1.4 Renewable Resources

new technology using molten salts as a heat source. Cost estimates for pilot plants such as the Natrium power plant are high and they will need to be operated at a close to baseload capacity factor to keep the cost of energy at a competitive level.

Nuclear generation is a baseload resource and does not provide the flexible energy storage services that will be required to integrate large amounts of renewable energy. When combined with cost, ongoing concerns about waste disposal, and the experimental nature of new nuclear technology options, nuclear power is not a viable generation alternative to the Project.

Solar energy, particularly photovoltaic solar (PV solar), is an emerging form of electric energy supply and is increasing in many parts of the western United States. It is one of the lowest cost energy sources available and does not generate greenhouse gas emissions. Solar output’s normal generation pattern (excluding interruptions due to cloud cover) features a mid-day peak and no generation during the night. The result is the wellestablished “duck curve,” with a steep ramp-up needed for generating capacity that aligns with increasing load in the early evening. Since PV solar is not a firm or dispatchable generation alternative, it is not a viable alternative to the Project. PV solar is a major driver of the need for energy storage resources like the proposed Project.

Wind energy is another leading source of carbon-free energy seeing widespread deployment. Where the wind resource is of high quality, the cost of wind energy is very low. Wind energy viability is particularly high in Wyoming, possessing high average annual wind speeds of 6.5 meters per second or higher at 80 meters above ground surface in over half of the state by area (Tetra Tech 2021). Wyoming is likely to export wind energy production to other states. Like PV solar, wind energy is not dispatchable, and it has a lower ability to predictably match demand. Therefore, use of wind energy, particularly in Wyoming, is a major driver of the need for energy storage resources like the proposed Project.

Wyoming’s geothermal resources are used for direct heating applications, mainly in Yellowstone National Park and Hot Springs State Park, and do not have adequate resources for commercial electricity generation (State of Wyoming Geological Survey 2015). However, the economics of geothermal power require that it operates as a baseload facility. Geothermal resources are site specific and require significant lead times and development risk. More generally, the cost of geothermal generation is depressing its inclusion in most resource plans. Additionally, geothermal generation is baseload in nature and not able to provide the energy storage services needed for integrating other renewable resources. Therefore, geothermal is not a viable generation alternative to the Project.

Conventional hydroelectric power has provided relatively firm, carbon-free energy in parts of the western United States, specifically the Pacific Northwest, California, and Colorado, for many decades. Wyoming currently has 21 dams that generate power, most of which are owned and operated by the Federal government. Across a wider region, there is potential for new, small hydropower additions to non-powered dams, but there are no plans