Grant Brummels 1 , Dr. Thomas Acker 2 , and Dr. Susan Williams 3

Introduction

The Navajo Nation is located in the Southwestern United States. Historically, energy development occurred on the reservation without much tribal involvement (Clow 2001). Decisions were made in Washington D.C., administered by the Bureau of Indian Affairs (BIA) (Wilkinson 1996). For the Navajo, a history of uranium, oil, gas, and coal extraction, each with its own important story, have set the stage for future energy decisions (McPherson 1998). This changed during the decade following the passage of the Indian Self-Determination and Education Assistance Act of 1975 (Ashley 2003). The Navajo government and its people began to have more influence over the future of their nation.

Our work focuses on wind energy. Navajo land within Arizona was analyzed using a Geographic Information System (GIS) to determine areas suitable for wind energy development. Our work is modeled after a study performed by the National Renewable Energy Laboratory (NREL), but includes additional data and higher-resolution data. Importantly, it utilizes recently published Southwest Regional Gap Analysis Program (SWReGAP) land cover data. These land cover data at 30m-resolution provide the location of sensitive ecosystems and urban/developed areas.

The Energy Policy Act of 2005 (EPACT) is a major motivator for our work. The bill incorporates provisions for wind energy development (USDOE 2005). It also includes, for the first time, a specific title dedicated to energy on Tribal Lands: Title V: Indian Energy (USDOE 2005).

Our work presents GIS analyses, techniques, and perspectives. The suitability of land is determined by land use, environmental considerations, and additional windy land factors such as slopes greater than 20%. Those areas of land determined to be unsuitable were considered wind energy development exclusions. These exclusions and the reasons for unsuitability are often easy to understand, but some are arbitrary and not as clearly understood. Particular attention is given to these exclusions.

Navajo Wind Energy Development Exclusions provides a tool for GIS professionals. This tool brings together a wide variety of GIS data, often high-resolution and computing-intensive data, and compares and contrasts these data to national wind power models. Together, they provide a foundation for understanding the future of wind energy development on the Navajo Nation.

Background

The Navajo Nation

The size of the Navajo Nation gives the Navajo tribal government prominence in Indian country. They govern and administer the largest reservation in the country (approximately 69,930 km 2 with nearly 300,000 members) (Fig. 1; Ahasteen 2005).

 Figure 1. The Navajo Nation (shown in green 69,930 km2 or approximately 24% of Arizona). The Navajo Nation surrounds the Hopi Nation. Canyon de Chelly National Park is the area in the eastern portion of the reservation, shaped like a delta.

The National Energy Policy Act of 2005 (EPACT)

EPACT was the first major federal energy policy in over a decade. It attempted to address a broad array of energy issues in the United States, but importantly, incorporated Indian energy issues into an actual Title (Title V: Indian Energy) for the first time in the history of federal energy legislation. EPACT describes a number of important policies that affect wind energy and wind energy in Indian country specifically (EPACT 2005) EPACT provides the federal policy cement needed to spark the next great build-up of energy, especially in the West. It impacts the Navajo Nation in ways that are unique, not only to the region, but also to tribes in general. A full discussion of the tribal impacts of EPACT is beyond the scope of this work, but some provisions are worth noting.

• The Production Tax Credit (PTC) was extended to the end of 2007: The PTC is the major federal incentive driving the wind industry today. It provides a direct tax credit for every kilowatt ∙ hour of electricity produced from a wide range of renewabl e energy sources, including wind.

• Tribal renewables will be double-credited toward the federal purchase requirement: EPACT calls for the federal electricity load to be provided by a certain percentage of renewable energy, beginning in 2007 and ramping up to 7.5% by fiscal 2013. While the federal load may seem insignificant, remember that the federal load is the largest load in the world. Renewable energy generated by tribes and delivered to satisfy the federal load will receive double the credits. In other words, 100 megawatts of tribal wind energy would be considered 200 megawatts of energy toward the 7.5% goal.
  
• Section 368: West-wide Energy Corridor Programmatic Environmental Impact Statement: This federal study has been in the pipeline for a number of yeas as a solution to the problem of extended uncertainty when planning energy on federal lands. The reason this is so important out west is that much of the land is under federal ownership status. To plan energy in the west, especially when planning the transmission of that energy, means interacting with federal lands. This study will identify corridors across these federal lands and perform programmatic environmental impact statements on those areas, dramatically decreasing planning uncertainty. Because the Navajo are adjacent to many of these federal lands, the results of this study will be telling of where they ‘sit’ in the energy corridor future of the West.

• Section 1813: Valuation of Tribal Energy Rights-of-Way: This issue strikes deep chords in Indian country. As one might imagine, historical values for energy rights-of-way (ROW) on Indian lands were undervalued, dramatically in some cases (USDOE 2006). Recently, following an era of Indian self-determination which, at times, has tipped the power scales back in favor of tribes, some energy ROW on tribal lands are now overvalued (USDOE 2006). The study implies a move toward some standard form of valuation for tribal ROW; however, most tribes view this language as a direct attack at sovereignty. The Navajo Nation is crossed by many energy ROW, including gas pipelines and electric transmission lines. The results of this study will impact the energy future of the tribe.

High-Resolution Wind Resource Data

The Wind Energy Resource Atlas of the United States, published in 1987, was the first major effort to map wind energy potential (Elliott et al. 1986). Maps from the atlas were published in this form, as well as a “gridded” form, which classifies the data into approximately 32-km pixels (Figure 2).

Figure 2. Wind Energy Resource Atlas of the United States (Elliot et. al. 1986).

Following this work, the National Renewable Energy Laboratory (NREL) created higher-resolution wind resource models that estimate the wind power potential at 200m resolution for many areas of the United States (Figure 3). These maps were completed for 30m, 50m, 70m, and 100m, but only validated at 50m (Figure 3). The general pattern is similar to Figure 2, however Figure 3 presents the data in more detail. Where high-resolution data were unavailable or not validated by NREL, the older, “gridded” wind resource data from Figure 2 were used. For Arizona, we used the higher resolution data for this study (Figure 4).

Figure 3. United States Wind Resource Map. This map uses newer, high-resolution wind resource data when available. Wind resources in areas without high-resolution data are shown with the older, 1986, wind resource data.

 Figure 4. The map on the left shows data from the 1986 Wind Resource Atlas. The map on the right shows the high-resolution results from NREL’s 2003 mapping effort.

Methods

For our analysis, windy land is defined as land with a wind resource greater than or equal to Class three as predicted by the high-resolution wind resource data. That is, predicted average annual wind speeds are large enough that wind energy may be produced economically. However, not all windy land may be developed for wind power. There are many development exclusions that must be considered. For instance, land that is owned by the National Park Service must be excluded 100% from consideration for development. Developable windy land, therefore, is the windy land that remains after all development exclusions have been applied. Finally, excluded windy land is windy land (Class 3 and above) that falls within a development exclusion.

A GIS was used to analyze wind energy development exclusions (WEDEs) on the Arizona portion of the Navajo Nation. We limited our analysis to Arizona data because WEDE datasets are generally available by state (Figure 5). Limiting the analysis to only the Arizona portion of the Navajo Nation limited our data inputs and processing while still assessing the majority of the windy lands on the entire Navajo Nation.

Figure 5. Navajo Wind Energy Development Exclusions study area. Only the Arizona portion of the reservation was analyzed.

Digital datasets were gathered that represented areas where wind energy projects should not be developed. Most datasets, once identified, were immediately ready for WEDE analysis. Other layers, like the non-ridgecrest forest WEDE required some processing.

This work includes a number of key higher-resolution datasets. Whereas past studies were limited to 1km resolution at best, this work brought 30m-resolution data to important exclusion categories like wetlands, urban/developed lands, and open water. Buffers were added to some, but not all WEDEs.

Consistent with the methodology applied by NREL, there are three general categories of WEDEs (Schwartz 2003) environmental exclusions, land use exclusions, and additional windy land factors (e.g. slopes greater than 20%)

Our work includes 11 WEDEs and their respective buffers (Table 1)

Table 1. Wind Development Exclusions

* ALRIS— Arizona Land Resource Information System

Non-ridgecrest forest exclusions were created by combining SWReGAP forest data with a layer derived from Jenness (2005) TPI. TPI categorizes the landscape into 10 different categories (Table 2) by comparing the results of a “small-neighborhood” (1000-m radius) and “large-neighborhood” (5000-m radius) analysis of a 90m digital elevation model (DEM). Pinyon-Juniper (PJ) forests were not included as WEDEs.

Table 2. List of 10 landscape categories derived by TPI (Jenness 2005)

1. canyons, deeply incised streams

2. mid-slope drainages, shallow valleys

3. upland drainages, headwaters

4. u-shaped valleys

5. plains

6. no areas reported this classification

7. upper slopes, mesas

8. local ridges/hills in valleys

9. mid-slope ridges, small hills in plains

10. mountain tops, high ridges

After removing WEDEs from the wind resource data for 50m and 70m heights, wind energy capacity (MW) was estimated using NREL’s conservative standard of 5MW per km2. This factor was applied to all areas of land with a wind resource of Class 3 and greater.

Results

Our work found the total potential wind energy capacity at 50m hub height, without applying WEDEs, to be 5770MW (Table 3). After removing all WEDEs, the wind energy capacity was found to be 4562MW, or 79% of the total wind energy capacity at 50m. At 70m hub height, 14,046MW of potential capacity was found. Of which, 11,806MW, or 84% of the total capacity at 70m was available for development after all WEDEs were applied.

Table 3. Total and developable potential installed wind capacity for 50m and 70m hub heights by wind class

Most developable windy land is Class 3 (Table 3). However, windy land is a small percentage of total land on the Navajo Nation (Table 4). WEDE’s are distributed across the Navajo Nation land (Figure 6).

Table 4. Windy land and developable windy land by wind class and compared to the entire area of the Navajo Nation (50m hub height).

Figure 6. Navajo Wind Energy Development Exclusions. WEDEs are shown in blue. Electric transmission lines are shown in red.

Over 90% of areas considered “woodlands” by SWReGAP data were Pinyon-Juniper (PJ) woodlands (Figure 7). PJ woodlands were not excluded for this study.

Wetlands in the southwestern portion of the Navajo Nation map are part of the Little Colorado River System (Figure 8 and 9). Wetlands in the northeastern portion are part of the de Chelly river system.

Figure 7. Navajo Woodlands. Pinyon-Juniper woodlands (not excluded in this work) are shown in light-green. Ponderosa pine woodlands (dark striped green), not on ridgecrests, were excluded 50%.

Figure 8. Navajo Wetlands (shown in red).

Figure 9. Examples of wetlands from SWReGAP data. Photo on right shows wetlands on the Little Colorado River near Cameron, AZ. Photo on left shows wetlands along Colorado River near Page, AZ. The canyon walls are 2000-3000 feet (convert to meters) tall.

Slopes were also an important WEDE category (Figure 10).

Figure 10. Sloped greater than 20% on Navajo Nation (outlined in red).

The TPI analysis for the entire state of Arizona resulted in no category 6 landscapes, so the line for ridgecrests was drawn between classification 5 and 7 (Figure 11). Classifications 7-10 were considered ridgecrests for WEDEs.

Figure 11. Topographic Position Index results for Arizona. Plains are shown in green. Areas shown in red and pink are drainages, valley, and canyons. Blue and gray areas are ridgecrests and mountain tops.

A more detailed analysis using TPI was conducted for Gray Mountain (Figure 12). The drainage to the north of Gray Mountain is the Little Colorado River, which drains into the Grand Canyon, the obvious feature in the northwest corner of the map.

Figure 12. Topographic Position Index results for Gray Mountain at two different scales.

For Gray Mountain most of the wind energy potential remains after all WEDEs are excluded (Figure 13).

Figure 13. WEDEs (blue) and wind resources for Gray Mountain.

Discussion

Understanding where to locate wind turbines is important for the energy future of the Navajo Nation. Our study provided maps and data that help energy planners and policy makers understand how much wind energy can be developed on the reservation. High-resolution data for land cover and elevation provide a good understanding of ecosystems and ridgecrests. Because we assessed the Navajo Nation, we uncovered interesting issues related to WEDE research on Indian lands.

Federal lands are key qualifiers for WEDEs. In many cases, the reasons federal lands are excluded relate to ecosystem qualities—they include protected land, wilderness area, or other valuable land because of the landscape and ecosystem supported. Indian lands, or course, do not have these types of federal lands, yet ecosystems rarely change according to political boundaries. As such, our study highlights the importance of looking at WEDEs from an ecosystem perspective when assessing WEDEs on Indian lands. While our work did not incorporate specific Navajo datasets, like those that show cultural sites or sites of historical significance, future WEDE work in Indian Country should utilize cultural information.

Incorporating 30m, SWReGAP data into the study provided a number of improvements over past studies and resulted in some key findings. Higher-resolution data was essential for identifying wetlands, especially in this region of the country. Wetlands were prominent on the Navajo nation.

Our work shows non-ridgecrest forest exclusions well. SWReGAP data proved useful in making this exclusion category clear by classifying forests into 53 different land cover classes . . Different types of forests with their different forest structures were easily identified and assessed individually. Pinyon-Juniper forests were shown to be the dominant forest on the Navajo Nation.

While WEDEs on the Navajo Nation excluded 21% of the total windy land at 50m, the large, contiguous areas of windy land in the western portion of the reservation were not excluded (Table 3, Figure 6). This is a positive sign for wind energy in the future of the Navajo Nation. Not only are these areas not excluded, but they are transected by existing electric transmission lines. Gray Mountain offers the most promising location for developing wind energy projects (Figure 13).

Conclusions

The Navajo Nation is well positioned geographically to take advantage of wind energy. They have access to sites with quality wind resources and access to regional transmission. Wind offers an alternative to typical fossil energy development, providing the energy without the pollution and carbon emissions, and without the use of water. However, our results indicate that wind is not suitable at all locations.

Wetlands were prominent on the Navajo Nation (Figure 8). Forests were also prominent on the Navajo Nation (Figure 7). While most GIS analyses using satellite classification techniques would group Ponderosa pine forests with PJ forests, by using the SWReGAP data, we were able to separate the two and understand the forest structure that wind energy projects may encounter. Because PJ forests are a large portion of the reservation and because they display different forest structure than Ponderosa forests, they were not included as a WEDE.

Planning for a wind energy project on the Navajo Nation can now proceed with at least a relatively broad understanding of where not to locate wind turbines. The public can be informed regarding wind energy and be assured that decisions are based on sound data. Wind developers can avoid problem areas and save money and time. Utility managers can estimate where wind energy projects could be sited within their control area. Finally, and perhaps most importantly, Tribal Council members can use our data and appreciate the future of wind energy on the Navajo Nation.

Literature Cited

Ahasteen, Larry L. October 19, 2005. Navajo Nation: Navajo Tribal Utility Authority: Wind Energy Feasibility Study on the Navajo Nation. Presentation at Department of Energy Tribal Energy Program Annual Meeting. Denver, CO. United States Department of Energy.

Ashley, Jeffrey J. S., J. Secody. 2003. Negotiated Sovereignty: Working to Improve Tribal-State Relations. Hubbard Praeger Publishers.

Clow, R Richmond . L. 2001. “Prologue: Tribes, Trusteeship, and Resource Management.” In Trusteeship in Change: Toward Tribal Autonomy in Resource Management. University Press of Colorado.

Elliot, D.L., C.G. Holladay, W.R. Barchet, H.P. Foote, and W.F. Sandusky. 1986. Wind Energy Resource Atlas of the United States. DOE/CH10093-4. DE86004442. Solar Technical Information Program. Solar Energy Research Institute (now the National Renewable Energy laboratory). Golden, CO. Available online: http://rredc.nrel.gov/wind/pubs/atlas/

Jenness, J. 2005. Topographic Position Index (tip_jen.avx) extension for ArcView 3.x. Jenness Enterprises. Available at: http://www.jennessent.com/arview/tpi.htm. TPI was applied to a 90m Digital Elevation Model.

Lowry, J. H, Jr., R. D. Ramsey, K. Boykin, D. Bradford, P. Comer, S. Falzarano, W. Kepner, J. Kirby, L. Langs, J. Prior-Magee, G. Manis, L. O’Brien, T. Sajwaj, K. A. Thomas, W. Rieth, S. Schrader, D. Schrupp, K. Schulz, B. Thompson, C. Velasquez, C. Wallace, E. Waller and B. Wolk. 2005. Southwest Regional Gap Analysis Project: Final Report on Land Cover Mapping Methods, RS/GIS Laboratory, Utah State University, Logan, Utah.

McPherson, Robert R. S., and David A. Wolf. 1998. Poverty, Politics, and Petroleum: The Utah Navajo and the Aneth Oil Field. American Indian Quarterly 21: 451-471.

Schwartz, M. Arizona Wind Resource, presentation to the Arizona Wind Working Group. August 6, 2003.

SWReGAP, Southwest Regional Gap Analysis Project.

United States Department of Energy. 2005. United States Energy Policy Act.

The full text of the Energy Policy Act of 2005 can be found online: http://frwebgate.access.gpo.gov/cgi-bin/getdoc.cgi?dbname=109_cong_bills&docid=f:h6enr.txt.pdf

United States Department of Energy. Section 1813 Study Public Meeting. April 18-20, 2006. Denver, CO.

Wilkinson, Charles C. F. 1996. Home dance, the Hopi, and Black Mesa coal: Conquest and endurance in the American Southwest. Brigham Young University Law Review 1996: 449-482.

Return to Table of Contents