Energy

Wind Energy
Wind Resource and Potential U.S. Wind Resources, Onshore and Offshore2
(80 meter height)
Approximately 2% of the solar energy striking the Earth’s surface is converted
into kinetic energy in wind. Wind turbines convert the wind’s kinetic energy to
electricity without emissions.1 The distribution of wind energy is heterogeneous,
both across the surface of the Earth and vertically through the atmosphere.
Average annual wind speeds of 6.5m/s or greater at 80m are generally considered
commercially viable. New technologies, however, are expanding the wind
resources available for commercial projects.3 In 2020, 8.4% of U.S. electricity was
generated from wind energy, but wind capacity is increasing rapidly.4
• High wind speeds yield more power because wind power is proportional to
the cube of wind speed.5
• Wind speeds are slower close to the Earth’s surface and faster at higher
altitudes. The average hub height of modern wind turbines is 90 meters.6
• Global onshore and offshore wind power potential at commercial turbine
hub heights could provide 840,000 TWh of electricity annually.7 Total global
electricity consumption from all sources in 2018 was about 23,398 TWh.8
• Similarly, the annual continental U.S. wind potential of 68,000 TWh greatly
exceeds annual U.S. electricity consumption of 3,802 TWh.4,7
• A 2015 study by the U.S. Department of Energy found wind could provide 20% of U.S. electricity by 2030 and 35% by 2050.9

Wind Technology and Impact

Horizontal Axis Wind Turbines
Horizontal Axis Wind Turbine Diagram10,15
• Horizontal axis wind turbines (HAWT) are the predominant turbine design in use today.
Low-speed High-speed
• The HAWT rotor comprises blades (usually three) symmetrically mounted to a hub. shaft shaft
The rotor is connected via a shaft to a gearbox and generator. The nacelle houses these Gearbox Generator
components atop a tower that sits on a concrete foundation.10 Hub Brake Nacelle
• HAWT come in a variety of sizes, ranging from 2.5 meters in diameter and 1 kW for
residential applications to 100+ meters in diameter and 10+ MW for offshore applications.
• The theoretical maximum efficiency of a turbine is ~59%, also known as the Betz Limit.
Most turbines extract ~50% of the energy from the wind that passes through the rotor area.9
• The capacity factor of a wind turbine is its average power output divided by its maximum
power capability.9 On land, capacity factors range from 0.26 to 0.52.11 The average 2019
capacity factor for projects built between 2014 and 2018 was 41%. In the U.S., the fleetwide
average capacity factor was 35%.6 Blades Tower
• Offshore winds are generally stronger than on land, and capacity factors are higher on
average (expected to reach 51% by 2022 for new projects), but offshore wind farms are more
expensive to build and maintain.11,12,13 Offshore turbines are currently placed in depths U.S. Wind Capacity16
up to 40-50m (about 131-164ft), but floating offshore wind technologies could greatly 130,000
expand generation potential as 58% of the total technical wind resource in the U.S.
U.S. Installed Wind Capacity (MW)

120,000
110,000
lies in depths greater than 60m.12,14 100,000 Cumulative Capacity
Installation, Manufacturing, and Cost 90,000
Annual Additions
80,000
• More than 60,000 utility-scale wind turbines are installed in the U.S., with a 70,000
cumulative capacity of 122.5 GW. U.S. wind capacity increased by 203.5% between 60,000
50,000
2010 and 2020, a 12% average annual increase.16 Global wind capacity increased by 40,000
14% annually, on average, from 2010 to 2020, reaching 743 GW in 2020.17 30,000
• U.S. average turbine size was 2.55 MW in 2019, up 5% from 2.43 MW in 2018.6 20,000
10,000
• Average capacity factor has increased from 25% for projects installed from 1998 to 0
2001 to 41% for projects built between 2014 and 2018.6
2003
2004
2005
2006
2007
2008
2009
2010
2011
2012
2013
2014
2015
2016
2017
2018
2019
2020

• On a capacity-weighted average basis, wind project costs declined by roughly $3,120/

kW between the early 1980’s and 2019. In 2019, costs were $1,436/kW.6
• The average installed cost of a small (<100 kW) turbine was approximately $8,300 per kW in 2019.18
• In 2017-19, new wind energy purchase contracts averaged 1.8¢/kWh, while the average residential electricity price was 13.2¢/kWh in 2020.4,6
• Texas (33,133 MW), Iowa (11,660 MW), and Oklahoma (9,048 MW) are the leading states in total installed wind capacity.16 Iowa generated
over 57% of its electricity from wind and had the second highest annual electricity generation from wind of any U.S. state in 2020.19

For Complete Set of Factsheets visit css.umich.edu

• In 2019, there were over 120,000 full-time workers in the U.S. wind industry and Global Wind Capacity, 202017
turbines and components were manufactured at over 500 facilities.20 350
• Large (>20 MW) wind projects require ~85 acres of land area per MW of installed

288.3
capacity, but 1% or less of this total area is occupied by roads, turbine foundations, or 300
Total Capacity (GW)
other equipment; the remainder is available for other uses.9

Installed Wind Capacity (GW)

250 2020 Capacity Added (GW)
• For farmers, annual lease payments provide a stable income of around $3,000/MW
of turbine capacity, depending on the number of turbines on the property, the value 200

157.4
of the energy generated, and lease terms.9

122.3
150
Energy Performance and Environmental Impacts
• Wind turbines can reduce the impacts associated with conventional electricity 100

62.9
generation. The 2019 U.S. wind capacity avoided an estimated 198 million metric

38.6
50

23.9

17.9

17.8

13.6
tons of CO₂ emissions.20
• According to a 2015 study, if 35% of U.S. electricity was wind-generated by 2050, 0

electric sector GHG emissions would be reduced by 23%, eliminating 510 billion kg
of CO₂ emissions annually, or 12.3 trillion kg cumulatively from 2013, and decreasing Top Wind-Producing Countries
water use by 15%.9
• A 2013 study found energy return on investment (EROI) (energy delivered/energy invested) for wind power of between 18-20:1.21
• Annual avian mortality from collisions with turbines is 0.2 million, compared with 130 million mortalities due to power lines and 300-1,000
million from buildings. The best way to minimize mortality is careful siting.9 Bat mortality due to wind turbines is less well studied. Research
shows that a large percentage of bat collisions occur in migratory species during summer and fall months when they are most active.9,22 The
wind industry has been testing methods that potentially reduce bat mortality by more than 50%.9
• Noise 350m from a typical wind farm is 35-45 dB. For comparison, a quiet bedroom is 35 dB and a 40 mph car 100m away is 55 dB.23
• As of 2013, several studies have conclusively determined that sound generated by wind turbines has no impact on human health.9
• Turbine foundations and transmission cables alter benthic habitats, but foundations can create pelagic habitats. Appropriate siting of offshore
wind farms is the most effective way to avoid conflicts.24
Solutions and Sustainable Actions
Policies Promoting Renewables
Policies that support wind and other renewables can address externalities associated with conventional electricity, such as health effects from
pollution, environmental damage from resource extraction, and long-term nuclear waste storage.
• Renewable Portfolio Standards (RPS) require electricity providers to obtain a minimum fraction of energy from renewable resources.25
• Feed-in tariffs set a minimum price per kWh paid to renewable electricity generators by retail electricity distributors.25
• Net metering — offered in 40 states, D.C., and four U.S. territories — allows customers to sell excess electricity back to the grid.26
• Capacity rebates are one-time, up-front payments for building renewable energy projects, based on the capacity (in watts) installed.
• The federal production tax credit (PTC) provides a 1-2¢/kWh benefit for the first ten years of a wind energy facility’s operation for projects
started by December 31, 2021.27 Small (<100 kW) installations can receive tax credits for between 22-26% of the capital and installation cost
based on the construction start date.28
• Section 9006 of the Farm Bill is the Rural Energy for America Program (REAP) that funds grants and loan guarantees for agricultural
producers and rural small businesses to purchase and install renewable energy systems.29
• System benefits charges are paid by all utility customers to create a fund for low-income support, renewables, efficiency, and R&D projects
that are unlikely to be provided by a competitive market.30
• The first U.S. commercial offshore wind farm began delivering electricity in 2016. In 2020, a second offshore wind farm completed
installation. As of June 2021, 9 states have offshore wind projects seeking leasing status.31
What You Can Do
• Make your lifestyle more efficient to reduce the amount of energy you use.
• Invest in non-fossil electricity generation infrastructure by purchasing “green power” from your utility.
• Buy Renewable Energy Certificates (RECs). RECs are sold by renewable energy producers for a few cents per kilowatt hour, customers can
purchase RECs to “offset” their electricity usage and help renewable energy become more competitive.25
• Consider installing your own wind system, especially if you live in a state that provides financial incentives or has net metering.

1. Gustavson, M. (1979) “Limits to Wind Power Utilization.” Science, 204(4388): 13-17. 17. Global Wind Energy Council (GWEC) (2021) Global Wind Report 2021.
2. U.S. Department of Energy (DOE), National Renewable Energy Lab (NREL) (2017) U.S. Wind 18. U.S. DOE, Pacific Northwest National Lab (PNNL) (2020) 2019 Distributed Wind Data Summary.
Resource Map. 19. U.S. EIA (2021) Electric Power Monthly February 2021.
3. U.S. DOE, Energy Efficiency and Renewable Energy (EERE) (2020) “U.S. Average Annual Wind 20. ACP (2021) “Wind Power Facts.”
Speed at 80 Meters.” 21. Hall, C., et al. (2013) EROI of different fuels and the implications for society. Energy Policy (64),
4. U.S. Energy Information Administration (EIA) (2021) Monthly Energy Review April 2021. 141-152.
5. Massachusetts Institute of Technology (2010) Wind Power Fundamentals. 22. U.S. Geological Survey, Fort Collins Science Center (2016) “Bat Fatalities at Wind Turbines:
6. U.S. DOE, Lawrence Berkely National Lab (LBNL) (2020) 2020 Wind Technologies Market Report. Investigating the Causes and Consequences.”
7. Lu, X., et al. (2009) “Global potential for wind-generated electricity.” Proceedings of National 23. U.S. DOE, EERE (2008) 20% Wind Energy by 2030: Increasing Wind Energy’s Contribution to U.S.
Academy of Sciences, 106(27). Electricity Supply.
8. U.S. EIA (2021) International Energy Statistics: Total Electricity Net Consumption. 24. European Comission (2020) Guidance Document on Wind Energy Developments and EU Nature
9. U.S. DOE (2015) Wind Vision Report. Legislation.
10. U.S. DOE, EERE (2021) “The Inside of a Wind Turbine.” 25. U.S. EPA (2021) “State Renewable Energy Resources.”
11. U.S. DOE, NREL (2015) “Transparent Cost Database: Capacity Factor” Open Energy Information. 26. DSIRE (2020) Net Metering Policies.
12. International Renewable Energy Agency (2018) Offshore Innovation Widens Renewable Energy 27. U.S. DOE, EERE (2021) Production Tax Credit and Investment Tax Credit For Wind.
Options. 28. U.S. DOE, EERE (2021) Advancing the Growth of the U.S. Wind Industry: Federal Incentives,
13. NREL (2020) 2018 Cost of Wind Energy Review. Funding, and Partnership Opportunities.
14. U.S. DOE, NREL (2016) 2016 Offshore Wind Energy Resource Assessment for the United States. 29. DSIRE (2018) “USDA - Rural Energy for America Program (REAP) Grants.”
15. California Energy Commission (2012) “Energy Quest: Wind Energy.” 30. DSIRE (2016) “Glossary.”
16. American Clean Power (ACP) (2021) ACP Market Report Fourth Quarter 2020. 31. U.S. Bureau of Ocean Energy Management (2021) State Activities

Cite as: Center for Sustainable Systems, University of Michigan. 2021. “Wind Energy Factsheet.” Pub. No. CSS07-09. September 2021