Land-Use Requirements of Modern Wind Power Plants in the United States

Technical Report

NREL/TP-6A2-45834

August 2009

Land-Use Requirements of

Modern Wind Power Plants

in the United States

Paul Denholm, Maureen Hand,

Maddalena Jackson, and Sean Ong

National Renewable Energy Laboratory

1617 Cole Boulevard, Golden, Colorado 80401-3393

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•

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Contract No. DE-AC36-08-GO28308

Technical Report

NREL/TP-6A2-45834

August 2009

Land-Use Requirements of

Modern Wind Power Plants

in the United States

Paul Denholm, Maureen Hand,

Maddalena Jackson, and Sean Ong

Prepared under Task No. WER9.3550

NOTICE

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Acknowledgments

Substantial assistance in preparing this analysis, including the land-cover data, mapping,

as well as general advice and guidance, was provided by Donna Heimiller, Anelia

Milbrandt, and Billy Roberts at the National Renewable Energy Laboratory (NREL).

Additional graphics and editorial support were provided by Jim Leyshon and Michelle

Kubik.

Table of Contents

Acknowledgments .......................................................................................................................... i

1 Introduction .................................................................................................................................1

2 Wind Power Plant Land-Use Metrics .......................................................................................1

2.1 Direct Impact Area ...............................................................................................................4

2.2 Total Wind Plant Area .........................................................................................................4

3 Wind Power Plant Land-Use Data ............................................................................................5

3.1 Direct Impact Area ...............................................................................................................6

3.2 Total Wind Plant Area .........................................................................................................6

3.3 Wind Power Plant Land-Cover and Configuration Data .....................................................6

4 Results ..........................................................................................................................................9

4.1 Summary Results ...............................................................................................................10

4.2 Direct Impact Area Results ................................................................................................11

4.3 Total Area Results ..............................................................................................................13

5 Alternative Area Metrics and Measurement Methods ..........................................................20

5.1 Habitat Impact Area ...........................................................................................................21

5.2 Uniform Estimation of Total Area Requirements ..............................................................21

6 Conclusions ................................................................................................................................22

References .....................................................................................................................................24

iii

List of Figures

Figure 1. Illustration of the two types of wind plant land use: total area and direct impact

area (including permanent and temporary) ......................................................................................3

Figure 2. Example of direct impact area ..........................................................................................6

Figure 3. Examples of wind power plant configurations .................................................................8

Figure 4. Locations of wind power plants evaluated in this study...................................................9

Figure 5. Distribution of permanent direct impact area .................................................................11

Figure 6. Distribution of temporary direct impact area .................................................................12

Figure 7. Distribution of total area requirements ...........................................................................14

Figure 8. Distribution of total area expressed as capacity density .................................................15

Figure 9. Direct impact area requirements (hectare/MW) as a function of wind power

plant size ..................................................................................................................................19

Figure 10. Capacity density as a function of wind power plant size .............................................20

Figure 11. Possible methodologies for assigning uniform land metrics to total area of

wind power plants ....................................................................................................................22

List of Tables

Table 1. Summary of Collected Wind Power Plant Area Data ......................................................10

Table 2. Projects with Detailed Direct Impact Data ......................................................................13

Table 3. Distribution of Direct Impact Area ..................................................................................13

Table 4. Wind Power Plant Configuration .....................................................................................16

Table 5. Land-Cover Data ..............................................................................................................17

Table 6. Relationship between Configuration and Land-Use Area ...............................................18

Table 7. Relationship between Land-Cover and Average Land-Use Area ....................................18

Table 8. Relationship between Land Cover and Configuration .....................................................19

Table 9. Direct impact area requirements (hectare/MW) as a function of wind power plant

size ...........................................................................................................................................19

1 Introduction

By the end of 2008, a combination of environmental, economic, and policy factors

resulted in the cumulative deployment of more than 25 gigawatts (GW) of wind

generation capacity in the United States (AWEA 2009a). Continued growth is anticipated

due to renewable portfolio standards and expected constraints on carbon emissions in the

electric sector. One of the concerns regarding large-scale deployment of wind energy is

its potentially significant land use. Estimates of land use in the existing literature are

often based on simplified assumptions, including power plant configurations that do not

reflect actual development practices to date. Land-use descriptions for many projects are

available from various permitting agencies and other public sources, but we are not aware

of any single source that compiles or summarizes this data. In addition, there is limited

information comparing land use for wind power plants across different terrain and plant

configurations. The existing data and analyses limit the effective quantification of land-

use impacts for existing and future wind energy generation, particularly in comparison to

other electricity generation technologies.

In this report, we provide data and analysis of the land use associated with modern, large

wind power plants (defined as greater than 20 megawatts (MW) and constructed after

2000). We begin by discussing standard land-use metrics as established in the life-cycle

assessment literature, and then discuss their applicability to wind power plants. We

identify two major “classes” of wind plant land use: 1) direct impact (i.e., disturbed land

due to physical infrastructure development), and 2) total area (i.e., land associated with

the complete wind plant project). We also provide data for each of these classes, derived

from project applications, environmental impact statements, and other sources. We also

attempt to identify relationships among land use, wind plant configuration, and

geography. We evaluated 172 existing or proposed projects, which represents more than

26 GW of capacity.

In addition to providing land-use data and summary statistics, we identify several

limitations to the existing wind project area data sets, and suggest additional analysis that

could aid in evaluating actual land use and impacts associated with deployment of wind

energy.

2 Wind Power Plant Land-Use Metrics

There are a number of existing and proposed metrics for evaluating land-use impacts.

While there is no generally accepted methodology (Canals et al. 2007), review of the life-

cycle assessment (LCA) literature suggests at least three general categories for evaluating

land-use impacts: 1) the area impacted, 2) the duration of the impact, and 3) the quality of

the impact (Koellner and Scholz 2008).

In this report, we focus on quantifying and summarizing the first component of land-use

impact identified above (area of impact), recognizing that the quality and duration of the

impact must be evaluated on a case-by-case basis. The quality of impact, which may also

be stated as a “damage function,” evaluates both the initial state of the land impacted, and

the final states across a variety of factors including soil quality and overall ecosystem

quality (Koellner and Scholz 2008).

Quantifying the area of a wind power plant is challenging given the discontinuous nature

of its configuration. “Area” includes not only land directly disturbed by installation of the

turbines, but also the surrounding area that potentially may be impacted. In reviewing

various environmental impact assessments and other evaluations of wind plant land use,

it appears that there are two general types of “areas” considered. The first is the direct

surface area impact (i.e., disturbed land) due to plant construction and infrastructure. The

second is more vaguely defined, but is associated with the total area of the wind power

plant as a whole. Figure 1 provides a simplified illustration of the two types of areas,

which are vastly different in both quantity and quality of impacts as discussed in

subsequent sections.

Figure 1. Illustration of the two types of wind plant land use: total area and direct impact

area

(including permanent and temporary)

The total project area map is adapted from an actual project application (U.S. DOE 2005). The direct

impact area is a simplified illustration meant to represent typical components and does NOT represent this

or any actual project.

2.1 Direct Impact Area

Development of a wind power plant results in a variety of temporary and permanent

(lasting the life of the project) disturbances. These disturbances include land occupied by

wind turbine pads, access roads, substations, service buildings, and other infrastructure

which physically occupy land area, or create impermeable surfaces. Additional direct

impacts are associated with development in forested areas, where additional land must be

cleared around each turbine. While land cleared around a turbine pad does not result in

impervious surfaces, this modification represents a potentially significant degradation in

ecosystem quality (Arnett et al. 2007).

In addition to permanent impacts, which last the life of the facility, there are temporary

impacts from plant construction. These impacts are associated with temporary

construction-access roads, storage, and lay-down. After plant construction is completed,

these areas will eventually return to their previous state. The amount of time required to

return to its “pre-disturbance condition” is estimated at two-three years for grasslands and

“decades” in desert environments (Arnett et al. 2007).

An illustration of the direct impact area is shown in the magnified section of Figure 1,

and demonstrates the components of direct impact, including the impermeable turbine

pad and road, the permanently altered clearing around the turbine, and the temporary lay-

down area. This illustration is not meant to represent any specific project and the actual

components and configuration of direct impact area will vary among projects.

2.2 Total Wind Plant Area

While the area and impacts associated with physical infrastructure described in Section

2.1 may be the easiest to quantify, the more commonly cited land-use metric associated

with wind power plants is the footprint of the project as a whole. However, unlike the

area occupied by roads and pads, the total area is more challenging to define and

subjective in nature. Generally, the total area of a wind power plant consists of the area

within a perimeter surrounding all of the turbines in the project. However, the perimeter

is highly dependent on terrain, turbine size, current land use, and other considerations

such as setback regulations. An example of the total area of a project is illustrated in

Figure 1, showing the individual turbine strings, and the very irregular perimeter. There is

no uniform definition of the perimeter or boundary surrounding a wind power plant – in

fact, the total area of a wind power plant could have a number of definitions. The

boundary could be defined based on the required turbine spacing as a function of rotor

diameter, or use a standardized setback from turbines at the edge of a project. As

discussed in Section 3, this paper relies on the area defined through project applications

or other documentation associated with each project.

The character of impact of the total area of a wind power plant is very different from the

direct impact area, or the area associated with other types of energy production facilities.

Many previous comparisons of total land use associated with energy production only

include the total area affected, and provide little discussion of the damage function as a

comparative metric. A wind plant in an agricultural area with low population and

minimum avian impacts would have a much lower damage function than an area mined

for coal or flooded by a hydropower project, for example. As a result, using the total area

metric without qualification may significantly overstate the land impacts of wind power

compared to other sources. Alternatively, wind power projects should consider the

impacts associated with habitat disruption, avian impacts, and aesthetics. Ultimately, the

actual quality of impacts, captured in a damage function, is needed to compare the land

impacts of wind to other sources.

3 Wind Power Plant Land-Use Data

Our goal was to collect and provide a summary of reported land-use data associated with

modern, large wind power plants. As a result, we restricted the sample of sites to projects

constructed after 2000 and with a nameplate capacity greater than 20 MW.

A variety of sources for land-use data were used for this study and fell into three general

categories. First, where available, we collected official project data from federal, state,

and local regulatory agencies, including environmental impact statements (EIS),

environmental assessments (EA), and project applications to utility regulatory bodies.

The availability of this data is highly dependent on state and local regulations. Some

states require very detailed environmental assessments, while others require little in the

way of analysis of potential land use. Second, we collected project fact sheets, news

releases, and other data provided by the project owner or developer. When no other

source of data could be located, we used news articles, Web sites and other secondary

sources. As a supplement to area data, we also collected location and land-cover data for

individual turbines from publicly available data sets. The following sections provide

details about the specific types and sources of data collected.

We included

proposed projects, but only those with detailed, formal applications (or environmental

assessments) to a regulatory agency.

3.1 Direct Impact Area

The direct impact area was identified in project materials as land “permanently

occupied,” “permanently disturbed,” or using similar wording. When provided, most

projects report a single number for land directly occupied; however, some provide a

breakdown of occupation categories. Figure 2 provides an example of a detailed table of

occupied area from a project application.

We excluded older projects largely because they use turbines less than 1 MW. This excludes several large

projects such as those in the Altamont Pass and Tehachapi regions in California.

Figure 2. Example of direct impact area (adapted from BLM 2008)

When provided, we recorded the permanent direct impact area data for five categories:

turbine pad, roads, substations, transmission, and other.

A number of applications also included temporary direct impact data associated with

plant construction. We recorded temporary direct impact area data in four categories:

temporary roads, staging, substation/transmission construction, and other.

3.2 Total Wind Plant Area

The total area was identified in project materials as “project area,” “lease area,” “site

boundary,” or similar terms. This area is not uniformly defined, and is often established

by the individual project developer; it also will vary between developers and between

states. In addition, many applications define the project area without a map or any

additional information about how this boundary is determined.

3.3 Wind Power Plant Land-Cover and Configuration Data

In addition to area data, two additional parameters associated with wind plants were

collected to aid in evaluating possible dependence of land use on wind plant

configuration and location.

For each wind power plant evaluated, we collected location data for each turbine in the

project from the Federal Aviation Administration (FAA 2009). This data set includes

latitude and longitude for each turbine. From this database, we then acquired the land-

cover type for each turbine using a U.S. Geological Survey data set (USGS 2006). Land

cover in this data set is described as “the nature of the land surface at a particular

location” with 21 classes of land cover. This data provides additional insight into the

potential impact – for example, turbines located in primarily agriculture area should have

significantly less impact than turbines located in forested area, which are more likely to

require additional clearing and have a greater potential for habitat fragmentation and

other adverse environmental impacts.

Once we collected the location data for each turbine, we also examined the overall wind

plant configuration to identify relationships between land-use area and configuration.

After examining the various configurations, we created four general categories: Single

String, Multiple Strings, Parallel Strings, and Clusters. These are qualitatively defined as

follows:

• Single String: A single long string of turbines, including projects with one or

more discontinuities.

• Multiple String: A series of identifiable strings of turbines, but not uniformly

oriented.

• Parallel String: A series of well-defined strings that are roughly parallel to each

other (i.e., strings do not intersect). This configuration is closest to the grid

spacing often used to represent an “ideal” plant layout.

• Cluster: Sites that have very few to no observable turbine strings.

Examples of these configurations are provided in Figure 3.

Figure 3.1. Single string configuration

(Waymart, Pennsylvania)

Figure 3.2. Multiple strings configuration

(Wyoming Wind Energy Center,

Wyoming)

Figure 3.3. Parallel string configuration

(Roscoe Wind Project, Texas)

Figure 3.4. Cluster configuration (Spring

Creek Wind Farm, Illinois)

Figure 3.

Examples of wind power plant configurations

In these representative cases, the different configurations are easily visible. However, it is

sometimes difficult to establish a single, uniform configuration for an entire plant, which

introduces an element of subjectivity to this metric.

4 Results

We obtained one or more categories of land-use data for 172 individual projects,

representing 26,462 MW of proposed or installed capacity. Of this capacity, 19,834 MW

was completed as of March 2009, 2,892 MW was under construction, and the remainder

consists of proposed projects. According to a the American Wind Energy Association

(2009b), as of March 2009, 28,206 MW wind capacity had been completed in the United

States, with 24,640 MW meeting our criteria as a large modern plant with a capacity of at

least 20 MW and constructed after 2000. As a result, we collected at least some

information on about 80% of the targeted installed wind capacity in the United States.

Figure 4 provides a map of project locations. A complete listing of all projects, data

sources, and individual project data is provided in the Appendix.

Figure 4. Locations of wind power plants evaluated in this study

4.1 Summary Results

Table 1 summarizes the direct impact area data and total area data for projects shown in

Figure 4 and listed in the Appendix. As noted earlier, this represents a mix of data from

the 172 projects. The number of projects where we obtained data for the corresponding

area metric is listed in the first row of Table 1 – for example, we were able to obtain total

impact area for 161 of the 172 projects, but only 52 of the projects had information on the

temporary direct impact area. The average area requirements (hectare/MW) were

calculated by summing the total area of all plants with corresponding land-use data and

dividing by the total capacity of those plants.

Table 1. Summary of Collected Wind Power Plant Area Data

Data Type

Direct Impact Area

Total Area

Permanent

Temporary

Number of Projects

with Corresponding

Data

93 52 161

Total Capacity (MW)

with Corresponding

Data

13,897 8,984 25,438

Total Number of

Turbines with

Corresponding Data

8,711 5,541 15,871

Total Reported Area

(km

)

37.6 61.4 8,778.9

Average Area

Requirements

(hectare/MW)

0.3± 0.3

0.7 ± 0.6 34.5 ± 22.4

This represents a weighted average and is not equal to the simple average. The simple average would sum

each individual land use requirement (area per unit capacity) and the divide the sum by the total number of

evaluated projects. This method would weight each wind plant equally, so that the land use “intensity” of a

small plant would count as much as a much larger project.

The standard deviation is also reported. It should be noted that the data sets do not represent normal

distributions as can be observed in Figures 5-7.

4.2 Direct Impact Area Results

There is substantial variation among the reported area requirements as indicated by the

large standard deviation values. For the permanent direct impact, the range is about 0.06

hectares/MW to about 2.4 hectares/MW; however, approximately 80% of the projects

(both number of projects and total capacity) report direct land use at below 0.4

hectares/MW. Figure 5 indicates the range of direct impact area for the projects that

provided this data. In this figure, the data were binned and reported as both the number of

projects and the total capacity (MW) in each bin of direct impact area (hectares/MW).

1000

2000

3000

4000

5000

6000

<0.1

0.1-0.2

0.2-0.3

0.3-0.4

0.4-0.5

0.5-1.0

1-1.5

>1.5

Number of Projects

Permanent Direct Impact Area (Hectares/MW)

Number of Projects

Figure 5. Distribution of permanent direct impact area

Figure 6 provides the distribution of temporary direct impact area. The temporary impact

area is much higher than the permanent area, with about 50% of the projects (both

number and capacity) reporting a temporary impact area of greater than 0.5 hectares/MW.

500

1000

1500

2000

2500

<0.1

0.1-0.2

0.2-0.3

0.3-0.4

0.4-0.5

0.5-1.0

1-1.5

>1.5

Number of Projects

Temporary Direct Impact Area (Hectares/MW)

Number of Projects

Figure 6. Distribution of temporary direct impact area

The overall average direct impact area is 0.3 ± 0.3 hectares/MW for permanent impact

and 0.7 ± 0.6 hectares/MW for temporary impact, or a total direct surface area disruption

of about 1.0 ± 0.7 hectares/MW.

The reported values can be compared to previous estimates of direct impacts. The Bureau

of Land Management (BLM 2005) estimated a direct impact area (both permanent and

temporary) of 0.4 to 1.2 hectares per turbine in the western United States. Assuming a 1.5

MW turbine, this corresponds to total direct impact area of 0.3 to 0.8 hectares/MW.

Strickland and Johnson (2006) estimate permanent infrastructure impacts of 0.3 to 0.4

hectares per turbine, and temporary impacts of 0.2 to 1.0 hectares per turbine. Assuming

a 1.5 MW turbine, this corresponds to a permanent impact area of 0.2 to 0.5 hectares/MW

and temporary impact area of 0.1 to 0.7 hectares/MW.

Where provided, we collected data that breaks out the occupation categories as described

previously. Less than a third of the projects that reported direct impact area provided

detailed data. Tables 2 and 3 provide summary statistics of this data.

Table 2. Projects with Detailed Direct Impact Data

Permanent

Temporary

Number of Projects with

Detailed Data

23 17

Total MW

4,257

3,642

Table 3. Distribution of Direct Impact Area

Permanent Impact

Category

% of Area

Turbine Area

10%

Staging Area

30%

Roads

79%

Temp Roads

62%

Substation

Sub/Trans

construction

Transmission

Other

Table 3 indicates that the majority of direct impacts are associated with roads. In most

cases, the road area provided in the documents only counts new road development or

road improvement. For further studies, it would be useful to more closely review project

documents to determine the amount of new roads that were constructed versus the extent

to which the project used the preexisting road network.

4.3 Total Area Results

For total area requirements, the range of values is from about 9 hectares/MW to 100

hectares/MW, with five “outliers” – three projects with requirements below 6

hectares/MW and two projects with reported areas of greater than 135 hectares/MW.

Figure 7 provides a distribution of the total area requirements (hectares/MW).

1000

2000

3000

4000

5000

6000

7000

8000

9000

<10

10-20

20-30

30-40

40-50

50-60

60-70

>70

Number of Projects

Total Project Area (Hectares/MW)

Number of Projects

Figure 7. Distribution of total area requirements

Many estimates of total area often express wind plant land use in terms of capacity

density (capacity per unit area, typically MW/km

). Excluding the outliers, the reported

data represents a capacity density range of 1.0 to 11.2 MW/km

and an overall average

capacity density of 3.0 ± 1.7 MW/km

. Figure 8 provides a distribution of the capacity

density data. Of the 161 projects with total land-use area data, 125 (representing 80% of

the evaluated capacity) have reported area of between 10 and 50 hectares/MW (or a

capacity density range of 2-10 MW/km

1000

2000

3000

4000

5000

6000

1--2

2--3

3--4

4--5

5--6

6--7

7--8

Number of Projects

Capacity Density (MW/km2)

Number of Projects

Figure 8. Distribution of total area expressed as capacity density

Previous estimates of total area are often based on theoretical potential to extract energy

over a particular area, such as the U.S. DOE (2008) estimate of 20 hectares/MW (equal to

a capacity density of 5 MW/km2). Other estimates assume turbines are configured in a

grid with a fixed array spacing, such as 5 rotor diameters by 10 rotor diameters (a 5D by

10D array), or some alternative fixed spacing (Manwell et al. 2002, Fthenakis and Kim

2009). For modern wind turbines, a 5D by 10D array yields an area of 13-20

hectares/MW, equal to a capacity density of 5-8 MW/km

(Denholm 2006). These

estimates represent minimum spacing to optimize energy extraction.

The overall average land use reported in this study is higher than estimates that use

optimal grid spacing due, in part, to irregular spacing seen in actual projects. However, in

reviewing the project applications and environmental assessments, we found several

potentially significant sources of overestimates of the land use associated with some

projects.

In some cases, developers lease (or propose to lease) all the land deemed necessary for a

multiphase project at once, and all of that land then gets associated with an initial phase

of the project rather than the final (larger) project.

We have also found that in several states, project areas are mapped based on discrete

sections (where a section is defined as a 1 square mile parcel

http://www.nationalatlas.gov/articles/boundaries/a_plss.html

), and that an entire section

is included if there is a turbine located anywhere on that section. This can actually lead to

double counting of sections, when two separate projects overlap on the same section, and

that section is assigned to both projects. Additional complete or partial sections may be

assigned to the project area surrounding the outermost edge of turbines. These factors

will tend to increase the reported land use, decreasing the reported capacity density of

wind projects.

One example of potential land-use overestimation is the Moraine II Project in Minnesota

(PPM Energy 2007). This project has the greatest total area of all evaluated projects equal

to 226 hectares/MW, or a capacity density of 0.44 MW/km

. This value was based on the

application, which states that “The site boundary in Minnesota encompasses an area of

approximately 26,992 acres.” Examining the project map, the site boundary includes 40

complete sections of land, while turbines are located on only six of these sections. While

this is the most extreme example, many other projects include large areas unoccupied by

“initial phase” wind turbines or associated infrastructure.

4.4 Dependence of Area on Configuration, Geography, and Plant Size

Despite the inconsistent methods used to report area, it may be useful to examine the

dependence of area requirements on configuration and geography. To further evaluate the

potential sources of variation in land area, we first assigned each project a configuration

and land-cover classification as discussed previously. Table 4 provides the distribution of

configurations of all wind plants evaluated.

Table 4. Wind Power Plant Configuration

Configuration Projects % of Projects MW % of Capacity

Parallel

Strings

67 39.0% 11704.5 44.2%

Single String

11 6.4% 1071.0 4.0%

Multiple

Strings

40 23.3% 5979.8 22.6%

Cluster

54 31.4% 7706.6 29.1%

As illustrated in Table 4, fewer than 50% of the evaluated projects resemble a grid

configuration, (noting that the parallel string configuration often only loosely

approximates an ideal grid.).

Table 5 provides the predominant land-cover classification data determined by the

combination of the turbine locations from the FAA database and the land-cover data from

the U.S. Geological Survey (USGS) discussed in Section 3. The three different forest

types (deciduous, mixed, and evergreen) are combined into a single category.

Table 5. Land-Cover Data

Primary Land Type Projects

% of

Projects

% of

Capacity

Shrubland

38 22.1% 7,169 27.1%

Forest

15 8.7% 1,711 6.5%

Grasslands/Herbaceous

34 19.8% 5,324 20.1%

Pasture/Hay

16 9.3% 1,997 7.5%

Row Crops

54 31.4% 8,199 31.0%

Small Grains

15 8.7% 2,063 7.8%

Tables 6 and 7 provide the average land-use data by configuration and land-cover

classification. It should be noted that by splitting the project data by category, we

substantially reduced the number of plants in each category. For example, while we

identified 67 projects having the parallel strings configuration, only 11 had temporary

land-use data available. We also calculate the average area and standard deviation using

all reported data, despite the fact that there are significant outliers (reflected in the large

standard deviation).

Table 6. Relationship between Configuration and Land-Use Area

Configuration

Average Area (hectares/MW)

Direct Impact

Area

(Permanent)

Direct Impact

Area (Temp)

Total Area

Parallel

Strings

0.33 ± 0.32 0.80 ± 0.55 34.7 ± 17.0

Multiple

Strings

0.21 ± 0.15 0.38 ± 0.33 27.7 ± 24.0

Single String

0.34 ± 0.28 1.00 ± 1.13 30.3 ± 18.3

Cluster

0.24 ± 0.24 0.78 ± 0.63 39.8 ± 22.0

Based on the data in Table 6, cluster configurations appear to have greater total area than

other configurations, probably due to irregular turbine placement resulting in greater

spacing between individual turbines.

Table 7. Relationship between Land-Cover and Average Land-Use Area

Primary Land Type

Average Area (hectares/MW)

Direct

Impact Area

(Permanent)

Direct

Impact Area

(Temporary)

Total Area

Shrubland

0.22 ± 0.12 0.63 ± 0.50 26.3 ± 12.8

Forest

0.36 ± 0.22 1.11 ± 1.14 18.3 ± 12.6

Grasslands/Herbaceous

0.41 ± 0.22 0.37 ± 0.11 35.7 ± 16.7

Pasture/Hay

0.24 ± 0.15 0.59 ± 0.66 27.4 ± 15.4

Row Crops

0.24 ± 0.28 0.87 ± 0.65 47.6 ± 25.1

Small Grains

0.31 ± 0.52 0.50 ± 0.17 24.5 ± 7.7

Evaluated wind plants in forested areas have the highest temporary impact area – and

higher than average permanent impact area – likely due to forest clearing for access

roads, turbine pads, and a setback area around each turbine. However, these projects also

have the lowest total reported area. Wind plants sited on land where the predominant land

cover is row crops have the greatest total area requirements. This relationship can be

observed in Table 8, which correlates turbine configuration with land cover and

illustrates that cluster projects are most commonly associated with row crops.

Table 8. Relationship between Land Cover and Configuration

Primary Land Type

Number of Projects

Parallel

Strings

Multiple

Strings

Single

String

Cluster

Shrubland

21 13 2 2

Forest

Grasslands/Herbaceous

20 6 3 5

Pasture/Hay

0 3 0 13

Row Crops

17 7 0 30

Small Grains

8 6 0 1

We also examined the relationship between overall wind power plant capacity (MW) and

reported land-use requirements (hectare/MW). Figures 9 and 10 relate direct impact area

and total area as a function of project size. In Figure 9, one temporary impact point equal

to 4.5 hectare/MW has been omitted for chart clarity.

0.25

0.5

0.75

1.25

1.5

1.75

2.25

2.5

0 100 200 300 400 500 600 700 800 900 1000

Wind Power Plant Size (MW)

Direct Impact Area (hectare/MW)

Permanent

Temporary

Figure 9. Direct impact area requirements (hectare/MW) as a function of

wind power plant size

Figure 10 illustrates the relationship between total area (measured in terms of capacity

density) and project size. Three outliers above 12 MW/km

are not shown. As with

Figure 9, there appears to be no significant trends, and very little correlation (with r-

values less than 0.05 for all relationships in the figures.)

0 100 200 300 400 500 600 700 800 900 1000

Wind Power Plant Size (MW)

Capacity Density (MW/km2)

Figure 10. Capacity density as a function of wind power plant size

5 Alternative Area Metrics and Measurement Methods

There are a number of limitations to the evaluation of land use in existing data sets.

Primarily, any metric that includes only area and does not include the quality of impact

(damage function) will be unable to completely capture the land-use impacts of wind

power plants or any electricity generation technology. However, there are additional

“area only” metrics that could improve understanding of the land-use impacts of wind

power plants. In this section, we suggest two additional area measurements that could be

generally applied. The first is habitat impact area, which attempts to more directly

measure the area of ecosystem impact. The second is a more general measure of total

area, incorporating a standardized methodology.

We also examined the relationship between turbine size and land use, hypothesizing that larger turbines

would require less direct land impact area per unit of capacity. However, we found no significant

relationship trends in the reported data.

5.1 Habitat Impact Area

One additional land-use metric that could be considered more generally would be a

“habitat impact area,” which measures the area of fragmentation or decrease in habitat

quality. (Impact on habitat is often considered and reported in individual project

applications and environmental assessments.) Summary estimates of regional ecosystem

impacts are provided by the National Research Council (2007) and Arnet et al. (2007). As

an example, Robel (2002) estimates turbines placed in certain grassland areas will reduce

the available habitat for greater prairie-chicken nesting by about 800 hectares for each

turbine (about 530 hectares/MW, assuming a 1.5 MW turbine). Turbines placed in

forested areas can create an “edge effect” (Jordaan et al. 2009), which results in

disruptions that can exceed 340 meters in all directions for certain species (Wood et al.

2006), or a habitat impact of more than 24 hectares/MW, assuming a 1.5 MW turbine.

These examples show the limitations of the simple metrics provided in this report, as well

as the limitation of quantifying wind power plant land use without qualifying their

impacts on a regional basis.

5.2 Uniform Estimation of Total Area Requirements

As discussed previously, there is no uniform definition of the total area of a wind power

plant. This paper describes the wind plant area in the United States that is reported to be

leased or otherwise associated with a project application. As discussed previously, the

measurement of total area varies by project developer and by state, and provides a limited

basis to compare projects regionally or to estimate land use in future wind generation

scenarios.

Addressing the limitations caused by using developer’s estimates of project areas would

require developing a more uniform metric for the total area of wind power plants based

on setbacks or other relation to turbines. Figure 11 provides an example of three potential

measures of total area that could be generally applied based on the availability of

individual turbine locations from the FAA database or other sources. The method is based

on the geometric concept of a “convex hull,” which can be described by visualizing a

rubber band stretched around the perimeter of a set of points. Applying this method to

calculate wind plant area requires establishment of several parameters. First, the setback

from the outermost edge of the wind turbines must be standardized. Second, the amount

of “relaxation” into the interior of the project must be established. The effect of different

relaxations is illustrated by buffer areas 2 and 3, where some of the open space inside the

outermost perimeter is eliminated. A final element to consider is the effect of any large

discontinuities in the project. A complicating issue in establishing these three parameters

is that they would probably vary depending on land-cover type. For example, setbacks

would be greater for turbines located in forested areas. If these parameters are

established, it should be relatively easy to determine the total land use associated with all

wind energy production in the United States.

Figure 11. Possible methodologies for assigning uniform land metrics to total area of wind

power plants

6 Conclusions

Although there is no uniformly accepted single metric of land use for wind power plants,

two primary indices of land use do exist – the infrastructure/direct impact area (or land

temporarily or permanently disturbed by wind power plant development) and the total

area (or overall area of the power plant as a whole).

Based on the collected data, direct impact is mostly caused by road development, as

opposed to the turbine pads and electrical support equipment. For 93 projects

representing about 14 GW of proposed or installed capacity, the average permanent direct

impact value reported was 0.3 ± 0.3 hectares/MW of capacity. Fewer projects (52

representing 9 GW of capacity) provide temporary direct impact data, with an overall

average of 0.7 ± 0.6 hectares/MW of capacity. This implies a total direct impact area

(both temporary and permanently disturbed land) of about 1 ± 0.7 hectare/MW, but with

a wide variation in this area.

We also found reported total-area data for 161 projects representing about 25 GW of

proposed or installed capacity. Excluding several outliers, the average value for the total

project area was about 34 ± 22 hectares/MW, equal to a capacity density of 3.0 ± 1.7

MW/km

. This capacity density is less than grid-based estimates used for optimizing

energy extraction. We believe that some of this difference is due to inclusion of land that

was set aside for future project expansion and double counting of land where projects

overlap. The limited detailed data available for many projects, including a number of

large projects, limits the ability to precisely identify the discrepancy between common

estimates and reported data. However, it is clear that the ideal grid configuration used for

some estimates is rarely used in practice, resulting in more widely spaced turbines.

Common estimates of wind land-use requirements represent, in part, the theoretical

potential to extract energy over a particular area. For example, estimates for wind

resource potential assign wind project capacity to geographic areas as small as 200 m

based on average wind resource over that grid cell. Existing projects site turbines in

locations that maximize energy capture accounting for normal terrain variations, avoiding

depressions, and exploiting ridges. While the theoretical approaches are often useful (as

indicated by the fact that many projects achieve capacity densities equal to or greater than

5 MW/km

), practical considerations tend to increase the area actually used by projects.

Without a systematic method to define project boundaries based solely on turbine

spacing, the total land area required for wind projects to effectively extract energy from

the flow cannot be determined. Although this paper presents the land area reported by

wind project developers in the United States at this time, additional methods are needed

to systematically determine land-use requirements for energy extraction, all while

considering continuing advances in turbine design and plant configurations.

Total land-area metrics for wind projects are not consistently defined and provide

information for different purposes. This paper explores the land area reportedly

associated with U.S. wind projects based on official documents. Other approaches would

explore turbine-specific dimensions (such as rotor diameter) to assess U.S. wind project

area optimized for energy extraction – perhaps leading to new “rule of thumb” estimates.

Finally, an automated methodology that defines a standard setback based on relative

turbine locations within projects would result in a systematic approach that may reduce

variation among projects.

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May 9, 2009.

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Strickland, D.; Johnson, D. (2006). “Overview of What We Know About Avian/Wind

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Workgroup Research Meeting VI, November 14, San Antonio, TX.

http://www.nationalwind.org/events/wildlife/20063/presentations/birds/strickland.pdf.

Accessed August 1, 2009

Appendix. Wind Power Plant Land-Use Data

Table A1. Land-Use Data

Name State

Turbines

Capacity

Total Area

(hectares)

Total Area Per

Unit Capacity

(Hectares

/MW)

Direct

Impact

Area

(Perm.)

(hectares)

Direct

Impact

Area

(Temp.)

(hectares)

Steel Park Wind Farm

448.7

29.92

Dry Lake Wind

Project I

2430.0

38.57

Bear River Wind Power

Project

4.0

12.6

Hatchet Ridge Wind

Project CA 49 125 1193.9 9.55 29.6 55.1

High Winds I & II CA 90 162 2430.0 15.00 42.5

Mountain View IV CA 49 49 671.9 13.71 4.5 5.8

Pine Tree Wind Project

aka Wind Turbine

Prometheus

120

3240.0

27.00

53.5

42.8

Shiloh I

100

150

2754.0

18.36

33.8

Shiloh II

176

2470.5

14.04

20.4

57.9

Solano Wind Project,

Phase IIB

1417.5

16.68

Cedar Creek Wind

Farm CO 274 300 15390.0 51.30

Cedar Point Wind

Project CO 150 300 8100.0 27.00

Colorado Green Wind

Project

108

162

4795.2

29.60

Spring Canyon

130

8931.9

68.71

27.9

62.0

Twin Buttes Wind

Power Project

3645.0

48.60

Buffalo Creek Wind

Farm IA 75 150 4455.0 29.70

Crystal Lake

180

350

16848.0

48.14

Endeavor

100

1822.5

18.23

Floyd County Wind

Farm Phase I

5.1

Hancock County Wind

Farm

148

7776.0

79.35

24.3

Intrepid

107

161

4860.0

30.28

21.7

Pioneer Prairie Wind

Farm Phase I

183

302

12150.0

40.24

Pomeroy Wind Project

Phase I

132

198

3321.0

16.77

Story County

100

150

3477.7

23.18

9.7

Top of Iowa Wind Farm

2389.5

29.87

40.5

Whispering Willow

Wind Farm (formerly

Franklin County Wind

Farm)

IA 250 500 37260.0 74.52

Cotteral Mountain

130

195

4657.5

23.88

82.2

147.8

Wolverine Creek

1247.4

19.49

Camp Grove Wind

Farm

100

150

5467.5

36.45

Crescent Ridge

Phase I

891.0

16.35

8.1

Grand Ridge Wind

Energy Center

2430.0

24.55

16.2

Mendota Hills

1053.0

20.89

12.8

Providence Heights

1944.0

27.00

8.1

Twin

Groves/Arrowsmith

240

396

8910.0

22.50

81.0

Rail Splitter Wind Farm

101

4455.0

44.33

EcoGrove I IL 67 101 2956.5 29.42

Fowler Ridge Wind

Farm Phase I IN 222 400 22275.0 55.69

Orion Energy wind

farm / Benton Wind

Farm

IN 87 130 3746.3 28.82

Meadow Lake Wind

Farm

200

10530.0

52.65

101.3

Central Plains Wind

Farm

2430.0

24.55

Elk River

100

150

3202.3

21.35

Flat Ridge Wind Farm

100

2025.0

20.25

Gray County Wind

Farm

170

112

2430.0

21.70

Meridian Way Wind

Farm

201

8100.0

40.30

Smoky Hills Wind Farm

Phase I

101

4050.0

40.18

24.3

Spearville KS 67 101 2025.0 20.15 27.1

Smoky Hills Wind Farm

Phase II KS 99 149 5670.0 38.18 85.1

Allegheny Heights

101

16.6

105.3

Mars Hill WInd

1944.0

46.29

13.2

Stetson Mountain

1944.0

34.11

13.4

65.4

Kibby Mountain and

Kibby Ridge

132

1177.7

8.92

40.5

Harvest Wind Farm

1296.0

24.55

Noble Thumb Wind

Park MI 106 159 10125.0 63.68

Chanarambie MN 53 80 2332.8 29.34 9.3

Elm Creek Wind Farm

5670.0

57.27

17.8

2.0

Fenton Wind Project

137

206

15552.0

75.68

25.9

166.5

Grand Meadow Wind

Farm / Wapsipinicon

Wind Project I

137

206

16848.0

81.99

55.5

405.0

Mower County Wind

Energy Center

3942.7

39.87

26.5

188.3

Jeffers Wind Energy

Center MN 32 60 3369.6 56.16 6.5 6.5

Minndakota Wind Farm

100

150

4466.9

29.78

17.8

3.2

Moraine II

10931.8

226.33

8.9

1.2

Moraine Wind Power

project

4050.0

79.41

Prairie Star Wind Farm

101

4050.0

40.22

32.8

67.3

Stoneray

100

6253.2

62.53

13.0

93.6

Trimont Wind MN 67 101 9072.0 90.27 16.2

Bluegrass Ridge

Project MO 27 57 2835.0 50.00

Conception Wind Farm MO 24 50 2835.0 56.25

Cow Branch MO 24 50 2835.0 56.25

Judith Gap

135

5791.5

42.90

Valley County Wind

Project MT 114 170 2736.2 16.10 23.9 75.2

Glacier / McCormick

Ranch Wind Farm

Phase I

MT 60 120 4860.0 40.50

Langdon Wind Project

106

159

12312.0

77.43

North Dakota Wind I&2 ND 41 62 1215.0 19.76 10.7 17.7

Tatanka Wind Farm

(SD/ND) ND 120 180 5702.4 31.68 48.6

Wilton Wind Energy

Center

3240.0

65.45

Ashtabula Wind Center

Phase II

133

200

19958.4

99.79

Ainsworth Wind Energy

Facility

4455.0

75.00

44.6

Elkhorn Ridge Wind

Energy Project

3383.8

42.35

Aragonne Wind LLC

3888.0

43.20

36.5

New Mexico Wind

Energy Center

136

204

3888.0

19.06

San Juan Mesa

120

1749.6

14.58

Cohocton Wind Farm

2308.5

25.65

13.0

196.8

Dairy Hills Wind Farm

120

2956.5

24.64

27.5

131.5

Dutch Hill Wind Farm

125

2308.5

18.47

High Sheldon Wind

Farm

129

2835.0

21.98

19.0

77.8

Jordanville

150

2551.5

17.01

24.3

158.4

Maple Ridge Phase I

(2005 portion)

195

322

8545.5

26.56

56.7

8.9

Marble River Wind

Farm

109

218

7820.6

35.87

54.3

238.3

Noble Altona

100

1678.3

16.78

39.3

21.3

Noble Bliss Wind Park

101

2053.8

20.44

37.7

26.8

Noble Chateaugay /

Noble Bellmont

129

3491.1

27.06

18.6

82.2

Noble Clinton Wind

Park

101

1817.2

18.08

38.8

31.1

Noble Ellenburg

917.3

11.33

48.6

Noble Wethersfield

128

3706.2

29.07

59.5

Blue Canyon Wind

Power

129

225

6480.0

28.74

Centennial Wind Farm OK 80 120 97.2

OK Wind Energy

Center -- A

102

486.0

4.76

Weatherford Wind

Energy Center

147

2106.0

14.33

Red Hills Wind Farm

123

2025.0

16.46

35.4

Arlington Wind Farm

Phase I

104

10.9

33.2

Biglow Canyon Phase I

225

400

10125.0

25.31

71.7

159.3

Cascade Wind Project OR 40 60 2349.0 39.15 22.9 20.6

Combine Hills 1 OR 105 105 5416.9 51.59 7.3

Condon Wind Project

1701.0

34.16

15.4

42.1

Elkhorn Wind Power

Project

101

4050.0

40.10

60.8

Klondike II

1782.0

23.76

178.2

Klondike III

124

300

7128.0

23.76

30.0

119.5

Leaning Juniper

(Arlington)

133

200

3468.8

17.34

26.0

282.9

Shepherd's Flat

303

910

13000.5

14.29

103.1

178.9

Stateline 3

279

184

8100.0

44.02

30.4

139.7

Hay Canyon

105

13.8

Allegheny Ridge Wind

Farm I

16.2

Allegheny Ridge Wind

Farm II

14.2

Waymart Wind Farm

347.5

5.79

MinnDakota Wind

Farm II

1608.1

29.78

121.5

South Dakota Wind

Energy Center

1012.5

25.00

Wessington Springs

2430.0

24.55

White Wind Farm

103

200

7257.6

36.29

37.7

253.5

Buffalo Ridge Wind

Farm (SD)

204

306

20032.5

65.47

Brazos Wind Ranch

160

7776.0

48.60

Callahan Divide

114

2430.0

21.32

Champion Wind Farm

127

5670.0

44.82

Desert Sky

107

161

3888.0

24.22

Elbow Creek Wind

Project

122

2713.5

22.26

Forest Creek Wind

Project

124

6075.0

48.91

Goat Mountain Wind

Ranch

109

150

4252.5

28.35

Horse Hollow Wind

Energy Center

419

733

19035.0

25.99

King Mountain (I&II)

214

278

6075.0

21.84

Llano Estacado Wind

Ranch at White Deer

2332.8

29.16

Lone Star Phase I (was

Cross Timbers or

Mesquite)

200

400

8100.0

20.25

Lone Star Phase II

(Post Oak)

100

200

15460.9

77.30

Peñascal Wind Farm

202

6075.0

30.07

121.5

Red Canyon Wind

Energy TX 56 84 3847.5 45.80

Roscoe Wind Farm

627

782

28350.0

36.28

Sherbino I Wind Farm

150

4050.0

27.00

Silver Star I Wind Farm

3057.8

50.96

Stanton Wind Farm

120

6885.0

57.38

Sweetwater Phase IV

(Mitsubishi portion)

135

4860.0

36.00

Sweetwater Phase IV

(Siemens portion)

106

4860.0

45.94

Trent Mesa

100

150

3628.8

24.19

Wildorado Wind Ranch

161

6480.0

40.25

Woodward Mountain

I & II TX 242 160 3785.1 23.66

Bull Creek Wind Farm TX 180 180 24300.0 135.00

Panther Creek Wind

Farm

111

167

9315.0

55.95

Wolf Ridge Wind Farm

113

4131.0

36.72

Ocotillo

1012.5

17.22

Gulf Winds Project

118

283

3179.7

11.23

Milford Wind Corridor

Project Phase I

159

300

10368.0

34.56

124.7

594.5

Big Horn

133

200

8541.5

42.81

34.0

95.6

Desert Claim

120

180

2121.0

11.78

33.4

141.1

Goodnoe Hills

1741.5

18.53

28.4

Hopkins Ridge Wind

Project

150

4455.0

29.70

66.8

87.9

Kittitas Valley Wind

Power Project WA 121 182 2835.0 15.62 37.7 126.0

Maiden Wind Farm WA 330 494 5265.0 10.66 101.7 430.5

Marengo Phase I

140

5390.6

38.39

Nine Canyon I and II

2073.6

32.55

19.8

Stateline 1&2

Combined

454

300

65.6

89.1

White Creek Wind I

205

3847.5

18.77

25.9

34.8

Wild Horse Wind

Power Project

136

204

3483.0

17.07

66.7

Windy Point Phase I

250

6031.7

24.13

62.4

126.4

Marengo Phase II

1741.5

24.81

Blue Sky Green Field

203

4293.0

21.20

28.4

100.0

Cedar Ridge Wind

Farm

3175.2

46.94

34.4

164.0

Forward Wind Energy

Center

133

200

13122.0

65.61

28.4

65.6

Beech Ridge Wind

Farm

124

186

810.0

4.35

121.5

Mountaineer Wind II

1782.0

27.00

79.4

298.1

Mt. Storm Phase I WV 200 300 3240.0 10.80 97.2

Foote Creek 1 WY 69 41 846.5 20.45 10.8

Glenrock Wind Energy

Project WY 66 99 5670.0 57.27

Seven Mile

Hill/Campbell Hill Wind

Project

4050.0

40.91

Table A2. Configuration, Land Cover, Status, and Data Source

Name State Configuration

Primary

Land Type

Secondary

Land Type

Development

Status

Source

Type

Steel Park Wind

Farm

parallel strings

Shrubland

73%

Evergreen

forest

20%

Proposed

Developer

Dry Lake Wind

Project I

parallel strings

Shrubland

88%

Grasslands/

herbaceous

Under Const

Third Party

Bear River Wind

Power Project

single string

Grasslands/

herbaceous

100%

Proposed

Application

Hatchet Ridge Wind

Project

single string

Evergreen

forest

92%

Shrubland

Proposed

Application

High Winds I & II CA

multiple

strings Shrubland 55%

Grasslands/

herbaceous 45% Completed Developer

Mountain View IV

parallel strings

Shrubland

100%

Proposed

Application

Pine Tree Wind

Project aka Wind

Turbine

Prometheus

multiple

strings

Grasslands/

herbaceous

69%

Shrubland

28%

Under Const

Application

Shiloh I

multiple

strings

Grasslands/

herbaceous

64%

Pasture/hay

36%

Completed

Developer

Shiloh II

multiple

strings

Pasture/hay

51%

Grasslands/

herbaceous

49%

Completed

Application

Solano Wind

Project, Phase IIB

multiple

strings

Pasture/hay

98%

Grasslands/

herbaceous

Completed

Application

Cedar Creek Wind

Farm CO parallel strings

Grasslands/

herbaceous 76% Fallow 12% Completed Developer

Cedar Point Wind

Project

parallel strings

Grasslands/

herbaceous

44%

Small

grains

29%

Under Const

Developer

Colorado Green

Wind Project

parallel strings

Grasslands/

herbaceous

92%

Small

grains

Completed

Developer

Spring Canyon

single string

Grasslands/

herbaceous

78%

Fallow

20%

Completed

Application

Twin Buttes Wind

Power Project CO parallel strings

Grasslands/

herbaceous 98%

Small

grains 2% Completed Developer

Buffalo Creek Wind

Farm IA parallel strings Row crops 88%

Grasslands/

herbaceous 10% Proposed Third Party

Crystal Lake

parallel strings

Row crops

93%

Pasture/hay

Completed

Application

Endeavor IA

multiple

strings Row crops 86% Pasture/hay 9% Completed Developer

Floyd County Wind

Farm Phase I IA parallel strings Row crops 98%

Grasslands/

herbaceous 2% Completed Third Party

Hancock County

Wind Farm IA cluster Row crops 91%

Grasslands/

herbaceous 3% Completed Developer

Intrepid IA

multiple

strings Row crops 92% Pasture/hay 6% Completed Developer

Pioneer Prairie

Wind Farm Phase I IA parallel strings Row crops 94%

Grasslands/

herbaceous 2% Completed Third Party

Pomeroy Wind

Project Phase I IA cluster Row crops 94%

Grasslands/

herbaceous 2% Completed Developer

Story County

parallel strings

Row crops

97%

Grasslands/

herbaceous

Completed

Application

Top of Iowa Wind

Farm IA parallel strings Row crops 85%

Grasslands/

herbaceous 11% Completed Application

Whispering Willow

Wind Farm

(formerly Franklin

County Wind Farm)

cluster

Row crops

95%

Pasture/hay

Under Const

Developer

Cotteral Mountain

single string

Shrubland

100%

Proposed

Application

Wolverine Creek ID cluster Pasture/hay 44% Shrubland 33% Completed Developer

Camp Grove Wind

Farm IL cluster Row crops 99% Pasture/hay 1% Completed Developer

Crescent Ridge

Phase I

cluster

Row crops

91%

Pasture/hay

Completed

Third Party

Grand Ridge Wind

Energy Center

cluster

Row crops

91%

Pasture/hay

Completed

Third Party

Mendota Hills

cluster

Row crops

89%

Pasture/hay

10%

Completed

Third Party

Providence Heights

cluster

Row crops

98%

Deciduous

forest

Completed

Developer

Twin

Groves/Arrowsmith

cluster

Row crops

100%

Completed

Developer

Rail Splitter Wind

Farm

cluster

Row crops

88%

Pasture/hay

Under Const

Third Party

EcoGrove I IL parallel strings Row crops 83% Pasture/hay 15% Under Const Third Party

Fowler Ridge Wind

Farm Phase I

cluster

Row crops

95%

Pasture/hay

Completed

Developer

Orion Energy wind

farm / Benton Wind

Farm

cluster

Row crops

79%

Pasture/hay

15%

Completed

Developer

Meadow Lake Wind

Farm IN parallel strings Row crops 82% Pasture/hay 17% Under Const Developer

Central Plains Wind

Farm

parallel strings

Small

grains

48%

Grasslands/

herbaceous

33%

Completed

Developer

Elk River

parallel strings

Grasslands/

herbaceous

79%

Pasture/hay

14%

Completed

Developer

Flat Ridge Wind

Farm

parallel strings

Small

grains

52%

Grasslands/

herbaceous

32%

Completed

Developer

Gray County Wind

Farm

parallel strings

Small

grains

64%

Grasslands/

herbaceous

30%

Completed

Developer

Meridian Way Wind

Farm

cluster

Grasslands/

herbaceous

71%

Small

grains

15%

Completed

Third Party

Smoky Hills Wind

Farm Phase I

cluster

Grasslands/

herbaceous

88%

Pasture/hay

Completed

Developer

Spearville

parallel strings

Small

grains

60%

Grasslands/

herbaceous

28%

Completed

Third Party

Smoky Hills Wind

Farm Phase II

multiple

strings

grasslands/

herbaceous

81%

Pasture/hay

Completed

Developer

Allegheny Heights MD single string

Deciduous

forest 100% Proposed Application

Mars Hill WInd

single string

Deciduous

forest

83%

Mixed

forest

17%

Completed

Application

Stetson Mountain ME single string

Deciduous

forest 92%

Mixed

forest 8% Completed Application

Kibby Mountain and

Kibby Ridge ME

multiple

strings

Evergreen

forest 57%

Mixed

forest 32% Under Const Third Party

Harvest Wind Farm

cluster

Row crops

97%

Pasture/hay

Completed

Third Party

Noble Thumb Wind

Park

cluster

Row crops

90%

Deciduous

forest

Completed

Developer

Chanarambie

cluster

Row crops

91%

Pasture/hay

Completed

Application

Elm Creek Wind

Farm

parallel strings

Row crops

100%

Completed

Application

Fenton Wind

Project

cluster

Row crops

88%

Pasture/hay

10%

Completed

Application

Grand Meadow

Wind Farm /

Wapsipinicon Wind

Project I

cluster

Row crops

97%

Pasture/hay

Completed

Application

Mower County

Wind Energy

Center

multiple

strings

Row crops

97%

Pasture/hay

Completed

Application

Jeffers Wind

Energy Center

cluster

Row crops

90%

Pasture/hay

10%

Completed

Application

Minndakota Wind

Farm I MN cluster Row crops 79% Pasture/hay 19% Completed Application

Moraine II MN

multiple

strings Row crops 79% Pasture/hay 21% Proposed Application

Moraine Wind

Power project MN parallel strings Row crops 56% Pasture/hay 44% Completed Third Party

Prairie Star Wind

Farm MN cluster Row crops 97% Pasture/hay 3% Completed Application

Stoneray

cluster

Row crops

91%

Pasture/hay

Proposed

Application

Trimont Wind

cluster

Row crops

95%

Pasture/hay

Completed

Application

Bluegrass Ridge

Project

cluster

Row crops

48%

Pasture/hay

40%

Completed

Third Party

Conception Wind

Farm

cluster

Pasture/hay

50%

Row crops

32%

Completed

Developer

Cow Branch

cluster

Row crops

79%

Pasture/hay

21%

Completed

Developer

Judith Gap

multiple

strings

Grasslands/

herbaceous

43%

Grasslands/

herbaceous

33%

Completed

Third Party

Valley County Wind

Project

multiple

strings

Shrubland

100%

Proposed

Application

Glacier /

McCormick Ranch

Wind Farm Phase I

parallel strings

Small

grains

47%

Fallow

41%

Completed

Third Party

Langdon Wind

Project

multiple

strings

Row crops

69%

Small

grains

21%

Completed

Unverified

North Dakota Wind

I&2

cluster

Row crops

100%

Completed

Application

Tatanka Wind Farm

(SD/ND)

parallel strings

Grasslands/

herbaceous

88%

Row crops

Completed

Developer

Wilton Wind Energy

Center

parallel strings

Row crops

82%

Grasslands/

herbaceous

15%

Completed

Developer

Ashtabula Wind

Center Phase II

parallel strings

Row crops

82%

Pasture/hay

Completed

Third Party

Ainsworth Wind

Energy Facility NE parallel strings

Grasslands/

herbaceous 97%

Emergent

herbaceous

wetlands

3% Completed Developer

Elkhorn Ridge Wind

Energy Project

multiple

strings

Row crops

78%

Pasture/hay

22%

Completed

Third Party

Aragonne Wind

LLC

parallel strings

Grasslands/

herbaceous

94%

Shrubland

Completed

Developer

New Mexico Wind

Energy Center

multiple

strings

Grasslands/

herbaceous

100%

Completed

Developer

San Juan Mesa

parallel strings

Grasslands/

herbaceous

91%

Shrubland

Completed

Developer

Cohocton Wind

Farm NY cluster Pasture/hay 37% Row crops 27% Completed Application

Dairy Hills Wind

Farm NY cluster Row crops 100% Proposed Application

Dutch Hill Wind

Farm NY cluster Pasture/hay 35% Row crops 33% Completed Third Party

High Sheldon Wind

Farm NY

multiple

strings Pasture/hay 51%

Mixed

forest 25% Proposed Application

Jordanville

cluster

Pasture/hay

53%

Deciduous

forest

27%

Proposed

Application

Maple Ridge Phase

I (2005 portion) NY cluster Pasture/hay 47%

Deciduous

forest 39% Completed Application

Marble River Wind

Farm

cluster

Deciduous

forest

39%

Pasture/hay

28%

Proposed

Application

Noble Altona

cluster

Deciduous

forest

82%

Row crops

Completed

Application

Noble Bliss Wind

Park NY cluster Pasture/hay 38%

Mixed

forest 30% Completed Application

Noble Chateaugay /

Noble Bellmont

cluster

Pasture/hay

47%

Deciduous

forest

38%

Completed

Application

Noble Clinton Wind

Park

cluster

Pasture/hay

38%

Pasture/hay

38%

Completed

Application

Noble Ellenburg NY cluster Pasture/hay 46%

Deciduous

forest 28% Completed Developer

Noble Wethersfield NY cluster Pasture/hay 51%

Mixed

forest 24% Completed Application

Blue Canyon Wind

Power

single string

Grasslands/

herbaceous

87%

Shrubland

11%

Completed

Developer

Centennial Wind

Farm

parallel strings

Grasslands/

herbaceous

86%

Shrubland

12%

Completed

Third Party

OK Wind Energy

Center -- A

parallel strings

Grasslands/

herbaceous

100%

Completed

Developer

Weatherford Wind

Energy Center

multiple

strings

Small

grains

80%

Pasture/hay

Completed

Developer

Red Hills Wind

Farm

parallel strings

grasslands/

herbaceous

84%

Shrubland

14%

Completed

Third Party

Arlington Wind

Farm Phase I

multiple

strings

Shrubland

51%

Grasslands/

herbaceous

28%

Completed

Application

Biglow Canyon

Phase I

multiple

strings

Small

grains

52%

Fallow

40%

Completed

Application

Cascade Wind

Project

multiple

strings

Deciduous

forest

100%

Proposed

Application

Combine Hills 1

multiple

strings

Shrubland

100%

Completed

Third Party

Condon Wind

Project OR

multiple

strings

Small

grains 55% Shrubland 27% Completed Application

Elkhorn Wind

Power Project OR parallel strings Shrubland 95%

Grasslands/

herbaceous 5% Completed Developer

Klondike II OR parallel strings

Small

grains 65% Fallow 35% Completed Developer

Klondike III OR parallel strings

Small

grains 49%

Small

grains 39% Completed Application

Leaning Juniper

(Arlington) OR parallel strings Shrubland 44% Fallow 27% Completed Application

Shepherd's Flat OR

multiple

strings Shrubland 54%

Grasslands/

herbaceous 31% Proposed Application

Stateline 3 OR parallel strings Shrubland 66% Fallow 16% Completed Application

Hay Canyon OR

multiple

strings

Small

grains 33% Fallow 33% Completed Application

Allegheny Ridge

Wind Farm I PA cluster

Deciduous

forest 83%

Mixed

forest 18% Completed Developer

Allegheny Ridge

Wind Farm II PA

multiple

strings

Deciduous

forest 54%

Mixed

forest 40% Proposed Developer

Waymart Wind

Farm PA single string

Deciduous

forest 88%

Mixed

forest 12% Completed Third Party

MinnDakota Wind

Farm II SD cluster Row crops 81% Pasture/hay 19% Completed Developer

South Dakota Wind

Energy Center SD

multiple

strings

Grasslands/

herbaceous 70%

Small

grains 11% Completed Developer

Wessington Springs

parallel strings

Grasslands/

herbaceous

63%

Pasture/hay

31%

Under Const

Developer

White Wind Farm

cluster

Row crops

52%

Pasture/hay

48%

Proposed

Application

Buffalo Ridge Wind

Farm (SD)

parallel strings

Row crops

67%

Pasture/hay

31%

Under Const

Application

Brazos Wind Ranch

parallel strings

Row crops

42%

Grasslands/

herbaceous

38%

Completed

Developer

Callahan Divide

multiple

strings

Evergreen

forest

38%

Shrubland

30%

Completed

Developer

Champion Wind

Farm

parallel strings

Row crops

78%

Shrubland

Completed

Developer

Desert Sky TX

multiple

strings Shrubland 89%

Grasslands/

herbaceous 11% Completed Third Party

Elbow Creek Wind

Project

cluster

Shrubland

81%

Grasslands/

herbaceous

17%

Completed

Developer

Forest Creek Wind

Project

parallel strings

Shrubland

89%

Grasslands/

herbaceous

11%

Completed

Third Party

Goat Mountain

Wind Ranch TX parallel strings Shrubland

100% Completed Third Party

Horse Hollow Wind

Energy Center

parallel strings

Shrubland

78%

Evergreen

forest

10%

Completed

Developer

King Mountain (I&II) TX parallel strings

Grasslands/

herbaceous 51% Shrubland 46% Completed Developer

Llano Estacado

Wind Ranch at

White Deer

parallel strings

Row crops

48%

Small

grains

25%

Completed

Developer

Lone Star Phase I

(was Cross Timbers

or Mesquite)

cluster

Grasslands/

herbaceous

74%

Shrubland

18%

Completed

Developer

Lone Star Phase II

(Post Oak)

cluster

Grasslands/

herbaceous

74%

Shrubland

18%

Completed

Developer

Peñascal Wind

Farm

Parallel

Strings

Grasslands/

herbaceous

88%

Shrubland

Under Const

Third Party

Red Canyon Wind

Energy TX cluster Row crops 42%

Grasslands/

herbaceous 38% Completed Developer

Roscoe Wind Farm TX parallel strings Row crops 85% Shrubland 5% Completed Developer

Sherbino I Wind

Farm TX parallel strings Shrubland 82%

Grasslands/

herbaceous 18% Completed Developer

Silver Star I Wind

Farm TX parallel strings

Grasslands/

herbaceous 45% Shrubland 31% Completed Developer

Stanton Wind Farm TX

multiple

strings Shrubland 59%

Grasslands/

herbaceous 21% Completed Developer

Sweetwater Phase

IV (Mitsubishi

portion)

parallel strings

Shrubland

90%

Evergreen

forest

Completed

Developer

Sweetwater Phase

IV (Siemens

portion)

parallel strings

Shrubland

80%

Grasslands/

herbaceous

20%

Completed

Developer

Trent Mesa

parallel strings

Shrubland

52%

Grasslands/

herbaceous

33%

Completed

Developer

Wildorado Wind

Ranch

parallel strings

Grasslands/

herbaceous

79%

Shrubland

17%

Completed

Third Party

Woodward

Mountain I & II

multiple

strings

Shrubland

100%

Completed

Developer

Bull Creek Wind

Farm

parallel strings

grasslands/

herbaceous

80%

Shrubland

17%

Completed

Third Party

Panther Creek

Wind Farm

multiple

strings

Shrubland

88%

Grasslands/

herbaceous

12%

Completed

Third Party

Wolf Ridge Wind

Farm

cluster

grasslands/

herbaceous

41%

Pasture/hay

31%

Completed

Third Party

Ocotillo TX

multiple

strings Shrubland 89%

Grasslands/

herbaceous 11% Completed Developer

Gulf Winds Project TX parallel strings

grasslands/

herbaceous 70% Shrubland 13% Under Const Third Party

Milford Wind

Corridor Project

Phase I

parallel strings

Shrubland

68%

Grasslands/

herbaceous

21%

Under Const

Application

Big Horn

parallel strings

Shrubland

62%

Grasslands/

herbaceous

19%

Completed

Application

Desert Claim

cluster

Small

grains

100%

Proposed

Application

Goodnoe Hills WA cluster Shrubland 55%

Grasslands/

herbaceous 19% Completed Application

Hopkins Ridge

Wind Project WA parallel strings Shrubland 100% Completed Application

Kittitas Valley Wind

Power Project

parallel strings

Shrubland

100%

Proposed

Application

Maiden Wind Farm WA parallel strings Shrubland 100% Proposed Application

Marengo Phase I

multiple

strings

Small

grains

51%

Grasslands/

herbaceous

27%

Completed

Third Party

Nine Canyon I and

parallel strings

Small

grains

50%

Small

grains

42%

Completed

Developer

Stateline 1&2

Combined

parallel strings

Shrubland

66%

Fallow

16%

Completed

Application

White Creek Wind I

multiple

strings

Shrubland

76%

Small

grains

13%

Completed

Developer

Wild Horse Wind

Power Project

parallel strings

Shrubland

100%

Completed

Application

Windy Point

Phase I

multiple

strings

Shrubland

49%

Grasslands/

herbaceous

34%

Completed

Application

Marengo Phase II

multiple

strings

Small

grains

95%

Fallow

Completed

Third Party

Blue Sky Green

Field

cluster

Row crops

56%

Pasture/hay

33%

Completed

Application

Cedar Ridge Wind

Farm

cluster

Pasture/hay

51%

Row crops

40%

Completed

Application

Forward Wind

Energy Center

cluster

Pasture/hay

52%

Row crops

43%

Completed

Application

Beech Ridge Wind

Farm

multiple

strings

Deciduous

forest

95%

Quarries/str

mines/grav

el pits

Under Const

Developer

Mountaineer Wind II

single string

Mixed

forest

36%

Deciduous

forest

27%

Completed

Application

Mt. Storm Phase I

parallel strings

Deciduous

forest

80%

Mixed

forest

11%

Completed

Developer

Foote Creek 1

parallel strings

Grasslands/

herbaceous

92%

Shrubland

Completed

Application

Glenrock Wind

Energy Project

multiple

strings

Shrubland

77%

Grasslands/

herbaceous

23%

Completed

Third Party

Seven Mile

Hill/Campbell Hill

Wind Project

Parallel

Strings

Shrubland

87%

Grasslands/

herbaceous

13%

Completed

Third Party

F1147-E(10/2008)

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1. REPORT DATE (DD-MM-YYYY)

August 2009

2. REPORT TYPE

Technical Report

3. DATES COVERED (From - To)

4. TITLE AND SUBTITLE

Land-

Use Requirements of Modern Wind Power Plants in the United

States

5a. CONTRACT NUMBER

DE-AC36-08-GO28308

5b. GRANT NUMBER

5c. PROGRAM ELEMENT NUMBER

6. AUTHOR(S)

P. Denholm; M. Hand; M. Jackson; and S. Ong

5d. PROJECT NUMBER

NREL/TP-6A2-45834

5e. TASK NUMBER

WER9.3550

5f. WORK UNIT NUMBER

7. PERFORMING ORGANIZATION NAME(S) AND ADDRESS(ES)

National Renewable Energy Laboratory

1617 Cole Blvd.

Golden, CO 80401-3393

8. PERFORMING ORGANIZATION

REPORT NUMBER

NREL/TP-6A2-45834

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13. SUPPLEMENTARY NOTES

14. ABSTRACT

(Maximum 200 Words)

This report provides data and analysis of the land use associated with modern, large wind power plants (defined as

greater than 20 megawatts (MW) and constructed after 2000). The analysis discusses standard land-use metrics as

established in the life-cycle assessment literature, and then discusses their applicability to wind power plants. The report

identifies two major “classes” of wind plant land use: 1) direct impact (i.e., disturbed land due to physical infrastructure

development), and 2) total area (i.e., land associated with the complete wind plant project). The analysis also provides

data for each of these classes, derived from project applications, environmental impact statements, and other sources. It

attempts to identify relationships among land use, wind plant configuration, and geography. The analysts evaluated 172

existing or proposed projects, which represents more than 26 GW of capacity. In addition to providing land-use data and

summary statistics, they identify several limitations to the existing wind project area data sets, and suggest additional

analysis that could aid in evaluating actual land use and impacts associated with deployment of wind energy.

15. SUBJECT TERMS

NREL; life-cycle assessment; wind power; wind energy; wind power plants; land use; wind capacity; wind project;

United States; land impact; Paul Denhom; Maureen Hand; Maddalena Jackson; Sean Ong

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