USEPA has reopened the comment period on its proposed rule regarding startup/shutdown issues for Coal- and Oil-Fired Electric Utility Steam Generating Units and Fossil-Fuel-Fired Electric Utility, Industrial-Commercial-Institutional, and Small Industrial-Commercial-Institutional Generating Units. USEPA is reopening the public comment period to address the following startup issues which were not resolved in the first round of the rulemaking:

  1. the definition of “startup”;
  2. types of “clean fuels” used during startup;
  3. use of default diluent gas cap values during periods of startup and shutdown;
  4. use of a default electrical production rate value to calculate output-based emission limits during startup and shutdown hours where the electrical load is zero; and
  5. the manner in which electric steam generating units (EGUs) that share a common stack demonstrate compliance during periods of startup and shutdown.

The commenters’ primary concerns dealt with the definition of “startup.” USEPA proposed to define the end of “startup” as “… when the EGU generates electricity that is sold or used for any other purpose (including on site use), or the EGU makes useful thermal energy (such as heat or steam) for industrial, commercial, heating, or cooling purposes …whichever is earlier.” Instead, commenters suggested that USEPA define “startup” as the “setting in operation of an affected source.” This would involve igniting the fuel in the boiler, producing steam to begin generating electricity either before or after the primary fuel is added to the boiler, and having all of the air pollution control devices (APCDs) operational. EGUs often remain in startup up mode beyond the first generation of electricity because many APCDs needed for compliance may not be technically or safely operated. Commenters also suggested that USEPA account for the operational differences among different types of EGUs (e.g. supercritical EGUs and subcritical EGUs). For example, commenters suggested that the end of startup for subcritical EGUs should be 4 hours after 25-percent load is first reached or 12 hours after first electricity generation, whichever occurs first.

As listed above, other startup issues are also open for public comment. Commenters have suggested that USEPA should expand the proposed list of “clean fuels” to include biodiesel and other renewable fuels. Commenters also suggest that while the work practice standards should be applied separately to each EGU that shares a common stack, the numerical emission limits should not apply if even one EGU sharing the common stack is starting up or shutting down.

Finally, USEPA seeks comments on the additional technical analyses it conducted in response to these comments.

Comments regarding these issues must be received by USEPA by August 26, 2013.