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
NREL is a national laboratory of the U.S. Department of Energy, Office of Energy Efficiency and Renewable Energy, operated by the Alliance for Sustainable Energy, LLC.
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
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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
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Wind Resource Map – United States
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Wind Resource Potential - United States
Capacity factor (CF) example: 1 MW turbine at 30% CF = 300 kW per year of output
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Michigan – Wind Resource Map and Potential
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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 analysis of 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
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Michigan Wind Map Changes Over Time
1987 & 2004 Wind Power Maps at 50 m
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2010 Wind Speed Map at 80 m
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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
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AWS Truewind Presentation
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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
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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
o About 20 towers had measurement levels greater than 60 m
– About 80 towers had easily identifiable periods-of-record of 2
years and longer
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Variations of Wind Speed vs Height
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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 hubheights is needed in order to estimate wind potential
with even greater accuracy
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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
o One tower had measurements at 80 m
o 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
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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/km2 of installed nameplate capacity
• Wind potential expressed in two ways
– Installed capacity in MW
– Annual generation in GWh
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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
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National Exclusion Map
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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
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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
Windy Land Area >= 30% Gross Capacity Factor at 80m
State
Michigan
US 48 Total
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Excluded2
(km2)
Total
(km2)
Available
(km2)
Available
% of State
Wind Energy Potential
% of Total Windy
Land Excluded
Installed
Capacity3
(MW)
Annual
Generation
(GWh)
19,761.3
7,952.9
11,808.5
7.85%
40.2%
59,042.3
169,221
2,571,180
479,391
2,091,789
26.89%
18.6%
10,458,945
36,919,551
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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
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Michigan – Wind Map and Potential
•
Michigan wind potential from areas with
CF>=30% is substantial:
–
–
•
Even for higher CF ranges at 80 m, the
Michigan wind potential is quite large:
–
–
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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
CF>=35%, about 11,600 MW
CF>=40%, almost 400 MW
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Arizona – Wind Map and Potential
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North Dakota Wind Map and Potential
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Comparison to Previous Studies
•
Previous national wind potential estimates in early 1990s versus new estimates
in 2010
–
–
–
•
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:
–
–
–
•
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.
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
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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
2
5.82
6.34
6.87
7.43
8.03
8.69
1.5
5.65
6.28
6.96
7.71
8.56
9.57
25%
30%
35%
40%
45%
50%
WPD
2.5
5.98
6.44
6.92
7.39
7.89
8.42
3
6.11
6.55
6.97
7.41
7.85
8.32
Capacity Factor
Capacity Factor
WS
1.5
300
412
561
763
1044
1460
25%
30%
35%
40%
45%
50%
Weibull k
2
231
298
379
480
605
769
2.5
207
259
320
391
475
578
3
197
242
292
349
417
496
Wind Speed Frequency Distributions
0.25
1.50
2.00
2.50
3.50
Frequency
0.2
0.15
Weibull k
0.1
0.05
0
0
5
10
15
20
25
Speed (m/s)
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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
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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%
–
–
–
–
•
Michigan wind potential from areas with CF>=30% is substantial:
–
–
•
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
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
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