The Annual Energy Outlook explores long-term energy trends in the United States
• Projections in the Annual Energy Outlook 2021 (AEO2021) are not predictions of what will happen, but rather, they are modeled projections of what may happen given certain assumptions and methodologies. By varying those assumptions and methodologies, AEO2021 can illustrate important factors in future energy production and use in the United States.
• Energy market projections are uncertain because many of the events that shape energy markets—as well as future developments in technologies, demographics, and resources— cannot be foreseen with certainty. To illustrate the importance of key assumptions, AEO2021 includes a Reference case and side cases that systematically vary important underlying assumptions.
• The U.S. Energy Information Administration (EIA) develops the AEO by using the National Energy Modeling System (NEMS), an integrated model that captures interactions of economic changes and energy supply, demand, and prices.
• The AEO is published to satisfy the Department of Energy Organization Act of 1977, which requires EIA’s Administrator to prepare annual reports on trends and projections for energy use and supply.