Observations on the transition to a net-zero energy system in the United States

Abstract The first detailed studies of how to achieve zero net CO2 emissions from energy and industry in the U.S. by mid-century have appeared in the last year. Our observations on the key findings include: (1) Reaching net-zero by mid-century is technically feasible and economically affordable but requires a large-scale infrastructure transformation. (2) The main economic challenge is not cost, it is political economy. (3) The future holds many uncertainties, but the priorities for this decade are clear. (4) In addition to the clear risks of delaying emissions reductions, there are also risks to setting targets without adequate attention to how they will be achieved. (5) Wind and solar electricity are the main sources of primary energy in a net-zero system, but the scale and pace of deployment poses a major land use and infrastructure siting challenge. (6) Maintaining the current level of gas thermal generating capacity through 2030 is essential for reliability, and may remain so through mid-century, but the plants will operate less frequently. (7) Hydrocarbon fuels are still necessary in a net-zero system, and all sources come with downsides that get worse with scale. (8) Carbon capture (but not necessarily geologic sequestration) is required in all net-zero systems, even ones based on 100% renewable primary energy. (9) Building electrification is a key strategy, but poorly designed policy can lead to serious equity problems. (10) All net-zero pathways involve tradeoffs. (11) Breakthroughs in technology and human behavior are not required technically to reach net-zero, but they may become so if mitigation options are too limited.