Nitrogen Oxide (NOx) SIP Call
U.S. EPA NOx Budget Program

The NOx State Implementation Plan (SIP) administered by the U.S. Environmental Protection Agency now includes most of the states east of the Mississippi, (AL, CT, DE, IL, IN, KY, MA, MD, MI, NC, NY, OH, PA, SC, TN, VA, WV and DC) the eastern portion of Missouri and portions of Georgia. The program requires these states to propose and implement seasonal emission "budget plans." The program aims to mitigate the significant transport of NOx across state lines and to facilitate cost effective NOx reductions throughout the region with a target of reducing NOx emissions by 85% from 1990 levels (to an emissions rate of 0.15 lbs/mmBtu). Affected emitters include electrical generating units and large stationary point sources with rated output greater than 25 MW or a maximum rated heat input capacity of greater than 250 mmBtu/hr.

The NOx season runs from May 1 to September 30 each year. Sources have until November 30 of each year to ensure they hold adequate allowances for the year just passed. Larger sources must ensure that they hold continuous emissions monitoring systems, while smaller sources may use estimation methods to calculate their requirements.

The NOx SIP Call market is expected to become increasingly active in the coming years as more participants enter the market and the emissions allowance cap is lowered. The EPA will re-evaluate the program every five years to adjust allowances and to review new sources.