EPA has signaled an intent to make its Mercury and Air Toxics Standards (MATS) rule — which imposes stringent emission limits on coal and oil-fired utilities beginning in 2015 — a bit easier to manage.  However, the proposed revision may still fall short of what is needed for half of the utilities in the country, according to EPA’s own analysis.

In adopting its final Mercury and Air Toxics Standards (MATS) rule, EPA exempted emissions during startup and shutdown from the numeric emissions standards that apply at all other times.  Instead, EPA adopted work practice standards to apply during such periods of operation that require the operation of all control equipment if feasible and the use of clean fuels during startup.  This approach was welcomed by utilities, given that most plants can’t start all their emission control equipment immediately.  But EPA defined “startup” far too narrowly — forcing utilities to comply with numeric limits long before controls were online and effective.

Since these startup and shutdown provisions had not been included in EPA’s initial proposal, in a notice published in the Federal Register on November 30, 2012, EPA agreed to reconsider them along with the new unit standards.  In April, EPA finalized its reconsidered new unit standards, but did not finalize any changes to the startup and shutdown provisions.  Now EPA has decided proposed a new definition of startup and is reopening the comment period on several other startup issues that present a potential concern for utility operators.

The newly proposed definition of “startup” ends 3 hours after reaching 25% capacity or 6 hours after the first generation of any electricity.  Although this proposed revision would certainly extend the “startup” time for utilities (at least as compared to the current definition), the proposal is based on a technical analysis performed by EPA that relies on average startup times across the industry.  Unfortunately, as is true with all averages, half of the actual values are higher than the average — which means that EPA’s analysis suggests half of the industry will take longer to startup than the startup times EPA has proposed.  In addition, EPA’s 3-hour / 6-hour proposal is based only on the initiation of control systems, when in reality many controls take several hours after initiation to reach the optimal operating conditions needed to comply with the MATS emission limits.

EPA will accept comments until August 26, 2013.  Click here to read EPA’s new proposal:  Proposed Reconsideration of Startup Issues