### Summary	of	Interagency	Working	Comments on	the	Draft	Language	under

EO 12866/13563	Interagency	Review.	Subject	to	Further	Policy	Review.

**ENVIRONMENTAL PROTECTION AGENCY (EPA )**  **Updated Version of 111(b) RIA and Response to Interagency Comments General Comments**  1) Reviewer recommends clarifying whether the sentence on page 1 -4 which includes “new non compliant natural gas -fired combustion turbine units” is referring to simply cycle combustion turbine units. Response: Sentence revised for clarity. 2) Reviewer recommends clarifying whether the reference on page 4 -4 to AEO 2013 should instead refer to 2014. Response: This is correct. The regiona l cost factors within the current version of IPM were developed using AEO 2013. These are not updated with each new version of AEO. 3) Reviewer recommends clarifying page 4 - 11, in the notes under figure 4 - 1, whether the renewables list should include wind. Re sponse: Wind is identified independently in the figure, so not included in the list. Category revised from “renewables” to “other renewables” for clarity. 4) Reviewer recommends clarifying whether the reference to “cofiring with 14 percent natural gas” on pag e 5 - 19 is correct. Response: Corrected – analysis assumes 34% natural gas co -firing . **Technical Comments** 1) Reviewer recommends updating page ES - 2 to reflect the revised preamble. a. Specifically the sentence about “BSER for natural gas -fired stationary combustio n turbines” and the “1,080 lb CO2/MWh” reference Response: Revisions made. 2) Reviewer recommends updating table ES - 1 to reflect the revised preamble. Response: Revisions made. Also revised Table 1 - 1. 3) Reviewer recommends reconciling the note under Table 4 - 3 to ensure consistency with the definition of “high economic growth” scenario in Table 4 -4. Response: Revisions made. 4) Reviewer recommends reconciling the notes under figure 5 - 1 about NG co -firing of 4 3% with the text in the paragraph above. Response: Revisions made.

### Summary	of	Interagency	Working	Comments on	the	Draft	Language	under

EO 12866/13563	Interagency	Review.	Subject	to	Further	Policy	Review. 5) Reviewer recommends clarifying the accounting for the greenhouse gas benefits of biomass energy in the RIA. Reviewer notes that the EPA SAB stated that it was not scientifically valid to assume that all biogenic feedstocks are carbon neutral, not is it scientifically valid to equate full stack emissions from biomass combustion with fossil sources. Despite this, EPA assumes a biomass emission factor of 195, equivalent to the direct stack em issions from biomass combustion. This is an inconsistency between the RI A and the language of the rule. Response: The table in the RIA presents the emission factors contained in the Integrated Planning Model. This part of the industry profile is simply mea nt to informative and does not influence the conclusions of the RIA. The policy aspects of this question will be addressed in the preamble. **Typographical Comments** All revisions made. 1) Reviewer recommends editing the sentence on page 1 - 2 which reads “has exp lained in detail how emissions of CO2 from the source category here cause or contribute significantly to the air pollution which endangers.” 2) Reviewer recommends editing the sentence on page 2 - 8 to read “Transmission is the term used to describe the bulk transfer of electricity”. 3) Reviewer recommends editing page 2 - 26 to refer to “highly efficient coal -fired designs” rather than “highly efficiency”. 4) Reviewer recommends editing page 4 - 8 to delete “projection is” in the sentence including “reference case is ‘ projection is a business - as - usual...” 5) Reviewer recommends editing page 4 - 8 to delete “in” from “2030 in is projected to...” 6) Reviewer recommends editing page 4 - 12 to replace “than” with “that” in the bullet titled State Renewable Portfolio Standards (RPS). 7) Re viewer recommends adding “in” on page 4 - 25 to the sentence including “For technologies that are included in the IPM Base Case...” **8)** Reviewer recommends rewording the sentence on page 5 - 14 that reads “In this scenario, we expect some compliance costs if a new N GCC unit...”