In 2005, the National Renewable Energy Laboratory (NREL) completed an assessment of the potential for solar and wind energy development on National Forest System (NFS) public lands managed by the US Department of Agriculture, U.S. Forest Service (USFS). This report provides an update of the analysis in the NREL report, and extends the analysis with additional siting factors for solar and wind energy. It also expands the scope to biomass and geothermal energy resources. Hydropower is acknowledged as another major renewable energy source on NFS lands; however, it was not analyzed in this project primarily because of the substantially different analysis that would be needed to identify suitable locations. Details about each renewable energy production technology included in the study are provided following the report introduction, including how each resource is converted to electrical power, and examples of existing power plants. The analysis approach was to use current and available Geographic Information System (GIS) data to map the distribution of the subject renewable energy resources, major siting factors, and NFS lands. For each major category of renewable energy power production, a set of siting factors were determined, including minimum levels for the renewable energy resources, and details for each of the other siting factors. Phase 1 of the analysis focused on replicating and updating the 2005 NREL analysis, and Phase 2 introduced additional siting factors and energy resources. Source data were converted to a cell?based format that helped create composite maps of locations meeting all the siting criteria. Acreages and potential power production levels for NFS units were tabulated and are presented throughout this report and the accompanying files.
NREL’s analysis included six criteria for photovoltaic solar power, the same as CSP except for the solar resource potential layer and slope. The criteria used in this study were as follows:
Stationary panel solar resource potential greater than or equal to 5.8 kWh/m2/day (see below).
Topographic slope less than or equal to 1%.
Within 25 miles of transmission lines at least 69 kV in capacity.
Within 25 miles of roads (down to rural local road classes) or railroads.
Outside of USFS Inventoried Roadless and Special Designated Areas.
Contiguous land parcel size of at least 40 acres.
Single‐axis tracking flat plate collector insolation data with a minimum threshold of 7 kWh/m2/day were used in the 2005 NREL analysis. However, results in this study are based on current stationary panel solar resource data because current single‐axis tracking data were not available. Values in the stationary panel data were not directly comparable to the single‐axis tracking data. A threshold level of 5.8 kWh/m2/day best resembled the geographic distribution of the older single‐axis PV data, and was used for the analysis so that the results of the NREL study could be more directly compared to this study.
The second phase of the analysis included the additional screening factors listed below. They were the same as the CSP analysis, except for the removal of water source availability because of the considerably lower water requirement for PV technology. Results were generated with and without the final distance‐to‐transmission factor given that it is a significant cost factor but eliminates most of the suitable locations (see Appendix B):
Outside of wetlands and floodplains.
Outside of open water, vegetated, forested, urban, or developed land cover types.
Outside of protected areas, including USFS experimental forests; FWS designated critical habitat; national scenic and historic trails; wilderness study areas; wild and scenic rivers; wilderness areas; national monuments; and national conservation areas.
PV data for Alaska of comparable and sufficient quality as that for the contiguous states are not yet available. Available low resolution PV data have insolation values well below the threshold set for this analysis, as would be expected for the northern latitudes of Alaska.