GLOSSARY of ENERGY TERMS

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. Omaha Public Power District produces a small amount of electricity from landfill gas.

Laser: A very intense, uniform beam of electromagnetic radiation. An abbreviation for Light Amplification by Simulated Emission of Radiation.

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: The angular distance north or south of the equator, measured in degrees of arc.

Layoff (Electric Utility): Excess capacity of a generating unit, available for a limited time under the terms of a power sales agreement.

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.

Leaded Gasoline: Gasoline containing tetraethyl lead, an important constituent in antiknock gasoline. Leaded gasoline is no longer sold in the United States.

Lease Condensate: A mixture consisting primarily of pentanes and heavier hydrocarbons which is recovered as a liquid from natural gas in lease separation facilities. This category excludes natural gas plant liquids, such as butane and propane, which are recovered at downstream natural gas processing plants or facilities.

Life–Cycle Cost: Amount of money necessary to own, operate and maintain a building, product or system over its useful life.

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.

Light-Duty Vehicles: Vehicles weighing less than 8,500 lbs. (include automobiles, motorcycles, and light trucks).

Light Oil: Lighter fuel oils distilled off during the refining process. Virtually all petroleum used in internal combustion and gas–turbine engines is light oil.

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.

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.

Liquification: 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.

Liquified Gases: Gases that have been or can be changed into liquid form. These include butane, butylene, ethane, ethylene, propane and propylene.

Liquified Natural Gas (LNG): Natural gas that has been condensed to a liquid, typically by cryogenically cooling the gas to minus 327.2 degrees Fahrenheit (below zero).

Liquified Petroleum Gas (LPG): LPG is also called propane. A mixture of gaseous hydrocarbons, mainly propane and butane that change into liquid form under moderate pressure. LPG is commonly used as a fuel for rural homes for space and water heating, as a fuel for barbecues and recreational vehicles, irrigation and grain drying and as a transportation fuel. It is normally created as a by–product of petroleum refining and from natural gas production.

Load: (1. The amount of electric power supplied to meet one or more end user's needs. (2. An end–use device or an end–use customer that consumes power. Load should not be confused with demand, which is the measure of power that a load receives or requires.

Load Centers: A geographical area where large amounts of power are drawn by end–users.

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, such as power plant or gas pipeline, that is utilized in a given period of time.

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.

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 kilowatthours are lost in the form of waste heat in electrical apparatus such as substation conductors. Line losses are kilowatts or kilowatthours lost in transmission and distribution lines under certain conditions.

Losses and Co-products: Losses and co-products from the production of fuel ethanol.  Ethanol losses and co-products are calculated as ethanol feedstock minus fuel ethanol production excluding denaturant.

Low–E: A special coating that reduces the emissivity of a window assembly, thereby reducing the heat transfer through the assembly.

Low–Sulfur Coal: Coal having one percent or less of sulfur by weight.

Low–Sulfur Oil: Oil having one percent or less of sulfur by weight.

Lower Operational Inventory (LOI): A level that is calculated by taking the lowest ever inventory level for each PADD and then adding them for a U.S. total. Consequently, the LOI represents a level that is below the lowest level that total U.S. inventories have ever reached. This is due to each PADD level being calculated at different times while the lowest U.S. total occurred only once, even though one or more PADDs at that time may not have been at their lowest ever level. Thus, the LOI is a hypothetical level that has never actually been reached. Although reaching the LOI or even falling below the LOI does not guarantee propane market stress, the level would in all probability represent a level that would begin to show some degree of market stress. But when a product reaches limited quantities, the price will rise to a level that will either provide for more product or cause consumers to limit their consumption of that product. Market conditions will always try to find an equilibrium in price and quantity over time.

Lubricants: Substances used to reduce friction between bearing surfaces. Petroleum lubricants may be produced from either distillates or residuals.

Lumen: A measure of the amount of light available from a light source equivalent to the light emitted by one candle.

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.