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Wind Glossary

Accelerated Depreciation – With accelerated meet minimum demands based on reasonable depreciation, wind energy projects can reduce the expectations of customer requirements. assessed value of their equipment on their financial values typically vary from hour to hour in most balance sheets over a shorter period of time. commercial and industrial areas. Also known as bas load demand. Access Roads – Roads that allow access to wind energy project sites and individual wind turbine Battery – For most wind energy projects, battery locations during the development, construction and systems are cost-prohibitive and not considered the operational phases of a project. Access roads are commercially viable to include as part of a constructed for long-term use and are built to commercial or utility-scale development accommodate heavy equipment and maintenance project for alternative energy; may also be called vehicles throughout the life of the project. galvanic battery or voltaic battery.

Air Pollution – The addition of harmful chemicals to Beaufort Scale – A scale used to classify wind speeds, the atmosphere that often result from the burning of devised in 1805 by Admiral Francis Beaufort of the fossil , especially in internal combustion engines. British Navy.

Alternative Energy – Energy that is produced from Blades – The large “arms” of wind turbines that alternative energy sources such as solar, wind or extend from the hub of a generator. Most turbines nuclear energy that serves as alternative energy have either two or three blades. Wind blowing over forms that produce traditional fossil- sources the blades causes the blades to “lift” and rotate. such as , oil and . Blades vary in length by turbine rating (MW) and manufacturer (i.e. GE, Siemens, Vestas etc.). The most American Wind Energy Association (AWEA) – common turbine blades in the US range between 116’ Formed in 1974, American Wind Energy Association and 164’ in length and are made of composite is a Washington DC based national trade association fiberglass or aluminum. Blades are designed to representing wind project developers, maximize the efficiency of wind energy production equipment suppliers, service providers, parts from a wind turbine generator. manufacturers, utilities, researchers and others involved in the wind energy industry. Brake – Wind turbine generators contain a disc brake that can be applied mechanically, electrically or Anemometer – Instrument that measures the speed hydraulically to stop the rotor for maintenance, of wind. Meteorological towers used for wind repair and in emergency situations. assessment have anemometers attached to the end of booms that extend from the tower in different Braking System – Device to slow a wind turbine’s directions. The anemometer collects data including shaft speed down to a safe level electrically or wind speed and direction and transmits it to the mechanically. controller. Then that information can be used to determine the long-term alternative energy potential Carbon Dioxide (CO2) – Naturally occurring gas, and and seasonal attributes of the wind at a specific also a by-product of burning fossil fuels and location. as well as land-use changes and other industrial processes. CO2 is the principal greenhouse gas that is Base Load Power – The minimum amount of power produced by human activity and influences climate that a utility or distribution company must make change. available to its customers. Base load power could also be described as the amount of power required to Carbon Monoxide (CO) – A colorless, odorless, to the grid, or certain planning conditions. highly poisonous gas, formed by the incomplete Curtailment is controlled by the regional combustion of carbon or a carbonaceous material transmission operator. such as gasoline. Cut-in Speed – Wind speed at which the turbine Circuit – The complete path of an electric current, blades begin to rotate and produce , including the generating apparatus intervening typically around 10 mph. resistors, or ; also known as an electric current. Cut-out Speed – Wind speed at which the turbine automatically stops the blades from turning and Climate – The meteorological conditions, including rotates out of the wind to avoid damage to the temperature, precipitation and wind that turbine, usually around 55 – 65 mph. characteristically prevail in a particular region. Deregulation – Process of changing policies and laws Climate Change – Changes in a climate system over of regulation in order to increase competition among decades or longer. The term often refers to changes suppliers of commodities and services. The Energy in climate that can be attributed directly or indirectly Policy Act initiated deregulation of the to human activities that altered the composition of industry in 1992. the global atmosphere – changes that are beyond the natural climate variability observed over comparable Direct Current – Type of electricity transmission and time periods. distribution by which electricity flows in one direction through the conductor, usually relatively Conductor – The material through which electricity low-voltage and high-current. To be used for typical is transmitted. Wind turbine generators require 120 volt or 220 volt household appliances. DC must electric lines with a conductor material (that is almost be converted to alternating current its opposite. always an aluminum alloy) to transmit the wind energy produced to a location where the wind energy Distributed Energy Resources – Commonly can be consumed and used as alternative energy. referred to as “”, and includes a variety of small, modular power-generating Controller – Wind turbine generators contain a technologies that are used to create alternative controller that starts up the machine at wind speeds energy and can be combined with wind energy of about 8 to 16 miles per hour (mph) and shuts off management and storage systems used to improve the machine at about 55-65 mph. Generally wind the operation of the electricity delivery system. turbine generators do not operate at wind speeds above 55 mph because they might be damaged by the Distributed Generation – Localized, on-site power, high winds. or “behind the meter” generation. Also known as distributed energy resources. Converter – Piece of equipment found within wind turbine generators that converts a direct current (dc) Distribution Electric Cooperatives – Service end- voltage to another dc voltage. users, such as residences and businesses that make up their membership and are often located in rural Coverage Ratio – Type of accounting ratio that helps areas. Distribution Electric Cooperatives commonly measure a company’s ability to meet its obligations purchase the majority of their power from Generation satisfactorily. A coverage ratio encompasses many and Transmission Cooperatives that typically different types of financial ratios. Typically, these purchase power centrally for multiple Distribution kinds of ratios involve a comparison of assets and Electric Cooperatives. They are also known as liabilities. The better the assets “cover” the liabilities, Distribution & transmission “D&T” Cooperatives. the better off the company is. Efficiency – The amount of active electrical power Curtailment – The forced shut-down of some or all of generated as a percentage of the received the wind turbine generators within a wind farm to by the turbine. mitigate issues associated with turbine loading export Electric Cooperative – This is a type of electric utility generators. It also permitted non-generator- utility for alternative energy in which all users are owning municipalities to purchased wholesale shareholders. This is common in rural areas that are electricity to use as alternative energy. expensive to serve because of the long distances between users. Frequently, the government – Process of storing or converting contributes in various ways to rural cooperatives to energy from one form to another for later use. An reduce costs to individual owner/users. The two example of an energy storage device is a battery. types of electric cooperatives are Distribution and Environment – All the natural and living things Transmission “D&T” Cooperatives and Generation around us including the earth, air, weather, plants and Transmission “G&T” Cooperatives. and animals. Electric Reliability Council of Texas (ERCOT) – Environmental Impact Statement (EIS) – Formed in 1970, one of eight independent System Environmental Impact Statements are required in Operators in North America, and the successors to the various parts of the U.S. as part of the permitting Texas Interconnected System (TIS). TIS originally stage of wind project development. EIS studies formed in 1941 when several power companies review proposed electric utility projects and the banded together to provide their excess generation potential for significant environmental impacts, capacity to serve industrial loads on the Gulf Coast including evaluation of alternatives and mitigation. supporting the U.S. World War II effort. ERCOT is one of nine regional electric reliability councils under Federal Energy Regulatory Commission (FERC) – North American Electric Reliability Corporation The Federal agency with jurisdiction over interstate (NERC) authority and the regional reliability councils electricity sales, whole electric rates, hydroelectric were formed following the Northeast Blackout of licensing, natural gas pricing, oil pipeline rates and 1965. gas pipeline certification. FERC is an independent regulatory agency within the Department of Energy Electric Utility – Organization responsible for the and is the successor to the Federal Power installation, operation or maintenance of an electric Commission. supply system. Electric utilities are generally owned by investors, municipalities or cooperatives. Feed-in Tariff (FIT) – Feed-In Tariffs, also known as payments are often included in Electricity – The energy of moving electrons, the nation state or local policy to encourage the adoption current of which is used as a source of power. of renewable energy sources. FITs typically include Electricity can be used as alternative energy. three key provisions: 1.) guaranteed grid access 2.) – Wind turbines extract or long-term contracts for the electricity produced and generate wind energy and convert that wind energy 3.) purchase prices that are methodologically based into electricity that is measured in kilowatt hours on the cost of the renewable energy generation and (kwh). tend towards grit parity.

Energy – The capacity for . Energy can be – Fuel sources or “feed-stocks”, including converted into different forms, but the total amount coal, oil and gas, burned with oxygen to produce of energy remains the same. Wind turbine generators energy. Fossil fuels are the most common fuel source extract wind energy and convert the energy into for the production of electricity in the U.S. electricity. Fuel – Any material that can be consumed to make Energy Payback – The time period it takes for a wind energy such as alternative energy. turbine to generate as much energy as is required to Gear Box – Gears connect the low-speed shaft to the produce the turbine, install it, maintain it throughout high-speed shaft and increase the rotational speed of its lifetime and, finally, scrap it. the shaft to the speed required by the generator. The Act of 1982 (EPAct) – Is a federal gear box is heavy and power losses from friction are statute that established additional forms of non- inherent in any gearing system. Generation and Transmission Cooperative (G&T) Grid – A common term referring to an electricity – G&T Cooperatives are power supply cooperatives transmission and distribution system. owned by a group of distribution cooperatives. Generally, G&Ts general power of purchased it from Grid Connected System – Residential electrical municipal, investor-owned utilities or independent system such as solar panels or wind turbines which power producers. act like a central generating plant, supplying power to the commercial grid. Generator – Device that produces electricity from , such as from a rotating turbine Guy Wires – Tensioned cables designed to add shaft. stability to tall, narrow structures; frequently used to support ship masts, radio masts and wind turbines. Gigawatt (GW) – Unit of power equal to 1 billion watts, 1 million kilowatts or 1000 megawatts. High-Speed Shaft – Shaft within a wind turbine generator that is driven by the rotation of the turbine Global Warming – Term used to describe the blades when propelled by wind to convert into wind increase in average global temperatures due to the energy. increase in greenhouse gases found within the Earth’s atmosphere. Horizontal –Axis Wind Turbines – Wind turbine generators, that support the turbine blades on the Green Credit – Way to purchase renewable electric outside and connects to the low speed rotor shaft generation. Green credits divide alternative energy inside the nacelle found on wind farms. generation into two separate products: the commodity energy and the renewable attributes Hub – The central part of the wind turbine generator, associated with the generation of the commodity which supports the turbine blades on the outside and energy. The green credit represents the renewable connects to the low-speed rotor shaft inside the attributes of a single megawatt of renewable energy. nacelle. This may also be known as green tags, renewable Independent Power Producers (IPPS) – These are energy credits or renewable energy certificates. private or public companies that independently Green Power – Popular term for alternative energy generate capacity or wholesale power for sale to produced from renewable energy resources such as utilities. IPPS are not utilities and do not own wind energy. transmission lines or sell on the retail market.

Greenfield – A Greenfield site is a site on which a Independent System Operator (ISO) – Organization power plant has not previously existed. A Greenfield formed at the direction or recommendation of the project is an alternative energy project in the early Federal Energy Regulatory Commission (FERC. In the stages of development. Alternative energy projects areas where an ISO is established, it coordinates advance pas the Greenfield stage when they enter controls and monitors the operation of the electrical into power purchased agreement negotiations, power system, usually within a single U.S. state, but construction or commercial operations. sometimes encompassing multiple states. RTO’s typically perform the same functions as ISO’s but Greenhouse Effect – Heating effect resulting from cover a larger geographic area. long-wave from the sun being trapped by greenhouse gases that have been produced from Inductive Reactance – Electrical current produces natural and human sources. and/or a magnetic field (such as in the windings of a motor). We refer to the tendency for current flow Greenhouse Gases – Gases that trap the heat of the and changes in flow to be influenced by magnetic sun in the Earth’s atmosphere, producing the fields as inductance. An AC circuit that contains only greenhouse effect; the two major greenhouse gases inductance, capacitance or a combination of the two are water vapor and carbon dioxide; lesser is defined by the total opposition to current flow greenhouse gases include methane, ozone, expressed in reactance. chlorofluorocarbons and nitrogen oxides. Installed/Rated/ – A wind compare the cost of energy across technologies. farm’s capacity is the most common term used to LCOE takes into account the installed system price describe the maximum possible electricity output and associated costs such as financing, land, from the wind farm. Generally, wind farms operate at insurance, transmission, operation and maintenance capacity approximately 30% - 40% of the time, and depreciation. The LCOE is a true apples-to- depending on the average wind speed and profile of apples comparison of electricity costs and is the most the wind at a specific site. common measure used by electric utilities or purchasers of power to evaluate the financial viability Interconnection – Process of linking a wind farm to and attractiveness of a wind energy project. the electric grit for the purpose of distribution electricity to a purchased of the power produced. Load – In reference to wind developments, load Interconnection rules vary by region and require describes the energy demand placed on a power permission from the local utility and regional generating facility or the energy consumed by a group transmission operator. of customer or set of equipment; usually expressed in amperes or watts. Inverter – An electrical device that converts direct current electricity to alternating current electricity. Mean Power Output (of a wind turbine) – Average The common U.S. household consumes energy in the power output of a wind farm at the mean wind speed form of kilowatt hours provided by alternating of the wind farm. current electricity. Mean Wind Speed – Average wind speed over a time Investment Tax Credit (ITC) – Form of financial period at a specific height. The mean wind speed is incentive that a state or federal government can used to determine the average amount of electricity implement to help consumers reduce the up-front produced over a time period for alternative energy “investment” cost of an expensive one-time purchase, potential. such as a small wind system. Typically a portion of the system’s purchase price can be taken as a credit Mechanical Energy – Energy possessed by an object against (subtracted from) the purchaser’s income tax due to its motion () or its potential payment. energy.

Kilowatt (KW) – Measure of the rate of electricity Median Wind Speed – The wind speed with 50% production. A wind farm’s wind turbine generator’s probability of occurring. size or production capacity is measured in megawatts Megawatt (MW) – Standard measure of electric and represents the rate at which the turbine can power plant generating capacity. One megawatt is produce electricity at a given wind speed. equal to one thousand kilowatts or 1 million watts. Kilowatt-Hour (kWh) – Measure of the amount of Megawatt-hour (MWh) – Is 1,000 kilowatt-hours or electricity produced over time. A wind farm’s wind 1 million watt hours. turbine generator that is rate at 1 MW (1.000 kw), operating for 1 year (8,760 hrs.), with a net Merchant Power Plant – Merchant power plants generating capacity of 40%, produces 3,504 differ from traditional rate-based power plants as to: megawatt hours (MWhrs) per year. (1 MW x 8.760 1.) how they are financed and 2.) where they sell the hours x 0.40 = 3,504 MWhrs). The average U.S. home electricity they generate. A merchant power plant is electric bill is expressed in KwH to reflect the amount funded by investors and sells electricity in the of electricity consumed during the previous month. competitive wholesale power market. Since a merchant plant is not required to serve any specific Leading Edge – Surface part of a wind turbine blade retail consumers, consumers are not obligated to pay on a wind farm that first comes into contact with the for the construction, operators or maintenance of the wind. plant. Levelized Costs of Energy (LCOE) – Levelized cost of electricity (LCOE) provides a common way to Met Tower – Is a metal structure that extends 60 Natural Gas – Hydrocarbon gas obtained from meters above ground and have booms that extend in underground sources, often in association with various directions and heights. The booms have and coat deposits. Natural gas is used as a anemometers located approximately 10 feet away heating fuel and for electricity generation and is from the tower that measure and verify the wind generally thought of as the most direct competition to resource found within a certain area of land. Met wind generated electricity. Both natural gas and towers commonly host a group of instruments, wind energy are considered intermittent and not base including anemometers and wind vanes that measure load generation sources. wind speed, direction and temperature at various heights above the ground. Negative Power Prices – Wind energy generators face very small costs of shutting down and starting Midwest Independent Transmission System back up, but they do face another cost when shutting Operator, Inc. (Midwest ISO or MISO) – down; loss of the Production Tax Credit and state Independent System Operator (ISO) and the Regional Renewable Energy Credit revenue which depend Transmission Organization (RTO) that provides open- upon generator output. It is economically rational for access transmission service and monitors the high- wind power producers to operate as long as the voltage transmission system throughout the Midwest subsidy exceeds their operating costs plus the U.S. and Manitoba, Canada. The Midwest ISO operates negative price they have to pay the market. Even if one of the world’s largest real-time energy markets the market value of the power is zero or negative, the and has 93, 600 miles of transmission lines under its subsidies encourage wind energy power producers to direction. keep churning the megawatts out.

Nacelle – The nacelle sits atop the tower and contains – Term used to describe grid- the gearbox, low and high speed shafts, generator, connected alternative energy generation in which the controller and brake. Some nacelles are large enough local electrical source, including wind turbines or for a helicopter to land on and have the appearance of solar panels, is connected to the electrical meter so a small mobile home or travel trailer at ground level. that excess generated electricity passes to the grid Wind turbine generators contain a rotor, located at can causes the meter to run backwards. the base of the blades that is attached to the nacelle. Non-Renewable Fuels – Fuel sources or feed-stocks National Environmental Policy Act (NEPA) – A U.S. that cannot be easily renewed or reproduced and environmental law that established a U.S. national commonly include oil, natural gas and coal. policy promoting the enhancement of the environment and also established the President’s North American Electric Reliability Corporation Council on Environmental Quality (CEQ). NEPA’s (NERC) – Non-profit corporation formed in 2006 as most significant effect was to set up procedural the successor to the North American Electric requirements for all federal government agencies to Reliability Council. It was established to develop and prepare Environmental Assessments (EAs) and maintain mandatory reliability standards for the bulk Environmental Impact Statements (EISs) and EISs electric system, with the fundamental goal of contain statements of the environmental effect of maintaining and improving the reliability of that proposed federal agency actions. NEPAs procedural system. NERC consists of regional reliability entities requirements apply to all federal agencies executive covering the interconnected power regions of the branch, NEPA does not apply to the President, to contiguous U.S., Canada and Mexico. Congress or to the federal courts. Open Access Same-Time Information System National Renewable Energy Laboratory (NREL) – (OASIS) – An internet-based system for obtaining A U.S. Dept. of Energy research facility funded to services related to electric power transmission in research renewable and alternative energy North America. It is the primary means by which technologies including solar, biomass, hydro, high-voltage transmission lines are nreserved for geothermal and wind energy. moving wholesale quantities of electricity. The OASIS concept was originally conceived with the Energy Policy Act of 1992, and formalized in 1996 through generator. Such agreements play a key role in the Federal Energy Regulatory Commission (FERC) financing of independently owned (i.e. not owned by Orders 888 and 889. a utility) electricity generating assets.

Peak Demand / Load – The maximum energy Prevailing Wind Direction – Direction from which demand or load in a specified time period. Electric the wind predominantly blows as a result of the utilities constantly manage the electric grit to prepare seasons, high and low pressure zones, the tilt of the for peak energy demand/load condition. earth on its axis and the rotation of the earth.

Peak Wind Speed – Maximum instantaneous wind Production Tax Credit – The result of the Energy speed that occurs within a specific period of time. Policy Act of 1992, a commercial tax credit that applies to wholesale electrical generators of wind Pitch – The angle between the edge of the blade and energy facilities based upon the amount of energy the plane of the blade’s rotation. Blades are turned or generated in a year. The renewable energy “pitched” out of the wind to control the rotor speed Production Tax Credit (PTC), a credit of 2.1 ¢ per and keep the rotor from turning in winds that are too kilowatt-hour, is the primary federal incentive for high or too low to produce electricity. wind energy and has been essential to the industry’s growth. Other electricity generation technologies PJM Interconnection, LLC (PJM) – Regional have their own forms of federal support, often Transmission Organization (RTO) which is part of the permanent in tax law so wind power would be Eastern Interconnection grit operating an electric disadvantaged in the absence of a PTC or other transmission system serving all or parts of DE, IL, IN, comparable incentive. Since its establishment in KY MD, MI, NJ, NC, OH, PA, TN, VA, WV and DC. PJM, 1992, the PTC has undergone a series of short-term headquartered in Valley Forge, PA, is currently the extensions and has been allowed to lapse in three world’s largest competitive wholesale electricity different years, 1999, 2001 and 2003. In February market. Over 500 companies are member of PJM, 2009 through the American Recovery and which serves 51 million customers and has 165 Reinvestment Act, Congress acted to provide a three- gigawatts of generating capacity. With 1,271 year extension of the PTC through Dec. 31 2012. generation sources, 56,000 miles of transmission Additionally, wind project developers can choose to lines and 6038 transmission substations. PJM covers receive a 30% investment Tax Credit (ITC) in place of 13 states, delivery 700 terawatt-hours of electricity the PTC for facilities placed in service in 2009 and every year. 2010, and also for facilities placed in service before Power – Energy that is capable or available for doing 2013 if construction begins before the end of 2010. work such as wind energy and alternative energy. The ITC then qualifies to be converted to a grant from the Department of Treasury. The Treasury Dept. Power Grid – Common term referring to an must pay the grant within 60 days of an application electricity transmission and distribution system; also being submitted. This policy is designed to help the known as a “utility grid”. wind energy industry continue to finance projects during these challenging economic times. Power Marketers – Companies that buy and sell electricity, but usually do not own or operate Public Utility Regulatory Policies Act of 1978 generation, transmission or distribution facilities, (PURPA) – Opened up competition in the generation independent power producers often utilized the market with the creation of qualifying facilities. services of power marketers to move power from the Later, the Energy Policy Act of 1992 (EPACT) point of generation to the purchaser of power. removed some constraints on ownership of electric generation facilities and encouraged increased Power Purchase Agreement (PPA) – Legal contract competition in the wholesale electric power business. between an electricity generator (provider) and a power purchaser (host). The power purchaser Qualifying Facilities – PURPA facilitated the purchases energy, and sometimes also capacity emergence of a group of non-utility electricity- and/or ancillary services from the electricity generating companies called qualifying facilities or QFs. Under PURPA, small power producers receive the electromotive force needed for a unit current status as a QF by meeting certain requirements for flow. The unit of resistance is ohms. ownership, operating methods and efficiency. Those requirements were established by the Federal Energy Restructuring (Electric Utility Restructuring) – Regulatory Commission (FERC). Introducing competition into the generation phase of electricity production, with a corresponding decrease Rated Wind Speed – Wind speed at which the in regulatory control. turbine is producing power at its rated capacity. The rated wind speed generally corresponds to the point Rotor – The part of a wind turbine generator where at which the turbine can perform most efficiently. blade and the hub come together. Because of the variability of the wind, the amount of Rotor Hub – Is the center of a turbine rotor that energy a wind turbine actually produces is lower than holds the blades in place and attaches to the shaft. its rated capacity over a period of time. The rotor refers to both the turbine blades and the Regional Transmission Organization (RTO) – An hub. organization that is responsible for moving electricity Shadow Flicker – Shadow flicker is the term used to over large interstate areas. Like a transmission describe what happens when rotating turbine blades system operator (TSO), an RTO coordinates controls come between the viewer and the sun causing a and monitors an electricity transmission grid that is moving shadow. Shadow flicker is almost never a larger with much higher voltages than the typical problem for residences near new wind farms, and in power company’s distribution grid. TSOs in Europe the few cases where it could be, it is easily avoided. cross state and provincial borders like RTOs. For some who have homes close to wind turbines, Renewable Energy – Energy that is derived from shadow flicker can occur under certain circumstances resources that are regenerative or that cannot be and can be disruptive when trying to read or watch depleted including wind energy, , television. However, the effect can be precisely biomass, geothermal and moving water; also known calculated to determine whether a flickering shadow as “alternative energy”. will fall on a given location near a wind farm and how many hours in a year it will do so. Potential problems Renewable Energy Credits (RECs) – A REC can be easily identified using these methods and represents the property rights to the environmental, solutions range from providing an appropriate social and other non-power qualities of renewable setback from the turbines to planting trees to disrupt electricity generation. A REC can be sold separately the effect. Normally, shadow flicker should not be a from the electricity associated with a renewable problem in the U.S. because at U.S. latitudes (except energy generation source. AK) the suns’ angle is not very low in the sky. If any effect is experienced, it is generally short-lived as in a Renewable Energy Standard – The Renewable few hours over a year’s time. Electricity Standard (RES), also known as a Renewable Portfolio Standard (RPS), uses the free Shaft – The rotating part in the center of a wind market to ensure that an increasing percentage of turbine or motor that transfers power. A high-speed alternative energy and electricity are produced from shaft drives the generator. A low-speed shaft is renewable sources like wind energy. The RES turned by a rotor at about 30 – 50 rpm. provides a predictable, competitive market, within which renewable energy generators compete with Southwest Power Pool (SPP) – Eleven regional each other to lower prices. RES policies currently utilities that entered into an Inter-Company exist in 28 U.S. states but not at the national level. Agreement on Dec. 14, 1941. The eleven companies were Arkansas Power & Light (a subsidiary of Resistance (R) – The property of a conductor, which Entergy), Louisiana Power & Light (a subsidiary of opposed the flow of an electric current resulting in Entergy) Mississippi Power & Light, Southwestern the generation of heat in the conducting material. Gas & Electric, Public Service Co of OK, Nebraska The measure of the resistance of a given conductor is Power, Texas Power & Light, Southern Light & Power, Oklahoma Gas & Electric, Kansas Gas & Electric and Unbundling – Process of separating a service into Empire District Electric. component parts (generation, transmission, distribution, ancillary services etc.) to allow Step-up Gearbox – Increases wind turbine electricity customers to choose where to buy each service production in stages by increasing the number of separately. Utility unbundling, overseen by generator revolutions produced by the rotor regulators, generally requires utilities to ensure that revolutions. the price of each service accurately reflects the cost of that service (plus a margin for profit). Substation – Facility that steps up or steps down the voltage in utility power lines. Voltage is stepped up Variable-Speed Wind Turbines – Wind turbine where power is sent through long-distance generators in which the rotor speed increases and transmission lines. It is stepped down where the decreases with changing wind speeds. Complex power is to enter local distribution lines. power control systems are required on variable speed turbines to insure that their power maintains a Tower – The base, physical structure in wind farms constant frequency compatible with the grid. that supports and elevates a wind turbine rotor and nacelle and is most often a steel cylinder with an Volt (V) – A unit of electrical force equal to that internal ladder which provides access for amount of electromotive force that will cause a steady maintenance and repairs. As wind speed increases current of one ampere to flow through a resistance of with heights, taller towers enable turbines to capture one ohm. more wind energy and generate more electricity. Watt – Rate of energy transfer equivalent to one – Wind farms often include an ampere under an electrical pressure of one volt. On electromagnetic device that changes the voltage of watt equals 1/746 horsepower, or one joule per alternating current electricity. A transformer is the second. It is the product of voltage and current electrical equipment that allows for a wind farm to (amperage). interconnect to electric lines. They consist of multiple individual coils of wire wound on a laminate core. Watt-hour (Wh) – Unit of electricity consumption of power from one circuit to another one watt over the period of one hour. using magnetic induction, usually to step voltage up or down. Works only with AC. Wind – Moving air; the wind’s movement is caused by the sun’s heat, the earth and the oceans, forcing air Transmission Utility – Is the regulated to rise and fall in cycles. owner/operator of only a transmission system as opposed to a generation and transmission system. Wind Class – System designed to rate the quality of the wind resource in an area, based on the average Tres Amigas Project – Focuses on uniting North annual wind speed. The scale ranges from 1 – 7 with America’s two major power grids (the Eastern 1 being the poorest wind energy resources and 7 Interconnection and the Western Interconnection) representing exceptional wind energy resources. and one minor grid (The Texas Interconnection) to enable faster adoption of renewable energy and Wind Energy – Power generated by converting the alternative energy (like wind energy) and increase mechanical energy of the wind into the reliability of the U.S. grid. through the use of wind generator.

Turbine – Term used for wind energy conversion Wind Farm – Term used in reference to the land, device that produces electricity; may also be called a wind turbine generators, electrical equipment and “wind turbine”. transmission lines for the purpose of generating wind energy and alternative energy. Turbulence – Swirling motion of the atmosphere that interrupts the flow of wind. Wind turbulence has Wind Power – Power generated by converting the a direct impact on the sting of a wind farm and the mechanical wind energy into electrical energy layout of turbines across the project footprint. through the use of a wind generator. Wind Powering America (WPA) – A U.S. in some hilly terrain where residences are located in Department of Energy initiative designed to promote sheltered dips or hollows downwind from turbines, the use of wind energy across the country with the turbine sounds may carry further and be more goal of quadrupling U.S. wind energy capacity by audible. This effect can generally be anticipated and 2010. avoided in the development process through adequate setbacks from homes. Wind Resource Assessment – Process of characterizing the wind resource and its wind energy Wind Turbine Rated Capacity – Amount of wind potential for a specific site or geographical area. energy a wind turbine can produce at tis rated wind speed. Wind Rose – Diagram that indicates the average percentage of time that the wind blows from different Wind Vane – Measures wind direction and directions, on a monthly or annual basis. communicates with the yaw drive to orient the turbine properly with respect to the wind. Wind Speed – Rate of flow of wind when it blows undisturbed by obstacles. Wind Velocity – Wind speed and direction in an undisturbed flow. Wind Speed Frequency Curve – Cure that indicates the number of hours per year that specific wind Windmill – Wind energy conversion system that is speeds occur. used to grind grain. However, the word windmill is commonly used to refer to all types of wind energy Wind Speed Profile – Profile of how the wind speed conversion systems. changes at different heights above the surface of the ground or water. Windpower Profile – Change in the power available in the wind due to changes in the wind speed or Wind Turbine Generator – A machine that captures velocity. the force of the wind; described as the installed wind turbine including the tower, nacelle, rotor, hub, Yaw – Means to rotate around a vertical axis, such as blades, foundation and related components designed a turbine tower. The yaw drive is used to keep a to convert wind energy into electricity. Most turbine rotor facing into the wind as the wind commercial wind generators are horizontal axis wind direction changes. turbines. If wind energy is used directly by machinery, such as for pumping water, cutting Yaw Drive – Upwind turbines on a wind farm that lumber or grinding stones, the machine is called a face into the wind, the yaw drive is used to keep the windmill. rotor facing into the wind as the wind direction changes. Downwind turbines don’t require a yaw Wind Turbine Noise – An operating modern wind drive; the wind blows the rotor downward. farm at a distance of 750 to 1000 feet is no noisier than a kitchen refrigerator or a moderately quiet Yaw Motor – Powers the yaw drive. room. The sound turbines produce is similar to a light whooshing or swishing sound, and is quieter than other types of modern-day equipment; even in rural or low-density areas, where there is little additional sound to make that of the wind turbines, the sound of the blowing wind if often louder. Exceptions to quiet operating turbines can occur in two instances; with older turbines from the 1980s and with contemporary turbines in some types of hilly terrain. Modern wind turbines have been designed to drastically reduce the noise of mechanical components so the most audible noise is the sound of the wind interacting with the rotor blade. However,