North Carolina Low-impact Solar Siting Analysis
Siting guidance based on biodiversity priorities and demographic considerations
Where should we site solar facilities to avoid disrupting natural systems?
We identified ~6 million acres that are suitable for solar development based on land cover type, proximity to the energy grid, and low value to biodiversity. This calculation is very coarse as our analysis ignores many practical siting factors. NC is projected to need an additional 11-35 GW of solar capacity to meet 2050 goals ( Konschnik et al. 2021 ), which on the high end would require ~250,000 of total land for solar facilities (at 7 ac/MW; Bolinger & Bolinger 2022 , Ong et al. 2013 ). Thus, it is possible to site facilities on land not critical to biodiversity protection.
Figure 1. Heat Map of Ecological Priorities
The Ecological Priority Heat Map consists of six distinct layers: 1. TNC’s Resilient and Connected Network 2. North Carolina’s Endangered Species distribution map 3. North Carolina’s Threatened Species distribution map 4. North Carolina’s Species of Conservation Concern distribution map 5. Protected areas and critical habitat areas 6. Exclusion areas
Figure 2. Three classes of value to biodiversity
In this Value to Biodiversity map, the normalized pixel values found in Figure 1 were placed into three distinct bins based on percentile thresholds. In green, all values that fall within the bottom 33rd percentile of data points represent those regions of least relative value to biodiversity. In yellow, values between the 33rd percentile and 66th percentile represent those regions with a middling relative value for biodiversity. In red, values above the 66th percentile represent those of most value to biodiversity.
Figure 3. Value to Biodiversity map is visualized within the 5km buffer around transmission lines in North Carolina
In Figure 3, there is a total area of ~22,032,084 acres within 5km buffers of North Carolina’s transmission lines.
Figure 4. Areas in acres in “value to biodiversity” categories within the 5km buffer around transmission lines (from Figure 3).
Value to Biodiversity and Environmental Justice
It is crucial that we view environmental justice considerations alongside those of biodiversity. Using the EPA’s EJScreen tool, we overlaid the same 5km-buffered transmission line infrastructure map atop EJScreen’s Demographic Index (Figure 5). The value for each census block group is an average value of those two percentage values; cooler colors indicate lower Demographic Index values (higher income, lower minority population), while warmer colors indicate those that are higher (lower income, higher minority population).
Figure 5. The Demographic Index is visualized within the 5km buffer around transmission lines in North Carolina. Transmission lines in the eastern and southeastern portions of the state see more overlap with census blocks that have higher demographic indices. In the west, transmission lines tend to intersect predominantly with counties that have lower demographic indices.
In comparing the Figure 3 and Figure 5, there is a major area of overlap between areas with the most value for biodiversity (Figure 3, red) and of counties with higher demographic indices (Figure 5, red) in the south-central region of the state. In the northeast, a large swath of counties with high demographic indices seem to overlap with an area dominated by pixels of some value to biodiversity.
This StoryMap is based on analysis done by Michael Levin for the North Carolina Chapter of The Nature Conservancy . An ArcGIS map package of the project can be downloaded here . For more information contact Liz Kalies (liz.kalies@tnc.org).
Disclaimer
The data and maps contained herein represent a high-level analysis of several critical ecological considerations within North Carolina and are intended to serve as a generally informative resource for developers considering construction of ground-mounted, utility-scale solar energy production facilities. This analysis is by no means comprehensive, and no final siting decisions should be based on this information alone. Rigorous local due diligence is required to determine the viability of any solar project. Both social and ecological considerations not factored into this analysis may be relevant, even crucial, to consider during the development process. Further, use of these data for screening purposes does not imply endorsement by The Nature Conservancy of individual solar projects.
Data Sources
