Glossary of Terms - L

• Landed Price - The actual delivered cost of oil to a refiner, taking into account all costs from production or purchase to the refinery.
• Langley - A unit or measure of solar radiation; 1 calorie per square centimeter or 3.69 Btu per square foot.
• Last Notice Day - The final day on which notices of intent to deliver on futures contracts may be issued.
• Last Trading Day - The final trading day for a particular delivery month futures contract or options contract. Any futures contracts left open following this session must be settled by delivery.
• Latent Cooling Load - The load created by moisture in the air, including from outside air infiltration and that from indoor sources such as occupants, plants, cooking, showering, etc.
• Latent Heat - The change in heat content that occurs with a change in phase and without change in temperature.
• Latent Heat of Vaporization - The quantity of heat produced to change a unit weight of a liquid to vapor with no change in temperature.
• Lattice - The regular periodic arrangement of atoms or molecules in a crystal of semiconductor material.
• Law(s) of Thermodynamics - The first law states that energy can not be created or destroyed; the second law states that when a free exchange of heat occurs between two materials, the heat always moves from the warmer to the cooler material.
• Layoff - Excess capacity of a generating unit, available for a limited time under the terms of a sales agreement.
• Lead Acid Battery - An electrochemical battery that uses lead and lead oxide for electrodes and sulfuric acid for the electrolyte.
• Leading Edge - In reference to a wind energy conversion system, the area of a turbine blade surface that first comes into contact with the wind.
• Lease - Financial instrument based upon the contango in the gold or silver market to finance precious metals inventory.
• Legal Tender - Coins that have been authorized by Congress. This includes circulating coins and all commemorative coins legislated by Congress.
• Levelized - A lump sum that has been divided into equal amounts over period of time.
• Levelized Life Cycle Cost - A total life cycle cost divided into equal amounts.
• Leverage Ratio - A measure that indicates the financial ability to meet debt service requirements and increase the value of the investment to the stockholders (i.e., the ratio of total debt to total assets).
• Liability - An amount payable in dollars or by future services to be rendered.
• Life Cycle Cost - The sum of all the costs both recurring and nonrecurring, related to a product, structure, system, or service during its life span or specified time period.
• Lift - The force that pulls a wind turbine blade, as opposed to drag.
• Lifting - Refers to tankers and barges loading cargoes of petroleum at a terminal or transshipment point.
• Light Crude - Crude oil with a low specific gravity and high API gravity due to the presence of a high proportion of light hydrocarbon fractions.
• Light Ends - The more volatile products of petroleum refining, such as butane, propane, and ethane.
• 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 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-Induced Defects - Defects, such as dangling bonds, induced in an amorphous silicon semiconductor upon initial exposure to light.
• Lightning Arrestor - This protects lines, transformers, and equipment from lightning surges by carrying the charge to the ground. Lightning arrestors serve the same purpose on a line as a safety valve on a steam boiler.
• Lignite - A brownish-black coal of low rank with high inherent moisture and volatile matter (used almost exclusively for electric power generation). It is also referred to as brown coal. Comprises two groups classified according to the following ASTM Specification D388-84 for calorific values on a moist material-matter-free basis:
• Limit - The maximum daily allowable amount a futures price may advance or decline in any one day's trading session. Limits are also placed on the number of positions a participant may hold in the market.
• Limit Order - A contingent order for an options or futures trade specifying a certain maximum (or minimum) price, beyond which the order (buy or sell) is not to be executed.
• Line - A line is a system of poles, conduits, wires, cables, transformers, fixtures, and accessory equipment used for the distribution of electricity to the public.
• Line Loss (or Drop) - Electrical energy lost due to inherent inefficiencies in an electrical transmission and distribution system under specific conditions.
• Line-Commutated Inverter - An inverter that is tied to a power grid or line. The commutation of power (conversion from dc to ac) is controlled by the power line, so that, if there is a failure in the power grid, the PV system cannot feed power into the line.
• Liquefied Natural Gas (LNG) - Natural gas which has been made liquid by reducing its temperature to minus 258 degrees Fahrenheit at atmospheric pressure. Its volume is 1/600 of gas in vapor form.
• Liquefied Petroleum Gas (LPG) - Propane, butane, or propane-butane mixtures derived from crude oil refining or natural gas fractionation. For convenience of transportation, these gases are liquefied through pressurization.
• Liquid Market - A market characterized by the ability to buy and sell with relative ease.
• Liquid Natural Gas (LNG) - Natural gas that has been super cooled under pressure to -259 degrees Fahrenheit. It ramins liquid at -116 degrees f and 673 psia. Liquidified natural gas is almost pure methane. In volume it occupies 1/600 of the space occupied in the vapor state at standard conditions.
• Liquidation - The closing out of futures and options positions.
• Liquid-Based Solar Heating System - A solar heating system that uses a liquid as the heat transfer fluid.
• Liquidity - A market is said to be "liquid" when it has a high level of trading activity and open interest.
• Liquid-To-Air Heat Exchanger - A heat exchanger that transfers the heat contained in a liquid heat transfer fluid to air.
• Liquid-To-Liquid Heat Exchanger - A heat exchanger that transfers heat contained in a liquid heat transfer fluid to another liquid.
• Lithium-Sulfur Battery - A battery that uses lithium in the negative electrode and a metal sulfide in the positive electrode, and the electrolyte is molten salt; can store large amounts of energy per unit weight.
• Live Steam - Steam available directly from a boiler under full pressure.
• Load (Electric) - The amount of electric power delivered or required at any specific point or points on a system. The requirement originates at the energy consuming equipment of the consumers.
• Load Building - Refers to programs that are aimed at increasing the usage of existing electric equipment or the addition of electric equipment. Examples include industrial technologies such as induction heating and melting, direct arc furnaces and infrared drying; cooking for commercial establishments; and heat pumps for residences. Load Building should include programs that promote electric fuel substitution. Load Building effects should be reported as a negative number, shown with a minus sign.
• Load Centers - A limited geographical area where large amounts of power are used by customers.
• 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 Duration Curve - A curve that displays load values on the horizontal axis in descending order of magnitude against the percent of time (on the vertical axis) that the load values are exceeded.
• Load Factor - The ratio of the average load supplied to the peak or maximum load during a designated period. Load factor, in percent, also may be derived by multiplying the kWh in a given period by 100, and dividing by the product of the maximum demand in kW and the number of hours in the same period.
• Load Following - The daily varying of power output by a generator.
• Load Forecast - Estimate of electrical demand or energy consumption at some future time.
• Load Leveling - The deferment of certain loads to limit electrical power demand, or the production of energy during off-peak periods for storage and use during peak demand periods.
• Load Management - Influencing the level and shape of demand for electrical energy so that demand conforms to present supply situations and long-run objectives and constraints.
• Load Profile or Shape - A curve on a chart showing power (kW) supplied (on the horizontal axis) plotted against time of occurrence (on the vertical axis) to illustrate the variance in a load in a specified time period.
• Load Ratio Share - Ratio of a transmission customer's network load to the provider's total load calculated on a rolling twelve-month basis.
• Load Shedding - Turning off or disconnecting loads to limit peak demand.
• Load Shifting - A load shape objective that involves moving loads from peak periods to off-peak periods. If a utility does not expect to meet its demand during peak periods but has excess capacity in the off-peak periods, this strategy might be considered.
• Local - An exchange member who buys or sells futures and/or options for his own account.
• Local Distribution Company (LDC) - Company that distributes natural gas primarily to end-users. A gas utility.
• Local Solar Time - A system of astronomical time in which the sun crosses the true north-south meridian at 12 noon, and which differs from local time according to longitude, time zone, and equation of time.
• Locked Market - A market where prices have reached their daily trading limit and trading can only be conducted at that price or prices which are closer to the previous settlement price.
• Log Law - In reference to a wind energy conversion system, the wind speed profile in which wind speeds increase with the logarithmic of the height of the wind turbine above the ground.
• Long - 1) The market position of a futures contract buyer whose purchase obligates him to accept delivery unless he liquidates his contract with an offsetting sale. 2) One who has bought a futures contract to establish a market position. 3) In the options market, position of the buyer of a call or put options contract. Opposite of short.
• Long Hedge - Purchase of futures against the future market price purchase or fixed price forward sale of a cash commodity to protect against price increases.
• Long the Basis - A person or firm that has bought the spot commodity and hedged with a sale of futures is said to be long the basis.
• Long Ton - A unit that equals 20 long hundredweight or 2,240 pounds. Used mainly in England.
• Long-Wave Radiation - Infrared or radiant heat.
• Loss of Load Probability (LOLP) - A measure of the probability that a system demand will exceed capacity during a given period; often expressed as the estimated number of days over a long period, frequently 10 years or the life of the system.
• Losses - The general term applied to energy (kWh) and capacity (kW) lost in the operation of an electric system. Losses occur principally as energy transformations from kWh to waste-heat in electrical conductors and apparatus. This waste-heat in electrical conductors and apparatus. This power expended without accomplishing useful work occurs primarily on the transmission and distribution system.
• Lot - Any definite quantity of a futures commodity of uniform grade; the standard unit of trading.
• Low Btu Gas - A fuel gas with a heating value between 90 and 200 Btu per cubic foot.
• Low Heat Value (LHV) - The low or net heat of combustion for a fuel assumes that all products of combustion, including water vapor, are in a gaseous state.
• Lower (Net) Heating Value - The lower or net heat of combustion for a fuel that assumes that all products of combustion are in a gaseous state. (See Net Heating Value below.)
• Low-Flow Solar Water Heating Systems - The flow rate in these systems is 1/8 to 1/5 the rate of most solar water heating systems. The low-flow systems take advantage of stratification in the storage tank and theoretically allows for the use of smaller diameter piping to and from the collector and a smaller pump.
• Lumen - An empirical measure of the quantity of light. It is based upon the spectral sensitivity of the photosensors in the human eye under high (daytime) light levels. Photometrically it is the luminous flux emitted with a solid angle (1 steradian) by a point source having a uniform luminous intensity of 1 candela.
• Lumens/Watt (lpw) - A measure of the efficacy (efficiency) of lamps. It indicates the amount of light (lumens) emitted by the lamp for each unit of electrical power (Watts) used.
• Luminaire - A complete lighting unit consisting of a lamp(s), housing, and connection to the power circuit.
• Luminance - The physical measure of the subjective sensation of brightness; measured in lumens.
• Lux - The unit of illuminance equivalent to 1 lumen per square meter.
• LV - Low volatile bituminous coal