Coal Market Module - NEMS Documentation
July 2025
Executive Summary
Purpose of the report
This report documents the objectives, and the conceptual and methodological approaches used in the development of the National Energy Modeling System's (NEMS) Coal Market Module (CMM) used to develop the Annual Energy Outlook 2025 (AEO2025). This report catalogues and describes the assumptions, methodology, estimation techniques, and source code of the CMM.
This document has three purposes. It is a reference document that provides a description of the CMM for model analysts and the public. It meets the legal requirement of the U.S. Energy Information Administration (EIA) to provide adequate documentation in support of its statistical and forecast reports (Public Law 93-275, Federal Energy Administration Act of 1974, Section 57(B)(1), as amended by Public Law 94-385). Finally, it facilitates continuity in module development by providing documentation from which energy analysts can undertake module evaluations, module enhancements, data updates, and parameter refinements to improve the quality of the module.
Model summary
The CMM provides annual projections of prices, production, and transportation of coal through 2050 for NEMS. The Coal Production Submodule (CPS) generates a set of minemouth coal supply curves by coal supply region, coal type, and mine type. The supply curves are passed to the Domestic Coal Distribution Submodule (DCDS), along with regional coal demand requirements from other NEMS components. The CMM provides regional delivered coal prices and quantities for the end-use sectors in NEMS. The DCDS solves for the interregional flows of coal from supply region to demand region by minimizing the production and transportation costs. The International Coal Distribution Submodule (ICDS) projects annual world coal trade flows from major international supply to major demand regions and provides annual forecasts of U.S. coal exports.
The current version of the CMM is built on a software platform called AIMMS.1 The NEMS coal project2 contains the code for all three coal submodules (CPS, DCDS, and ICDS), which is normally called by the NEMS main integration routine. NEMS now resides as part of a GitHub platform. The main Python based integration routine interfaces with the NEMS restart file and passes variables between the various modules. Figure A shows integration of the CMM submodules between themselves and the other NEMS modules. Once completed as a fully integrated NEMS run, the coal AIMMS coal project can be used to review results. In addition NEMS has report writers that display graphical and tabular results for all the active NEMS modules.
Figure A. Information flow between the Coal Market Module (CMM) and other components of the National Energy Modeling System (NEMS)
Model archival citation
The documentation is archived as part of the NEMS production runs.
Notes and sources
1 AIMMS (Advanced Interactive Multidimensional Modeling System) is a software system designed for modeling and solving large-scale optimization and scheduling-type problems. It consists of an algebraic modeling language, an integrated development environment for both editing models and creating a graphical user interface around these models, and a graphical end-user environment.
2 The coal code and input files are now part of a GitHub project found in \git\NEMS\models\coal\ .