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Energy.gov - Energy industry terms Category: Earth and Environment > Energy industry terms Date & country: 26/02/2017, USA Words: 1299

Motor Speed
The number of revolutions that the motor turns in a given time period (i.e. revolutions per minute, rpm).

Moisture Control
The process of controlling indoor moisture levels and condensation.

Monoculture
The planting, cultivation, and harvesting of a single species of crop in a specified area.

Monolithic
Fabricated as a single structure.

Motor
A machine supplied with external energy that is converted into force and/or motion.

Module
The smallest self-contained, environmentally protected structure housing interconnected photovoltaic cells and providing a single dc electrical output; also called a panel.

Moisture Content
The water content of a substance (a solid fuel) as measured under specified conditions being the: Dry Basis, which equals the weight of the wet sample minus the weight of a (bone) dry sample divided by the weight of the dry sample times 100 (to get percent); Wet Basis, which is equal to the weight of the wet sample minus the weight of the dry sample divided by the weight of the wet sample times 100.

Minority Carrier Lifetime
The average time a minority carrier exists before recombination.

Mixing Valve
A valve operated by a thermostat that can be installed in solar water heating systems to mix cold water with water from the collector loop to maintain a safe water temperature.

Modified Degree-Day Method
A method used to estimate building heating loads by assuming that heat loss and gain is proportional to the equivalent heat-loss coefficient for the building envelope.

Microclimate
The local climate of specific place or habitat, as influenced by landscape features.

Microgroove
A small groove scribed into the surface of a solar photovoltaic cell which is filled with metal for contacts.

Micrometer
One millionth of a meter (10-6 m).

Mill
A common monetary measure equal to one-thousandth of a dollar or a tenth of a cent.

Minority Carrier
A current carrier, either an electron or a hole, that is in the minority in a specific layer of a semiconductor material; the diffusion of minority carriers under the action of the cell junction voltage is the current in a photovoltaic device.

Metric Ton
(Tonne) A unit of mass equal to 1,000 kilograms or 2,204.6 pounds.

Methanol
(CH₃OH; Methyl alcohol or wood alcohol) A clear, colorless, very mobile liquid that is flammable and poisonous; used as a fuel and fuel additive, and to produce chemicals.

Metal Halide Lamp
A high-intensity discharge lamp type that uses mercury and several halide additives as light-producing elements. These lights have the best Color Rendition Index (CRI) of the High-Intensity Discharge lamps. They can be used for commercial interior lighting or for stadium lights.

Megawatt
One thousand kilowatts, or 1 million watts; standard measure of electric power plant generating capacity.

Megawatt-hour
One thousand kilowatt-hours or 1 million watt-hours.

Mercury Vapor Lamp
A high-intensity discharge lamp that uses mercury as the primary light-producing element. Includes clear, phosphor coated, and self-ballasted lamps.

Met
An approximate unit of heat produced by a resting person, equal to about 18.5 Btu per square foot per hour.

Medium Pressure
For valves and fittings, implies that they are suitable for working pressures between 125 to 175 pounds per square inch.

Mean Wind Speed
The arithmetic wind speed over a specified time period and height above the ground (the majority of U.S. National Weather Service anemometers are at 20 feet (6.1 meters).

Mechanical Systems
Those elements of building used to control the interior climate.

Median Wind Speed
The wind speed with 50 percent probability of occurring.

MCF
An abbreviation for one thousand cubic feet of natural gas with a heat content of 1,000,000 Btus, or 10 therms.

Medium Btu Gas
Fuel gas with a heating value of between 200 and 300 Btu per cubic foot.

Mean Power Output
(of a Wind Turbine) The average power output of a wind energy conversion system at a given mean wind speed based on a Raleigh frequency distribution.

Mass Burn Facility
A type of municipal solid waste (MSW) incineration facility in which MSW is burned with only minor presorting to remove oversize, hazardous, or explosive materials. Mass burn facilities can be large, with capacities of 3000 tons (2.7 million kg) of MSW per day or more. They can be scaled down to handle the waste from smaller communities, and modular plants with capacities as low as 25 tons (22.7 thousand kg) per day have been built. Mass burn technologies represent over 75% of all the MSW-to-energy facilities constructed in the United States to date. The major components of a mass burn facility include refuse receiving and handling, combustion and steam generation, flue gas cleaning, power generation (optional), condenser cooling water, residue ash hauling and landfilling.

Make-Up Air
Air brought into a building from outside to replace exhaust air.

Marginal Cost
The cost of producing one additional unit of a product.

Masonry
Material such as brick, rock, or stone.

Masonry Stove
A type of heating appliance similar to a fireplace, but much more efficient and clean burning. They are made of masonry and have long channels through which combustion gases give up their heat to the heavy mass of the stove, which releases the heat slowly into a room. Often called Russian or Finnish fireplaces.

Magnetic Ballast
A type of florescent light ballast that uses a magnetic core to regulate the voltage of a florescent lamp.

Lux
The unit of illuminance equivalent to 1lumen per square meter.

Magma
Molten or partially molten rock at temperatures ranging from 1,260 F to 2,880 F (700 C to 1600 C). Some magma bodies are believed to exist at drillable depths within the Earth's crust, although practical technologies for harnessing magma energy have not been developed. If ever utilized, magma represents a potentially enormous resource.

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.

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. As reference, a 100-watt incandescent lamp emits about 1600 lumens.

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.

Low-Pressure Sodium Lamp
A type of lamp that produces light from sodium gas contained in a bulb operating at a partial pressure of 0.13 to 1.3 Pascal. The yellow light and large size make them applicable to lighting streets and parking lots.

Low Flush Toilet
A toilet that uses less water than a standard one during flushing, for the purpose of conserving water resources.

Low-E Coatings & (Window) Films
A coating applied to the surface of the glazing of a window to reduce heat transfer through the window.

Low-Emissivity Windows & (Window) Films
Energy-efficient windows that have a coating or film applied to the surface of the glass to reduce heat transfer through the window.

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.)

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
(Energy) A general term applied to the energy that is converted to a form that can not be effectively used (lost) during the operation of an energy producing, conducting, or consuming system.

Low Btu Gas
A fuel gas with a heating value between 90 and 200 Btu per cubic foot.

Long-Wave Radiation
Infrared or radiant heat.

Loose Fill Insulation
Insulation made from rockwool fibers, fiberglass, cellulose fiber, vermiculite or perlite minerals, and composed of loose fibers or granules can be applied by pouring directly from the bag or with a blower.

Long Ton
A unit that equals 20 long hundredweight or 2,240 pounds. Used mainly in England.

Load Shifting
A load management objective that moves loads from on-peak periods to off-peak periods.

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.

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.

Load Forecast
An estimate of power demand at some future period.

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
To influence the demand on a power source.

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 Shedding
Turning off or disconnecting loads to limit peak demand.

Live Steam
Steam available directly from a boiler under full pressure.

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 average energy demand (load) to maximum demand (peak load) during a specific period.

Liquid-Based Solar Heating System
A solar heating system that uses a liquid as the heat transfer fluid.

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.

Light Quality
A description of how well people in a lighted space can see to do visual tasks and how visually comfortable they feel in that space.

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.

Line Loss
(or Drop) Electrical energy lost due to inherent inefficiencies in an electrical transmission and distribution system under specific conditions.

Lethe
A measure of air purity that is equal to one complete air change (in an interior space).

Levelized Life Cycle Cost
A total life cycle cost divided into equal amounts.

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.

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.

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.

Langley
A unit or measure of solar radiation; 1 calorie per square centimeter or 3.69 Btu per square foot.

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.

Landscaping
Features and vegetation on the outside of or surrounding a building for aesthetics and energy conservation.

Lagoon
In wastewater treatment or livestock facilities, a shallow pond used to store wastewater where sunlight and biological activity decompose the waste.

Lamp
A light source composed of a metal base, a glass tube filled with an inert gas or a vapor, and base pins to attach to a fixture.

Kilowatt
(kW) A standard unit of electrical power equal to one thousand watts, or to the energy consumption at a rate of 1000 Joules per second.

Kilowatt-hour
A unit or measure of electricity supply or consumption of 1,000 Watts over the period of one hour; equivalent to 3,412 Btu.

Kinetic Energy
Energy available as a result of motion that varies directly in proportion to an object's mass and the square of its velocity.

Kneewall
A wall usually about 3 to 4 feet high located that is placed in the attic of a home, anchored with plates between the attic floor joists and the roof joist. Sheathing can be attached to these walls to enclose an attic space.

Kaplan Turbine
A type of turbine that has two blades whose pitch is adjustable. The turbine may have gates to control the angle of the fluid flow into the blades.

Kerosene
A type of heating fuel derived by refining crude oil that has a boiling range at atmospheric pressure from 400 degrees to 550 degrees F.

Kilovolt-Ampere
(kVa) A unit of apparent power, equal to 1,000 volt-amperes; the mathematical product of the volts and amperes in an electrical circuit.

Joule's Law
The rate of heat production by a steady current in any part of an electrical circuit that is proportional to the resistance and to the square of the current, or, the internal energy of an ideal gas depends only on its temperature.

Junction
A region of transition between semiconductor layers, such as a p/n junction, which goes from a region that has a high concentration of acceptors (p-type) to one that has a high concentration of donors (n-type).

Isolated Solar Gain System
A type of passive solar heating system where heat is collected in one area for use in another.

Jacket
The enclosure on a water heater, furnace, or boiler.

Joist
A structural, load-carrying building member with an open web system that supports floors and roofs utilizing wood or specific steels and is designed as a simple span member.

Joule
A metric unit of energy or work; the energy produced by a force of one Newton operating through a distance of one meter; 1 Joule per second equals 1 Watt or 0.737 foot-pounds; 1 Btu equals 1,055 Joules.