The National Energy Modeling System (NEMS) is an integrated energy-economy modeling system for the United States that projects the production, imports, conversion, and consumption of energy, subject to assumptions on macroeconomic and financial factors, world energy markets, resource availability and costs, cost and performance characteristics of energy technologies, and demographics. NEMS is developed and maintained by the Energy Information Administration (EIA) of the U.S. Department of Energy (DOE).

The Office of Policy uses a version of NEMS maintained and run by OnLocation, Inc. (OP-NEMS) which includes enhancements that enable the Office of Policy to examine possible pathways to achieve U.S. greenhouse gases (GHG) emission reduction goals of 50-52 percent economy-wide by 2030 and net-zero emissions by 2050. Because OP-NEMS only projects CO2 emissions related to the energy sector, external assumptions must be provided for non-CO2 greenhouse gases and land sinks.

OP-NEMS starts with the CO2 Carbon, Transport, Utilization and Storage-NEMS (CTUS-NEMS) 2020 version of NEMS developed by OnLocation for the National Energy Technology Laboratory (NETL) and supported by the DOE Office of Fossil Energy and Carbon Management (FECM) that includes enhancements for biomass and industrial carbon capture, transport, and storage. Additional applications of clean hydrogen production and use and expanded sustainable biofuels production and use were included using inputs provided by the Office of Energy Efficiency and Renewable Energy (EERE). Additional model granularity related to building energy efficiency that were developed for the Building Technologies Office (using BTO-NEMS) were also layered on.

OP-NEMS is used to develop potential pathways reflecting various technology and policy goals. Further documentation about NEMS can be found at