Title: Moderate Transmission Expansion Offers Limited Savings for U.S. Power Decarbonization

Abstract: Government analyses and policy documents frequently highlight the necessity of significant interregional transmission growth to integrate renewable energy and maintain grid reliability within a decarbonized power sector. This study utilizes the open-source Switch capacity expansion model, which incorporates granular details of current U.S. generation and transmission networks, as well as hourly operations for solar, wind, and storage assets, to assess the impact of interregional transmission. We examine three 2050 scenarios: least-cost, carbon-priced, and zero-emissions. Our findings indicate that an optimal national strategy would increase interregional transmission capacity by more than threefold. However, this expansion lowers the cost of a zero-emission system by merely 7% compared to a baseline relying on existing infrastructure, as resources such as solar and wind siting, nuclear power, and energy storage act as effective substitutes.

The economic impacts vary by region, with transmission infrastructure generally benefiting wind and hydrogen sectors more than solar and battery storage. Sensitivity analyses reveal diminishing returns on investment: achieving one-twelfth of the additional capacity required for full expansion yields one-fifth of the total benefits. Furthermore, cost reductions associated with batteries and hydrogen deliver system savings that are equal to or exceed those provided by interregional transmission.

Additionally, upgrading existing corridors with advanced conductors—effectively doubling capacity per link at half the expense of constructing new lines—results in only a 1.6% reduction in overall system costs. This suggests that the advantages of reconductoring are limited and may require complementary strategies, such as new connections on critical corridors or further declines in battery prices, to reach their full potential. These outcomes imply that while expanding transmission is economically viable, a wide array of flexible resources can offset the need for massive grid construction, and the specific value of transmission depends heavily on evolving technologies and cost structures.

Source: arXiv Generated at: 2026-06-02 00:00:00 UTC