Wind Energy History

Today, wind energy is one of the fastest-growing forms of electricity generation. Yet this seemingly new energy source is actually thousands of years old. As long ago as the first century A.D., windmills milled corn and irrigated crops in Persia. In the 12th century, windmills spread throughout Asia and Europe, becoming ubiquitous in Holland.

Over the centuries, wind energy moved ships, pumped water and ground grain. By the 1800s, windmills were in heavy use in Australia and the United States. In fact, by 1850, American Midwest settlers’ use of windmills totaled 1.4 billion horsepower-hours-of-work, mostly for pumping water and turning sawmills. By the 1930s, more than 5 million American windmills were operating, many of which were connected to electric generators to power household lighting and radios.

This growing U.S. reliance on wind energy slowed with the enactment of the Rural Electrification Act in 1936. One of the most significant parts of President Franklin D. Roosevelt’s New Deal, the act enabled many rural Americans to bring electricity to their homes and farms for the first time; before the enactment, electricity powered just 10 percent of American farms. By 1950, rural cooperatives’ power lines had brought electricity to 90 percent of farms. As an effect, the last major wind generators closed by 1959.

The oil crisis of the 1970s combined with fossil fuels’ increasing impact on the environment compelled leaders to return to wind energy as a promising power source. Today, U.S. wind turbines generate 15,000 megawatts of electricity per day, powering the equivalent of 3.75 million homes. With concentrated efforts, wind energy could provide 20 percent of our nation’s energy needs by 2030.

Wind Energy How-To

Converting wind, or air in motion, into electricity begins with a wind turbine.

A wind turbine, much like a windmill, tops a tower at least 100 feet off the ground, capturing faster, less turbulent wind.

Turbines catch the wind's energy with propeller-like blades, much like airplane wings, mounted on the shaft to form a rotor.

When the wind blows, a pocket of low-pressure air forms on the downwind side of each blade. This low-pressure air pocket then pulls the blade toward it, causing the rotor to turn; this is called lift. Compared to the wind’s force against the front of the blade, called drag, lift is much stronger. The combination of lift and drag spins the rotor like an airplane’s propeller, and the turning shaft spins a generator, converting mechanical energy into electricity.

The generator then sends the wind’s electricity to a power grid, a system of transmission and distribution power lines that transport electricity to towns and cities. However, the generator’s current must transfer its energy at the same frequency at which the grid is operating, called in phase, to prevent power surges. Because the wind’s power rises and falls, each wind turbine features an internal controller that maintains the current’s power quality, which is the stability of frequency and voltage and lack of electrical noise on the power grid.

In addition, a computerized SCADA (supervisory control and data acquisition) system helps regulate energy output, protects the turbine and prevents power surges. SCADA tracks how much electricity each turbine is producing, the temperature inside and outside of each turbine, wind direction, lightning strikes, and service or repair needs. When a problem is detected, SCADA shuts down the turbine and notifies a technician.

Most large wind turbines (larger than 10kW) do not store the energy they create into batteries; rather they send the energy to the electrical grid for all to use.

Resources and Links

• American Wind Energy Association (www.awea.org). Promotes wind power growth through advocacy, communication and education.
• Center for Renewable Energy and Sustainable Technology (www.crest.org). Supports advancement of renewable energy technology through policy research, and seeks to define growth strategies for renewables that respond to competitive energy markets and environmental needs.
• Energy Efficiency and Renewable Energy (www.eere.energy.gov). Works to provide clean, abundant, reliable and affordable energy.
• Minnesota Department of Commerce (www.commerce.state.mn.us). Ensures equitable commercial and financial transactions and reliable utility services.
• National Renewable Energy Laboratory (www.nrel.gov/wind). Offers business and research opportunities and has a strong history of working with industry, academia, government agencies, and a diversity of businesses, including small businesses.
• Online Renewable Energy Education Module (www.crest.org). Discusses solar and wind power, small hydropower systems, and geothermal and biomass energy production; includes overview, theory, application, and case studies.
• Wind Energy Tour (www.windpower.org/en/tour/index.htm). Offered by the Danish Wind Turbine Association.
• Wind on the Wires (www.windonthewires.org). Works to place wind power on a level playing field with other electrical technologies in the Upper Midwest.
• Windustry (www.windustry.org). Works to increase wind energy opportunities for rural landowners and communities by providing technical support and creating tools for analysis.

Wind Energy Facts

• Wind energy is clean. It generates no harmful emissions or pollutants.
• Wind energy is renewable. We’ll never run out of this energy resource.
• Wind energy is safe. Wind energy is generally considered one of the safest energy technologies.
• Wind energy pays for itself. A wind turbine recovers the energy required to create it after a few months of operation.
• Wind energy leaves a small footprint. Turbines usually occupy less than 2 percent of a wind farm’s land.
• Wind energy is popular. Many consumers are willing to spend more for green power.
• Wind power is good for the pocketbook. Wind power generates supplemental income for landowners.
• Wind energy boosts the economy. Wind power plants contribute to the local economy during both construction and operation.
• Wind energy provides jobs. The renewable energy industry is providing a steady flow of new jobs in both urban and rural areas of our country.
• Wind energy is economical. Wind power plant electricity generating costs have dropped by 90 percent in the last 20 years. In addition, wind energy benefits from having no risks associated with environmental regulatory compliance (air and water pollution) nor fossil fuel prices.
• Wind energy is good for local economies. Wind power reduces United States’ reliance on imported fossil fuels, which can cost hundreds of millions of dollars every year.
• Wind energy is growing. One of the world’s fastest-growing forms of electricity generation, U.S. wind power generates more than 15,000 megawatts of electricity every day, powering the equivalent of 3.75 million homes.

Glossary

air pollution: contaminants in air that prevent normal air dispersion and interfere with biological processes
alternative energy: popular term for unconventional energy
asynchronous generator: an electric generator that produces alternating current electricity to match an existing power source
battery: energy storage device made up of one or more
electrolyte cells
breeze: wind classified as light, gentle, moderate, fresh, or strong
carbon dioxide (CO2): a colorless, odorless noncombustible greenhouse gas that contributes to global climate change
carbon monoxide (CO): a colorless, odorless and poisonous combustible gas
central power plant: a large power plant that generates power for distribution to multiple customers
chemical energy: the energy liberated in a chemical reaction, as in the combustion of fuels
circuit: a device, or system of devices, that allows electrical current to flow through and voltage to occur across positive and negative terminals
circuit breaker: a device used to interrupt an electrical circuit, and thereby protect electrical equipment, when an overload exists
climate: a geographic region’s prevailing or average weather conditions
conductor: material through which electricity is transmitted, such as an electrical wire
conduit: a tubular material used to encase and protect electrical conductors
constant-speed wind turbines: wind turbines—operating at a constant RPM—designed for optimal energy capture at a specific rotor diameter and a particular wind speed
conventional fuel: fossil fuels such as coal, oil and natural gas
converter: a device that transforms electricity to a desired quality and quantity
cycle: an alternating current electricity, flowing in one direction from zero to a maximum voltage, then dropping back to zero, then rising to a maximum voltage in opposite direction; number of complete cycles per second (60 cycles in U.S.) determines current frequency
cyclone: air spinning (counterclockwise in Northern Hemisphere, clockwise in Southern Hemisphere) inward toward centers of low air pressure
deregulation: the process of changing regulation policies and laws to increase competition among suppliers of commodities and services
direct current (DC): a type of electricity transmission and distribution, usually low voltage and high current, by which electricity flows in one direction through the conductor
distribution: the process of distributing electricity, usually referring to the portion of power lines between a utility’s power pole and transformer and a customer’s point of connection
doldrums: a virtually windless band near Equator with calms, squalls and light shifting winds
downburst: a severe localized downdraft from a thunderstorm; also known as a microburst
downwind wind turbine: a horizontal axis wind turbine in which the rotor is downwind of tower
electricity: the energy of moving electrons, the current of which is used as a source of power
electricity generation: the process of producing electricity by transforming other forms or sources of energy into electrical energy
electrolyte: nonmetallic conductor that carries current
emission: substance or pollutant emitted as a result of a process
energy: capacity for work that can be converted into different forms
energy storage: process of storing or converting energy from one form to another for later use
environment: all natural and living things, including earth, air, weather, plants, and animals
fossil fuels: fuels—oil, natural gas and coal—formed in the ground from decayed remains of dead plants and animals over millions of years
frequency: number of cycles, measured in hertz, through which an alternating current passes per second
fuel: any material that can be consumed to make energy
gearbox: a protective casing for a system of gears
generator: a device that converts mechanical energy into electrical energy
gigawatt (GW): a unit of power equal to 1 million kilowatts
global warming: term describing increase in average global temperatures due to the greenhouse effect
green credit: the purchase of the renewable attributes of a single megawatt of renewable energy; also known as green tags, renewable energy credits or renewable energy certificates
green power: term describing energy produced from renewable energy resources
greenfield: a site on which a power plant has not previously existed
greenhouse effect: a heating effect resulting from the sun’s long-wave radiation being trapped by greenhouse gases produced by natural and human sources
greenhouse gases: such gases as water vapor, carbon dioxide, methane and low-level ozone—transparent to solar radiation and opaque to long wave radiation—that contribute to the greenhouse effect
grid: an electricity transmission and distribution system; also known as a power grid and a utility grid
gust: a sudden brief increase in wind speed
hertz (Hz): a measurement of the number of cycles or wavelengths of electrical energy per second; the U.S. electricity supply has a standard frequency of 60 hertz
horizontal axis wind turbines: turbines on which the axis of the rotor’s rotation is parallel to the wind stream and the ground
jet stream: a meandering and relatively narrow belt of strong winds, generally found at high altitudes, embedded in normal wind flow
joule (J): a metric unit of energy or work; 1 joule per second equals 1 watt
kilowatt (kW): a standard unit of electrical power equal to 1,000 watts
kilowatt-hour (kWh): a unit of electricity supply or consumption of 1,000 watts over the period of 1 hour
kinetic energy: energy available as a result of motion; equal to one half the mass of the body in motion multiplied by the square of its speed
knot: 1 nautical mile per hour (1.15 MPH) leading edge: the portion of a wind turbine’s blade that first contacts the wind
lift: the force that pulls a wind turbine blade
mean power output: average power output of a wind energy conversion system at any given mean wind speed
mean wind speed: average wind speed over a specified time period and height above the ground
mechanical energy: energy of motion or of potential for motion
median wind speed: the wind speed with 50 percent probability of occurring
megawatt (MW): the standard measure of electric power plant generating capacity; 1 megawatt equals 1,000 kilowatts or 1 million watts
megawatt-hour (MWh): 1,000 kilowatt-hours or 1 million watt-hours
met tower: meteorological towers that verify the wind resource found within a certain area of land
nacelle: the cover for a wind turbine’s gearbox, drive train and generator
natural gas: a hydrocarbon gas—generally containing a high percentage of methane, varying amounts of ethane, and inert gases—obtained from underground sources and used as a heating fuel and for electricity generation
nitrogen oxides NOx): the products of all combustion processes formed by combining nitrogen and oxygen; a primary cause of acid rain
nonrenewable fuels: such fuels as oil, natural gas and coal that cannot be easily renewed or reproduced
oil: a product of crude oil that is used for space heating, diesel engines and electricity generation.
peak wind speed: the maximum instantaneous wind speed that occurs within a specific period of time
power: energy capable of or available for doing work
power grid: an electricity transmission and distribution system; also known as a utility grid
power quality: stability of frequency and voltage and lack of electrical noise on the power grid
prevailing wind direction: direction from which the wind predominantly blows as a result of the seasons, high and low pressure zones, the tilt of the earth’s axis and the earth’s rotation
renewable energy: energy derived from regenerative resources or those that cannot be depleted; includes wind, solar, biomass, geothermal and moving water
rotor: blades and other rotating components of a wind turbine
solar energy: electromagnetic energy transmitted from the sun
solid fuels: any fuel in solid form, including wood, peat, lignite, coal, pulverized coal, coke, charcoal briquettes and pellets
step-up gearbox: a gearbox that boosts turbine electricity production in stages, increasing the number of generator revolutions produced by rotor revolutions
sulfur dioxide (SO2): a colorless gas by-product of combusted fossil fuels containing sulfur; a primary cause of acid rain
sustainable energy: energy that takes into account current energy needs, energy needs to come and a future healthful environment
trade wind: prevailing tropical winds, northeasterly in the Northern Hemisphere and southeasterly in the Southern Hemisphere; also known as the trades
turbine: a wind energy conversion device that produces electricity
turbulence: a swirling atmospheric motion that interrupts wind flow
utility grid: an electricity transmission and distribution system; also known as a power grid
variable-speed wind turbines: turbines, whose rotor speed changes with wind speed, requiring complex power control systems to maintain a constant frequency compatible with the power grid
volt: a unit of electrical force
voltage: the amount of electromotive force, measured in volts, existing between two points
watt (W): the rate of energy transfer calculated by multiplying voltage by current
watt-hour (Wh): a unit of electricity consumption of 1 watt over the period of 1 hour
wind: air rising and falling in cycles caused by the sun's heat, the earth and the oceans
wind energy: electrical energy generated by converting the wind’s mechanical energy with a wind generator; also known as wind power
Wind Energy Conversion System (WECS): a system that includes all of the necessary equipment—rotor, nacelle, generator, tower, electrical components, foundation, transformer, cabling, controller, etc.—to convert wind energy into electricity and delivers it to a substation
wind farm: a piece of land on which wind turbines generate electricity
wind generator: a wind energy conversion system designed to produce electricity
wind power: electrical energy generated by converting the wind’s mechanical energy with a generator; also known as wind energy
wind power plant: a group of wind turbines interconnected to a common utility system
wind resource assessment: the process of characterizing wind and its energy potential for a specific site or geographical area
wind rose: a diagram showing the distribution of wind direction and speed at a location over a month or year
wind speed: rate of wind flow when blowing undisturbed by obstacles
wind speed frequency curve: a curve that indicates the number of hours per year that specific wind speeds occur
wind speed profile: a profile of how the wind speed changes at different heights above the surface of the ground or water
wind turbine: a wind energy conversion device that produces electricity
wind turbine rated capacity: amount of power a wind turbine can produce at its rated wind speed
wind velocity: wind speed and direction in an undisturbed flow
windmill: a wind energy conversion system used to grind grain; may refer to all types of wind energy conversion systems
windpower profile: the change in the power available in the wind due to changes in wind speed or velocity