We are pleased to announce a major update to the U.S. Energy Policy Simulator (EPS). Model version 4.0 includes new features such as an entirely rebuilt electricity sector with hourly electricity dispatch, seven new power plant types, electricity storage, estimation of wholesale electricity prices, and more. This update also incorporates impacts of recent U.S. policy developments, including the Inflation Reduction Act (IRA) and the Infrastructure Investment and Jobs Act (IIJA), which enables users to better understand how U.S. emissions are expected to evolve. Our updated business-as-usual scenario (BAU) represents our best estimate of energy use and emissions through 2050 given all current policies and expected technology costs. The BAU scenario looks markedly different than previous EPS versions, mainly due to the IRA, the landmark federal law passed in August 2022 to invest in clean energy, clean industrial processes, climate-smart agriculture, and forest management. EPS 4.0 projects the U.S. is on track to more than double its pace of emissions reductions this decade compared to the decarbonization rate achieved in the 2010s, thanks primarily to bold federal climate policies adopted over the last few years, as well as to falling costs of clean energy and state, local, and private sector action.