The Capacity Expansion Regional Feasibility (CERF) model is a geospatial model for scenario analysis of electricity system expansions, CERF is unique in that it determines suitable siting locations using a combination of traditional, static siting constraints (e.g., federally and state-protected lands) with dynamic constraints (e.g., cooling water availability and population growth) and then simulates an economic competition between technologies using an algorithm that minimizes 'net locational costs" to choose specific siting locations within suitable areas. The net locational costs are calculated for each technology type and depend on the distance to the existing transmission system and other infrastructure, technology-specific marginal operating costs, and technology- and location-specific marginal energy values. In effect, the algorithm posits the existence of a regional planner who determines the costs and benefits of having new generation in different locations and sites power plants in order from lowest to highest net locational cost. Technologies that share the same suitable areas compete for siting locations based on the locational economics. CERF can be parameterized either manually for customized scenarios, arbitrarily for use in uncertainty characterization, or from ancillary inputs provided by contributing socioeconomic/policy, hydrologic, and production cost models for the purpose of integrated assessment.