New Wind Maps and Resource Potential Estimates for the United States

1. New Wind Maps and Resource Potential Estimates for the United States Michigan Wind Working Group Webinar Dennis Elliott, Marc Schwartz, Donna Heimiller, Steve Haymes – NREL Michael Brower – AWS Truewind, LLC March 31, 2010

2. Presentation Outline • Overview • History of wind maps and resource potential estimates • AWS Truewind methodology and involvement with NREL • NREL’s validation of AWS Truewind model data • Development of wind potential estimates – data and methods • Wind potential - key findings • Comparison to previous studies • Conclusions

3. Overview • Significance of this project: • New wind energy potential estimates for contiguous United States and each state at 80-m and 100-m heights • First comprehensive update of the U.S. wind potential in almost two decades • Based on very high-resolution (200-m resolution) wind resource data • Capacity factor (representative of power output from large wind turbines), instead of power classes (theoretical energy in the wind), to develop wind potential estimates • Excluded areas unlikely to be developed • Major products developed for contiguous U.S. and each state: • Mean wind speed maps at 80-m height • Charts of wind potential at 80-m and 100-m heights in MW of installed capacity as a function of capacity factor (not adjusted for losses) • Tables of windy land area and wind potential at 80-m and 100-m heights for various capacity factor ranges. Wind potential in MW (or GW) of installed capacity and annual generation in GWh. • Available on web link: http://www.windpoweringamerica.gov/wind_maps.asp • Development of products: • Collaborative project between NREL and AWS Truewind • Supported by U.S. Department of Energy’s Wind Powering America program

4. Wind Resource Map – United States

5. Wind Resource Potential - United States Capacity factor (CF) example: 1 MW turbine at 30% CF = 300 kW per year of output

6. Michigan – Wind Resource Map and Potential

7. History of U.S. Wind Maps and Potential Estimates • 1979-1987: First comprehensive U.S. wind resource assessment, culminating in the U.S. Wind Resource Atlas • Wind power class maps at 50-m height (about 25-km spatial resolution) • Based largely on weather station data and limited tower data • 1990-1993: First detailed analysisof U.S. wind potential, resulting in national and state wind potential estimates • Estimates of land area and wind potential by power class at 50m • Based on wind power class maps from 1987 U.S. Wind Atlas and landform classification maps • Excluded sensitive environmental lands and incompatible land-use areas • 2001-2008:High resolution (1-km or finer) wind power maps at 50m for 39 states and updated wind potential for selected states • Numerical modeling by AWS Truewind and validation by NREL and consultants • WPA program with co-funding by states and other organizations • 2009-2010:Wind speed maps and potential estimates at 80-m and 100-m heights for contiguous U.S. and each state • Collaborative project between NREL and AWS Truewind • Estimates of land area and wind potential by capacity factor ranges

8. Michigan Wind Map Changes Over Time 1987 & 2004 Wind Power Maps at 50 m 2010 Wind Speed Map at 80 m

9. Michigan Offshore Wind Resource Map at 90 m • Highest speeds close to shore are located: • In Lake Michigan along west shoreline of state • In Lake Superior near Keweenaw Peninsula • Shallow water areas with good wind resource are located: • In Saginaw Bay • In Lake Huron east of the Thumb

10. AWS Truewind Presentation

11. Model Validation- Method • NREL’s validation of model 80 m wind speed • Purpose was to identify gross disagreements between model 80 m wind speed and measured data • Model wind speeds provided to NREL by AWS Truewind • Capacity factor estimates not included in this analysis • Validation limited to 19 key WPA states • 6 Western (OR, WA, ID, NV, UT, AZ) • 6 Midwestern (MO, IL,WI, IN, MI, OH) • 7 Eastern/Appalachian (NY, NJ, PA, MD, WV, KY, TN) • Average wind speed from towers were compared to model wind speed values • Time series of wind speed data from the towers were not analyzed

12. Model Validation- Tower Information • Tower information from over 1600 sites was provided to NREL • Approximate location, highest measurement level, wind speeds at highest level and at 80 m, shear exponent, and period-of-record • NREL defined the subset of 304 towers in the 19 states used in the analysis • Almost all towers were from proprietary sources • Data from towers 45 m and higher were analyzed • About 20 towers had measurement levels greater than 60 m • About 80 towers had easily identifiable periods-of-record of 2 years and longer

13. Variations of Wind Speed vs Height

14. Model Validation- National Results • No gross differences were found between measured and model 80 m data that would preclude these data from being used for wind potential estimates • Regions where additional measurements are crucial • Ridge crest sites in northeastern U.S. • Interior sites in western U.S. • National network of measurements at turbine hub- heights is needed in order to estimate wind potential with even greater accuracy

15. Model Validation- Michigan Results • Tower information from 28 sites in Michigan provided to NREL • All towers were from proprietary sources • Data from towers 45 m and higher were analyzed • One tower had measurements at 80 m • The other 27 towers were 45 m to 60 m in height • Four towers had easily identifiable periods-of-record of 2 years and longer • Comparison of model and measurement wind speeds: • Model lower than measurements at towers near Saginaw Bay and western side of “Thumb” • Model higher than measurements in other regions of state • Model validation uncertainty • Many towers were on open farmland but near heavily treed areas • Not clear whether positive bias is due to model overestimation of wind speed or underestimation of wind shear • No modifications to model wind speeds for Michigan were made

16. Development of Wind Potential Estimates • AWS Truewind produced a national dataset of estimated gross capacity factor (not adjusted for losses) • Spatial resolution of 200 m • Heights of 80 m and 100 m • Land-based areas only (no offshore), 48 contiguous states • NREL used the gross capacity factor (CF) data to estimate the land area and wind potential as a function of CF for each state and U.S. • Windy land defined as areas with >= 30% CF, which are generally considered to be suitable for wind energy development • Areas with CF >=30% have mean annual wind speeds of about 6.4 m/s and greater • Excluded sensitive environmental lands and incompatible land-use areas (details to follow) • For wind potential, assumed 5 MW/km2of installed nameplate capacity • Wind potential expressed in two ways • Installed capacity in MW • Annual generation in GWh

17. Wind Potential Exclusion Methodology • NREL has developed a set of national exclusions based on consultation with industry and internal expertise • Utilize data available nationally and apply consistently across the U.S. • Eliminates potentially sensitive environmental lands • National Park Service administrated areas • Fish and Wildlife administrated areas • Other categories such as inventoried roadless areas, wilderness areas, national recreation areas. • Eliminate incompatible land use areas for land based development • Urban areas and airports • Water and wetland features • Consideration of alternate use or difficulty in development – 50% exclusions • USFS and Department of Defense lands • Non-ridgecrest forest lands

18. National Exclusion Map

19. Michigan Areas Excluded from Developable Wind Potential • 1) Potentially sensitive environmental lands: • - National Park Service and Fish and Wildlife Service • - Wildlife, wilderness, recreation areas, and other specially designated areas on federal land • - State and private environmental lands where data was available • - Half of the remaining U.S. Forest Service and Department of Defense lands • 2) Potentially incompatible land use: • - Urban areas, airports, wetlands and water bodies • - Half of non-ridge crest forested areas • 3) Other factors: • - Slopes greater than 20% • - A 3 kilometer area surrounding environmental and land use excluded areas (except water bodies) Excluded 40% of the windy land >= 30% gross capacity factor at 80 m Excluded 44% of the windy land >= 35% gross capacity factor at 80 m

20. Results of Exclusions – Example • Results represent the application of nationalized, relatively conservative exclusion scenario using national scale data • Total windy land reported to represent full state potential • Additional analysis could be done to present results by type of exclusion, or utilizing state-specific exclusion scenarios

21. Wind Potential – Key Findings • U.S. wind potential from areas with CF>=30% is enormous: • At 80 m, almost 10,500 GW capacity and 37 million GWh of annual generation • At 100 m, 12,000 GW capacity and nearly 45 million GWh of annual generation • Most of the wind potential comes from the windy central regions, but many eastern and western states have significant wind potential. • 35 states more than 1000 MW capacity at 80 m • 38 states more than 1000 MW capacity at 100 m • Even for higher CF ranges at 80 m, the U.S. wind potential is quite large: • CF>=35%, more than 8000 GW and 28 states >1000 MW • CF>=40%, more than 5500 GW and 19 states >1000 MW

22. Michigan – Wind Map and Potential • Michigan wind potential from areas with CF>=30% is substantial: • At 80 m, 59,000 MW capacity and 169,000 GWhof annual generation • At 100 m, 179,000 MW capacity and 523,000 GWhof annual generation • Even for higher CF ranges at 80 m, the Michigan wind potential is quite large: • CF>=35%, about 11,600 MW • CF>=40%, almost 400 MW

23. Arizona – Wind Map and Potential

24. North Dakota Wind Map and Potential

25. Comparison to Previous Studies • Previous national wind potential estimates in early 1990s versus new estimates in 2010 • New estimates for CF>=30% at 80 m height and old estimates for >=Class 3 at 50 m • New estimate (37 million GWh/yr) more than 3 times old estimate (11 million GWh/yr). For Michigan, new estimate is 2.6 times old estimate. • New windy land area estimate about twice the old estimate. For Michigan, new estimate is 1.7 times old estimate. • Previous estimates based on: • Wind power class maps at 50 m and 25-km spatial resolution from 1987 U.S. Wind Atlas • Old wind turbine technology, assumed 25% efficiency and 25% losses • Fairly restrictive land-use exclusions, e.g. excluded 30% agricultural lands • New estimates based on: • Capacity factor map data at 80 m and 100 m and 200-m spatial resolution from advanced numerical computing and more 1600 measurement sites • New wind turbine technology, using composite power curves from large utility-scale wind turbines to estimate capacity factor • Detailed GIS data sets for environmental and land-use exclusions. Exclusions updated by input from national experts, e.g., no agricultural exclusions. • Wind resource classification different between old and new studies • Power classes represent theoretical energy in the wind • Capacity factor represents power output from large wind turbines • Wind resource greater at 80 m than at 50 m due increase of wind resource with height

26. Capacity Factor vs Wind Speed and Power Mean Wind Speed (WS) and Wind Power Density (WPD) as functions of Capacity Factor and Weibull k Weibull k

27. Variation of Wind Power Class and Capacity Factor Mean wind speed = 7.0 m/s but different Weibull k • California wind corridor • Weibull k = 1.5, Power Class = 5, Capacity Factor = 35% • Eastern U.S. • Weibull k = 2, Power Class = 4, Capacity Factor = 36% • Midwest U.S. • Weibull k = 2.5, Power Class = 3, Capacity Factor = 36% • Specific areas • Weibull k = 3, Power Class = 2, Capacity Factor = 35% Note: Capacity factors are rounded to the nearest whole percent

28. Conclusions • NREL has developed, through a joint project with AWS Truewind LLC, updated wind potential estimates for each of the 48 contiguous states and an updated national total • The potential estimates are based on Capacity Factor categories at 80 m and 100 m above ground • The results show that the contiguous United States has enormous wind potential: For areas with CF>=30% • At 80 m, almost 10,500 GW capacity and 37 million GWh of annual generation • At 100 m, 12,000 GW capacity and nearly 45 million GWh of annual generation • 35 states more than 1000 MW capacity at 80 m • 38 states more than 1000 MW capacity at 100 m • Michigan wind potential from areas with CF>=30% is substantial: • At 80 m, 59,000 MW capacity and 169,000 GWh of annual generation • At 100 m, 179,000 MW capacity and 523,000 GWh of annual generation • Michigan wind potential is quite large even for higher CF ranges at 80 m: • CF>=35%, about 11,600 MW • CF>=40%, almost 400 MW