| (Acres) Anglian Centre For Renewable Energy: The purpose of a wave energy device is to harvest the energy in the waves. Since wave energy is a renewable resource, the environmental impact is limited to the resources used for production, set-up and dismantling. The evaluation of wave energy devices should be based on the relation between realistic energy production and monetary investment – a simple case of kilowatts per dollar. |
| (Anev) Associazione Nazionale Energia Del Vento: Edinburgh company planning to install two 375kw Pelamis devices, which are semi-submerged, articulated structures composed of cylindrical sections linked by hinged joints in Machir Bay, Islay for power generation. |
| (Bwea) British Wind Energy Association: |
| (Spie) The International Society For Optical Engineering : Describes and markets technology to convert the enormous energy found in ocean waves to energy for seawater desalination, water purification and electricity generation. |
| (Wec) World Energy Council: World’s first commercial wave power station (500 kW) connected to national grid in Britain, Scotland, Islay Island. (November 22, 2000) |
| Accc (Austrian Council On Climate Change: Information about a series of interactive wind and wave atlases providing wind and wave climate statistics worldwide. |
| Ace (American Coalition For Ethanol): ACRES is concerned with promoting renewable energy through education and research. The web site contains information on renewable energy technologies and web resources for teachers, and higher education students. |
| Acfas: The Italian Association of Wind Energy operators / (added 09/2005) |
| Action Without Borders: Information on the wind energy industry in the UK, with news, FAQ, overview of UK wind farms, reports, and studies. The BWEA is the professional and trade body for all those involved in the wind energy industry in UK. |
| Adventist Development And Relief Agency: Organization supports application of climate specific architectural design, green construction materials, and engineering practices. |
| Aebiom – European Biomass Association: Organization dedicated to advancing engineering, scientific and commercial applications of optical, photonic, imaging, electronic, and optoelectronic technologies. / (added 09/2005) |
| Aee (Association Of Energy Engineers): A non-governmental energy policy forum, which promotes the sustainable supply and use of energy. Through its studies, technical and regional programmes, the WEC shares information, collaborates on new technologies and offers policy and strategy recommendations. |
| Affordablecomfort : Austrian Council on Climate Change / (added 09/2005) |
| Aga (American Gas Association): ACE is an organization that promotes the use of ethanol for its clean burning abilities. Their large web site features ethanol related legislation updates, news, publications and links. |
| Air Conditioning Contractors Of America (Acca) : |
| Alaska Conservation Foundation: |
| Alliant Energy/Second Nature: |
| All-Russian Institute For Scientific And Technical Information (Viniti) : Trade association for the European biomass industry / (added 09/2005) |
| American Bamboo Society: The AEE is a group of over 8,000 professionals committed to helping their firms or clients increase energy efficiency, utilize innovative energy service options, enhance environmental management programs, upgrade facility operations, and improve equipment performance. Their web site features a large amount of energy engineering information for those wishing to explore the technical aspects of energy efficiency. |
| American Gas Association (Aga): |
| American Hydrogen Association Northwest: AGA, representing natural gas utilities, acts as a clearinghouse for gas energy information, providing information on technical and energy policy matters. / (added 09/2005) |
| American Methanol Institute: |
| American Physical Society: |
| American Solar Energy Society (ASES): AGA, representing natural gas utilities, acts as a clearinghouse for gas energy information, providing information on technical and energy policy matters. |
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DSE Energy Glossary
| Obligation To Serve | The obligation of a utility to provide electric service to any customer who seeks that service, and is willing to pay the rates set for that service. Traditionally, utilities have assumed the obligation to serve in return for an exclusive monopoly franchise. |
| Occupancy Sensor | A control device that senses the presence of a person in a given space, commonly used to control lighting systems in buildings. |
| Ocean Energy | can be used as either thermal energy or the mechanical energy of tides and waves. |
| Ocean Thermal Gradient (OTG) | Temperature differences between deep and surface water. Deep water is likely to be 25 to 45 degrees Fahrenheit colder. The term also refers to experimental technology that could use the temperature differences as a means to produce energy. |
| Octane | A rating scale used to grade gasoline as to its antiknock properties. Also any of several isometric liquid paraffin hydrocarbons, C8H18. Normal octane is a colorless liquid found in petroleum boiling at 124.6 degrees Celsius. |
| Octane Rating | A measure of a gasolineàs resistance to exploding too early in the engine cycle, which causes knocking. The higher the rating, the lower the chance of premature ignition. |
| Off-Peak | The period of low energy demand, as opposed to maximum or peak demand. |
| Off-Peak Power | The amount of power generation during a period of low consumer demand. |
| Offroad | Any nonstationary device, powered by an internal combustion engine or motor, used primarily off the highways to propel, move, or draw persons or property, and used in any of the following applications: marine vessels, construction/farm equipment, locomotives, utility and lawn and garden equipment, offroad motorcycles, and offhighway vehicles. |
| Ohm | A measure of the electrical resistance of a material equal to the resistance of a circuit in which the potential difference of 1 volt produces a current of 1 ampere. |
| Ohm (Ω) | The unit that quantifies a material’s resistance to electron flow. |
| Ohm’s Law | Basic formula defining the relationship between voltage, amperage, and resistance. Commonly stated as E = I x R, or Voltage = Amperage x Resistance. |
| Ohm’s Law | A simple mathematical formula that allows either voltage, current or resistance to be calculated when the other two values are known. The formula is V = I x R, where V is the voltage, I is the current, and R is the resistance. |
| Oil (Fuel) | A product of crude oil that is used for space heating, diesel engines, and electricity generation. |
| Oil Shale | A type of rock containing organic matter that produces large amounts of oil when heated to high temperatures. |
| Oligopoly | A few sellers who exert market control overprices. |
| One-Axis Tracking | A PV System structure that is capable of rotating on a single axis in order to track the movement of the sun. |
| On-Peak | Energy supplied during periods of relatively high system demands as specified by the utility. |
| Opec | Acronym for Organization of Petroleum Exporting Countries founded in 1960 for unify and coordinate petroleum polices of the members. Headquarters is in Vienna, Austria. |
| Open Circuit | When an electrical circuit is interrupted by breaking the path at one or more points, stopping the electrons from flowing. A light switch opens an electrical circuit when it turns off the light. |
| Open Circuit Voltage | The maximum voltage produced by an illuminated solar PV cell, module, or array when no load is connected. OCV increases as the temperature of the PV material decreases. |
| Open Circuit Voltage (Voc) | The maximum possible voltage across a PV array, module, or cell. The voltage across the terminals of a photovoltaic cell, module, or array with no load applied when the cell is exposed to standard insolation conditions, measured with a voltmeter. |
| Open Loop System | A fresh water or "direct" solar hot water system, generally for use in freeze-free climates. |
| Open-Circuit Volatage | The maximum possible voltage across a PV call or module when no current is flowing. |
| Open-Circuit Voltage (Voc) | The maximum possible voltage across a photovoltaic cell; the voltage across the cell in sunlight when no current is flowing. |
| Operating Point | Defined by the current and voltage that a module or array produces when connected to a load. It is dependent on the load or the batteries connected to the output terminals. |
| Options | An option is a contractual agreement that gives the holder the right to buy (call option) or sell (put option) a fixed quantity of a security or commodity (for example, a commodity or commodity futures contract), at a fixed price, within a specified period of time. May either be standardized, exchange-traded, and government regulated, or over-the-counter customized and non-regulated. |
| Orientation | Placement according to the directions N, S, E, or W. |
| Original Equipment Manufacturer (Oem) | refers to the manufacturers of complete vehicles or heavyduty engines, as contrasted with remanufacturers, converters, retrofitters, up-fitters, and repowering or rebuilding contractors who are overhauling engines, adapting or converting vehicles or engines obtained from the OEMs, or exchanging or rebuilding engines in existing vehicles. |
| Outage (Electric Utility) | An interruption of electric service that is temporary (minutes or hours) and affects a relatively small area (buildings or city blocks). See BLACKOUT. |
| Outer Continental Shelf (Ocs) | The submerged lands extending from the out limit of the historic territorial sea (typically three miles) to some undefined outer limit, usually a depth of 600 feet. In the United States, this is the portion of the shelf under federal jurisdiction. See CONTINENTAL SHELF. |
| Outgas | See gassing. |
| Outgassing | The emission of gasses by a material. See also GASSING. |
| Outside Air | Air taken from outdoors and not previously circulated through the HVAC system. |
| Over Generation | A condition that occurs when total PX participant demand is less that or equal to the sum of regulatory must-take generation, regulatory must-run generation, and reliability must-run generation. |
| Overcharge | Applying a current to a fully charged battery. This can damage the battery. |
| Overcurrent | Current that exceeds the rated current of the equipment or the ampacity of a conductor, resulting from overload, short circuit, or ground fault. |
| Overcurrent Device | A safety fuse or breaker designed to open a circuit when an overcurrent occurs. |
| Overhang | Any horizontal projection that serves as a shading element for a window. |
| Over-Speed | When the wind forces the blades to go faster than what your generator can handle. My blades slow down in higher winds. |
| Oxides Of Nitrogen | See NOx. |
| Oxygenate | a term used in the petroleum industry to denote octane components containing hydrogen, carbon and oxygen in their molecular structure. Includes ethers such as MTBE and ETBE and alcohols such as ethanol or methanol. The oxygenate is a prime ingredient in reformulated gasoline. The increased oxygen content given by oxygenates promotes more complete combustion, thereby reducing tailpipe emissions. |
| Ozone | A kind of oxygen that has three atoms per molecule instead of the usual two. Ozone is a poisonous gas, but the ozone layer in the upper atmosphere shields life on earth from deadly ultraviolet radiation from space. The molecule contains three oxygen atoms (O3). |
DSE Energy Glossary
| Nacelle | The cover for the gearbox, drive train, and generator of a wind turbine. |
| Nanohydro | Any hydro plant that produces less than 100 watts. |
| Nasuca | The National Association of Utility Consumer Advocates. NASUCA includes members from 38 states and the District of Columbia. It was formed "to exchange information and take positions on issues affecting utility rates before federal agencies, Congress and the courts. |
| National Electrical Code (Nec) | A document that describes the legal standards for residential and commercial wiring practices with safety as the prime objective. Many U.S. jurisdictions base their wiring inspections on the NEC. |
| National Electrical Manufacturers Association (Nema) |
This organization sets standards for some non-electronic products like junction boxes. |
| National Grid | The sum of all the connected transmission systems and distribution systems within the participating jurisdictions. In Australia it is called the National Electricity Market (NEM). |
| Natural Gas | A colourless gas that can be used as fuel in the generation of electricity, in the production of mechanical energy or in heat. |
| Natural Gas Vehicle | vehicles that are powered by compressed or liquefied natural gas. |
| Natural Gasoline | A mixture of liquids extracted from natural gas and suitable for blending with ordinary oil-derived gasoline. |
| Natural Monopoly | A situation where one firm can produce a given level of output at a lower total cost than can any combination of multiple firms. Natural monopolies occur in industries which exhibit decreasing average long-run costs due to size (economies of scale). According to economic theory, a public monopoly governed by regulation is justified when an industry exhibits natural monopoly characteristics. |
| NEC | See National Electrical Code. |
| Nema | See National Electrical Manufacturers Association. |
| Net Metering | State by state legislation that requires utilities to purchase renewably produced electricity at the same price that they sell it, until a building’s monthly or annual energy use is offset. |
| Neutron | A basic particle that is a little heavier than a proton. It is said to have neutral electrical charge. |
| Newton | The newton [N] is the SI unit of force. One newton is the force required to give a mass of 1 kilogram an acceleration of 1 metre per second per second. It is named after the English mathematician and physicist Sir Isaac Newton (1642-1727). |
| NGV (Natural Gas Vehicle) | vehicles that are powered by compressed or liquefied natural gas. |
| Nickel Cadmium Battery | A battery containing nickel and cadmium plates and an alkaline electrolyte. |
| Nickel-Cadmium Battery | A rechargeable battery high a higher storage densities than that of lead-acid. |
| Nickel-Cadmium Battery (Nicad) | A form of rechargable battery, having higher storage densities than that of lead-acid batteries, that uses a mixture of nickel hydroxide and nickel oxide for the anode, and cadmium metal for the cathode. The electrolyte is potassium hydroxide. |
| Nitrogen Oxides (NOX) | formed in combustion; appear as yellowish-brown clouds; can irritate lungs, cause lung diseases, lead to formation of ozone (which is harmful in the lower atmosphere, but necessary as protection from UV rays in the upper atmosphere). |
| Noise | Unwanted electrical signals produced by electric motors and other machines that can cause circuits and appliances to malfunction. |
| Nominal Voltage | A reference voltage used to describe batteries, modules, or systems (for example, a 12 volt or 24 volt battery, module, or system). |
| Non-Depletable Energy Sources | Energy which is not obtained from depletable energy sources. |
| Non-Firm Energy | Electricity that is not required to be delivered or to be taken under the terms of an electric purchase contract. |
| Non-Renewable Fuels | Fuels that cannot be easily renewed or reproduced, such as oil, natural gas, and coal. |
| Nonrenewable Resource | resources that are not replaced or regenerated naturally within a period of time that is useful; this includes fossil fuels, uranium and other minerals. |
| Nonresidential Building | — any building which is heated or cooled in its interior, and is of an occupancy type other than Type H, I, or J, as defined in the Uniform Building Code, 1973 edition, as adopted by the International Conference of Building Officials. |
| NOPR | A Notice of Proposed Rulemaking. A designation used by the FERC for some of its dockets. |
| Normal Operating Cell Temperature (NOCT) | The estimated temperature of a solar PV module when it is operating under 800 W/m2 irradiance, 20°C ambient temperature and a wind speed of 1 meter per second. NOCT is used to estimate the nominal operating temperature of a module in the field. |
| Northeaster Or Nor’easter | A strong wind blowing across New England from the northeast, typically bringing gales and wet weather. Northeasters can also blow across the Great Lakes. |
| Norther | A winter wind that sweeps across the southern United States and then out over the Gulf of Mexico. It can start in Canada and eventually cover the entire Mississippi Valley. |
| Nosecone | The pointed piece farthest toward the wind on a wind generator, designed primarily for cosmetic purposes, but also protects the blade attachment points and generator from the weather. |
| Notus | The South Wind in Greek mythology. (“Auster” in Latin.) |
| NOX | Oxides of nitrogen that are a chief component of air pollution that can be produced by the burning of fossil fuels. Also called nitrogen oxides. |
| N-Type | Negative semiconductor material in which there are more electrons than holes; current is carried through it by the flow of electrons. |
| N-Type Semiconductor | A semiconductor produced by doping an intrinsic semiconductor with an electron-donor impurity (e.g., phosphorus in silicon). |
| N-Type Silicon | Silicon doped with an element (usually phosphorus) that has more electrons in it’s atomic structure than silicon does. |
| Nuclear Energy | Power obtained by splitting heavy atoms (fission) or joining light atoms (fusion). A nuclear energy plant uses a controlled atomic chain reaction to produce heat. The heat is used to make steam run conventional turbine generators. |
| Nuclear Power | The energy produced by splitting atoms (such as uranium) in a nuclear reactor. |
| Nuclear Regulatory Commission (NRC) | An independent federal agency that ensures that strict standards of public health and safety, environmental quality and national security are adhered to by individuals and organizations possessing and using radioactive materials. The NRC is the agency that is mandated with licensing and regulating nuclear power plants in the United States. It was formally established in 1975 after its predecessor, the Atomic Energy Commission, was abolished. |
| NUG | A non-utility generator. A generation facility owned and operated by an entity who is not defined as a utility in that jurisdictional area. |
Links to Energy Maps
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DSE Energy Glossary
| M100 | 100 percent (neat) methanol used as a motor fuel in dedicated methanol vehicles, such as some heavy-duty truck engines. |
| M85 | a blend of 85 percent methanol and 15 percent unleaded regular gasoline, used as a motor fuel. |
| Magma | hot, thick, molten (liquid) rock found beneath the Earth’s surface; formed mainly in the mantle. |
| Magnet | A piece of material that has the natural ability to attract iron. |
| Magnetic Declination | The number of degrees east or west of true south from magnetic south. |
| Magnetic Field | A detected force that exists around a magnet or electrical field. |
| Magneto Hydro Dynamics (Mhd) | A means of producing electricity directly by moving liquids or gases through a magnetic field. |
| Maintenance Free Battery | A sealed battery to which water cannot be added to maintain the level of the electrolyte solution. |
| Maintenance-Free Battery | A sealed battery to which water cannot be added to maintain electrolyte level. |
| Major Natural Gas Producer | any person who produces natural gas in amounts determined by the commission as having a major effect on energy supplies. MAJOR MARKETER |
| Majority Carrier | Current carriers (either free electrons or holes) that are in excess in a specific layer of a semiconductor material (electrons in the n-layer, holes in the p-layer) of a cell. |
| Mantle | the semi-molten interior of the Earth that lies between the core and the crust making up nearly 80% of the Earth’s total volume; extends down to a depth of about 1800 miles (2,900 kilometers) from the surface. |
| Marginal Cost | In the utility context, the cost to the utility of providing the next (marginal)kilowatt-hour of electricity, irrespective of sunk costs. |
| Market Clearing Price | The price at which supply equals demand. The Day Ahead and Hour Ahead Markets. |
| Market Participant | An entity, including a Scheduling Coordinator, who participates in the energy marketplace through the buying, selling, transmission, or distribution of energy or ancillary services into, out of, or through the ISO-controlled grid. |
| Market-Based Price | A price set by the mutual decisions of many buyers and sellers in a competitive market. |
| Marketer | An agent for generation projects who markets power on behalf of the generator.The marketer may also arrange transmission, firming or other ancillary services as needed. Though a marketer may perform many of the same functions as a broker, the difference is that a marketer represents the generator while a broker acts as a middleman. |
| Marsh Gas | A common term for gas that bubbles to the surface of the water in a marsh or swamp. It is colorless, odorless and can be explosive. |
| Master File | A file maintained by the PX for use in bidding and bid evaluation protocol that contains information on generating units, loads, and other resources eligible to bid into the PX. |
| Maximum Power Point | The point on a PV module’s voltage/amperage curve where the product of current and voltage is a maximum (measured in watts). |
| Maximum Power Point (MPP) | Operating a PV array at that voltage will produce maximum power. The point on the current-voltage (I-V) curve of a module under illumination, where the product of current and voltage is maximum. [UL 1703] This corresponds to the point on an I-V curve that represents the largest area rectangle that can be drawn under the curve. For a typical silicon cell panel, this is about 17 volts for a 36 cell configuration. |
| Maximum Power Point Tracker (MPPT) | A power conditioning unit that automatically operates the PV generator at its MPP under all conditions. An MPPT will typically increase power delivered to the system by 10% to 40%, depending on climate conditions and battery state of charge. |
| Maximum Power Point Tracking (Mppt) | Electronically tracking the maximum power point of a PV module to achieve the highest possible output, by (in simplest terms) using surplus voltage to boost amperage. |
| Maximum Power Tracking | Operating a photovoltaic array at the peak power point of the array’s I-V curve where maximum power is obtained. Also called peak power tracking. |
| MCF | One thousand cubic feet or natural gas, having an energy value of one million Btu. A typical home might use six MCF in a month. |
| Mean Power Output (Of A Wind Turbine) | The average power output of a wind energy conversion system at any given mean wind speed. |
| Mean Wind Speed | The average wind speed over a specified time period and height above the ground. |
| Mechanical Energy | the energy an object has because of its motion or position and the forces acting on it. |
| Mechanical System | See HVAC system. |
| Median Wind Speed | The wind speed with 50% probability of occurring. |
| Megawatt | 1,000,000 watts of power or 1,000 kilowatts. |
| Megawatt (MW) | 1,000 kilowatts, or 1 million watts; standard measure of electric power plant generating capacity. |
| Megawatt Hour (MwH) | One thousand kilowatt-hours, or an amount of electricity that would supply the monthly power needs of 1,000 typical homes in the Western U.S. (This is a rounding up to 8,760 kWh/year per home based on an average of 8,549 kWh used per household per year [U.S. DOE EIA, 1997 annual per capita electricity consumtpion figures]). |
| Megawatt-Hour | 1,000 kilowatt-hours or 1 million watt-hours. |
| Megawatt-Hour (MwH) | 1,000 kilowatt-hours or 1 million watt-hours. |
| Met Tower | Meteorological towers erected to verify the wind resource found within a certain area of land. |
| Meter | A device which measures and records the production or consumption of electrical energy. |
| Methane | A light hydrocarbon that is the main component of natural gas and marsh gas. It is the product of the anaerobic decomposition of organic matter, enteric fermentation in animals and is one of the greenhouse gases. Chemical formula is CH4. |
| Methane (Ch4) | the simplest of hydrocarbons and the principal constituent of natural gas. Pure methane has a heating value of 1,1012 Btu per standard cubic foot. |
| Methane Gas | A chemical compound that is a major part of natural gas. |
| Methanol (Also Known As Methyl Alcohol, Wood Alcohol, Ch3oh) |
a liquid formed by catalytically combining carbon monoxide (CO) with hydrogen (H2) in a 1:2 ratio, under high temperature and pressure. Commercially it is typically made by steam reforming natural gas. Also formed in the destructive distillation of wood. |
| Methyl Tertiary Butyl Ether (MTBE) | an ether manufactured by reacting methanol and isobutylene. The resulting ether has a high octane and low volatility. MTBE is a fuel oxygenate and is permitted in unleaded gasoline up to a level of 15 percent. It is one of the primary ingredients in reformulated gasolines. |
| Microburst | A strong localized downdraft from a thunderstorm. Also called a downburst. |
| Microgroove | A small groove scribed into the surface of a cell which may be filled with metal for contacts. |
| Microhydro | Hydro-electric plants producing more than 100 watts and less than 2,000 watts. |
| Micrometer | One millionth of a meter. |
| Microwave | Electromagnetic radiation with wavelengths of a few centimeters. It falls between infrared and radio wavelengths on the electromagnetic spectrum. The radio wave beam can deliver electrical energy over long distances. |
| Mil | One-tenth of one cent $0.001. |
| Milliamps | One Thousandth of an amp. |
| Mineralized | containing minerals; for example, mineralized geothermal water contains dissolved minerals from inside the Earth. |
| Minimum Generation | Generally, the required minimum generation level of a utility systemós thermal units. Specifically, the lowest level of operation of oil-fired and gas-fired units at which they can be currently available to meet peak load needs. |
| 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. |
| Minority Carrier Lifetime | The average time a minority carrier exists before recombination. |
| Mistral | A penetrating, stormy, dry and cold wind that blows through the Rhone Valley of France toward the Mediterranean coast. |
| Modified Sine Wave | A waveform that has at least three states (i.e., positive, off, and negative). Has less harmonic content than a square wave. |
| Modularity | The use of complete sub-assemblies to produce a larger system. Also the use of multiple inverters connected in parallel to service different loads. |
| Module | An encapsulated panel containing a number of electrically connected PV cells. |
| Module Derate Factor | A factor that lowers the photovoltaic module current to account for field operating conditions such as dirt accumulation on the module. |
| Module De-Rating Factor | A factor that lowers the power output of a module to account for field operating conditions e.g. Dirt build-up on the module. |
| Molecule | The smallest group of atoms held together by electrostatic forces. |
| Molecules | extremely tiny particles of which all materials are made . |
| Monocrystalline Solar Cell | A form of solar cell made from a thin slice of a single large crystal of silicon. |
| Monolithic | Fabricated as a single structure, as used to describe thin film series interconnected PV cells on a single sheet substrate. |
| Monopoly | The only seller with control over market sales. |
| Monopsony | The only buyer with control over market purchases. |
| Monsoon | Any seasonal wind that blows toward a continent in summer and away from it in winter. |
| Motor | A device that converts electrical energy into mechanical energy. |
| Movistor | Metal Oxide Varistor. Used to protect electronic circuits from surge currents such as those produced by lightning. |
| MTBE (Methyl Tertiary-Butyl Ether) | A clean- burning oxygenate with high octane and low volatility added to unleaded gasoline to reduce carbon monoxide emissions. |
| Mud Pot (Paint Pot) | thermal surface feature which occurs where there is not enough water to support a geyser or hot spring even though there may be some hot water below. Steam and gas vapors bubble up through mud formed by the interaction of gases with rock. |
| Multi-Bladed | More than two blades. |
| Multicrystalline | A material that has solidified at a rate such that many small crystals (crystallites) form. The atoms within a single crystallite are symmetrically arranged with a particular orientation, whereas the crystallites themselves are differently oriented. The multitude of grain boundaries in the material (between the crystallites) reduce the cell efficiency. Multicrystalline is also referred to as polycrystalline. |
| Multicrystalline Cell | See POLYCRYSTALLINE CELL |
| Multijunction Device | A high-efficiency photovoltaic device containing two or more cell junctions, each of which is optimized for a particular part of the solar spectrum. |
| Multi-Junction Device | A PV device containing two or more cell junctions each of which may be different in nature and optimized to absorb a particular part of the solar spectrum in order to achieve higher overall cell efficiency. |
| Multi-Stage Controller | A charge controller that allows different charging currents as the battery approaches full state of charge. |
| Municipal Electric Utility | A power utility system owned and operated by a local jurisdiction. |
| Municipal Solid Waste | Locally collected garbage, which can be processed and burned to produce energy. |
| Municipal Utility | A provider of utility services owned and operated by a municipal government. |
| Municipalization | The process by which a municipal entity assumes responsibility for supplying utility service to its constituents. In supplying electricity, the municipality may generate and distribute the power or purchase wholesale power from other generators and distribute it. |
DSE Energy Glossary
| 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. |
| Landman | An in-house or independent land management consultant who negotiates terms of land leases with land owners. |
| Landscaping | Features and vegetation on a section of ground for decoration and/or energy conservation. |
| Langley | Unit of solar irradiance, one calorie per square centimeter. 1 L = 41.84 kj/m2. |
| Langley (L) | Unit of solar irradiance. One gram calorie per square centimeter. 1 L = 85.93 kwh/m2. |
| Laser | The light energy amplified by electrical impulses. |
| 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 | A location’s distance north or south of the equator measured in degrees. |
| Lattice | The regular periodic arrangement of atoms or molecules in a crystal of semiconductor material. |
| Lava | molten magma that has reached the Earth’s surface. |
| 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. |
| Layoff (Electric Utility) | Excess capacity of a generating unit, available for a limited time under the terms of a power sales agreement. |
| Lead Acid Battery | A battery that consists of lead based plates surrounded by a sulfuric acid electrolyte. |
| Lead-Acid Battery | A general category that includes batteries with plates made of pure lead, lead-antimony, or lead-calcium immersed in an acid electrolyte. |
| Leaded Gasoline | Gasoline containing tetraethyl lead, an important constituent in antiknock gasoline. Leaded gasoline is no longer sold in the United States. |
| Leading Edge | The blade edge that faces toward the direction of rotation. |
| Levanter | Wind that blows through the Straits of Gibraltar, funneled through the gap between the high plateau of Spain and the Atlas Mountains of North Africa. |
| Life | The period during which a system can operate above a specified performance level. |
| 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. |
| Life-Cycle Cost | The estimated cost of owning and operating a photovoltaic system for the period of its useful life. |
| Lifeline Rates | Rates charged by a utility company for the low income, the disadvantaged and senior citizens. The rates provide a discount for minimum necessary utilities, such as electricity requirements of typically 300 to 400 kilowatt/hours per month. |
| Lift | The force that pulls a wind turbine blade. |
| Light Emitting Diode | A semi conductor device composed of a p-n junction designed such that electrons emit visible light during their migration across the junction. |
| Light Emitting Diode (Led) | A semiconductor device composed of a PN junction designed such that electrons cause visible light during their migration across the junction. |
| 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 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. |
| Light-Induced Defects | Defects, such as dangling bonds, induced in an amorphous silicon semiconductor upon initial exposure to light. |
| Lightning | A static electrical discharge beween two clouds or between a cloud and the earth accompanied by a flash of light. |
| Lightning Arrestor | Devices that protect electronics from lightning-induced surges by carrying the charge to ground. |
| 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. |
| Line Loss | Voltage drop over a length or wire. You are at risk to this if your wire is too small for the load going through it or the voltage is too low for the distance it must travel. |
| Line Wire Loss | refers to the voltage or power lost due to the resistance of any wire or wires in any electrical circuit. |
| Line/Wire Loss | The voltage drop or energy loss due to the resistance of wire in an electrical circuit. See VOLTAGE DROP |
| Linear Current Booster | an electronic circuit that matches PV output directly to a motor. Used in array direct water pumping. |
| Linear Current Booster (Lcb) | An electronic circuit that matches PV output directly to a motor by converting unneeded voltage to higher usable current. Used in array-direct water pumping. |
| Line-Commutated Inverter | An inverter that is tied to a power grid or line. The commutation of power (conversion from direct current to alternating current) is controlled by the power line, so that, if there is a failure in the power grid, the photovoltaic system cannot feed power into the line. |
| Liquefaction | 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. |
| Liquefied Gases | Gases that have been or can be changed into liquid form. These include butane, butylene, ethane, ethylene, propane and propylene. |
| Liquid Brine | A type of geothermal energy resource that depends on naturally occurring hot water solution found within the earth. Technology for this novel energy source is being developed in the Salton Sea area in Southern California. |
| Liquid Electrolyte Battery | A battery containing a liquid solution of an electrolyte in a solvent. Can be called a flooded battery too. |
| Liquid Petroleum Gas | See LPG. |
| Lng (Liquefied Natural Gas) | Natural gas that has been condensed to a liquid, typically by cryogenically cooling the gas to minus 260 degrees Fahrenheit (below zero). |
| Load | Anything that draws power from an electric circuit. |
| Load Centers | A geographical area where large amounts of power are drawn by end-users. |
| Load Circuit | The wire, switches, fuses, etc. That connect the load to the power source. |
| Load Current | The current required to power the electrical device. |
| Load Current (A) | The current required by the electrical device. |
| 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 |
| 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. |
| Load Resistance | The electrical resistance of the load. |
| 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 kilowatt-hours are lost in the form of waste heat in electrical apparatus such as substation conductors. LINE LOSSES are kilowatts or kilowatt-hours lost in transmission and distribution lines under certain conditions. |
| Low Voltage Cut-Off | The voltage at which a controller will disconnect the load from the battery. |
| Low Voltage Cutoff (LVC) | The voltage level at which a charge controller will disconnect the load from the battery. |
| Low Voltage Disconnect | The voltage at which a charge controller will disconnect the load from the batteries to prevent over-discharging. |
| Low Voltage Disconnect (LVD) | The voltage at which the charge controller will disconnect the load from the batteries to prevent over-discharging. |
| Low Voltage Disconnect Hysteresis | The voltage difference between the low voltage disconnect set point and the voltage at which the load will be reconnected. |
| Low Voltage Warning | A warning buzzer or light that indicates the low battery voltage set-point has been reached. |
| Low-E | A special coating that reduces the emissivity of a window assembly, thereby reducing the heat transfer through the assembly. |
| Low-E Glass | Glass coated with layers of metal or metal oxide. The coating emits very little radiation in the long-wave (infrared) spectrum, which diminishes heat loss from the building interior, and reduces heat gain in hot weather. |
| Low-Sulfur Oil | Oil having one percent or less of sulfur by weight. |
| LPG (Liquefied Petroleum Gas) | A mixture of gaseous hydrocarbons, mainly propane and butane that change into liquid form under moderate pressure. LPG or propane is commonly used as a fuel for rural homes for space and water heating, as a fuel for barbecues and recreational vehicles, and as a transportation fuel. It is normally created as a by-product of petroleum refining and from natural gas production. |
| Lumen | A unit of measurement quantifying the amount of light emitted from a light source. |
| 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. |
DSE Energy Glossary
| Jack Pump | A submerged pump mechanically activated by a rod extending above the well head to a reciprocating engine, motor or any other rotating device. |
| Jet Stream | A meandering and relatively narrow belt of strong winds embedded in the normal wind flow, generally found at high altitudes. |
| Joule | A metric measurement of force equal to one Newton operating through the distance or one metre. |
| Joule (J) | A metric unit of energy or work. One joule per second equals 1 watt. |
| 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). |
| Junction Box | A photovoltaic (PV) generator junction box is an enclosure on the module where PV strings are electrically connected and where protection devices can be located, if necessary. |
| Junction Diode | A semiconductor device with a junction and a built-in potential that passes current better in one direction than the other. All solar cells are junction diodes. |
| Kaplan Turbine | A type of turbine that has two blades whose pitch is adjustable. |
| Kbtu | One-thousand (1,000) Btus. |
| Kerosene | Certain colorless, low-sulfur oil products that burn without producing much smoke. |
| Khamsin | A hot, dry wind that blows from the Sahara Desert to Egypt for about fifty days each spring. Egyptians call it “rih al khamsin,” which means “the wind of fifty days.” |
| Kilovolt (Kv) | One-thousand volts (1,000). Distribution lines in residential areas usually are 12 kv (12,000 volts). |
| Kilowatt | 1000 Watts = 1Kw or 1 Kilowatt |
| Kilowatt (Kw) | A standard unit of electrical power equal to 1000 watts, or to the energy consumption at a rate of 1000 joules per second. 1 kWh = ten 100 watt bulbs all burning at the same time for one hour. 10 bulbs x 100 watts each x 1 hour = 1,000 watts hours or 1kWh. |
| Kilowatt-Hour (Kwh) | One thousand watt-hours. Unit of energy used to perform work (energy and work are equivalent in units, energy being the potential value and work the achieved value). Fuel equivalents One barrel of crude oil contains roughly 1,700 KWH One ton of coal contains roughly 7,500 KWH One gallon of gasoline contains roughly 37 KWH One cubic foot of natural gas contains 0.3 KWH One ton of uranium ore contains 164 million KWH 1.34 horsepower-hours. 1 KWH = 3,400 BTU. Can be compared to 860 calories (food energy value). |
| Kinetic Energy | Energy available as a result of motion. (Kinetic energy is equal to one half the mass of the body in motion multiplied by the square of its speed.) |
| Knot | One nautical mile per hour (1.15 MPH). |
| Kona | A stormy, rain-bearing wind from the Southwest or SSW in Hawaii. Kona is a Polynesian word meaning “leeward.” |
DSE Energy Glossary
| Imbalance Energy | The real-time change in generation output or demand requested by the ISO to maintain reliability of the ISO-controlled grid. Sources of imbalance energy include regulation, spinning and non-spinning reserves, replacement reserve, and energy from other generating units that are able to respond to the ISO’s request for more or less energy. |
| Impermeable | does not allow liquids to pass through easily. Certain rock types and clay soil are impermeable. |
| Imports (Electric Utility) | Power capacity or energy obtained by one utility from others under purchase or exchange agreement. |
| Impoundment | A body of water confined by a dam, dike, floodgate or other artificial barrier. |
| Incandescent Lamp | An electric lamp in which a filament is heated by an electric current until it emits visible light. |
| Incandescent Light | An electric lamp that is evacuated or filled with an inert gas and contains a filament (commonly tungsten). The filament emits visible light when heated to extreme temperatures by electric current through it. Incandescent lightbulbs are one of the most inefficient ways to light a home. They produce a great deal of heat along with the light, and use three to four times as much energy for the same light output as compact fluorescent lightbulbs. |
| Incident Light | Light that shines on to the surface of a PV cell or module. |
| Independent Power Producer | An Independent Power Producer (IPP) generates power that is purchased by an electric utility at wholesale prices. The utility then resells this power to end-use customers. Although IPPs generate power, they are not franchised utilities, government agencies or QFs. IPPs usually do not own transmission lines to transmit the power that they generate. |
| Independent Power System | A power generation system that is independent of the mains grid. |
| Indirectly Conditioned Space | See conditioned space, indirectly. |
| Indium Oxide | A wide band gap semiconductor that can be heavily doped with tin to make a highly conductive, transparent thin film. Often used as a front contact or one component of a heterojunction solar cell. |
| Induction Generator | A generator that produces energy by the production of a magnetic field by the proximity of a electric charge. Commonly made from old induction motors. |
| Induction Motor | An AC motor in which the rotating armature has no electrical connections to it and consists of alternating plates. |
| Induction Motor (Ac) | A type of electric motor that requires a high surge to start, and a stable voltage supply, making it a challenge to run using a solar-electric system. |
| Infiltration | The uncontrolled inward leakage of air through cracks and gaps in the building envelope, especially around windows, doors and duct systems. |
| Infiltration Barrier | A material placed on the outside or the inside of exterior wall framing to restrict inward air leakage, while permitting the outward escape of water vapor from the wall cavity |
| Infrared Light. | Electromagnetic radiation whose wavelengths lie in the range from .75 micrometers to 1000 micrometers. |
| 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. |
| Infrastructure | generally refers to the recharging and refueling network necessary to successful development, production, commercialization and operation of alternative fuel vehicles, including fuel supply, public and private recharging and refueling facilities, standard specifications for refueling outlets, customer service, education and training, and building code regulations. |
| Injection Well | a well through which geothermal water is returned to an underground reservoir after use. Geothermal production and injection wells are constructed of pipes layered inside one another and cemented into the earth and to each other. This protects any shallow drinking water aquifers from mixing with deeper geothermal water. |
| Input Voltage | This is determined by the total power required by the alternating current loads and the voltage of any direct current loads. Generally, the larger the load, the higher the inverter input voltage. This keeps the current at levels where switches and other components are readily available. |
| In-Situ Combustion | An experimental means of recovering hard-to-get petroleum by burning some of the oil in its natural underground reservoir. Also called FIREFLOODING. |
| In-Situ Gasification | Converting coal into synthetic gas at the place where the coal is found in nature. |
| Insolation | The amount of sunlight reaching an area, usually expressed in Watt hours per square meter per day. |
| Installer | Usually a retailer and installer of PV Systems |
| Insulation | A material used to prevent the flow of electricity. Normally used on electrical wires to prevent electric shock. Typical materials used include plastics such as PVC and polypropylene. |
| Insulation, Thermal | A material having a relatively high resistance of heat flow and used principally to retard heat flow. See R-VALUE. |
| Insulator | A material (such as plastic or glass) that does not permit electricity to pass through it readily. |
| Intake | In a hydro system, the structure that receives the water and feeds it into the penstock (pipeline). Usually incorporates screening or filtering to keep debris and aquatic life out of the system. |
| Integrated Resource Planning Principles | The underlying principles of IRP can be distinguished from the formal process of developing an approved utility resource plan for utility investments in supply- and demand-side resources. A primary principle is to provide a framework for comparing a variety of supply- and demand-side and transmission resource costs and attributes outside of the basic provision (or reduction) of electric capacity and energy. These resources may be owned or constructed by any entity and may be acquired through contracts as well as through direct investments. Another principle is the incorporation of risk and uncertainty into the planning analysis. The public participation aspects of IRP allow public and regulatory involvement in the planning rather than the siting stage of project development. |
| Integrated Resource Planning(Irp) | A public planning process and framework within which the costs and benefits of both demand- and supply-side resources are evaluated to develop the least-total-cost mix of utility resource options. In many states, IRP includes a means for considering environmental damages caused by electricity supply/transmission and identifying cost-effective energy efficiency and renewable energy alternatives. IRP has become a formal process prescribed by law in some states and under some provisions of the Clean Air Act amendments of 1992. |
| Integrator | Integrates PV components in to a complete PV System |
| Interchange (Electric Utility) | The agreement among interconnected utilities under which they buy, sell and exchange power among themselves. This can, for example, provide for economy energy and emergency power supplies. |
| Interconnect | A conductor within a module or other means of connection which provides an electrical interconnection between the solar cells. [UL 1703] |
| Interconnection (Electric Utility) | The linkage of transmission lines between two utilities, enabling power to be moved in either direction. Interconnections allow the utilities to help contain costs while enhancing system reliability. |
| Inter-Connector | A transmission line or group of transmission lines that connects the transmission networks in adjacent regions. |
| Interested Party | any person whom the commission finds and acknowledges as having a real and direct interest in any proceeding or action carried on, under, or as a result of the operation of, this division. |
| Internal Combustion Engine | An engine in which fuel is burned inside the engine. A car’s gasoline engine or rotary engine is an example of a internal combustion engine. It differs from engines having an external furnace, such as a steam engine. |
| Interruptible Service (Electric Utility) | Electricity supplied under agreements that allow the supplier to curtail or stop service at times. |
| Intertie | A transmission line that links two or more regional electric power systems. |
| Intrinsic Layer | A layer of semiconductor material, used in a photovoltaic device, whose properties are essentially those of the pure, undoped, material. |
| Intrinsic Semiconductor | An undoped semiconductor. |
| Inverter | A device that converts DC electricity (anywhere from 12 to 600 VDC) to AC electricity (typically 120/240 VAC). |
| Investor-Owned Utilities | A private company that provides a utility, such as water, natural gas or electricity, to a specific service area. |
| Ion | An atom that has lost or gained electrons and by doing so, becomes electrically charged. |
| IOU | An investor owned utility. A company, owned by stockholders for profit, that provides utility services. A designation used to differentiate a utility owned and operated for the benefit of shareholders from municipally owned and operated utilities and rural electric cooperatives. |
| IPP | INDEPENDENT POWER PRODUCER. An private entity that operates a generation facility and sells power to electric utilities for resale to retail customers. |
| Irradiance | The direct, diffuse, and reflected solar radiation that strikes a surface. Usually expressed in kilowatts per square meter. Irradiance multiplied by time equals insolation. |
| ISC | See SHORT CIRCUIT CURRENT. |
| ISDN | INTEGRATED SERVICES DIGITAL NETWORK. A 128 Kbps (kilobytes per second) digital telephone service available in many parts of the country though not universally available that may be able to substitute for fiber optic cable in every respect except possibly television transmission. |
| ISO | INDEPENDENT SYSTEM OPERATOR. A neutral operator responsible for maintaining instaneous balance of the grid system. The ISO performs its function by controlling the dispatch of flexible plants to ensure that loads match resources available to the system. |
| Ispra Guidelines | Guidelines for the assessment of photovoltaic power plants, published by the Joint Research Centre of the Commission of the European Communities, Ispra, Italy. |
| I-Type Semiconductor | 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. |
| I-V Curve | A graph that plots the current versus the voltage from a PV cell as the electrical load (or resistance) is increased from short circuit (no load) to open circuit (maximum voltage). The shape of the curve characterizing cell performance. Three important points on the I-V curve are the open-circuit voltage, short-circuit current, and peak or maximum power (operating) point. |
| I-V Data | The relationship between current and voltage of a photovoltaic device in the power-producing quadrant, as a set of ordered pairs of current and voltage readings in a table, or as a curve plotted in a suitable coordinate system |
DSE Energy Glossary
| Haboob | A squall of billowing dust that blows across the Syrian Desert when a monsoon collides with dry air currents above it. |
| Halogen Lamp | A special type of incandescent globe made of quartz glass and a tungsten filament, enabling it to run at a much higher temperature than a conventional incandescent globe. Efficiency is better than a normal incandescent, but not as good as a fluorescent light. |
| Harmattan | A very hot wind with dangerous cross-currents that blows southwest from central Africa and across the Sudan, typically December through February. It is often preceded by “the smokes,” clouds of stinging, red dust. |
| Harmonic Content | Frequencies in the output waveform in addition to the primary frequency (usually 50 or 60 Hz.) Energy in these harmonics is lost and can cause undue heating of the load. |
| H-Coal Process | A means of making coal cleaner so it will produce less ash and less sulfur emissions. |
| Head | The difference in elevation between two parts of a liquid-based system. In hydro power, the difference between a source of water and the location at which the water from that source may be used (synonym vertical drop). With pumps, the vertical distance the pump must move the water. |
| Headrace | A flume or channel that feeds water into a hydro turbine. |
| Health Spa | an establishment (often commercial) which is visited by guests seeking therapy and relaxation; many center around hot mineral springs or use hot water from geothermal wells. |
| Heat Balance | The outdoor temperature at which a building’s internal heat gain (from people, lights and machines) is equal to the heat loss through windows, roof and walls. |
| Heat Capacity | The amount of heat necessary to raise the temperature of a given mass one degree. Heat capacity may be calculated by multiplying the mass by the specific heat. |
| Heat Engine | An engine that converts heat to mechanical energy. |
| Heat Exchanger | a device in which heat is transferred by conduction through a metal barrier from a hotter liquid or gas, to warm a cooler liquid or gas on the other side of the metal barrier. Types of heat exchangers include "shell and tube," and "plate." |
| Heat Gain | an increase in the amount of heat contained in a space, resulting from direct solar radiation, heat flow through walls, windows, and other building surfaces, and the heat given off by people, lights, equipment, and other sources. |
| Heat Loss | A decrease in the amount of heat contained in a space, resulting from heat flow through walls, windows, roof and other building surfaces and from exfiltration of warm air. |
| Heat Pump | A device typically used for heating and cooling of buildings by drawing from or dissipating into the ambient temperature of air or water. When cooling, a heat pump works like a refrigerator. When heating, it also works like a fridge, except the heat produced is used to heat a space. |
| Heat Rate | A number that tells how efficient a fuel-burning power plant is. The heat rate equals the Btu content of the fuel input divided by the kilowatt-hours of power output. |
| Heat Sink | A medium or container to which heat flows. Thermal mass walls and floors in a passive solar home act as a heat sink during the day. |
| Heat Storm | Heat storms occur when temperatures exceed 100 degrees Fahrenheit over a large area for three days in a row. Normal hot temperatures cause electricity demand to increase during the peak summertime hours of 4 to 7 p.m. when air conditioners are straining to overcome the heat. If a hot spell extends to three days or more, however, nighttime temperatures do not cool down, and the thermal mass in homes and buildings retains the heat from previous days. This heat build-up causes air conditioners to turn on earlier and to stay on later in the day. As a result, available electricity supplies are challenged during a higher, wider peak electricity consumption period. |
| Heat Transfer | Heat is transferred from one substance or location to another by three methods—radiation, convection and conduction. The sun’s rays are a good example of radiation; warm air rising is heat movement by convection; and touching a hot iron or frying pan with your hand is heat transfer by conduction. |
| Heating Degree Day | A unit that measure the space heating needs during a given period of time. |
| Heating Load | The rate at which heat must be added to a space in order to maintain the desired temperature within the space. |
| Heating Value | The amount of heat produced by the complete combustion of a given amount of fuel. |
| Heavy Water | A type of hydrogen atom that may be used as fuel for fusion power plants. Also called DEUTERIUM, it is found in abundance in the seas. |
| Hedging Contracts | Contracts which establish future prices and quantities of electricity independent of the short-term market. Derivatives may be used for this purpose. (See Contracts for Differences, Forwards, Futures Market, and Options.) |
| Heliochemical | Using solar radiation to cause chemical reactions. |
| Heliothermal | A process that uses the sun’s rays to produce heat. |
| Helm Wind | A wind that blows down the slopes of small, smooth hills. Helm winds are common in the British Isles. |
| Hertz | The frequency of electrical current described in cycles per second. |
| Hertz (Hz) | A measure of the number of cycles or wavelengths of electrical energy per second. The United States electricity supply has a standard frequency of 60 hertz. |
| Heterojunction | A region of electrical contact between two different materials. |
| High Voltage Disconnect | The voltage at which a charge controller will disconnect the photovoltaic array from the batteries to prevent overcharging. |
| High Voltage Disconnect Hysteresis | The voltage difference between the high voltag disconnect set point and the voltage at which the full photovoltaic array current will be reapplied. |
| High-Sulfur Coal | Coal whose weight is more than one percent sulfur. |
| Hms:O | The unit of measurement of the electrical resistance of a material to the flow of current. |
| Hole | The vacancy where an electron would normally exist in a solid; behaves like a positively charged particle. |
| Homojunction | The region between an n-layer and a p-layer in a single material, photovoltaic cell. |
| Horizontal-Axis Wind Turbines | Turbines on which the axis of the rotor’s rotation is parallel to the wind stream and the ground. |
| Horsepower | A measure of the capacity to generate energy or do work. 1 horsepower = 746 watts. |
| Horsepower (Hp) | A unit for measuring the rate of doing work. One horsepower equals about three-fourths of a kilowatt (745.7 watts). |
| Hot | (Colloquial) |
| Hot Dry Rock | A geothermal resource created when impermeable, subsurface rock structures, typically granite rock 15,000 feet or more below the earth’s surface, are heated by geothermal energy. The resource is being investigated as a source of energy production. |
| Hot Spot | A phenomenon where one or more cells within a PV module or array act as a resistive load, resulting in local overheating or melting of the cells. |
| Hot Springs | a natural spring that puts out water warmer than body temperature and therefore feels hot; may collect in pools or flow into streams an lakes. A geothermal phenomenon. |
| HSPF (Heating Seasonal Performance Factor) | A measure of heating efficiency for the total heating output of a central air-conditioning heat pump. Efficiency is derived according to federal test methods by using the total Btus during its normal usage period for heating divided by the total electrical energy input in watt-hours during the same period |
| Hub | The center mount for the blades. Laser cut like mine are hard to beat. |
| HVAC (Heating Ventilation And Air Conditioning) | A system that provides heating, ventilation and/or cooling within or associated with a building. |
| Hybrid System | A PV system that includes solar PV and some other electricity generating power source. |
| Hybrid Vehicle | Usually a hybrid EV, a vehicle that employs a combustion engine system together with an electric propulsion system. Hybrid technologies expand the usable range of EVs beyond what an all-electric-vehicle can achieve with batteries only. |
| Hydroelectric Power | Electricity produced by falling water that turns a turbine generator. Also referred to as HYDRO. |
| Hydroelectric Spill Generation | Hydroelectric generation in existence prior to January 1, 1998, that has no storage capacity and that, if backed down, would spill. This term also refers to a hydro resource that has exceeded or has inadequate storage capacity and is spilling, even though generators are operating at full capacity. |
| Hydroelectricity | Electric energy made by the conversion of energy produced from running water. |
| Hydro-Electricity | Any electricity that is generated by the flow of water. |
| Hydrogen Fuel Cell | A device that converts hydrogen to DC electricity. |
| 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. |
| Hydrometer | A hydrometer is an instrument for measuring the density of liquids in relation to the density of water. The hydrometer is used to indicate the state of charge in lead-acid cells by measuring the specific gravity of the electrolyte. |
| Hydronic Heating | A system that heats a space using hot water which may be circulated through a convection or fan coil system or through a radiant baseboard or floor system. |
| Hydronic Heating System | A type of heating system where water is heated in a solar collector or boiler, and is pumped to heat exchangers or radiators in rooms. Radiant floor systems have a grid of tubing laid out in the floor for distributing the heat. Temperature of the space is controlled by regulating the flow and/or temperature of the circulating water. |
| Hydropower | captures the energy in flowing water and uses it to generate electricity. |
| Hydrothermal | hydro means water and thermal means heat. Literally hydrothermal means hot water. Steam and hot water reservoirs are hydrothermal reservoirs. Hot dry rock resources and magma resources are not considered to be hydrothermal resources. |
| Hydrothermal Systems | Underground reservoirs that produce either dry steam or a mixture of steam and water. |
| Hygas | A process that uses water to help produce pipeline-quality gas from coal. |
DSE Energy Glossary
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The DSE Energy Glossary is a collection of terms and their respective definitions. |