An official website of the United States government.

This is not the current EPA website. To navigate to the current EPA website, please go to This website is historical material reflecting the EPA website as it existed on January 19, 2021. This website is no longer updated and links to external websites and some internal pages may not work. More information »

Clean Air Markets

NEEDS v.5.15 User Guide

View a user guide for the the updated National Electric Energy Data System (NEEDS), the database used to construct the "model" plants that represent existing and planned/committed units in EPA modeling applications.

View Power Sector Modeling Platform v.5.15 for related information.

You may need a PDF reader to view some of the files on this page. See EPA’s About PDF page to learn more.