Copy of `Energy.gov - Energy industry terms`

The wordlist doesn't exist anymore, or, the website doesn't exist anymore. On this page you can find a copy of the original information. The information may have been taken offline because it is outdated.

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

Irradiance
The direct, diffuse, and reflected solar radiation that strikes a surface.

Ion
An electrically charged atom or group of atoms that has lost or gained electrons; a loss makes the resulting particle positively charged; a gain makes the particle negatively charged.

Ionizer
A device that removes airborne particles from breathable air. Negative ions are produced and give up their negative charge to the particles. These new negative particles are then attracted to the positive particles surrounding them. This accumulation process continues until the particles become heavy enough to fall to the ground.

Investor Owned Utility
(IOU) A power provider owned by stockholders or other investors; sometimes referred to as a private power provider, in contrast to a public power provider that is owned by a government agency or cooperative.

Investment Tax Credit
A tax credit granted for specific types of investments.

Intrinsic Layer
A layer of semiconductor material (as used in a solar photovoltaic device) whose properties are essentially those of the pure, undoped, material.

Interruptible Load
Energy loads that can be shut off or disconnected at the supplier's discretion or as determined by a contractual agreement between the supplier and the customer.

Internal Gain
The heat produced by sources of heat in a building (occupants, appliances, lighting, etc).

Internal Mass
Materials with high thermal energy storage capacity contained in or part of a building's walls, floors, or freestanding elements.

Internal Rate of Return
A widely used rate of return for performing economic analysis. This method solves for the interest rate that equates the equivalent worth of an alternative's cash receipts or savings to the equivalent worth of cash expenditures, including investments. The resultant interest rate is termed the internal rate of return (IRR).

Interconnection
A connection or link between power systems that enables them to draw on each other's reserve capacity in time of need.

Intermittent Generators
Power plants, whose output depends on a factor(s) that cannot be controlled by the power generator because they utilize intermittent resources such as solar energy or the wind.

Internal Combustion Electric Power Plant
The generation of electric power by a heat engine which converts part of the heat generated by combustion of the fuel into mechanical motion to operate an electric generator.

Insulator
A device or material with a high resistance to electricity flow.

Integrated Heating Systems
A type of heating appliance that performs more than one function, for example space and water heating.

Integrated Resource Plan
(IRP) A plan developed by an electric power provider, sometimes as required by a public regulatory commission or agency, that defines the short and long term capacity additions (supply side) and demand side management programs that it will undertake to meet projected energy demands.

Insolation
The solar power density incident on a surface of stated area and orientation, usually expressed as Watts per square meter or Btu per square foot per hour.

Installed Capacity
The total capacity of electrical generation devices in a power station or system.

Insulation
Materials that prevent or slow down the movement of heat.

Insulation Blanket
A pre-cut layer of insulation applied around a water heater storage tank to reduce stand-by heat loss from the tank.

Industrial Process Heat
The thermal energy used in an industrial process.

Inert Gas
A gas that does not react with other substances; e.g. argon or krypton; sealed between two sheets of glazing to decrease the U-value (increase the R-Value) of windows.

Infrared Radiation
Electromagnetic radiation whose wavelengths lie in the range from 0.75 micrometer to 1000 micrometers; invisible long wavelength radiation (heat) capable of producing a thermal or photovoltaic effect, though less effective than visible light.

Indirect Solar Gain System
A passive solar heating system in which the sun warms a heat storage element, and the heat is distributed to the interior space by convection, conduction, and radiation.

Induction
The production of an electric current in a conductor by the variation of a magnetic field in its vicinity.

Induction Generator
A device that converts the mechanical energy of rotation into electricity based on electromagnetic induction. An electric voltage (electromotive force) is induced in a conducting loop (or coil) when there is a change in the number of magnetic field lines (or magnetic flux) passing through the loop. When the loop is closed by connecting the ends through an external load, the induced voltage will cause an electric current to flow through the loop and load. Thus rotational energy is converted into electrical energy.

Independent Power Producer
A company or individual that is not directly regulated as a power provider. These entities produce power for their own use and/or sell it to regulated power providers.

Instantaneous Efficiency
(of a Solar Collector) The amount of energy absorbed (or converted) by a solar collector (or photovoltaic cell or module) over a 15 minute period.

Incandescent
These lights use an electrically heated filament to produce light in a vacuum or inert gas-filled bulb.

Incident Solar Radiation
The amount of solar radiation striking a surface per unit of time and area.

Impulse Turbine
A turbine that is driven by high velocity jets of water or steam from a nozzle directed to vanes or buckets attached to a wheel. (A pelton wheel is an impulse hydro turbine).

Ignition Point
The minimum temperature at which combustion of a solid or fluid can occur.

Illuminance
A measure of the amount of light incident on a surface; measured in foot-candles or Lux.

Illumination
The distribution of light on a horizontal surface. The purpose of all lighting is to produce illumination.

Impoundment
A body of water confined by a dam, dike, floodgate or other artificial barrier.

Hydrothermal fluids
These fluids can be either water or steam trapped in fractured or porous rocks; they are found from several hundred feet to several miles below the Earth's surface. The temperatures vary from about 90 F to 680 F (32 C to 360 C) but roughly 2/3 range in temperature from 150 F to 250 F (65.5 C to 121.1 C). The latter are the easiest to access and, therefore, the only forms being used commercially.

Ignite
To heat a gaseous mixture to the temperature at which combustion takes place.

Hydrogenated Amorphous Silicon
Amorphous silicon with a small amount of incorporated hydrogen. The hydrogen neutralizes dangling bonds in the amorphous silicon, allowing charge carriers to flow more freely.

Hydronic Heating Systems
A type of heating system where water is heated in a boiler and either moves by natural convection or is pumped to heat exchangers or radiators in rooms; radiant floor systems have a grid of tubing laid out in the floor for distributing heat. The temperature in each room is controlled by regulating the flow of hot water through the radiators or tubing.

Hybrid System
A renewable energy system that includes two different types of technologies that produce the same type of energy; for e.g., a wind turbine and a solar photovoltaic array combined to meet a power demand.

Hydroelectric Power Plant
A power plant that produces electricity by the force of water falling through a hydro turbine that spins a generator.

Hydrogen
A chemical element that can be used as a fuel since it has a very high energy content.

Humidity
A measure of the moisture content of air; may be expressed as absolute, mixing ratio, saturation deficit, relative, or specific.

Humidifier
A device used to maintain a specified humidity in a conditioned space.

Hub Height
The height above the ground that a horizontal axis wind turbine's hub is located.

Horsepower Hour
(hph) One horsepower provided over one hour; equal to 0.745 kilowatt-hour or 2,545 Btu.

Hot Air Furnace
A heating unit where heat is distributed by means of convection or fans.

Hot Dry Rock
A geothermal energy resource that consists of high temperature rocks above 300 F (150 C) that may be fractured and have little or no water. To extract the heat, the rock must first be fractured, then water is injected into the rock and pumped out to extract the heat. In the western United States, as much as 95,000 square miles (246,050 square km) have hot dry rock potential.

Homojunction
The region between an n-layer and a p-layer in a single material, photovoltaic cell.

Horizontal-Axis Wind Turbines
Turbines in which the axis of the rotor's rotation is parallel to the wind stream and the ground.

Horsepower
(hp) A unit of rate of operation. Electrical hp: a measure of time rate of mechanical energy output; usually applied to electric motors as the maximum output; 1 electrical hp is equal to 0.746 kilowatts or 2,545 Btu per hour. Shaft hp: a measure of the actual mechanical energy per unit time delivered to a turning shaft; 1 shaft Hp is equal to 1 electrical Hp or 550 foot pounds per second. Boiler Hp: a measure to the maximum rate to heat output of a steam generator; 1 boiler Hp is equal to 33,480 Btu per hour steam output.

Hole
The vacancy where an electron would normally exist in a solid; behaves like a positively charged particle.

Home Energy Rating Systems
(HERS) A nationally recognized energy rating program that gives builders, mortgage lenders, secondary lending markets, homeowners, sellers, and buyers a precise evaluation of energy losing deficiencies in homes. Builders can use this system to gauge the energy quality in their home and also to have a star rating on their home to compare to other similarly built homes.

High-Intensity Discharge Lamp
A lamp that consists of a sealed arc tube inside a glass envelope, or outer jacket. The inner arc tube is filled with elements that emit light when ionized by electric current. A ballast is required to provide the proper starting voltage and to regulate current during operation.

High-Pressure Sodium Lamp
A type of High-Intensity Discharge (HID) lamp that uses sodium under high pressure as the primary light-producing element. These high efficiency lights produce a golden white color and are used for interior industrial applications, such as in warehouses and manufacturing, and for security, street, and area lighting.

Hemispherical Bowl Technology
A solar energy concentrating technology that uses a linear receiver that tracks the focal area of a reflector or array of reflectors.

Hertz
A measure of the number of cycles or wavelengths of electrical energy per second; U.S. electricity supply has a standard frequency of 60 hertz.

Heterojunction
A region of electrical contact between two different materials.

Higher Heating Value
(HHV) The maximum heating value of a fuel sample, which includes the calorific value of the fuel (bone dry) and the latent heat of vaporization of the water in the fuel. (See moisture content and net (lower) heating value, below.)

Heliothermal
Any process that uses solar radiation to produce useful heat.

Heliothermic
Site planning that accounts for natural solar heating and cooling processes and their relationship to building shape, orientation, and siting.

Heliothermometer
An instrument for measuring solar radiation.

Heliotropic
Any device (or plant) that follows the sun's apparent movement across the sky.

Heating, Ventilation, and Air-Conditioning (HVAC) System
All the components of the appliance used to condition interior air of a building.

Heliochemical Process
The utilization of solar energy through photosynthesis.

Heliodon
A device used to simulate the angle of the sun for assessing shading potentials of building structures or landscape features.

Heliostat
A device that tracks the movement of the sun; used to orient solar concentrating systems.

Heating Seasonal Performance Factor
(HSPF) The measure of seasonal or annual efficiency of a heat pump operating in the heating mode. It takes into account the variations in temperature that can occur within a season and is the average number of Btu of heat delivered for every watt-hour of electricity used by the heat pump over a heating season.

Heating Value
The amount of heat produced from the complete combustion of a unit of fuel. The higher (or gross) heating value is that when all products of combustion are cooled to the pre-combustion temperature, water vapor formed during combustion is condensed, and necessary corrections have been made. Lower (or net) heating value is obtained by subtracting from the gross heating value the latent heat of vaporization of the water vapor formed by the combustion of the hydrogen in the fuel.

Heating Fuel Units
Standardized weights or volumes for heating fuels.

Heating Fuels
Any gaseous, liquid, or solid fuel used for indoor space heating.

Heating Load
The rate of heat flow required to maintain a specific indoor temperature; usually measured in Btu per hour.

Heating Season
The coldest months of the year; months where average daily temperatures fall below 65 degrees Fahrenheit creating demand for indoor space heating.

Heating Degree Day(s)
(s) The number of degrees per day that the daily average temperature (the mean of the maximum and minimum recorded temperatures) is below a base temperature, usually 65 degrees Fahrenheit, unless otherwise specified; used to determine indoor space heating requirements and heating system sizing. Total HDD is the cumulative total for the year/heating season. The higher the HDD for a location, the colder the daily average temperature(s).

Heating Capacity
(Also specific heat) The quantity of heat necessary to raise the temperature of a specific mass of a substance by one degree.

Heat Transfer
The flow of heat from one area to another by conduction, convection, and/or radiation. Heat flows naturally from a warmer to a cooler material or space.

Heat Transfer Fluid
A gas or liquid used to move heat energy from one place to another; a refrigerant.

Heat Transmission Coefficient
Any coefficient used to calculate heat transmission by conduction, convection, or radiation through materials or structures.

Heat Storage Capacity
The amount of heat that a material can absorb and store.

Heat Register
The grilled opening into a room by which the amount of warm air from a furnace can be directed or controlled; may include a damper.

Heat Sink
A structure or media that absorbs heat.

Heat Source
A structure or media from which heat can be absorbed or extracted.

Heat Storage
A device or media that absorbs heat for storage for later use.

Heat Pump Water Heaters
A water heater that uses electricity to move heat from one place to another instead of generating heat directly.

Heat Rate
The ratio of fuel energy input as heat per unit of net work output; a measure of a power plant thermal efficiency, generally expressed as Btu per net kilowatt-hour.

Heat Recovery Ventilator
A device that captures the heat from the exhaust air from a building and transfers it to the supply/fresh air entering the building to preheat the air and increase overall heating efficiency.

Heat Gain
The amount of heat introduced to a space from all heat producing sources, such as building occupants, lights, appliances, and from the environment, mainly solar energy.

Heat Loss
The heat that flows from the building interior, through the building envelope to the outside environment.

Heat Pipe
A device that transfers heat by the continuous evaporation and condensation of an internal fluid.

Heat Pump
An electricity powered device that extracts available heat from one area (the heat source) and transfers it to another (the heat sink) to either heat or cool an interior space or to extract heat energy from a fluid.

Heat Exchanger
A device used to transfer heat from a fluid (liquid or gas) to another fluid where the two fluids are physically separated.

Heat Balance
Energy output from a system that equals energy input.

Heat Content
The amount of heat in a quantity of matter at a specific temperature and pressure.

Heat Engine
A device that produces mechanical energy directly from two heat reservoirs of different temperatures. A machine that converts thermal energy to mechanical energy, such as a steam engine or turbine.

Heat Absorbing Window Glass
A type of window glass that contains special tints that cause the window to absorb as much as 45% of incoming solar energy, to reduce heat gain in an interior space. Part of the absorbed heat will continue to be passed through the window by conduction and reradiation.

Heat
A form of thermal energy resulting from combustion, chemical reaction, friction, or movement of electricity. As a thermodynamic condition, heat, at a constant pressure, is equal to internal or intrinsic energy plus pressure times volume.

Ground Reflection
Solar radiation reflected from the ground onto a solar collector.

Guy Wire
Cable use to secure a wind turbine tower to the ground in a safe, stable manner.

Harmonic(s)
A sinusoidal quantity having a frequency that is an integral multiple of the frequency of a periodic quantity to which it is related.

Head
A unit of pressure for a fluid, commonly used in water pumping and hydro power to express height a pump must lift water, or the distance water falls. Total head accounts for friction head losses, etc.