Summary	of	Interagency	Working	Comments	on	Draft	Language	under	

EO12866/13563	Interagency	Review.		Subject	to	Further	Policy	Review.

Note: Page numbers throughout this document correspond to the page numbers in the redline/strikeout 

version of the RIA.

PRIORITY COMMENTS

Incentives for EGU Modification and Reconstruction

Pages: ES-2, ES-4 and 6-2, and throughout document

Page ES-4 states: “Historically, the EPA has been notified of very few modifications (for criteria 

pollutants) or reconstructions under the NSPS provisions. As such, the EPA anticipates few covered units 

will trigger the reconstruction or modification provisions in the period of analysis. 

Therefore, based on the analysis presented in Chapter 4 of this RIA, the EPA anticipates that the EGU 

New, Modified, and Reconstructed Source GHG Standards will result in negligible CO2 emission changes, 

energy impacts, quantified benefits, costs, and economic impacts by 2022. Accordingly, the EPA also 

does not anticipate this rule will have any significant impacts on the price of electricity, employment or

labor markets, or the U.S. economy.” 

Page 6-2 states: “Instead, the EPA has determined that it is appropriate to establish standards of 

performance at this time for large-scale modifications of steam generating units, such as major facility 

upgrades involving the reconstruction or replacement of steam turbines and other equipment upgrades 

that result in substantial increases in a unit’s potential hourly CO2 emissions rate. The EPA does not 

have sufficient information at this time to predict the full array of actions that existing steam generating 

units may undertake, including those in response to applicable requirements under an approved CAA 

section 111(d) plan.”

Reviewer reiterates that it is concerned that using historical data on large modifications and 

reconstructions may not be an accurate way to assess future decisions about reconstruction or 

modifications because incentives in the future differ from historical incentives.

In a separate submission reviewer provided EPA staff with data on 7 examples of modifications to fossil 

steam EGUs that resulted in unit capacity increases ranging from 8% to 20%. Reviewer hopes that these 

data will provide a rationale for strengthening the technical basis for the “large modification” threshold. 

Reviewer found the technical basis for the 10% “large modification” threshold to be unclear given the 

current explanation and examples that are included in the Preamble, and suggests clarifying. In addition, 

Reviewer would be happy to consult with EPA to determine and strengthen the technical basis for an 

appropriate “large modification” threshold. 

Response: EPA has already provided a response to this comment when it was received on the preamble. 
Summary	of	Interagency	Working	Comments	on	Draft	Language	under	

EO12866/13563	Interagency	Review.		Subject	to	Further	Policy	Review.

Page 2 of 5

TECHNICAL COMMENTS

P. 2-5, Table 2-2 (Redline/strike out version)

Reviewer notes that the 2012 data in Table 2.2 of the RIA appears to be inconsistent with the referenced 

EIA data. For coal, the data appears to be 2014 data, for natural gas 2012 data, for nuclear 2013 data, 

for hydro not clear but possibly 2013, petro not sure, for wind 2013 data.

Reviewer recommends double checking the 2012 data provided in table 2.2 of the RIA.

Response: Table revised.

P. 2-29 (Redline/strike out version)

“(4) conventional coal-fired generation with carbon capture and storage (CCS).”

Reviewer recommends rephrasing to read: “(4) conventional highly efficient coal-fired generation (e.g., 

modern supercritical or ultra-supercritical steam units) with partial carbon capture and storage (CCS)” 

as this is the technology that has been identified as BSER by EPA in this rulemaking.

In addition, reviewer recommends beginning the list of approaches with number (4), given that this is 

the BSER in this rulemaking.

Response: Revisions made.

P. 2-33 (Redline/strike out version)

“The resulting CO2 emission rate is expected to be ~800 pounds per MWh produced.”

Reviewer suggests clarifying whether the emissions rate quoted here is on a net or gross basis. 

Response: We believe that this is gross, but have not been able to find any source to validate this 

assumption. No updates made at this time, but would be happy to incorporate revision if anyone from

Interagency can point to a source that confirms whether it is net or gross.

P. 2-41 (Redline/strike out version)

“160 lb/MMBtu-net”

Reviewer recommends correcting the text to remove the “-net” designation as it does not apply to an 

input standard. 

Response: Revision made.

P 2-42 (Redline/strike out version)

“To qualify, plants must capture and store emissions so that they emit less than 1,100 lbs CO2/MWh, 

among other requirements.”

Reviewer recommends clarifying to specify whether this is a gross or net emission rate.
Summary	of	Interagency	Working	Comments	on	Draft	Language	under	

EO12866/13563	Interagency	Review.		Subject	to	Further	Policy	Review.

Page 3 of 5

Response: We believe that this is gross, but have not been able to find any source to validate this 

assumption. No updates made at this time, but would be happy to incorporate revision if anyone from

Interagency can point to a source that confirms whether it is net or gross.

P. 4-2 (Redline/strike out version)

“The purpose of the sales threshold criterion is to permit gas-fired combustion turbines that only sell a 

small portion of the gross electricity generated to the grid (“peaking units”) to not have to meet the 

same emission standard as a combustion turbine unit designed primarily to generate base and 

intermediate electricity to be sold to the grid.”

Reviewer recommends replacing the phrase “peaking units” with “non-base load units” to conform with 

the terminology in the preamble. 

Response: Revision made.

P. 4-27, (Redline/strike out version), Figure 4-3. Illustrative Wholesale Levelized Cost of Electricity of 

Alternative New Generation Technologies by Cost Component

Reviewer notes that this figure indicates that an SCPC unit will require 18 percent capture to meet the 

1,400 lb CO2/MWh-gross standard, which is not consistent with the rule preamble. The rule preamble 

shows that the same unit will require 16 percent capture to meet the 1,400 lb/MWh Gross standard. 

Reviewer suggests checking the consistency of this assumption.

Reviewer notes that the LCOE estimates in this figure differ from the LCOE estimates provided in the 

rule preamble. Reviewer recommends using a consistent set of LCOE estimates throughout the 

rulemaking and supporting materials and analyses. 

Response: 18% was an error in the figure – this has been corrected. LCOE estimates and related analyses 

updated based on 7/28 version of preamble.

P. 4-33 (Redline/strike out version)

“Thus, in practice, the EPA expects that potential CT units would not meet the applicability requirements 

finalized in this rule and would therefore, not be subject to the standards of performance.”

Reviewer notes that these CT units likely would meet the applicability criteria for the clean fuels 

standards contained in the most recent version of the 111(b) preamble. Reviewer suggests updating text 

to reflect this. 

Response: Revision made.

P. 4-34 (Redline/strike out version)

“Furthermore, the design net efficiencies for currently available potentially impacted aeroderivative 

simple cycle combustion turbines range from approximately 32 percent for smaller designs to 39 

percent for the largest intercooled designs. The efficiencies of industrial frame units range from 30 

percent for smaller designs to 36 percent for the largest units.” 
Summary	of	Interagency	Working	Comments	on	Draft	Language	under	

EO12866/13563	Interagency	Review.		Subject	to	Further	Policy	Review.

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Reviewer notes that simple cycle turbines are available at efficiencies greater than those quoted here, 

and suggests updating accordingly. See: http://site.geenergy.com/prod_serv/products/tech_docs/en/downloads/ger4222a.pdf. 

Response: The values reported in the RIA are based on the high heating value of the fuel. This is 

explained in a footnote. Text was added to explain that the low heating value efficiencies would be 

higher.

P. 4-34 (Redline/strike out version)

“The EPA therefore does not expect new CT units to be constructed, that would meet the applicability 

requirements.”

Reviewer notes that these CT units likely would meet the applicability criteria for the clean fuels 

standards contained in the most recent version of the 111(b) preamble. Reviewer suggests updating text 

to reflect this.

Response: Revision made.

P. 4-34, Footnote 58 (Redline/strike out version)

“CT cost, performance, and financial assumptions from AEO 2013.”

Reviewer notes that these assumptions are cited from AEO 2013. Reviewer notes that more recent 

AEO2015 cost and financial assumptions are available at: 

http://www.eia.gov/forecasts/aeo/pdf/electricity_generation.pdf. Reviewer notes that more recent CT 

performance assumptions are available at: 

http://www.eia.gov/forecasts/aeo/assumptions/pdf/electricity.pdf. Reviewer suggests using the most 

recent data available. 

Response: Updating this figure requires some amount of data processing. At this time, sufficient staff 

resources are not available for this task. We do not expect that the updated data would substantially 

change the overall conclusion the figure supports. 

Page 5-8

“As explained previously, the power sector has moved away from the construction of coal-fired power 

plants in favor of other generation options (e.g., natural gas-fired power plants) due, in part, to the 

significant cost differential.”

Reviewer suggests editing text as indicated above to correct an inaccuracy.

Response: Revision made.
Summary	of	Interagency	Working	Comments	on	Draft	Language	under	

EO12866/13563	Interagency	Review.		Subject	to	Further	Policy	Review.

Page 5 of 5

P. 5-20, Figure 5-1, Footnote 2 (Redline/strike out version)

“A non-compliant 550 MW (net capacity) unit SCPC requires NG co-firing at 34% to achieve a 1,400 

lb/MWh CO2 emission rate. A non-compliant 620 MW (net) IGCC unit requires 6 percent NG co-firing. 

LCOE costs for co-firing were estimated assuming a levelized $6.19/MMBtu price of delivered gas.”

Reviewer notes that the natural gas co-firing rates quoted here differ from the natural gas co-firing rates 

quoted in the 111(b) preamble. Reviewer also notes that the natural gas co-firing rates described here 

differ from the co-firing rates described on page 2-29 of the RIA (Redline/strike out version). Reviewer 

suggests using a consistent set of co-firing rates throughout the preamble and RIA.

Response: 7/28 version of the preamble includes the same co-firing rates (34% for SCPC, 6% for IGCC) as 

the RIA. The rates described in Chapter 2 refer to maximum expected potential co-firing, which differs 

from the representative unit analyzed in the RIA.

P. 5-20, (Redline/strike out version) Figure 5-1 Levelized Cost of Electricity, Uncontrolled Coal and Coal 

with Partial CCS (1,400 lb/MWh gross), and throughout RIA.

Reviewer notes that the NETL LCOE estimates displayed in this table (and throughout the RIA) for SCPC 

units with partial CCS as well as for IGCC units use higher financing costs in comparison to the SCPC unit 

without capture. Reviewer recommends adding a footnote to clarify this.

The financing costs used in the NETL analysis are detailed on page 7 of the following report:

“A high-risk financial structure resulting in a capital charge factor (CCF) of 0.124 is used to evaluate the 

costs of all cases with CO2 capture (non-capture case uses a conventional financial structure with a CCF 

of 0.116).”

“Cost and Performance Baseline for Fossil Energy Plants Supplement: Sensitivity to CO2 Capture Rate in 

Coal-Fired Power Plants,” DOE/NETL-2015/1720, June 22, 2015. Available at 

http://www.netl.doe.gov/File%20Library/Research/Energy%20Analysis/Publications/BitBase_Partial_Ca

pture_final.pdf. 

Response: Note added in relevant location.