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

P-Type Semiconductor
A semiconductor in which holes carry the current; produced by doping an intrinsic semiconductor with an electron acceptor impurity (e.g., boron in silicon).

R-Factor
See R-Value.

R-Value
A measure of the capacity of a material to resist heat transfer. The R-Value is the reciprocal of the conductivity of a material (U-Value). The larger the R-Value of a material, the greater its insulating properties.

U-Value
(see Coefficient of Heat Transmission) The reciprocal of R-Value. The lower the number, the greater the heat transfer resistance (insulating) characteristics of the material.

P/N
A semiconductor (photovoltaic) device structure in which the junction is formed between a p-type layer and an n-type layer.

P-I-N
A semiconductor (photovoltaic) device structure that layers an intrinsic semiconductor between a p-type semiconductor and an n-type semiconductor; this structure is most often used with amorphous silicon PV devices.

I-V Curve
A graphical plot or representation the current and voltage output of a solar photovoltaic cell or module as a load on the device is increased from short circuit (no load) condition to the open circuit condition; used to characterize cell/module performance.

N-Type Semiconductor
A semiconductor produced by doping an intrinsic semiconductor with an electron-donor impurity (e.g., phosphorous in silicon).

I-Type Semiconductor
A semiconductor material that is left intrinsic, or undoped so that the concentration of charge carriers is characteristic of the material itself rather than of added impurities.

Zoning
The combining of rooms in a structure according to similar heating and cooling patterns. Zoning requires using more than one thermostat to control heating, cooling, and ventilation equipment.

Zone
An area within the interior space of a building, such as an individual room(s), to be cooled, heated, or ventilated. A zone has its own thermostat to control the flow of conditioned air into the space.

Yurt
An octagonal shaped shelter that originated in Mongolia, and traditionally made from leather or canvas for easy transportation.

Yaw
The rotation of a horizontal axis wind turbine around its tower or vertical axis.

Working Fluid
A fluid used to absorb and transfer heat energy.

Wound Rotor Motors
A type of motor that has a rotor with electrical windings connected through slip rings to the external power circuit. An external resistance controller in the rotor circuit allows the performance of the motor to be tailored to the needs of the system and to be changed with relative ease to accommodate system changes or to vary the speed of the motor.

Wingwall
A building structural element that is built onto a building's exterior along the inner edges of all the windows, and extending from the ground to the eaves. Wingwalls help ventilate rooms that have only one exterior wall which leads to poor cross ventilation. Wingwalls cause fluctuations in the natural wind direction to create moderate pressure differences across the windows. They are only effective on the windward side of the building.

Wire
(Electrical) A generic term for an electrical conductor.

Wood Stove
A wood-burning appliance for space and/or water heating and/or cooking.

Window
A generic term for a glazed opening that allows daylight to enter into a building and can be opened for ventilation.

Windpower Curve
A graph representing the relationship between the power available from the wind and the wind speed. The power from the wind increases proportionally with the cube of the wind speed.

Windpower Profile
The change in the power available in the wind due to changes in the wind speed or velocity profile; the windpower profile is proportional to the cube of the wind speed profile.

Wind Velocity
The wind speed and direction in an undisturbed flow.

Windmill
A WECS that is used to grind grain, and that typically has a high-solidity rotor; commonly used to refer to all types of WECS.

Wind Speed Profile
A profile of how the wind speed changes with height above the surface of the ground or water.

Wind Turbine
A term used for a wind energy conversion device that produces electricity; typically having one, two, or three blades.

Wind Turbine Rated Capacity
The amount of power a wind turbine can produce at its rated wind speed, e.g., 100 kW at 20 mph. The rated wind speed generally corresponds to the point at which the conversion efficiency is near its maximum. Because of the variability of the wind, the amount of energy a wind turbine actually produces is a function of the capacity factor (e.g., a wind turbine produces 20% to 35% of its rated capacity over a year).

Wind Speed Frequency Curve
A curve that indicates the number of hours per year that specific wind speeds occur.

Wind Rose
A diagram that indicates the average percentage of time that the wind blows from different directions, on a monthly or annual basis.

Wind Speed
The rate of flow of the wind undisturbed by obstacles.

Wind Speed Duration Curve
A graph that indicates the distribution of wind speeds as a function of the cumulative number of hours that the wind speed exceeds a given wind speed in a year.

Wind Power Plant
A group of wind turbines interconnected to a common power provider system through a system of transformers, distribution lines, and (usually) one substation. Operation, control, and maintenance functions are often centralized through a network of computerized monitoring systems, supplemented by visual inspection. This is a term commonly used in the United States. In Europe, it is called a generating station.

Wind Resource Assessment
The process of characterizing the wind resource, and its energy potential, for a specific site or geographical area.

Wind Energy
Energy available from the movement of the wind across a landscape caused by the heating of the atmosphere, earth, and oceans by the sun.

Wind Energy Conversion System (WECS) or Device
An apparatus for converting the energy available in the wind to mechanical energy that can be used to power machinery (grain mills, water pumps) and to operate an electrical generator.

Wind Generator
A WECS designed to produce electricity.

Wholesale Wheeling
The wheeling of electric power in amounts and at prices that generally have been negotiated in long term contracts between the power provider and a distributor or very large power customer.

Wheeling
The process of transmitting electricity over one or more separately owned electric transmission and distribution systems. (See Wholesale and Retail Wheeling.)

Wave Form
The shape of the phase power at a certain frequency and amplitude.

Wave Power
The concept of capturing and converting the energy available in the motion of ocean waves to energy.

Wavelength
The distance between similar points on successive waves.

Weatherization
Caulking and weatherstripping to reduce air infiltration and exfiltration into/out of a building.

Weatherstripping
A material used to seal gaps around windows and exterior doors.

Watt-hour
A unit of electricity consumption of one Watt over the period of one hour.

Wattmeter
A device for measuring power consumption.

Water Wall
An interior wall made of water filled containers for absorbing and storing solar energy.

Water Wheel
A wheel that is designed to use the weight and/or force of moving water to turn it, primarily to operate machinery or grind grain.

Watt
The rate of energy transfer equivalent to one ampere under an electrical pressure of one volt. One watt equals 1/746 horsepower, or one joule per second. It is the product of Voltage and Current (amperage).

Water Turbine
A turbine that uses water pressure to rotate its blades; the primary types are the Pelton wheel, for high heads (pressure); the Francis turbine, for low to medium heads; and the Kaplan for a wide range of heads. Primarily used to power an electric generator.

Water Jacket
A heat exchanger element enclosed in a boiler. Water is circulated with a pump through the jacket where it picks up heat from the combustion chamber after which the heated water circulates to heat distribution devices. A water jacket is also an enclosed water-filled chamber in a tankless coiled water heater. When a faucet is turned on water flows into the water heater heat exchanger. The water in the chamber is heated and transfers heat to the cooler water in the heat exchanger and is sent through the hot water outlet to the appropriate faucet.

Wall
A vertical structural element that holds up a roof, encloses part or all of a room, or stands by itself to hold back soil.

Wall Orientation
The geographical direction that the primary or largest exterior wall of a building faces.

Wafer
A thin sheet of semiconductor (photovoltaic material) made by cutting it from a single crystal or ingot.

Volt
A unit of electrical force equal to that amount of electromotive force that will cause a steady current of one ampere to flow through a resistance of one ohm.

Voltage
The amount of electromotive force, measured in volts, that exists between two points.

Volt-Ampere
A unit of electrical measurement equal to the product of a volt and an ampere.

Water Source Heat Pump
A type of (geothermal) heat pump that uses well (ground) or surface water as a heat source. Water has a more stable seasonal temperature than air thus making for a more efficient heat source.

Vertical-Axis Wind Turbine
(VAWT) A type of wind turbine in which the axis of rotation is perpendicular to the wind stream and the ground.

Visible Light Transmittance
The amount of visible light that passes through the glazing material of a window, expressed as a percentage.

Visible Radiation
The visible portion of the electromagnetic spectrum with wavelengths from 0.4 to 0.76 microns

Vented Heater
A type of combustion heating appliance in which the combustion gases are vented to the outside, either with a fan (forced) or by natural convection.

Ventilation
The process of moving air (changing) into and out of an interior space either by natural or mechanically induced (forced) means.

Ventilation Air
That portion of supply air that is drawn from outside, plus any recirculated air that has been treated to maintain a desired air quality.

Vent Pipe
A tube in which combustion gases from a combustion appliance are vented out of the appliance to the outdoors.

Vent Damper
A device mounted in the vent connector that closes the vent when the heating unit is not firing. This traps heat inside the heating system and house rather than letting it draft up and out the vent system.

Vapor Retarder
A material that retards the movement of water vapor through a building element (walls, ceilings) and prevents insulation and structural wood from becoming damp and metals from corroding. Often applied to insulation batts or separately in the form of treated papers, plastic sheets, and metallic foils.

Variable-Speed Wind Turbines
Turbines in which the rotor speed increases and decreases with changing wind speed, producing electricity with a variable frequency.

Vent
A component of a heating or ventilation appliance used to conduct fresh air into, or waste air or combustion gases out of, an appliance or interior space.

Useful Heat
Heat stored above room temperature (in a solar heating system).

Vacuum Evaporation
The deposition of thin films of semiconductor material by the evaporation of elemental sources in a vacuum.

Valence Band
The highest energy band in a semiconductor that can be filled with electrons.

Unitary Air Conditioner
An air conditioner consisting of one or more assemblies that move, clean, cool, and dehumidify air.

Unvented Heater
A combustion heating appliance that vents the combustion by-products directly into the heated space. The latest models have oxygen-sensors that shut off the unit when the oxygen level in the room falls below a safe level.

Unglazed Solar Collector
A solar thermal collector that has an absorber that does not have a glazed covering. Solar swimming pool heater systems usually use unglazed collectors because they circulate relatively large volumes of water through the collector and capture nearly 80 percent of the solar energy available.

Ultimate Analysis
A procedure for determining the primary elements in a substance (carbon, hydrogen, oxygen, nitrogen, sulfur, and ash).

Ultraviolet
Electromagnetic radiation in the wavelength range of 4 to 400 nanometers.

Underground Home
A house built into the ground or slope of a hill, or which has most or all exterior surfaces covered with earth.

Turbine
A device for converting the flow of a fluid (air, steam, water, or hot gases) into mechanical motion.

Turn Down Ratio
The ratio of a boiler's or gasifier's maximum output to its minimum output.

Two-Axis Tracking
A solar array tracking system capable of rotating independently about two axes (e.g., vertical and horizontal).

Two-Tank Solar System
A solar thermal system that has one tank for storing solar heated water to preheat the water in a conventional water heater.

Tungsten Halogen Lamp
A type of incandescent lamp that contains a halogen gas in the bulb, which reduces the filament evaporation rate increasing the lamp life. The high operating temperature and need for special fixtures limits their use to commercial applications and for use in projector lamps and spotlights.

Tube-Type Collector
A type of solar thermal collector that has tubes (pipes) that the heat transfer fluid flows through that are connected to a flat absorber plate.

True Power
The actual power rating that is developed by a motor before losses occur.

True South
The direction, at any point on the earth that is geographically in the northern hemisphere, facing toward the South Pole of the earth. Essentially a line extending from the point on the horizon to the highest point that the sun reaches on any day (solar noon) in the sky.

Tube
(Fluorescent Light) A fluorescent lamp that has a tubular shape.

Tube-In-Plate-Absorber
A type of solar thermal collector where the heat transfer fluid flows through tubes formed in the absorber plate.

Trickle (Solar) Collector
A type of solar thermal collector in which a heat transfer fluid drips out of header pipe at the top of the collector, runs down the collector absorber and into a tray at the bottom where it drains to a storage tank.

Triple Pane
(Window) This represents three layers of glazing in a window with an airspace between the middle glass and the exterior and interior panes.

Trombe Wall
A wall with high thermal mass used to store solar energy passively in a solar home. The wall absorbs solar energy and transfers it to the space behind the wall by means of radiation and by convection currents moving through spaces under, in front of, and on top of the wall.

Transmission Lines
Transmit high-voltage electricity from the transformer to the electric distribution system.

Traveling Grate
A furnace grate that moves fuel through the combustion chamber.

Trellis
An architectural feature used to shade exterior walls; usually made of a lattice of metal or wood; often covered by vines to provide additional summertime shading.

Transmission
The process of sending or moving electricity from one point to another; usually defines that part of an electric power provider's electric power lines from the power plant buss to the last transformer before the customer's connection.

Transmission and Distribution Losses
The losses that result from inherent resistance in electrical conductors and transformation inefficiencies in distribution transformers in a transmission and distribution network.

Trailing Edge
The part of a wind energy conversion device blade, or airfoil, that is the last to contact the wind.

Transformer
An electromagnetic device that changes the voltage of alternating current electricity. It consists of an induction coil having a primary and secondary winding and a closed iron core.

Total Internal Reflection
The trapping of light by refraction and reflection at critical angles inside a semiconductor device so that it cannot escape the device and must be eventually absorbed by the semiconductor.

Tracking Solar Array
A solar energy array that follows the path of the sun to maximize the solar radiation incident on the PV surface. The two most common orientations are (1) one axis where the array tracks the sun east to west and (2) two-axis tracking where the array points directly at the sun at all times. Tracking arrays use both the direct and diffuse sunlight. Two-axis tracking arrays capture the maximum possible daily energy.

Total Incident Radiation
The total radiation incident on a specific surface area over a time interval.

Total Harmonic Distortion
The measure of closeness in shape between a waveform and it's fundamental component.