Pathways to Deep Decarbonization in the United States

Abstract:

Limiting anthropogenic warming to less than 2°C will require a reduction in global net greenhouse gas (GHG) emissions on the order of 80% below 1990 levels by 2050. Thus, there is a growing need to understand what would be required to achieve deep decarbonization (DD) in different economies. We examined the technical and economic feasibility of such a transition in the United States, evaluating the infrastructure and technology changes required to reduce U.S. GHG emissions in 2050 by 80% below 1990 levels. Using the PATHWAYS and GCAM models, we found that this level of decarbonization in the U.S. can be accomplished with existing commercial or near-commercial technologies, while providing the same level of energy services and economic growth as a reference case based on the U.S. DOE Annual Energy Outlook. Reductions are achieved through high levels of energy efficiency, decarbonization of electric generation, electrification of most end uses, and switching the remaining end uses to lower carbon fuels. Incremental energy system cost would be equivalent to roughly 1% of gross domestic product, not including potential non-energy benefits such as avoided human and infrastructure costs of climate change. Starting now on the deep decarbonization path would allow infrastructure stock turnover to follow natural replacement rates, which reduces costs, eases demand on manufacturing, and allows gradual consumer adoption. Energy system changes must be accompanied by reductions in non-energy and non-CO2 GHG emissions.