MEMORANDUM

TO:		Docket No. EPA-HQ-OAR-2009-0769

FROM:   	Serpil Kayin

	    	US EPA/OAR/OAP/CAMD

SUBJECT:  	Explanation of Contents of SO2 EGU Controls File Used in
Proposed SO2 RIA

DATE:   	November 23, 2009

The baseline in the proposal SO2 RIA for EGUs includes the control
strategy used in the Final Ozone NAAQS RIA that was completed in March
2008.  The baseline strategy was developed to simulate attainment for
the Ozone NAAQS in 2020. This strategy also accounted for extensive
reductions in SO2 emissions from electricity generating units (EGUs) as
implemented in the Clean Air Interstate Rule (CAIR).  While the US
District Court for District of Columbia has remanded the CAIR, it still
is in full effect.  No additional controls for SO2 from EGUs are
implemented in the baseline.   

Consistent with the baseline, the Integrated Planning Model (IPM)
version 3.0 was used to develop the background for the control strategy
applied for the alternative standard of 50 ppb.  In this analysis, EGU
controls were applied to uncontrolled coal-fired units of size 100 MW
and larger within the 50 km radius of violating monitors.   These units
were given the option of retrofitting with a Wet Flue Gas
Desulfurization (FGD) scrubber with 95 percent SO2 reduction efficiency
or retire. 

The attached spreadsheet file contains unit level cost differences (as a
function of fixed operating and maintenance (FOM), variable operating
and maintenance (VOM), capital, and fuel costs) between the baseline and
control policy simulations for those units that are controlled in the
strategy.  It should be noted that the control strategy results in the
retirement of three units (total capacity of approximately 400 MW).  In
addition, some units switch to different grades of coal and dispatch
differently compared to the baseline.   

Documentation of IPM version 3.0, including detailed cost and
performance assumptions can be found at    HYPERLINK
"http://www.epa.gov/airmarkt/progsregs/epa-ipm/index.html" \l "newbc"  
http://www.epa.gov/airmarkt/progsregs/epa-ipm/index.html#newbc .  

cc:	Larry Sorrels, US EPA/OAR/OAQPS/HEID

	

