Document ID: ./input/supremecourt_opinions/opinions/23pdf/23a349_0813.pdf
Page Number: 36.0

14 

OHIO v. EPA 

BARRETT, J., dissenting 

  Crucially,  the  final  rule  suggests  that  EPA  calculated 
cost-effectiveness  thresholds  based  on  the  likely  cost  and 
impact  of  available  emissions-reduction  technology  given 
national, industry-wide data.  Contrary to the Court’s spec-
ulations, ante, at 12, these thresholds and the FIP’s result-
ing emissions limits appear not to depend on the number of 
covered  States.    Consider  the  plan’s  approach  to  power 
plants (“electric generating units,” or EGUs).  EPA assessed 
the  cost  and impact of different  NOx mitigation  strategies 
that EGUs could implement.  One strategy was to fully op-
erate  “selective  catalytic  reduction”  (SCR)  technology.    88 
Fed. Reg. 36655; see id., at  36720.  EPA estimated that a 
“representative  marginal  cost”  for  this  strategy  would  be 
$1,600  per  ton,  and  a  “reasonable  level  of  performance” 
would  be  0.08  lb/mmBtu—based  on  “nationwide”  power 
plant “emissions data.”  Id., at 36720–36721.  EPA thus de-
termined  that  SCR  optimization  was  a  “viable  mitigation 
strategy for the 2023 ozone season” and built this assump-
tion into the plan’s emissions limits.  Id., at 36720.  In other 
words,  EPA  relied  on  nationwide  industry  data  to  select 
cost thresholds that corresponded to how much it would cost 
to  use  particular  emissions-reduction  technologies,  and  it 
applied  that  “uniform  control  stringency  to  EGUs  within 
the covered upwind states.”  Id., at 36680.7 

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marketplace  for  emissions.    Ibid.    With  respect  to  other  sources,  EPA 
determined that nine industries in the covered States produced the most 
significant emissions.  Id., at 36817.  The rule requires sources in each of 
those  industries  to  meet  specific  emissions  limits  that  were  calculated 
based on the reductions that they can cost-effectively achieve.  Ibid. 

7 EPA ultimately selected (based on nationwide data) a cost threshold 
of $1,800 per ton of NOx reduction that would apply in earlier years, and 
a cost threshold of $11,000 per ton that would apply in later years.  88 
Fed. Reg. 36749, 36846.  These cost thresholds corresponded to the cost 
of  different  emissions-control  measures:  For  example,  EGUs  can  “ret-
rofi[t ] state-of-the-art combustion controls” and “[o]ptimiz[e] idled SCRs” 
for less than $1,800 per ton, and they can “instal[l  new] SCRs” for less