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 wind power:

 Wind power class of 4 or greater for 50‐m turbine hub heights.

 Topographic slope less than or equal to 20%.

 Within 25 miles of transmission lines at least 69 kV in capacity.

 Within 25 miles of roads (down to rural local road classes).

 Outside of USFS Inventoried Roadless Areas and Special Designated Areas.

 At least 3 km from urban areas.

The NREL study also screened their initial wind power analysis to be in the proximity of a major load center or major transmission line connecting to a load center, but their assumptions were not quantified so the analysis in this study was limited to the transmission line criteria listed above.

The second phase of the analysis included the revised and additional screening factors listed below. The urban area criterion from the first phase was omitted because the developed land cover types in the criteria below served the same purpose:

 Wind power class of 4 or greater for 50‐, 80‐, and 100‐m hub heights.

 Outside of wetlands and floodplains.

 Outside of open water, vegetation, forest, urban and 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.

 At least 500 m from radar systems.

Wind power data were available for Alaska, and using the threshold of a wind power class of 4 or greater at a 100 m hub height, 2,357,633 acres of NFS land met the criterion. But its lower overall population density, smaller and more isolated communities, rugged terrain, large but remote NFS lands, and limited electrical transmission infrastructure cause nearly all of Alaska’s NFS lands to be eliminated based on the screening factors used for the rest of the analysis.