Land Use, Transmission Expansion, and Supply-Chain Scale-Up Implications of Alternative Scenarios for 100% Carbon-free Electricity Generation in the American West

Abstract:

Multiple states and utilities have established policies and commitments to reach 100% of electricity from renewable and other carbon-free sources in the coming decades. Strategies to transition the U.S. economy as a whole to net-zero emissions by 2050 likewise require decarbonization of electricity production while expanding electricity supply to fuel greater shares of end-use sectors. Due to recent and projected cost reductions, wind and solar power are likely to represent a majority of electricity supply in the least-cost, 100% carbon-free Western electricity system. However, deploying wind and solar at this scale entails historic sustained capacity addition rates, significant land area to site renewable energy facilities, and expansion of electricity transmission to deliver power. Land use availability and conflicts, challenges associated with transmission expansion, and supply chain constraints may, therefore, present critical non-cost related bottlenecks to least-cost portfolios for electricity decarbonization. This study employs a spatially- temporally- and operationally resolved electricity system capacity expansion model and the Modeling to Generate Alternatives (MGA) technique to generate a set of maximally different portfolios for 100% carbon-free electricity supply in the Western Interconnection all with similar costs. We consider the uncertainty in electricity demand growth and availability of long-duration energy storage and “clean firm” generation technologies. We then quantitatively evaluate these portfolios based on several non-cost related metrics, including total area and spatial distribution of land requirements for wind and solar siting across Western states, transmission expansion requirements, and pace of capacity additions for each technology. This work finds significant flexibility to change both the technological composition and spatial distribution of carbon-free electricity resources. We focus in particular on (a) strategies to minimize potential conflicts between wind and solar expansion and other land-use priorities in the American west and (b) tradeoffs between renewable energy siting and associated transmission expansion on the one hand, and the challenges of scaling up nascent clean firm generating resources on the other hand.