RESPONSE
TO
SIGNIFICANT
PUBLIC
COMMENTS
ON
THE
PROPOSED
CLEAN
AIR
MERCURY
RULE
Received
in
response
to:

Proposed
National
Emission
Standards
for
Hazardous
Air
Pollutants;
and,
in
the
Alternative,
Proposed
Standards
of
Performance
for
New
and
Existing
Stationary
Sources:
Electric
Utility
Steam
Generating
Units
(
69
FR
4652;
January
30,
2004)

Supplemental
Notice
for
the
Proposed
National
Emission
Standards
for
Hazardous
Air
Pollutants;
and,
in
the
Alternative,
Proposed
Standards
of
Performance
for
New
and
Existing
Stationary
Sources:
Electric
Utility
Steam
Generating
Units
(
69
FR
12398;
March
16,
2004)

Proposed
National
Emission
Standards
for
Hazardous
Air
Pollutants;
and,
in
the
Alternative,
Proposed
Standards
of
Performance
for
New
and
Existing
Stationary
Sources,
Electric
Utility
Steam
Generating
Units:
Notice
of
Data
Availability
(
69
FR
69864;
December
1,
2004)

Docket
Number
OAR­
2002­
0056
4.0
PERFORMANCE
STANDARDS
FOR
OIL­
FIRED
ELECTRIC
UTILITY
STEAM
GENERATING
UNITS
US
Environmental
Protection
Agency
Emissions
Standards
Division
Office
of
Air
Quality
Planning
and
Standards
Research
Triangle
Park,
North
Carolina
27711
15
March
2005
i
General
Outline
1.0
INTRODUCTION
AND
BACKGROUND
2.0
APPLICABILITY
AND
SUBCATEGORIZATION
3.0
PERFORMANCE
STANDARDS
FOR
COAL­
FIRED
ELECTRIC
UTILITY
STEAM
GENERATING
UNITS
4.0
PERFORMANCE
STANDARDS
FOR
OIL­
FIRED
ELECTRIC
UTILITY
STEAM
GENERATING
UNITS
5.0
MERCURY
CAP­
AND­
TRADE
PROGRAM
6.0
MERCURY
EMISSIONS
MONITORING
7.0
IMPACT
ESTIMATES
8.0
COMPLIANCE
WITH
EXECUTIVE
ORDERS
AND
STATUTES
9.0
NODA
10.0
OTHER
Appendix
A
LIST
OF
COMMENTERS
4­
1
4.0
PERFORMANCE
STANDARDS
FOR
OIL­
FIRED
ELECTRIC
UTILITY
STEAM
GENERATING
UNITS
4.1
NEED
FOR
REGULATION
Comment:

One
commenter
(
OAR­
2002­
0056­
2046)
questioned
the
threshold
decision
to
regulate
nickel
(
Ni)
emissions
from
oil­
fired
units
at
all.
According
to
the
commenter,
based
on
what
it
termed
conservative
assumptions
(
i.
e.,
assumptions
that
overstate
the
risk),
EPA
concluded
in
its
1998
Report
to
Congress
on
the
emission
of
hazardous
air
pollutants
(
HAP)
from
oil­
fired
units
that
Ni
emissions
from
these
units
were
responsible
for
one
excess
cancer
case
every
5
years.
According
to
the
commenter,
the
Agency
concluded
in
the
same
report
that
only
11
units
in
the
country
contributed
to
an
excess
maximum
individual
risk
of
cancer
of
one­
in­
a­
million,
but
only
barely
so.
The
commenter
provided
updated
information
indicating
that
many
of
these
units
have
changed
their
operations
so
as
to
drastically
limit
their
oil
use,
or
have
shut
down
entirely.
Moreover,
the
commenter
added
that
there
is
information
to
suggest
that
EPA's
assumptions
regarding
the
toxicity
of
Ni
emissions
from
oil­
fired
units
were
overly
conservative.
The
commenter
recommended
that
EPA
re­
evaluate
its
conclusion
that
these
emissions
warrant
regulation
at
all.

One
commenter
(
OAR­
2002­
0056­
2828)
stated
that
EPA
should
not
set
a
MACT
standard
for
Ni
emissions
from
electric
utility
steam
generating
units
because
the
cost/
benefit
ratio
of
the
proposed
MACT
is
exorbitant
and
EPA's
risk
assessment
is
extremely
over­
conservative
and
greatly
overstates
risks
which
are
not
significant.
The
commenter
stated
that
EPA
assumed
that
Ni
emissions
from
electric
generating
units
are
50
percent
Ni
subsulfide
although
a
more
realistic
estimate
based
on
data
that
became
available
to
EPA
after
the
Report
To
Congress
was
issued
indicates
that
the
level
of
Ni
subsulfide
in
electric
utility
emissions
is
far
lower
than
even
10
percent,
and
may
actually
be
0
percent.

The
commenter
noted
that
in
the
proposed
rulemaking,
EPA
asked
for
comment
on
the
finding
in
the
Utility
RTC
that
only
11
of
137
oil­
fired
utility
units
considered
in
the
Utility
RTC
posed
an
inhalation
risk
to
human
health
of
greater
than
one
in
one
million.
The
commenter
noted
that
this
estimate
is
for
the
year
1990,
for
which
it
is
estimated
that
a
population
of
110,000
would
be
exposed
to
a
risk
greater
than
one­
in­
one­
million.
The
commenter
further
noted
that
in
2010,
after
imposition
of
the
requirements
of
the
Clean
Air
Act
(
CAA),
EPA
estimates
that
the
population
at
risk
decreases
to
11,000
because
several
of
the
11
units
have
already
been
converted
to
natural
gas,
are
burning
more
gas
or
are
shut
down.
According
to
the
commenter,
EPA
did
not
specify
which
of
the
11
units
these
are
although
it
seems
reasonable
that
the
number
of
power
plants
would
be
substantially
less
than
11.

Regarding
the
cost­
benefit
calculation,
the
commenter
stated
that
a
cost
benefit
calculation
using
EPA's
numbers
shows
a
cost­
benefit
ratio
of
$
2.08
billion
dollars
per
avoided
cancer
case,
clearly
exorbitant
and
unjustifiable.
According
to
the
commenter,
using
more
reasonable
numbers
4­
2
for
the
percent
of
emissions
that
are
Ni
subsulfide
would
result
in
even
higher
cost
per
avoided
cancer.

One
commenter
(
OAR­
2002­
0056­
2504)
stated
that
the
scientific
risk
data
does
not
support
the
need
for
regulating
Ni.

One
commenter
(
OAR­
2002­
0056­
2891)
stated
that
risks
posed
by
Ni
emissions
from
oil­
fired
generators
are
negligible
and
do
not
justify
a
finding
that
the
regulation
of
such
units
is
appropriate
and
necessary.

One
commenter
(
OAR­
2002­
0056­
3402)
submitted
that
there
is
a
serious
question
as
to
whether
Ni
emissions
from
oil­
fired
units
should
initially
have
been
or
should
now
be
regulated
at
all,
in
light
of
evidence
relating
to
the
decreasing
use
of
oil
generation
and
the
toxicity
of
Ni
emissions.
The
commenter
recommended
that
EPA
re­
evaluate
its
conclusion
that
these
emissions
warrant
regulation
at
all.

One
commenter
(
OAR­
2002­
0056­
2850)
supported
exempting
Ni
emissions
from
oil­
fired
plants
as
there
is
no
public
health
justification
for
developing
regulations.
According
to
the
commenter,
any
actions
taken
by
their
industry
that
could
raise
the
cost
of
electricity
to
consumers
should
bring
commensurate
health
and
environmental
benefits.

One
commenter
(
OAR­
2002­
0056­
2452)
noted
that
the
power
generation
industry
has
changed
significantly
since
EPA's
1998
Report
to
Congress.
The
commenter
stated
that
updated
data
on
the
nation's
oil­
fired
units
and
their
operating
characteristics
are
important
to
developing
a
sound
final
rule.

Response:

Based
on
the
comments
received,
EPA
has
reexamined
the
available
information
relating
to
both
the
number
of
oil­
fired
units
and
the
combinations
of
fuels
fired
in
such
units.
Based
on
that
reexamination,
EPA
believes
that
Ni
emissions
from
oil­
fired
Utility
Units
have
been
substantially
reduced
since
the
1998
Utility
Report
to
Congress
through
a
combination
of
unit
closures
and
fuel
switching.
In
addition
to
the
information
provided
by
the
commenters,
EPA
analyzed
the
latest
information
provided
by
the
U.
S.
Department
of
Energy,
Energy
Information
Administration
(
DOE/
EIA),
particularly
with
regard
to
the
11
plants
identified
as
causing
the
greatest
risk.
The
11
oil­
fired
plants
identified
in
the
Utility
Study
as
having
a
cancer
maximum
individual
risk
of
greater
than
10­
6
based
on
Ni
emissions
were
comprised
of
42
individual
units.
Of
those
42
units,
12
units
have
permanently
ceased
operation
or
are
out
of
service.
(
OAR­
2002­
0056­
2046
at
pp.
12
­
13;
OAR­
2002­
0056­
5998).
In
addition,
6
of
the
original
42
units
have
reported
to
the
U.
S.
Department
of
Energy
(
DOE)
that
their
fuel
mix
now
includes
natural
gas.
Earlier
reports
did
not
show
these
units
as
using
natural
gas
as
a
fuel.
(
OAR­
2002­
0056­
5998).
The
use
of
natural
gas
as
a
part
of
their
fuel
mix
would
decrease
the
Ni
emissions
from
these
6
units.
Similarly,
another
5
units
report
using
a
mix
of
natural
gas
and
distillate
oil
(
rather
than
residual
oil)
in
2003.
(
OAR­
2002­
0056­
5998).
Since
distillate
oil
contains
less
Ni
than
the
residual
oil
previously
burned
by
these
units,
it
is
reasonable
to
assume
that
these
units
4­
3
currently
emit
less
Ni
than
was
previously
the
case.
Another
2
units
now
fire
a
residual
oil/
natural
gas
mixture
and
have
limited
their
residual
oil
use
through
permit
restrictions
to
no
greater
than
10
percent
of
the
fuel
consumption
between
April
1
and
November
15,
with
natural
gas
being
used
for
at
least
90
percent
of
total
fuel
consumption.
(
OAR­
2002­
0056­
2046
at
p.
13).
Finally,
five
units
have
effectively
eliminated
their
mercury
emissions
since
the
Utility
Study
by
switching
to
burning
natural
gas
exclusively.
(
OAR­
2002­
0056­
2046
at
pp.
12
­
13;
OAR­
2002­
0056­
5998).
Taken
as
a
whole,
these
changes
mean
that
30
of
the
original
42
units
identified
in
the
Utility
Study
have
taken
steps
to
effectively
reduce
or
actually
eliminate
their
Ni
emissions.
Of
the
original
11
plants
identified
in
the
Utility
Study,
only
2,
both
in
Hawaii,
have
units
for
which
actions
that
will
result
in
reduced
Ni
emissions
do
not
appear
to
have
been
taken.
("
Analysis
of
operating
oil­
fired
electric
utility
steam
generating
units,"
OAR­
2002­
0056­
6178).
In
addition
to
the
closure
of
the
12
units
identified
as
being
of
potential
concern
in
the
Utility
Study,
there
has
been
a
steady
decrease
in
the
number
of
oil­
fired
Utility
Units
generally
over
the
past
decade
and
this
trend
is
likely
to
continue.
In
fact,
the
latest
DOE/
EIA
projections
(
OAR­
2002­
0056­
5999)
estimate
no
new
utility
oil­
fired
generating
capacity
and
decreasing
existing
oil­
fired
generating
capacity
through
2025,
with
an
additional
29.2
gigawatts
of
combined
oil­
and
natural
gas­
fired
existing
capacity
being
retired
by
2025.
Based
on
the
foregoing,
EPA
concludes
that
it
is
not
appropriate
to
regulate
oil­
fired
Utility
Units
under
section
112
because
we
do
not
anticipate
that
the
remaining
level
of
utility
Ni
emissions
will
result
in
hazards
to
public
health.

4.2
OTHER
Because
EPA,
in
the
final
rule,
is
not
taking
final
action
on
the
proposal
to
regulate
Ni
emissions
from
oil­
fired
units,
we
are
not
providing
responses
to
the
remaining
comments
received
on
the
proposal
to
regulate
such
emissions.
