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Wind Supply Curves and Location 

Scenarios in the West: Summary 

of the Clean and Diverse Energy 

Wind Task Force Report 

Preprint 

M. Milligan (Consultant) and B. Parsons 

National Renewable Energy Laboratory 

R. Shimshak 

Renewable Northwest Project

D. Larson and T. Carr 

Western Interstate Energy Board

Wind Task Force of the Clean and Diversified Energy 

Advisory Committee

To be presented at WINDPOWER 2006 

Pittsburgh, Pennsylvania 

June 4–7, 2006 

Conference Paper 

NREL/CP-500-40050 

June 2006 
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Wind Supply Curves and Location Scenarios in the West: Summary of the Clean 

and Diverse Energy Wind Task Force Report 

Michael R. Milligan, Consultant 

Brian Parsons 

National Renewable Energy Laboratory 

1617 Cole Blvd. 

Golden, CO 80401 

michael_milligan@nrel.gov

Phone: 303-384-6927 

Fax: 303-384-6901 

Rachel Shimshak, Director 

Renewable Northwest Project 

917 SW Oak, Suite 303 

Portland, OR 97205 

Phone: 503-223-4544 

Fax: 503-223-4554 

Doug Larson and Thomas Carr 

Western Interstate Energy Board 

1515 Cleveland Pl., Suite 200 

Denver, CO 80202 

Phone: 303-573-8910 

Wind Task Force of the 

Clean and Diversified Energy Advisory Committee 

Abstract 

In 2004, the Western Governors’ Association (WGA) adopted a resolution to add 30 

gigawatts (GW) of clean energy capacity in the West, with associated improvements in 

efficiency. To implement this proposal, the WGA formed the Clean and Diversified 

Energy Advisory Committee (CDEAC) and created a series of task forces that would 

advise the CDEAC on clean power generation technologies and develop 

recommendations to help achieve the Governors’ goal of 30, GW of clean power. The 

Wind Task Force developed a set of supply curves for each WGA state under various 

assumptions of transmission availability. The supply curves were based on extensive 

wind map GIS data, paired with GIS transmission data. (The authors are all members of 

the Wind Task Force). The findings indicate that the wind resource in the WGA footprint 

can economically more than achieve the WGA target for clean energy development. The 

analysis also provides a first look at the cost impact of transmission availability on the 

supply curve that can move wind to the market. In addition to the supply curves, potential 

wind development in the WGA footprint was analyzed so that transmission studies could 

help further quantify transmission needs in the West that could help support the WGA 

goals. 

1
Introduction

As part of the CDEAC effort, the Wind Task Force developed a report1 that assessed 

wind supply in the WGA states. This Task Force Report developed supply curves for 

wind in the WGA states that were based on varying assumptions about wind technology 

cost and performance and transmission availability. Because wind energy is currently 

under development in several states in response to renewable energy requirements or 

utility acquisitions of wind energy, the Task Force developed a set of scenarios based on 

the current drivers for new wind projects. 

The Wind Task Force was only one of several task forces. Task forces for solar, biomass, 

geothermal, clean coal, energy efficiency, and transmission all performed similar 

analyses that could help the Governors assess how to achieve the 30-gigawatt (GW) clean 

power goal in the West. Additional work was also performed by ABB Engineering, 

which took the existing base case representation of the Western Interconnection (as 

specified by the Seams Steering Group of the Western Interconnection, or SSG-WI, and 

the Western Electricity Coordinating Council, or WECC) and modeled several clean 

energy cases to evaluate the performance of the transmission system. 

In this paper, we present the supply curves and scenarios that were developed by the 

Wind Task Force. Much of this information has been adapted from the original Wind 

Task Force report. 

Wind energy capacity in the WGA states by the end of 2005 amounted to 6,490 MW. 

This is about 70% of the U.S. total. 

 

1

 The full Wind Task Force report can be found at http://www.westgov.org/wga/initiatives/cdeac/Windfull.pdf. 

2
Washington

390

Oregon

338

California

2150

Montana

138

Wyoming

288

Colorado

229

New Mexico

407

North Dakota

98

South Dakota

44

Nebraska

73

Kansas

264

Texas

1995

Western Governors’ Association

Footprint: Wind Installed end of 2005

Nevada

Arizona

Utah

1

Idaho

75

Figure 1. Installed wind capacity end of 2005 (AWEA) 

As the following map shows, western states have the best wind energy resources in the 

United States. 

3
Figure 2. Wind resource map of the United States 

4
Supply Curve Development for Wind in the WGA Footprint 

The Wind Task Force developed wind energy supply curves for states in the WGA region 

within the continental United States. These supply curves describe the amount of wind 

energy that can be produced in the specified regions at alternative prices. This section 

describes the assumptions underlying the wind supply curves and then provides some 

illustrative findings. A complete collection of wind supply curves for each state is 

contained in the appendix. 

The wind supply curve analysis is based on extensive wind resource information and key 

assumptions linking regional wind resources to the transmission system. 

Wind resources are mapped in an extensive GIS system that contains average wind speed 

for grids of varying sizes, depending on the mapping location and effort. Areas with 

higher wind speeds can deliver energy at a lower cost than sites with low wind speeds. 

The analysis converts wind speed data in each grid area to derive the potential wind 

power based on information about modern wind turbines. Areas that are unusable for 

wind plants are screened out of the database. 

Recently updated maps are available for most states in the WGA footprint. These maps 

provide detailed resolution to yield results with a high level of confidence. The wind 

maps for Kansas and Texas have not been fully updated. Therefore some high-quality 

wind resources in these two states may be overlooked by the current state maps and are 

not represented in the supply curves. 

A second critical feature of the supply curve analysis relates to the information and 

assumptions about the transmission system. The supply curves represent the cost of wind 

energy as delivered to the transmission backbone. The supply curves were derived under 

two transmission system assumptions. In the first case, we assume the transmission 

system has no available capacity to deliver wind energy to the nearest load center. New 

transmission must be built to deliver wind energy, assuming a cost of $1000 per MWmile for the new lines. In a second case, we assume the existing transmission system has 

20% of its capacity available to deliver wind energy to the nearest load center. Once the 

20% transmission capacity is used up, however, new transmission must be built to carry 

additional energy to the nearest load center. New transmission is assumed to cost $1000 

per MW-mile. 

A number of simplifications are involved in this aspect of the analysis. First, our database 

does not contain dynamic line ratings. Instead, the line capacity is based solely on voltage 

and length. Second, we do not know the loading patterns of the lines throughout the year, 

nor do we know how different operating conditions affect the line. We also do not have 

detailed information on specific paths that can be used to determine whether the 20% of 

wind capacity is available on the line. Based on the work of SSG-WI and others, we 

believe that this is a rough approximation that serves the purpose of developing a set of 

supply curves that can help us assess the overall cost and potential of wind in the WGA 

footprint. 

5
In many parts of the West, transmission paths are congested during peak flow periods. 

Analysis by the SSG-WI showed that many transmission paths were constrained only for 

a very small percent of the year (e.g., less than 5%). During the rest of the year (e.g., 

95%), these paths are not constrained by actual flows. Potential tariff reforms (various 

flexible-firm arrangements) provide the opportunity to more efficiently utilize the 

existing transmission system. Based on the emerging tariff reforms and efficiency gains 

for transmission, we believe that with the right set of policy and system operational 

practices that in the near term wind can obtain access to some needed transmission assets 

to move energy to markets. These near-term changes could yield more transmission 

capacity for wind without new transmission construction. 

In the long term, however, the transmission system in the West will need significant 

upgrades to bring wind and other needed energy sources to market. The wind resource is 

not evenly distributed. When evaluating the economics of wind locations, one must often 

balance low-cost wind resource (requiring a long transmission build) against a highercost wind resource (requiring a shorter transmission build). The supply curves described 

above are valuable in assessing this tradeoff because the cost of transmission is explicitly 

factored into the cost calculation. 

Although the best available information has been used to develop these supply curves, a 

number of caveats must be identified when interpreting the results. First, the supply 

curves were based on current wind technology. In recent years, wind energy technology 

has made significant advances, resulting in new turbines every 1 to 3 years. To the extent 

that this continues, the supply curves will overestimate the longer term future cost of 

wind energy. Second, the supply curve can exhibit linear step shape. Each point on a 

supply curve is linked to a specific location’s wind power class that is used to convert 

wind speed to power. The step occurs when the high-class resource is exhausted and the 

next site is from a lower-class (higher-cost) wind resource. Each cell within the map grid 

is represented by the mid-point of the appropriate power density for that wind class. 

Third, other factors have an impact on the cost of delivered wind energy but cannot be 

readily captured in the supply curve (e.g., power purchase agreements, transmission 

access and tariffs, and ownership structure). Fourth, the cost curves do not include the 

cost to integrate the variable wind resource into the operating mix of generation 

resources. This integration cost is variable, depending on the characteristics of the 

generation portfolio in the region, the wind resource, and the wind penetration rate (ratio 

of wind energy or capacity to system energy or capacity). Recent studies estimate 

integration costs in the range of less than $1/MWh to about $5/MWh, depending on the 

characteristics of the mix of conventional fuels, size of load and control area, and 

penetration of wind relative to overall load in the specific utility system. Fifth, future 

policy changes are not reflected in this analysis. Finally, during the course of the work 

that led to these supply curves, the price of wind turbines increased substantially. The 

primary causes of this increase include the recent high cost of steel, the weak U.S. dollar, 

and pent-up demand for wind turbines that was finally released when the Production Tax 

Credit (PTC) was renewed. It is difficult to assess whether this cost run-up is a temporary 

phenomenon or part of a longer-term trend. 

6
Wind supply curves for the WGA states are shown below. These curves illustrate the vast 

wind potential in the respective states. For all supply curves in this report, the cost of 

wheeling, integration, and distribution are not included. Costs also do not consider the 

PTC. The aggregate WGA supply curve shows that at a price of $50/MWh, wind can 

supply more than 30 GW of capacity. At $60/MWh, the quantity of wind that can be 

supplied is more than 100 GW. Clearly the barrier to developing significant wind 

generation in the West is not hindered by the resource itself. The primary barriers are 

related to transmission availability and other issues discussed elsewhere in this report. 

Wind supply curves were derived under three cases. The first case assumes that 20% of 

the existing transmission capacity is available to deliver wind to load. When that 

transmission capacity is exhausted, new transmission is built to the nearest city, and the 

remaining wind energy supplies up to 20% of the city’s energy. 

The second supply curve case assumes that there is no capability on the grid that can 

deliver wind. Therefore, transmission must be built to deliver all the wind energy to load. 

The third supply curve case is the same as the second case, but stops once 30 GW of 

wind capacity has been developed. This case shows the contributions of each state and 

the upper bound cost of 30 GW of wind in the WGA footprint. 

7
 30

 40

 50

 60

 70

 80

 90

 0 100000 200000 300000 400000 500000

Cost ($/MWh)

Installed Capacity (MW)

Wind Energy Supply Curve - 20% of Existing Lines and 20% of Peak City Demand - Total

Total supply - Total

Class 3 - Total

Class 4 - Total

Class 5 - Total

Class 6 - Total

Class 7 - Total

Cost does not include wheeling cost, integration cost, distribution cost or PTC

Figure 3. Wind supply curves for WGA states assuming 20% available transmission

8
 30

 40

 50

 60

 70

 80

 90

 0 5000 10000 15000 20000 25000 30000 35000 40000 45000

Cost ($/MWh)

Installed Capacity (MW)

Wind Energy Supply Curve - 20% of Peak City Demand - Total

Total supply - Total

Class 3 - Total

Class 4 - Total

Class 5 - Total

Class 6 - Total

Class 7 - Total

Cost does not include wheeling cost, integration cost, distribution cost or PTC

Figure 4. Wind supply curves for WGA states assuming no available transmission; wind pays for all 

transmission 

9
 30

 40

 50

 60

 70

 80

 90

 0 5000 10000 15000 20000 25000 30000 35000

Cost ($/MWh)

Installed Capacity (MW)

Wind Energy Supply Curve - 20% of Peak City Demand (30 GW) - Total

Total supply - Total

Class 3 - Total

Class 4 - Total

Class 5 - Total

Class 6 - Total

Class 7 - Total

Cost does not include wheeling cost, integration cost, distribution cost or PTC

Figure 5. Wind supply curves for WGA states assuming no available transmission, capped at 30 GW 

The impact of transmission availability is difficult to overstate. As shown in the graphs in 

Figure 3 and Figure 4, there is approximately five times more wind energy at $50/MWh 

in the first case (20% transmission capacity available) relative to the second case (zero 

capacity available – build-only case where wind pays for all transmission). At $60/MWh, 

these cases show that wind could supply more than 100 GW in the 20% transmission 

availability case and approximately 24 GW if new transmission is required to move all 

the wind energy. We believe that these two cases represent reasonable bounds on the 

quantities and costs of wind in the WGA footprint. We suspect that the actual costs and 

supplies lie in between these two cases. In the third case that caps wind energy at 30 GW, 

the supply curve indicates that 30 GW of wind is available in WGA at a cost of about 

$64/MWh or less, using the most conservative transmission assumptions. 

Table 1 collects some of the key points of the supply curves presented in Figure 3 and 

Figure 4 so that the impact of transmission can be more clearly seen. 

10
Table 1. Impact of Transmission on Wind Supply in WGA Footprint 

Price ($/MWh) Wind Supply 

(MW) at 20% 

Existing 

Transmission 

Availability 

Wind Supply 

(MW) with No 

Existing 

Transmission 

Availability 

Difference (MW) 

60 115,000 25,000 90,000

70 215,000 39,000 176,000

80 320,000 40,000 280,000

Detailed supply curves for each state for the 20% existing transmission availability 

scenario are shown in Appendix B. Figure 6 and Figure 7 below illustrate the impact of 

transmission on several key states. It is evident from the supply curve development that 

there is an enormous wind resource potential in the WGA states that is reasonably close 

to the transmission infrastructure and cost competitive with other resources. 

No Transmission Case

0

5000

10000

15000

20000

25000

MT SD WY

Wind MW Supply

$60/MWh

$70/MWh

$80/MWh

20% Transmission Case

0

20000

40000

60000

80000

100000

MT SD WY

Wind MW Supply

$60/MWh

$70/MWh

$80/MWh

Figure 6. Transmission impact on supply, selected states 

20% Transmission Case

0

2000

4000

6000

8000

10000

12000

14000

AZ NV ND NM

Wind MW Supply

$60/MWh

$70/MWh

$80/MWh

No Transmission Case

0

200

400

600

800

1000

1200

1400

1600

1800

2000

AZ NV ND NM

Wind MW Supply

$60/MWh

$70/MWh

$80/MWh

Figure 7. Transmission impact on supply, other selected states 

11
Selected States: Availability of Transmission and Impact on Supply 

Figure 8 re-arranges some of the data from some of the selected states above, and also 

includes the entire WGA footprint. The left panel of the graph shows the wind supply at a 

price of $60/MWh that would be available if no existing transmission were available, as a 

percentage of the wind supply if 20% of the existing transmission were available. The 

graph shows that across the WGA, the wind supply at $60/MWh is about 20% of the 

supply that could be available if 20% of the existing grid could be used to transport wind. 

There is clearly a large variation for individual states: in Montana less than 10% of the 

supply exists with no available transmission compared to the 20% transmission 

availability case. For the states of ND, SD, NM, and WY this percentage ranges from 

about 10%-20%, and for NV the percentage is about 60%. 

The right side of the graph shows a similar picture at a wind cost of $80/MWh. In this 

case just over 10% of the WGA wind supply exists if no existing transmission is 

available, compared to the 20% transmission availability case. No state shows more than 

30% of the supply when we compare the no existing transmission case to the 20% 

existing transmission case. These results show that there is not a one-size-fits-all quantity 

of wind that is stranded by lack of available transmission, and that for the WGA states as 

a whole about 20% of the supply at a $60/MWh cost can be tapped if no transmission can 

deliver wind to load. 

Wind Supply for Selected States and WGA: No Available 

Transmission as Percent of 20% Existing Transmission 

Available (@wind cost of $80/MWh)

0.0

10.0

20.0

30.0

40.0

50.0

60.0

70.0

MT ND WGA NM WY SD NV

State

Percent of Wind Supply

Wind Supply for Selected States and WGA: No Available 

Transmission as Percent of 20% Existing Transmission 

Available (@wind cost of $60/MWh)

0.0

10.0

20.0

30.0

40.0

50.0

60.0

70.0

MT ND SD NM WY WGA NV

State

Percent of Wind Supply

Figure 8. Selected state transmission impacts of transmission at wind costs of $60/MWh and $80/MWh

12
Transmission System Availability

Existing analyses on historic flows on major transmission paths in the Western 

Interconnection suggest the existing transmission system could be utilized more 

efficiently and provide transmission capacity for new wind resources. 

SSG-WI has conducted an analysis of actual flows for the years 1998-2002 using data 

from the WECC’s Extra High Voltage database. The graph below shows summary data 

from SSG-WI’s 2003 report on actual flows. The figure below shows the percentage of 

time that major transmission paths reached at least 75% of the Operating Transfer 

Capacity (OTC) limit during the highest summer, spring, and winter season from 1998-

2002. The data suggest that many paths operate significantly below their physical 

capacity. 

Path Loading - % of Time > 75% of Path OTC during a Seasonal 

Period

Maximum Seasonal Loadings for each Path 

Winter 98-99 thru Spring 2002 

0

10

20

30

40

50

60

70

80

90

100

19 27 50 22 47 30 36 3 8 6 35 48 17 66 65 15 31 23 NJD 20 49 18 16 45 32 24 5 26 46 34 14 51 4

Path Number

% Time > 75% OTC

50 %

25 %

Summer 

Spring 

Winter 

Figure 9. Estimated transmission congestion on key paths in the west. Source: Western 

Interconnection Transmission Path Flow Study, SSG-WI, February 2003 

Tapping the potential excess capacity on the existing transmission system is problematic 

under many existing open-access transmission tariffs. Many transmission tariffs 

differentiate between network service and point-to-point service. For point-to-point 

service, a generator can obtain firm service for a period of up to 10 years if sufficient 

available transmission capability (ATC) is available. Alternatively, non-firm service can 

be obtained for time periods up to 1 year. For ATC to be available, the transmission 

operator must assess whether the requested path capacity is available all year (or up to 10 

years for long-term service). If the path is projected to be constrained for even a few 

13
hours during the period, firm service won’t be offered and the generator must resort to 

obtaining non-firm service. 

For wind developers, lenders providing project financing require that the proposed 

project must be able to deliver the energy to market long-term. Non-firm transmission 

service, however, is reserved and scheduled on an as-available basis and subject to 

curtailment and interruption. Non-firm is also offered on a stand-alone basis for a limited 

duration of time, generally for a period of 1 month or less. This can jeopardize the 

financing and ultimate success of wind projects. 

These considerations have prompted a number of studies and potential policy changes. 

The proposals below would encourage a more efficient use of the existing transmission 

system and provide new transmission opportunities for wind energy generation. Followup studies have been proposed to further examine actual flows versus available ATC 

posted on transmission providers’ Open Access Same Time Information Systems 

(OASIS) sites for highly constrained paths. 

Wind Scenario Development

This section describes integrated resource plans (IRPs) and renewable portfolio standards 

(RPSs) in the West. IRPs and RPSs are helping drive wind development in some parts of 

the West, and the scenario development is based in part on this information. 

Wind in Western IRPs and RPS Requirements 

A recent study by Lawrence Berkeley Laboratory (LBL) by Bolinger and Wiser (2005) 

examined the implications for renewable energy under existing western utility IRPs and 

state RPS requirements. The information from this study provided the foundation for the 

specification of wind development Scenario One, described in a later section of this 

paper. 

The LBL study examined RPS states and attempted to quantify the types of renewable 

energy sources to be developed. But there remained a large portion of the RPS for which 

the type of renewable fuel is unspecified. Given the relative current prices of renewable 

generation, it is likely that the largest portion of this unspecified renewable source would 

go to wind. However, if prices of other renewable sources were to decline over the study 

horizon period, then we would expect relatively less wind and more generation from 

sources like solar. 

From the group of IRPs examined by LBL, it appears that more than 3,600 MW of wind 

capacity could be developed by eight utilities by 2014. This development is mainly 

concentrated in the Northwest, although Colorado would also develop a relatively large 

quantity of wind in this time frame under current IRP visions. 

14
Table 2. Wind Additions from IRPs in the West (LBL) 

Cumulative Wind (MW)

2004 2005 2006 2007 2008 2009 2010 2011 2012 2013 2014

Wind: Pacificorp 0 0 100 300 500 700 900 1100 1300 1420 1420

Wind: Idaho Power 0 0 100 200 200 200 350 350 350 350 350

Wind: Avista 0 0 0 0 18 18 75 75 75 75

Wind: PGE 0 0 0 195 195 195 195 195 195 195 195

Wind: PSE 0 150 150 350 350 550 550 750 750 900 900

Wind: Northwestern 0 150 150 150 150 150 150 150 150 150 150

Wind: SDG&E 0 0 0 0 0 0 0 6 11 17

Wind: PSCo 0 500 500 500 500 500 500 500 500 500 500

75

22

Total 0 800 1000 1695 1913 2313 2720 3126 3331 3607 3612

Some highlights of the IRP information are included here (Bolinger and Wiser, 2005). 

1. PacifiCorp: 65 MW near Idaho Falls, ID (Wolverine Creek). According to a 

presentation given at the IRP Public Input meeting 

(www.pacificorp.com/File/File52811.pdf), there are a dozen projects on the short 

list, comprising 1800 MW of wind capacity. This is expected to be split between 

PacifiCorp’s east and west systems, but details are not available. Based on 

information obtained from “Plans for PacifiCorp” (OregonLive.com, Jul 16, 

2005), PacifiCorp is planning to build 100 MW of wind without the need for 

additional transmission. However, an additional 300 MW of planned wind will 

require new transmission upgrades. 

2. Idaho Power: Assume approximately 350 MW from the Idaho region by about 

2014. According to Idaho Power’s plan, the wind would likely be within the 

control area, so transmission costs are not developed or reported. 

3. Avista: About 75 MW of wind capacity, location to be determined according to 

LBL analysis. Avista has installed 35 MW of wind and is looking for a larger 

addition in the 2005 IRP (in process). Location will matter only relative to 

economics and transmission access/cost. 

4. PGE: Most likely to add wind in the Columbia Gorge area (estimated 195 MW). 

5. Puget Sound (SE of Seattle): about 900 MW of wind capacity is anticipated in 

the Columbia Gorge or central Washington. 

6. Northwestern: Most/all additions, 150 MW total, are likely to be developed in 

Montana. Transmission expansion costs are not stated, but presumably the wind 

development would fall within Northwestern’s control area. 

7. SDGE: Beginning a study, but it is not clear where wind will be developed. 

SDGE has indicated that it has a 20% RPS-like goal. 

8. PSCo: Likely wind in eastern CO, possibly near the Wyoming state line, and 

additional capacity near Lamar. The need for new transmission is unclear. 

Although the transmission system may need expansion, PSCo is apparently 

planning to develop wind within its control area and has not provided cost 

estimates for transmission. 

The California utilities PG&E, SCE, and SDG&E have provided some insight regarding 

anticipated transmission needs for renewable energy procurement but have not 

communicated a plan or timetable to address these needs. SCE is evaluating potential 

15
transmission expansion in the Tehachapi region, and PG&E has estimated a potential 

transmission cost of $170 million to $230 million to meet its 20% renewable energy 

target (Bolinger and Wiser, 2005). 

According to Bolinger and Wiser, “Especially as wind additions grow in the West, it will 

be necessary to develop and incorporate into IRPs improved assessments of the 

transmission costs of accessing varying quantities of wind generation. Few resource plans 

currently incorporate this capability, instead choosing to establish strict and sometimesarbitrary limits on the amount of wind additions allowed.” 

In California there is considerable effort to determine the location of potential renewable 

generation to meet the RPS, and the associated transmission required to bring the energy 

to market. According to a consultant’s report for the California Energy Commission 

(2005), “There is inadequate information on the extent to which the grid design is 

adequate for deliverability during non-peak time periods” and “There is no 

comprehensive region-wide peak and non-peak evaluation of the grid’s performance and 

potential impacts on transfer capability, as a result of a changing resource mix. Such an 

evaluation would help California utilities and others in the WECC to better understand 

what, if anything, they need to do to maintain existing transmission path ratings.” The 

report recommends that transmission studies should be improved so that appropriate 

decisions can be made regarding transmission expansion and renewable locations. 

In these cases, transmission is an issue that the utilities are examining with varying 

degrees of effort and precision, although generally transmission adequacy has not been 

thoroughly considered relative to possible renewable development plans. In many cases, 

the location of the wind development could be in part determined by transmission access. 

In other cases, relatively short lines could potentially be built to connect the wind plant to 

the existing grid. Beyond these general observations, the role of the existing, constrained 

transmission system is not immediately apparent. By implication, it is not clear how 

much wind energy can be developed without improvements to transmission utilization or 

additional transmission or both. 

Another aspect of renewable development in California is the “least cost, best fit” 

requirement. If the utility needs tend toward a specific type of generation, such as base 

load, then it is possible that renewable generation that have characteristics of base load 

generation (like biomass or geothermal) could be chosen, even if the energy price is 

higher than wind. Because this outcome is uncertain, the Wind Task Force report 

included several potential cases that illustrate the impact of these alternative development 

possibilities. 

Eight WGA states have recently enacted RPS or Energy/Environmental Portfolio 

Standards (EPS) to encourage the development of renewable energy resources such as 

solar, wind, biomass, and geothermal energy. An EPS/RPS requires electric utilities in 

the state to generate a certain percentage of electric energy from renewable energy 

sources. The requirements generally only apply to investor-owned utilities; however, 

Colorado’s applies to any utility with more than 40,000 customers. (However, rural 

cooperatives can opt out with a vote of their members.) Other states frequently encourage 

16
municipal and rural electric cooperatives to adopt similar requirements. The following 

table shows the current requirements in WGA states. Arizona and California are 

considering changes to their programs. 

Table 3. Renewable Portfolio Standards in WGA States2

State Date 

Enacted 

Requirements 

Arizona 2001 0.2% in 2001, increasing to 1.1% in 2007-2012 

50% solar electric in 2001-2003; 60% solar electric in 2004-2012

California 2002 

revised in 

2004 

20% by end of 2010 

Goal for 33% by 2020 

Colorado 2004 3% by 2007; 6% by 2011; 10% by 2015 

4% or the renewable energy must come from solar electric generation 

technologies; 1/2 of this 4% located on-site at customers' facilities

Hawaii 2001 

revised in 

2004 

7% by end of 2003; 8% by end of 2005, 10% by end of 2010, 15% by end 

of 2015, 20% by end of 2020 (including existing renewables) 

Montana 2005 5% in 2008; 10% in 2010; 15% in 2015 

Nevada 2001 

revised in 

2005 

6% in 2005, rising to 20% by 2015 

5% of the energy portfolio must be solar 

part of the requirement may be met by energy savings from efficiency 

measures 

New Mexico 2002 

revised in 

2004 

5% in 2006, rising to 10% in 2011 

Some sources have a higher "value" for accumulating credits (wind 1 

credit per kilowatt-hour, solar 3 credits per kilowatt-hour)

Texas 1999 

revised in 

2005 

Renewable generation capacity of 2,280 MW in 2008 rising to 5,880 in 

2015 (about 5% of state demand), 500 MW other than wind; 

goal of reaching 10,000 MW in 2025 

Source: Database of State Incentives for Renewable Energy 

Figure 10 is from Bolinger and Wiser (2005) and shows approximately 3,600 MW of 

wind development by 2014, according to published load serving entity resource plans. 

 

2

 This table shows RPS requirements in place at the time the Wind Task Force report was developed. Since 

that time, the Arizona Corporation Commission approved increasing the portfolio mix to 15% renewables 

by 2025 and an additional requirement that 30% of the renewables come from distributed generation 

resources. This was under review at the Arizona Attorney General’s office at the time of this writing. 

17
0

500

1,000

1,500

2,000

2,500

3,000

3,500

4,000

2004 2005 2006 2007 2008 2009 2010 2011 2012 2013 2014

Projected Online Date

Nameplate Capacity (MW)

Wind: SDG&E

Wind: Avista

Wind:

Northwestern

Wind: PGE

Wind: Idaho

Power

Wind: PSCo

Wind: PSE

Wind: Pacificorp

Other Resources:

Idaho Power and

SDG&E

PSE

By 2014:

- 3,610 MW of Wind

- 190 MW of Other 

Renewables

Figure 10. Wind development in IRPs analyzed by LBL 

Figure 11, also from Bolinger and Wiser (2005) illustrates potential wind development 

from RPS requirements in the WGA region. According to this analysis, full 

implementation of RPS requirements in the WGA region would add nearly 10,000 MW 

of wind by 2015. 

12,000

10,000

8,000 Arizona

Texas

Figure 11. LBL’s estimate of wind development induced by RPS requirements in the West 

0

2,000

4,000

6,000 MW Nevada

New Mexico

Colorado

California

Hawaii

2005 2006 2007 2008 2009 2010 2011 2012 2013 2014 2015

Year

18
Wind Scenarios 

Based on the supply curve analysis, RPS requirements, and IRP evidence described 

above, we develop three scenarios that represent alternative projections of the future 

under a different set of assumptions. These three scenarios are described as follows: 

Scenario 1. Wind development that is either in progress or can be reasonably 

assumed to occur based on existing plans with minimal new transmission additions. 

Evidence from prior work on the ability of new transmission tariffs and related policy 

implementation was assumed to help stimulate wind additions. This represents a nearterm goal. 

Scenario 2. Wind development that would occur with additional transmission 

expansion as identified and analyzed in sub-regional or regional transmission studies. 

Some of this wind development could possibly occur with minimal transmission 

additions, but the additional wind in this scenario needs new transmission. Some of 

this transmission expansion is already under study and would not be built for wind 

alone. Most of this development can be located either to the individual connection 

point, county, transmission corridor, or other geographic location within the state. 

While not all of this wind capacity will be built per se, it represents a realistic path to 

the future if transmission availability is not a barrier. The exception is Nebraska, a 

state with significant potential that has not yet been subject to detailed transmission 

analysis. 

Scenario 3. Wind development that is harder to predict than in the previous 

scenarios. In some cases this wind development is under study but may depend on 

specific expansion of the grid or combinations of policy evolution. These also 

represent scenarios that have been analyzed under “high-wind” expansion scenarios. 

In Kansas we have identified a significant quantity of potential wind development 

that has not, to our knowledge, been subject to detailed transmission studies. 

Therefore, it is possible that additional wind development is currently under 

consideration in the WGA but has not yet been analyzed by subregional or regional 

transmission groups. The rapid recent pace of wind development suggests that the 

prediction offered by this scenario is imprecise. 

Possible Near-Term Wind Development without Transmission Expansion 

To construct a plausible reference case that does not depend on transmission expansion, 

we have examined preliminary rough estimates of the development path in the Northwest 

Transmission Assessment Committee (NTAC) area. It is important to point out that the 

modeling effort at NTAC has not been completed, so this information will certainly 

change once those results become available. The wind development that could be 

reasonably anticipated in the Northwest is approximately 35% of the development that is 

likely to occur if there is some transmission expansion. 

19
In the Northwest region, the Bonneville Power Administration (BPA) has devoted 

considerable effort to developing a new transmission tariff. Although this is still in 

process, the objective is to offer additional transmission that is considered as conditional 

firm on paths that have little or no ATC. As part of the process of examining the level of 

conditional firm service that BPA could provide, BPA also recalculated ATC on several 

key transmission corridors and found several hundred megawatts of additional ATC. The 

“no-transmission” scenario in the Northwest therefore depends on some combination of 

new ATC and conditional firm transmission capacity becoming available. Therefore, the 

no-transmission case is not a business-as-usual scenario but instead a scenario that 

incorporates more efficient usage of the existing wires. 

Additional non-wires alternatives would potentially include (a) the release or re-use of 

unused ATC, and (b) the development and use of real-time line ratings. The latter would 

improve the odds of uncovering additional ATC because static line ratings are used on 

many paths. There is a need to study and identify, in a comprehensive way, grid locations 

that are favorable for near-term generation additions that require no or minimal grid 

upgrades. 

Because utilities have not thoroughly evaluated transmission needs relative to renewable 

requirements, it is not possible to predict with confidence a level of wind generation that 

would be stranded by the lack of transmission. If we assume that other areas within the 

WGA footprint are similar to the Northwest, with new transmission tariffs and additional 

ATC resulting from more detailed analysis, then it might be reasonable to predict that 

approximately 35% of the low-end 2015 wind scenario (developed in a later section of 

this report) would occur. This would represent approximately 9 GW of wind. Without the 

development of new transmission tariffs and revised ATC calculations, perhaps 20% of 

the wind scenario would be developed (approximately 5 GW). These numbers have not 

been confirmed by detailed transmission modeling, which would increase our confidence 

in the estimates. 

Scenario 1 assumes an additional wind capacity of 5,000-9,175 MW by 2015. As 

discussed below, the lower end of this range, 5,000 MW of wind capacity, is likely if 

there is no significant increase in the usage efficiency of the existing transmission system, 

such as re-evaluation of ATC or flexible-firm transmission service. If these and other 

institutional improvements can increase the grid efficiency, it is possible that about 9,000 

MW of wind can be accommodated with no significant transmission additions. 

20
Washington

1090

Oregon

625

California

3300

Montana

470

Wyoming

355

Colorado

500

New Mexico

150

North Dakota

125

South Dakota

250

Nebraska

0

Kansas

250

Texas

1000

Total: 9,175 MW

Western Governors’ Association

Wind Additions: Scenario 1

Nevada

679

Arizona

156

Utah

100

Idaho

125

Figure 12. WGA Scenario 1 

Other Analyses of Wind and Transmission 

One primary goal of the CDEAC Wind Task Force is to identify the possible locations 

and sizes of wind development in the WGA region in the 2015 time frame. The primary 

source of information for this material is the large and growing body of work undertaken 

by regional and subregional transmission planning groups in the west. In Texas we used 

information developed by ERCOT and incorporated recent and ongoing work from the 

Midwest Independent System Operator (MISO) and the Southwest Power Pool (SPP). 

The Kansas Energy Council has developed detailed information about possible wind 

development in that state, including locations, capacity, and the wind developer that is 

anticipated to build the wind plants. In addition, we consulted recent work by the BLM, 

which utilized a GIS database and modeling from NREL to analyze wind development 

relative to BLM lands in the west. The GIS and modeling used by the BLM work is the 

same as that used by the CDEAC Wind Task Force to develop the supply curves for 

wind. 

All the data we examined are not equally solid. For example, the Northwest Transmission 

Assessment Committee (www.nwpp.org/ntac/) has developed a detailed set of scenarios 

of likely wind development in the Northwest. Many of the projects are in process, or have 

obtained, permits required for construction. 

21
The Rocky Mountain Area Transmission Study (RMATS) analyzed several scenarios for 

generation expansion trajectories in the West. Some of these scenarios included 

significant wind generation, but much of that wind generation would be stranded under 

the current transmission configuration (although this difficulty is shared by other 

generation fuels also). SSG-WI developed a similar set of scenarios in the transmission 

study undertaken in 2003 and was updating that work while the Wind Task Force report 

was in process. 

The Kansas Energy Council has a detailed wind scenario that describes potential wind 

development in that state. The SPP has performed a transmission study examining parts 

of Texas, Oklahoma, and Kansas (those portions in the Eastern Interconnection). Because 

the SPP work did not cover the entire state of Kansas, we used only the Kansas Energy 

Council information in developing the single scenario for Kansas. 

MISO is in the advanced stages of the Northwest Exploratory Study, which examines the 

congested transmission paths moving from the Dakotas to the load centers in Minnesota. 

The study examines the impact of more than 1,000 MW of wind in the Dakotas. In its 

previous transmission planning effort known as MTEP 2003 (MISO Transmission 

Expansion Plan), MISO analyzed 4,500 MW of wind capacity in the Dakotas. 

Of the states we analyzed, Arizona and Nebraska were the most difficult. Although 

Arizona has an excellent solar resource, its wind resource is less than what is found in 

many other WGA states. Although this can be confirmed by examining wind resource 

maps, these maps do not always recognize high-quality wind sites that may be too small 

or too difficult to capture by the GIS mapping processes. Many wind capacity trajectories 

for Arizona are null. However, we received information from the Arizona Wind Working 

Group that between 2,800 and 3,300 MW of wind capacity is currently under predevelopment consideration. It is hard to know the likelihood of so much wind in Arizona, 

and these estimates are higher than what we expected. One factor that favors wind 

development in Arizona is that the state has a significant load, even though transmission 

from wind regions to load centers would be an issue. But compared to high-resource/lowload states such as Wyoming and Montana, which would both require longer lines to 

deliver wind energy to load, the required transmission in Arizona would be less by 

comparison. 

In Nebraska, utilities and utility customers have not expressed an interest in wind energy. 

As a result, wind development plans in Nebraska are essentially non-existent. A 

deliberative poll was carried out in Nebraska that indicated a high level of consumer 

interest in developing wind generation. If the deliberative poll accurately represents 

consumer preference in Nebraska, and if this preference is translated into policy or utility 

action, it is possible that significant wind development could take place. But under the 

business-as-usual scenario, and given the 73 MW of existing wind capacity in Nebraska, 

it is difficult to project likely outcomes over the 10-year horizon. The result is that we 

have a very large range of plausible wind development in Nebraska and little useful 

information to help determine the likely path that this development will take. 

22
Scenario 2 postulates 25,266 MW of new wind development as shown below. Scenario 3 

is the high case scenario with 54,724 MW of additional wind capacity. Some of the 

Scenario 3 capacity may be intended for import to California markets that could be 

displaced by in-state wind development in California. This potential inconsistency is 

discussed later in this report. 

23
Washington

1090

Oregon

1405

California

7535

Montana

470

Wyoming

1900

Colorado

1000

New Mexico

200

North Dakota

500

South Dakota

750

Nebraska

100

Kansas

2500

Texas

3641

Total: 25,266 MW

Western Governors’ Association

Wind Additions: Scenario 2

Nevada

1150

Arizona

2800

Utah

100

Idaho

125

Figure 13. WGA Scenario 2 

Washington

2247

Oregon

2753

California

9303

Montana

2100

Wyoming

5355

Colorado

1750

New Mexico

6000

North Dakota

2900

South Dakota

2900

Nebraska

1000

Kansas

2500

Texas

8641

Total: 54,724 MW

Western Governors’ Association

Wind Additions: Scenario 3

Nevada

2770

Arizona

3300

Utah

570

Idaho

635

Figure 14. WGA Scenario 3 

24
Discussion of Selected Key States 

In this section, we examine some key points that relate the supply curves with various 

elements of the wind scenarios found in transmission studies. Some interesting 

observations can be made by looking at South Dakota, a state with an enormous wind 

resource. Of the transmission planning efforts that we are aware of, the highest wind 

scenario for South Dakota is 3,150 MW. The results of the supply curve for South Dakota 

(using the assumptions that 20% of existing transmission is available for wind and new 

lines are built when that is exceeded) indicate that there is more than 3,500 MW of wind 

in South Dakota at a price of $50/MWh or less. At $60/MWh, the quantity of wind 

increases to almost 24,000 MW. When this is compared to our supply curve Scenario 3 

that builds up to 30,000 MW in the WGA footprint by building all transmission, South 

Dakota shows about 200 MW of wind at a price of $50/MWh or less and about 3,000 

MW of wind at a price of $60/MWh or less. Clearly, transmission constraints strand a 

very large portion of wind in South Dakota. This is also true in other states, although to a 

lesser extent, in the WGA footprint. 

25
 30

 40

 50

 60

 70

 80

 90

 0 50000 100000 150000 200000 250000

Cost ($/MWh)

Installed Capacity (MW)

Wind Energy Supply Curve - 20% of Existing Lines and 20% of Peak City Demand - South Dakota

Total supply - South Dakota

Class 3 - South Dakota

Class 4 - South Dakota

Class 5 - South Dakota

Class 6 - South Dakota

Class 7 - South Dakota

 30

 40

 50

 60

 70

 80

 90

 0 1000 2000 3000 4000 5000 6000 7000

Cost ($/MWh)

Installed Capacity (MW)

Wind Energy Supply Curve - 20% of Peak City Demand (30 GW) - South Dakota

Total supply - South Dakota

Class 3 - South Dakota

Class 4 - South Dakota

Class 5 - South Dakota

Class 6 - South Dakota

Class 7 - South Dakota

Figure 15. South Dakota wind supply curves with (a) 20% availability of existing transmission 

and (b) no available existing transmission. 

26
It is also worth noting that the capacity that appears in the tables is not always consistent. 

The New Mexico Wind Task Force (not part of CDEAC) has developed a wind export 

scenario that would provide for approximately 4,000 MW to 6,000 MW of wind capacity 

in New Mexico that would deliver energy to load centers in Arizona or California, 

possibly using a high-voltage DC line. Examination of the California supply curve (20% 

of Existing Lines and 20% of Peak City Demand) shows approximately 9,000 MW of 

wind in California at a cost of $60/MWh or less. On the New Mexico supply curve, we 

see approximately 6,000 MW of wind supply at just over $55/MWh. Given the costcompetitiveness of the wind resource in California with the resource in New Mexico, it is 

not clear that a New Mexico export case would be the preferred way to deliver wind 

energy to California. Further analysis and refinement would be necessary to answer this 

question. However, unless the New Mexico wind is used to export to Arizona load 

centers, a scenario with 6,000 MW to 8,000 MW of wind in California and 4,000 MW to 

6,000 MW of wind in New Mexico may not be consistent. 

 30

 40

 50

 60

 70

 80

 90

 0 5000 10000 15000 20000 25000 30000 35000 40000 45000

Cost ($/MWh)

Installed Capacity (MW)

Wind Energy Supply Curve - 20% of Existing Lines and 20% of Peak City Demand - California

Total supply - California

Class 3 - California

Class 4 - California

Class 5 - California

Class 6 - California

Class 7 - California

 30

 40

 50

 60

 70

 80

 90

 0 2000 4000 6000 8000 10000 12000 14000

Cost ($/MWh)

Installed Capacity (MW)

Wind Energy Supply Curve - 20% of Existing Lines and 20% of Peak City Demand - New Mexico

Total supply - New Mexico

Class 3 - New Mexico

Class 4 - New Mexico

Class 5 - New Mexico

Class 6 - New Mexico

Class 7 - New Mexico

Figure 16. New Mexico wind supply curve assuming 20% of existing transmission is available 

for wind.

27
Conclusions and Summary 

The supply curves developed for the Wind Task Force illustrate that a very significant 

wind potential exists in the WGA states. It is also clear that transmission is a potential 

barrier to much of this wind development, and the no-transmission supply case illustrates 

the magnitude of this impact. However, although these supply curves have been 

developed with the best information available, there are several caveats. Most of the 

wind-speed data are from 50 meters, significantly lower than the hub height of modern 

wind turbines. We were unable to represent advances in turbine technology. In addition, 

our transmission availability assumptions, along with static line ratings, will compromise 

these results. However, we believe that these supply curves and scenario developments 

represent valuable information that can be used to help analyze future wind development 

in the WGA states. 

This work also highlights the need for map/GIS data that is at hub-heights that are 

representative of current and future wind developments. However, states such as TX and 

NB do not even have data that correspond to the other states within the WGA footprint, 

which significantly clouds our ability to assess potential wind development in those states 

(although TX appears to be off to an ambitious start). 

Conceptual plans to build large wind plants so that the energy can be exported to large 

power markets are not necessarily coordinated with plans to serve the load. This is 

apparent in looking at the NM export plan. Although this plan appears plausible and may 

indeed unfold, it is not clear that CA would be interested in purchasing this wind energy. 

Further work is required to evaluate the possibilities related to this scenario. 

It is also clear that increasing the utilization of the existing transmission grid may offer 

the ability to transport wind and other sources of electricity to markets. In the absence of 

incentives or tariff reform however, some power sources may be required to pay for new 

transmission which may not be the least-cost solution. 

Acknowledgements 

We thank Donna Heimiller and George Scott of NREL for their significant contributions 

to the supply curve development effort. 

28
Appendix A 

Western Governors’ Association 

Clean and Diversified Energy Initiative 

Wind Task Force Members

Chair: Rachel Shimshak, Renewable Northwest Project 

Hap Boyd, GE Wind 

James Caldwell, PPM (Pacific Power Marketing) 

Steve Dayney and Mark McGree, Xcel Energy 

Steve Ellenbecker, Wyoming Governor’s Office 

Robert Fullerton, Western Area Power Administration 

Robert Gough, Intertribal Council on Utility Policy 

Roger Hamilton, Wind on the Wires (West) 

Ron Lehr, American Wind Energy Association 

Elliot Mainzer and Allan Ingram, Bonneville Power Administration 

Mac McLennan, Tri-State Generation and Transmission 

Michael Milligan, National Renewable Energy Laboratory 

Lee Otteni, Bureau of Land Management 

Brian Parsons, National Renewable Energy Laboratory 

Jim Ploger, Kansas Corporation Commission 

Steve Ponder, FPL Energy 

Ron Rebenitsch, Basin Electric 

Virinder Singh, PacifiCorp 

Ronn Smith, Wyoming Outdoor Council 

Jim States, Rocky Mountain Oilfield Testing Center 

Chris Wentz, New Mexico Energy and Minerals Department 

Weston Williams, Kevin M. Payne, and Warren Weinstein, Southern California Edison 

Staff Support 

Doug Larson, Western Interstate Energy Board 

Thomas Carr, Western Interstate Energy Board 

Will Singleton, Resolve 

Acknowledgement: 

Bill Schroeder of Intermountain Rural Electric Association participated in the Wind Task 

Force but did not support the report’s final conclusions. 

29
Appendix B 

State Wind Supply Curves Assuming 20% Existing Transmission Availability 

30
Figure 17. Arizona and California wind supply curves assuming 20% of existing transmission is 

available for wind. 

31
Figure 18. Colorado and Idaho wind supply curves assuming 20% of existing transmission is 

available for wind. 

32
Figure 19. Kansas and Montana wind supply curves assuming 20% of existing transmission is 

available for wind. 

33
Figure 20. Nebraska and Nevada wind supply curves assuming 20% of existing transmission is 

available for wind. 

34
Figure 21. New Mexico and North Dakota wind supply curves assuming 20% of existing transmission 

is available for wind. 

35
Figure 22. Oregon and South Dakota wind supply curves assuming 20% of existing transmission is 

available for wind. 

36
Figure 23. Texas and Utah wind supply curves assuming 20% of existing transmission is available for 

wind. 

37
Figure 24. Washington and Wyoming wind supply curves assuming 20% of existing transmission is 

available for wind. 

38
Figure 25. Total WGA area wind supply curves assuming 20% of existing transmission is available 

for wind. 

39
Appendix C 

Detailed Wind Scenarios 

The tables and maps on the following pages illustrate the amount and location of 

potential wind development under the three scenarios developed from existing 

transmission studies and from the California Energy Commission. 

In the tables, the columns labeled 2015 Range of Installed Capacity do not represent 

maximum and minimum wind capacities; they illustrate plausible ranges of development 

based on existing information, assuming that the required grid expansion takes place. 

The list that follows should provide a rich set of locations and capacities for the CDEAC 

Integration and Transmission Task Forces for the next steps of the CDEAC process. As 

with the previous work in SSG-WI and RMATS, it is likely that some new transmission 

would be required regardless of the specific scenario and its resource mix. 

Each table shows the location and capacity estimate of wind generation, a numbered key 

to the maps that appear in Figure 26 and Figure 27 (both maps are the same – one shows 

transmission and the other doesn’t), and the CEC estimates (the CEC estimates cover 

only the WECC) for comparison. 

Table Keys: 

• NTAC = Northwest Transmission Assessment Committee 

• RMATS = Rocky Mountain Area Transmission Study. The number after the 

“RMATS” designates the RMATS scenario number (i.e., RMATS/4 is Scenario 4 

from RMATS) 

• CEC/SVA = California Energy Commission Strategic Value Analysis 

• MISO/NW = Midwest Independent System Operator Northwest Exploratory 

Study 

• MTEP 2003 = MISO Transmission Expansion Plan, 2003 

40
Table 4. Wind Development Scenario 1: No Transmission Upgrades 

41
Table 5. Wind Development Scenarios 2 and 3. Note that Map Key refers to Figure 26 and Figure 27 

Wind Development Scenarios 2 and 3 

Substation/Location 2015 Range of Map Key CEC

Installed Capacity

Washington NTAC NTAC

Hopkins Ridge Walla Walla 115 kV 150 150 2

Wild Horse Vantage 230 kV 240 240 1

Wild Horse 2 Vantage 230 kV 120 120 1

Big Horn Big Eddy 230 kV 250 250 2

Last Mile Co-op Big Eddy 230 kV 200 200 2

Saddleback 70 2

Columbia Wind 80 2

Columbia Hills 125 2

Goodnoe Hills 150 2

Kittitas Valley 236 1

Desert Claim 159 1

Roosevelt 100 2

Nine Canyon II 33 2

Stateline (Sacajawea) 100 2

Other Big Eddy 230 kV 130 130 2

Unspecified 104

Subtotal Washington 1090 2247 899

42
Substation/Location 2015 Range of Map Key CEC

Installed Capacity

Oregon NTAC NTAC

Klondike 2 Big Eddy 230 kV 75 75 2

Klodike 3/Orion John Day 500 kV 300 300 2

Klodike 3/Orion John Day 500 kV 600 600 2

Arlington/Leaning J. Dalreed 230 kV 100 100 2

Arlington/Leaning J. Dalreed 230 kV 200 200 2

Willow Creek 180 2

Shepherds Flat 1000 2

Combine Hills 63 2

Other Dalreed 230 kV 130 130 2

Unspecified 105

Subtotal Oregon 1405 2753 899

Substation/Location 2015 Range of Map Key CEC

Installed Capacity

Idaho RMATS NTAC

Ridgeline Goshen 161 kV 125 65 12

Hagerman Upper Salmon 138 kV 50

Cotterel Mountain Minidoka 138 kV 200 6

Burley Minidoka 138 kV 20 6

Other ID Goshen 161 kV 150 12

Other ID Midpoint 150

Subtotal Idaho 125 635 18

Montana NTAC NTAC

Judith Gap Judith Gap 230 kV 150 150

Gore Hill Great Falls 230 kv 10 10

Other MT Great Falls 230 kv (?) 310 310

Subtotal Montana 470 470

2015 Range of Map Key CEC

Installed Capacity

California CEC/SVA (4GW Tehachapi)

Solano Vaca-Dixon 100 100 3

Solano Vaca-Dixon-Contra Costa 275 275 3

Alameda Contra Costa-Tesla 132 132 3

Los Angeles - Kern Pardee-Vincent 2376 2376 4

Los Angeles-Kern Tehachapi 500 500 4

San Diego Los Coches-Miguel 700 700 4

Imperial 82 82 5

San Diego Glencliff 50 50 5

Riverside 1416 1416 5

San Bernardino Etiwanda 280 280 4

Additional Tehachapi 1624 3392 4

Subtotal California 7535 9303 4800

43
2015 Range of Map Key CEC

Installed Capacity

Nevada Dracker

NV State 

Office of 

Energy

Northern NV/Pacific DC Intertie 1150 1150 8

Northern NV 1620 7

Subtotal Nevada 1150 2770 442

2015 Range of Map Key CEC

Installed Capacity

Colorado (RMATS)

RMATS/3 

and CEC

RMATS/4

Colorado East 800 1500 27

Colorado West 200 250 26

Subtotal Colorado 1000 1750 1006

2015 Range of Map Key CEC

Installed Capacity

Wyoming RMATS RMATS/2 RMATS/4

WY-Big Horn Basin 250 250 21

WY-Jim Bridger 0 230 23

Wy-Central 0 800 24

WY-Southwest 1150 2450 23

WY-Black Hills 0 125 22

WY-Laramie River 500 1500 25

Subtotal Wyoming 1900 5355 698

2015 Range of Map Key CEC

Installed Capacity

Utah RMATS RMATS/2 RMATS/4

UT-North 100 320 13-14

UT-South 0 250 15-16

Subtotal Utah 100 570 413

2015 Range of Map Key CEC

Installed Capacity

Montana RMATS NTAC RMATS/4

MT-West 150 1000 11

MT-Broadview 310 1000 20

MT-Colstrip 10 100 40

Subtotal Montana 470 2100 767

44
2015 Range of Map Key CEC

Installed Capacity

CEC

Task Force, 

Governor's 

Office

New Mexico Task Force 200 6000 28-29 200

2015 Range of Map Key

Installed Capacity

North Dakota MISO MISO/NW MTEP 2003

Central/Antelope Valley 250 250 30

Near Ellendale 250 250 31

Unspecified 2400

Subtotal North Dakota 500 2900

2015 Range of Map Key

Installed Capacity

South Dakota MISO MISO/NW MTEP 2003

Near Ellendale 250 250 31

Huron 250 250 33

Watertown/Blair 250 250 32

Unspecified 2150

Subtotal South Dakota 750 2900

Substation/Location 2015 Range of Map Key

Installed Capacity

Subtotal Nebraska Potential 100 1000 34

Substation/Location 2015 Range of Map Key

Installed Capacity

Kansas - KS Energy Council

RES-W Central (From Energy Council 30 30 35

HMH Energy SW map) 200 200 36

Zilkha SE 100 100 39

Clipper SW 100 100 38

EnXco SW 100 100 38

TradeWind N Central 250 250 37

Zilkha N Central 250 250 37

Orion NE 100 100 39

DisGen E 150 150 39

JW Prairie E 120 120 39

TradeWind E 201 201 39

Greenlight/HMH SE 150 150 39

Greenlight SE 300 300 39

TradeWind SE 200 200 39

Unspecified 249 249

Subtotal Kansas 2500 2500

45
46

Substation/Location 2015 Range of Map Key

Installed Capacity

Texas ERCOT/Legislature Brief

Panhandle (Amarillo) 236 2236 40

South Plains (Lubbock) 80 1080 41

Far West (Guadalupe) 0 200 42

McCamey 750 1250 43

Morgan/Sweetwater 1100 1400 44

Abilene 1175 1475 48

Vernon 0 200 45

South Coast 300 800 47

Subtotal Texas 3641 8641

2015 Range of Map Key

Installed Capacity

800 10

00 17

00 18

300 19

00

,724

Arizona WWG

Mohave County (NW) 700

Coconino County (N Central) 900 11

Navajo/Apache Counties (NE) 1000 11

Cochise/Graham Counties (SE) 200

Subtotal Arizona 2800 33

WGA Total 25,266 54
7

8

9

3

4

5

2

1 11

20

21 22

25 23 24

26 27

6a 12

14

13

16

15

30

31

32

33

28

29

18 10 17

19

35 39

36 38

37

34

40

41

47

43 44

48

45

46

42

6b

47

Figure 26. Location of wind scenarios showing transmission grid 
48

7

8

9

3

4

5

2

1 11

20

21 22

25 23 24

26 27

6a 12

14

13

16

15

30

31

32

33

28

29

18 10 17

19

35 39

36 38

37

34

4041

47

43 44

48

45

46

42

6b

Figure 27. Location of wind scenarios without showing transmission grid 
Appendix D: Data Sources and Wind Capacity Estimates 

NTAC (Northwest Transmission Assessment Committee). Study in progress July 2005. 

RMATS (Rocky Mountain Area Transmission Study, Phase 1, 2004). Alternative 

scenarios. 

CEC/SVA (California Energy Commission, Strategic Value Analysis, in process July 

2005). Paper presentation at Windpower 2005. 

CEC/SSG-WI (California Energy Commission Proposed Reference Case, 2005-2016). 

Presented at the SSG-WI Technical Support Meeting July 13, 2005. Portland. 

Dracker, Northern Nevada Renewable Energy Resources and Delivery Options. Nevada 

Renewable Energy Task Force, August 26, 2004. 

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to Nevada Transmission Systems, Nevada State Office of Energy, Office of the 

Governor. April 28, 2005. 

New Mexico Wind Task Force 

MISO/NW (Midwest Independent System Operator Northwest Exploratory Study) 

MTEP 2003, MISO Transmission Expansion Project 

Nebraska Energy Office 

Kansas Energy Council 

ERCOT White Paper to the Texas Legislature 

Arizona Wind Working Group 

State Incentives Web site www.dsireusa.org/

New Mexico RPS www.nmprc.state.nm.us/utility/pdf/3619finalrule.pdf

Montana RPS www.dsireusa.org/documents/Incentives/MT08R.htm

Nevada RPS www.dsireusa.org/documents/Incentives/NV01R.htm

Arizona RPS www.dsireusa.org/documents/Incentives/AZ03R.htm

SPP Expansion Plan

49
References 

Bolinger, M.; R. Wiser. Balancing Cost and Risk: The Treatment of Renewable Energy 

in Western Utility Resource Plans. Lawrence Berkeley National Laboratory, August, 

2005. http://eetd.lbl.gov/EA/EMP. 

Bureau of Land Management, U.S. Department of the Interior, Final Programmatic 

Environmental Impact Statement on Wind Energy Development on BLM-Administered 

Lands in the Western United States, 2005. 

http://windeis.anl.gov/ 

California Energy Commission, Assessment of Reliability and Operational Issues for 

Integration of Renewable Generation, CEC Consultant Report, July 2005. CEC-700-

2005-009-F available at www.energy.ca.gov/2005publications/CEC-700-2005-009/CEC700-2005-009-F.PDF. 

Electric Reliability Council of Texas, Transmission Issues Associated With Renewable 

Energy in Texas: Informal White Paper for the Texas Legislature, 2005; March 28, 2005. 

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smissionWhitePaperFINAL.pdf

Midwest ISO, Transmission Expansion Plan 2003 (MTEP-03), June 19, 2003. 

http://www.midwestiso.org/plan_inter/documents/expansion_planning/MTEP%202002-

2007%20Board%20Approved%20061903.pdf

Parsons, B.; M. Milligan; R. Zavadil; D. Brooks; B. Kirby; K. Dragoon; J. Caldwell. Grid 

Impacts of Wind Power: A Summary of Recent Studies in the United States, European 

Wind Energy Conference, Madrid, Spain, June 2003. 

Rocky Mountain Area Transmission Study, RMATS Phase I Report, 2004. 

http://psc.state.wy.us/htdocs/subregional/Reports.htm 

Seams Steering Group-Western Interconnection, Western Interconnection Path Flow 

Study, February 2003. 

http://www.ssgwi.com/documents/320-2002_Report___final_pdf.pdf

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Western Interconnection System, October 2003. 

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FERC_Filing___103103___FINAL_TransmissionReport.pdf 

Smith, J.C.; E.A. DeMeo; B. Parsons; M. Milligan. Wind Power Impacts on ElectricPower-System Operating Costs: Summary and Perspective on Work to Date, 

WINDPOWER 2004, Chicago, IL, March 2004. 

http://www.uwig.org/operatingimpacts.html 

http://www.nrel.gov/docs/fy04osti/35946.pdf 

50
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Wind Supply Curves and Location Scenarios in the West: Summary 

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This paper presents supply curves and scenarios that were developed by the Wind Task Force. Much of this 

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wind energy; wind supply curves; location scenarios; West; Wind Task Force of the Clean and Diversified Energy 

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