2. |
| Laser | The light energy amplified by electrical impulses. |
| Latent Heat | A change in the heat content that occurs without a corresponding change in temperature, usually accompanied by a change of state (as from liquid to vapor during evaporation). |
| Latent Load | The cooling load caused by moisture in the air. |
| Latitude | A location’s distance north or south of the equator measured in degrees. |
| Lattice | The regular periodic arrangement of atoms or molecules in a crystal of semiconductor material. |
| Lava | molten magma that has reached the Earth’s surface. |
| Lay Up | Lay up is another term for cold storage and describes the status of equipment (such as a power plant) that has been placed in storage ("mothballed") for latter use. |
| Layoff (Electric Utility) | Excess capacity of a generating unit, available for a limited time under the terms of a power sales agreement. |
| Lead Acid Battery | A battery that consists of lead based plates surrounded by a sulfuric acid electrolyte. |
| Lead-Acid Battery | A general category that includes batteries with plates made of pure lead, lead-antimony, or lead-calcium immersed in an acid electrolyte. |
| Leaded Gasoline | Gasoline containing tetraethyl lead, an important constituent in antiknock gasoline. Leaded gasoline is no longer sold in the United States. |
| Leading Edge | The blade edge that faces toward the direction of rotation. |
| Levanter | Wind that blows through the Straits of Gibraltar, funneled through the gap between the high plateau of Spain and the Atlas Mountains of North Africa. |
| Life | The period during which a system can operate above a specified performance level. |
| Life Extension | A term used to describe capital expenses which reduce operating and maintenance costs associated with continued operation of electric utility boilers. Such boilers usually have a 40 year operating life under normal circumstances. |
| Life-Cycle Cost | The estimated cost of owning and operating a photovoltaic system for the period of its useful life. |
| Lifeline Rates | Rates charged by a utility company for the low income, the disadvantaged and senior citizens. The rates provide a discount for minimum necessary utilities, such as electricity requirements of typically 300 to 400 kilowatt/hours per month. |
| Lift | The force that pulls a wind turbine blade. |
| Light Emitting Diode | A semi conductor device composed of a p-n junction designed such that electrons emit visible light during their migration across the junction. |
| Light Emitting Diode (Led) | A semiconductor device composed of a PN junction designed such that electrons cause visible light during their migration across the junction. |
| Light Trapping | The trapping of light inside a semiconductor material by refracting and reflecting the light at critical angles; trapped light will travel further in the material, greatly increasing the probability of absorption and hence of producing charge carriers. |
| Light Water Reactor (Lwr) | A nuclear power unit that uses ordinary water to cool its core. The LWR may be a boiling water reactor or a pressurized water reactor. |
| Light-Induced Defects | Defects, such as dangling bonds, induced in an amorphous silicon semiconductor upon initial exposure to light. |
| Lightning | A static electrical discharge beween two clouds or between a cloud and the earth accompanied by a flash of light. |
| Lightning Arrestor | Devices that protect electronics from lightning-induced surges by carrying the charge to ground. |
| Lignite | Brownish black coal having qualities in between those of bituminous coal and peat. The texture of the original wood often is visible in lignite. |
| Line Loss | Voltage drop over a length or wire. You are at risk to this if your wire is too small for the load going through it or the voltage is too low for the distance it must travel. |
| Line Wire Loss | refers to the voltage or power lost due to the resistance of any wire or wires in any electrical circuit. |
| Line/Wire Loss | The voltage drop or energy loss due to the resistance of wire in an electrical circuit. See VOLTAGE DROP |
| Linear Current Booster | an electronic circuit that matches PV output directly to a motor. Used in array direct water pumping. |
| Linear Current Booster (Lcb) | An electronic circuit that matches PV output directly to a motor by converting unneeded voltage to higher usable current. Used in array-direct water pumping. |
| Line-Commutated Inverter | An inverter that is tied to a power grid or line. The commutation of power (conversion from direct current to alternating current) is controlled by the power line, so that, if there is a failure in the power grid, the photovoltaic system cannot feed power into the line. |
| Liquefaction | The process of making synthetic liquid fuel from coal. The term also is used to mean a method for making large amounts of gasoline and heating oil from petroleum. |
| Liquefied Gases | Gases that have been or can be changed into liquid form. These include butane, butylene, ethane, ethylene, propane and propylene. |
| Liquid Brine | A type of geothermal energy resource that depends on naturally occurring hot water solution found within the earth. Technology for this novel energy source is being developed in the Salton Sea area in Southern California. |
| Liquid Electrolyte Battery | A battery containing a liquid solution of an electrolyte in a solvent. Can be called a flooded battery too. |
| Liquid Petroleum Gas | See LPG. |
| Lng (Liquefied Natural Gas) | Natural gas that has been condensed to a liquid, typically by cryogenically cooling the gas to minus 260 degrees Fahrenheit (below zero). |
| Load | Anything that draws power from an electric circuit. |
| Load Centers | A geographical area where large amounts of power are drawn by end-users. |
| Load Circuit | The wire, switches, fuses, etc. That connect the load to the power source. |
| Load Current | The current required to power the electrical device. |
| Load Current (A) | The current required by the electrical device. |
| Load Diversity | The condition that exists when the peak demands of a variety of electric customers occur at different times. This is the objective of "load molding" strategies, ultimately curbing the total capacity requirements of a utility. |
| Load Factor | A percent telling the difference between the amount of electricity a consumer used during a given time span and the amount that would have been used if the usage had stayed at the consumer’s highest demand level during the whole time. The term also is used to mean the percentage of capacity of an energy facility |
| Load Management | Steps taken to reduce power demand at peak load times or to shift some of it to off-peak times. This may be with reference to peak hours, peak days or peak seasons. The main thing affecting electric peaks is air-conditioning usage, which is therefore a prime target for load management efforts. Load management may be pursued by persuading consumers to modify behavior or by using equipment that regulates some electric consumption. |
| Load Resistance | The electrical resistance of the load. |
| Loop Flow | The difference between scheduled and actual power flows on electric transmission lines. |
| Losses (Electric Utility) | Electric energy or capacity that is wasted in the normal operation of a power system. Some kilowatt-hours are lost in the form of waste heat in electrical apparatus such as substation conductors. LINE LOSSES are kilowatts or kilowatt-hours lost in transmission and distribution lines under certain conditions. |
| Low Voltage Cut-Off | The voltage at which a controller will disconnect the load from the battery. |
| Low Voltage Cutoff (LVC) | The voltage level at which a charge controller will disconnect the load from the battery. |
| Low Voltage Disconnect | The voltage at which a charge controller will disconnect the load from the batteries to prevent over-discharging. |
| Low Voltage Disconnect (LVD) | The voltage at which the charge controller will disconnect the load from the batteries to prevent over-discharging. |
| Low Voltage Disconnect Hysteresis | The voltage difference between the low voltage disconnect set point and the voltage at which the load will be reconnected. |
| Low Voltage Warning | A warning buzzer or light that indicates the low battery voltage set-point has been reached. |
| Low-E | A special coating that reduces the emissivity of a window assembly, thereby reducing the heat transfer through the assembly. |
| Low-E Glass | Glass coated with layers of metal or metal oxide. The coating emits very little radiation in the long-wave (infrared) spectrum, which diminishes heat loss from the building interior, and reduces heat gain in hot weather. |
| Low-Sulfur Oil | Oil having one percent or less of sulfur by weight. |
| LPG (Liquefied Petroleum Gas) | A mixture of gaseous hydrocarbons, mainly propane and butane that change into liquid form under moderate pressure. LPG or propane is commonly used as a fuel for rural homes for space and water heating, as a fuel for barbecues and recreational vehicles, and as a transportation fuel. It is normally created as a by-product of petroleum refining and from natural gas production. |
| Lumen | A unit of measurement quantifying the amount of light emitted from a light source. |
| Lumen Maintenance Control | An electrical control device designed to vary the electrical consumption of a lighting system in order to maintain a specified illumination level. |
| Lumens/Watt | A measure of the efficacy of a light fixture; the number of lumens output per watt of power consumed. |
| Luminaire | A complete lighting unit consisting of a lamp or lamps together with the parts designed to distribute the light, to position and protect the lamps and to connect the lamps to the power supply. |
| Lux | A unit of illumination equal to the direct illumination on a surface that is everywhere one meter from a uniform point source of one candle; a unit of illumination that is equal to one lumen per square meter. Also see footcandle. |
