December 19, 2012 

MEMORANDUM 

From: William H. Maxwell 

EPA/SPPD/ESG (D243-01) 

To: Docket Number EPA-HQ-OAR-2009-0234 

Subject: Meeting with Utility Air Regulatory Group (UARG) 

Attendees: 

Lee Zeugin, Hunton & Williams 

Bill Wehrum, Hunton & Williams 

Mike Geers, Duke Energy 

Michael Rossler, EEI 

Sarah Markham, Southern Company 

Ralph Roberson, RMB Consulting 

Peter Tsirigotis, EPA 

Nick Hutson, EPA 

Robert Wayland, EPA (by phone) 

Ravi Srivastava, EPA (by phone) 

William Maxwell, EPA (by phone) 

Discussion: 

A general discussion was held regarding clarifying questions from Utility Air Regulatory Group on the 

proposed Mercury and Air Toxics Standards (MATS) reconsideration issues. The attached documents 

were discussed. 
MATS Startup and Shutdown 

EPA Meeting 

December 19, 2012 

Key Messages 

 Startup does not simply end when either steam or electricity is produced. Startup involves 

the “setting in operation” of the boiler and its associated air pollution control systems, which 

does not necessarily occur with the first appearance of steam or electricity. 

 Emissions during startup and shutdown can be highly variable and sufficient data does not 

exist to establish separate emission standards during these periods. Work practice standards 

during startup and shutdown are appropriate. 

 Emissions variability during startup generally occurs until the emission control devices can 

be fully engaged or operating. These are the exact emissions that EPA states “it do[es] not 

have sufficient data...on which to set emissions standards.” 

 Southern Company suggests that EPA revise the startup definition to include the complete 

“setting in operation” of the boiler and its associated emission control systems and to 

recognize that various control systems must be phased in according to their unique time, 

temperature, and/or pressure requirements. This could be accomplished through a unit by 

unit work practice plan that is developed and submitted to the Title V permitting authority. 

Background 

The proposed definition of startup does not account for the actual period of startup for 

which the work practice standards are needed. Startup does not simply end when either steam or 

electricity is produced. Neither does mercury control immediately then reach peak performance. 

Startup involves the “setting in operation” of the boiler and its associated air pollution control 

systems, which does not necessarily occur with the first appearance of steam or electricity. 

Defining startup as Southern Company suggests above would ensure that all pollution control 

equipment is started in a safe and environmentally efficient manner. 

The figures below show two actual startups from Southern Company coal-fired power 

plants. The figures labeled (a) illustrate the start and duration of various activities that take place 

during startup including: 

 Supplemental fuel fire

 Steam usage

 Coal fire

 Precipitator energized1

 Unit online (i.e., selling electricity to the grid)

 Scrubber in service2

 SCR inlet opening3

 Ammonia flow for the SCR

 25 percent load

The figures labeled (b) below illustrate mercury emissions during startup. 

 

1

 Electrostatic Precipitators (ESPs) may be only partially energized during initial startup and appropriate ESP 

operation is unit specific. 

2

 Scrubbers may be in service, but not functioning properly at the beginning of startup. Scrubber operation is unit 

specific. Scrubbers may be under required bypass for blackstart situations. 

3

 The end of the SCR inlet opening bar denotes that the SCR is completely open and ready for ammonia injection 

once the appropriate temperature is reached. 
Figure 1(a). Startup Events of a 900 MW Supercritical Unit on April 16, 2011 

Figure 1(b). Mercury Emissions During 900 MW Supercritical Unit Startup on April 16, 2011 

End of

Startup as

Defined by

EPA in final

rule (steam

use)

End of Startup

as Defined by

EPA in

proposed

reconsideration

(electricity

generation)
Figure 2(a). Startup Events of a 900 MW Supercritical Unit on May 5, 2011 

Figure 2(b). Mercury Emissions for 900 MW Supercritical Unit Startup on May 5, 2011 

End of Startup

as Defined by

EPA in

proposed

reconsideration

(electricity

generation)

End of

Startup as

Defined by

EPA in final

rule (steam

use)

SUPER-CRITICAL SYSTEM START-UP

STEP 1:

C. Cvetic 

12/17/2012
SUPER-CRITICAL SYSTEM START-UP

STEP 2:

C. Cvetic 

12/17/2012
SUPER-CRITICAL SYSTEM START-UP

STEP 3:

C. Cvetic 

12/17/2012
SUPER-CRITICAL SYSTEM START-UP

STEP 4:

C. Cvetic 

12/17/2012
SUPER-CRITICAL SYSTEM START-UP

STEP 5:

C. Cvetic 

12/17/2012
SUPER-CRITICAL SYSTEM START-UP

STEP 6:

C. Cvetic 

12/17/2012
SUPER-CRITICAL SYSTEM START-UP

STEP 7:

C. Cvetic 

12/17/2012
SUPER-CRITICAL SYSTEM START-UP

STEP 8:

C. Cvetic 

12/17/2012
SUPER-CRITICAL SYSTEM START-UP

STEP 9:

C. Cvetic 

12/17/2012
SUPER-CRITICAL SYSTEM START-UP

STEP 10:

C. Cvetic 

12/17/2012
SUPER-CRITICAL SYSTEM START-UP

STEP 11:

C. Cvetic 

12/17/2012
WHZ_01_AEP_1-5101-10.dgn 10/27/2011 11:22:46 AM