Economy-wide evaluation of CO2 and air quality impacts of electrification in the United States.

Adopting electric end-use technologies instead of fossil-fueled alternatives, known as electrification, is an important economy-wide decarbonization strategy that also reduces criteria pollutant emissions and improves air quality. In this study, we evaluate CO2 and air quality co-benefits of electrification scenarios by linking a detailed energy systems model and a full-form photochemical air quality model in the United States. We find that electrification can substantially lower CO2 and improve air quality and that decarbonization policy can amplify these trends, which yield immediate and localized benefits. In particular, transport electrification can improve ozone and fine particulate matter (PM2.5), though the magnitude of changes varies regionally. However, growing activity from non-energy-related PM2.5 sources-such as fugitive dust and agricultural emissions-can offset electrification benefits, suggesting that additional measures beyond CO2 policy and electrification are needed to meet air quality goals. We illustrate how commonly used marginal emissions approaches systematically underestimate reductions from electrification.

The role of natural gas in reaching net-zero emissions in the electric sector.

Replacing coal with natural gas has contributed to recent emissions reductions in the electric sector, but there are questions about the near- and long-term roles for gas under deep decarbonization. In this study, we assess the potential role for natural gas and carbon removal in deeply decarbonized electricity systems in the U.S. and evaluate the robustness of these insights to key technology and policy assumptions. We find that natural-gas-fired generation can lower the cost of electric sector decarbonization, a result that is robust to a range of sensitivities, when carbon removal is allowed under policy. Accelerating decarbonization to reach net-zero in 2035 entails greater contributions from natural gas than in 2050. Nonetheless, wind and solar have higher generation shares than natural gas for most regions and scenarios (52-66% variable renewables for net-zero scenarios versus 0-19% for gas), suggesting that natural gas generation can be substituted more easily than its capacity.

Implications of variations in renewable cost projections for electric sector decarbonization in the United States.

The costs of wind and solar technologies have dropped rapidly, but unknowns about technological change and emissions policies create uncertainty about future deployment. We compare projections of U.S. wind and solar costs across published studies and use an energy systems model to evaluate how these reductions could alter electric sector planning decisions and costs under deep decarbonization. Model results indicate that wind and solar are the largest generation resources for many scenarios and regions, but shares depend on assumptions about costs, policy targets, and policy timeframes (spanning 14% to 67% of national generation by 2035). Renewables cost reductions lower decarbonization costs and reduce projections for nuclear and carbon-captured-equipped generation, but policy decisions have a larger influence on future trajectories. Lower wind and solar costs have more limited impacts on deployment of carbon removal technologies and the capacity of clean firm technologies in reaching net-zero emissions in the electric sector.

Impact of carbon dioxide removal technologies on deep decarbonization of the electric power sector.

Carbon dioxide removal technologies, such as bioenergy with carbon capture and direct air capture, are valuable for stringent climate targets. Previous work has examined implications of carbon removal, primarily bioenergy-based technologies using integrated assessment models, but not investigated the effects of a portfolio of removal options on power systems in detail. Here, we explore impacts of carbon removal technologies on electric sector investments, costs, and emissions using a detailed capacity planning and dispatch model with hourly resolution. We show that adding carbon removal to a mix of low-carbon generation technologies lowers the costs of deep decarbonization. Changes to system costs and investments from including carbon removal are larger as policy ambition increases, reducing the dependence on technologies like advanced nuclear and long-duration storage. Bioenergy with carbon capture is selected for net-zero electric sector emissions targets, but direct air capture deployment increases as biomass supply costs rise.