Document ID: EPA-HQ-OAR-2005-0029-0016
Agency: epa
Document Type: Supporting & Related Material
Title: 
Posted Date: 2005-06-30T04:00Z

1
MEMORANDUM
DATE:
June
20,
2005
SUBJECT:
NOX
Control
Technologies
for
Stationary
Diesel
ICE
FROM:
Tanya
Parise,
Alpha­
Gamma
Technologies,
Inc.

TO:
Sims
Roy,
EPA
OAQPS
ESD
Combustion
Group
The
purpose
of
this
memorandum
is
to
present
information
on
different
types
of
nitrogen
oxides
(
NOx)
controls
that
can
be
applied
to
stationary
internal
combustion
engines
(
ICE)
operating
on
diesel
fuel.

Introduction
Several
control
technologies
capable
of
reducing
NOx
emissions
from
stationary
ICE
are
discussed
within
this
memorandum.
Add­
on
or
post­
combustion
controls
(
also
referred
to
as
secondary
methods
of
control)
for
NOx
are
control
methods
designed
to
treat
the
exhaust
emissions
from
stationary
ICE
once
NOx
emissions
have
formed.
Onengine
or
in­
cylinder
controls
(
also
referred
to
as
primary
methods
of
control)
for
NOx
are
control
methods
designed
to
minimize
the
amount
of
NOx
formed.
Control
methods
that
are
commercially
available
and
control
technologies
that
are
under
development
are
discussed.
Table
1
presents
a
summary
of
the
NOx
emissions
reductions
that
can
be
achieved
for
the
control
methods
discussed
in
this
paper.

Commercially
Available
Add­
On
Control
Selective
Catalytic
Reduction
Selective
catalytic
reduction
(
SCR)
has
been
on
the
market
and
proven
reliable
for
over
15
years.
However,
it
has
not
been
widely
used
for
engines.
Miratech,
Johnson
Matthey,
Engelhard,
RJM,
Wartsila
and
Catalyst
Products
are
some
manufacturers
that
make
SCR.
Selective
catalytic
reduction
is
often
used
in
combination
with
an
oxidation
catalyst
and
is
the
only
commercially
proven
secondary
NOx
reduction
method
for
lean
burn
gas
and
diesel
engines.
The
following
requirements
and
difficulties
are
associated
with
applying
SCR:
Table
1.
Summary
of
NOx
Controls
for
Stationary
Diesel
ICE
Control
Method
NOx
Reduction
(%)
Applicable
Engines
Cost
Other
Pollutant
Reductions
(%)
Concerns/
Requirements
Commercially
Available
Add­
On
Controls
Selective
Catalytic
Reduction
>
90
Lean
Burn,
Diesel,
and
Dual­
Fuel
$
121/
hp
(
capital)
1
$
36/
hp
(
annual)
1
PM:
0­
30,
HC:
50­
90,

CO:
50­
90
(
with
oxidation
catalyst)
Ammonia
slip
a
concern.
Requires
<
500
ppm
sulfur
fuel.

NOxTech
®
90­
95
Diesel
and
Lean
Burn
Natural
Gas
PM:
60­
80,
VOC:
90,

CO:
50­
70
Trace
ammonia
of
<
2­
5
ppmv.

Commercially
Available
On­
Engine
Controls
Ceramic
Coating
40
Diesel
2
CO:
80,
NMHC:
60
Ignition/
Injection
Timing
Retard
0­
40
(
RB)

0­
20
(
LB)

15­
30
(
CI)
All
Engines
$
12,000­$
25,000
(
capital)
3
$
6,300­$
81,000
(
annual)
CO
and
HC:
Little
effect
for
SI
engines,
no
definite
trend
in
diesel,

and
slight
increase
in
dual­
fuel.
Combustion
instability,
loss
of
power,
impacts
exhaust
valve
life
and
turbocharger
performance.

Increase
in
brake­
specific
fuel
consumption.

Water
Injection
25­
35
All
Engines
4
No
HAP
Reduction
Exhaust
Gas
Recirculation
48­
80
All
Engines
No
HAP
Reduction
Under
Development
NOx
Adsorber
>
90
5
Diesel
and
Gasoline
(
EMx
 
:
Natural
Gas
and
Diesel)
PM:
10­
30,
HC:
90,
CO:

90
6
Sulfur
degradation
and
catalyst
durability.

Requires
<
15
ppm
sulfur
fuel.

Ozone
Injection
85­
95
All
Engines
Typically
includes
a
heat
recovery
steam
generator
and
economizer.

Lean
NOx
Catalyst
<
30
7,8
Lean
Burn
and
Diesel
CO:
60,
NMHC:
60
1
Based
on
averaging
cost
information
from
NESCAUM
and
from
Diesel
&
Gas
Turbine
Worldwide.

2
Tests
are
underway
to
determine
the
effect
on
gas
fired
engines.

3
Costs
are
based
on
installing
an
ignition
system,
however
in
certain
cases
the
ignition
system
is
standard
equipment
and
no
purchased
equipment
is
required.
In
this
case,
capital
costs
are
expected
to
be
$
4,000
or
less.

4
Note
that
in
Table
4
of
the
NJ
SOTA
Manual
for
RICE,
water
injection
is
listed
as
not
applicable
to
SI
lean
burn
engines.

5
Note
that
in
information
from
EC/
R's
update
to
EPA's
ACT,
EMx
 
has
been
shown
to
reduce
NOx
by
95
percent
from
lean
burn
engines
and
98.9
percent
from
diesel
engines.

6
Note
that
according
to
EC/
R's
update
to
EPA's
ACT,
SCONOx
®
has
been
shown
to
reduce
CO
and
VOC
by
up
to
95
percent
in
lean
burn
engine
exhaust.

7
Note
that
information
from
the
Manufacturers
of
Emission
Controls
Association
stated
that
one
stationary
diesel
engine
has
been
equipped
with
a
lean
NOx
catalyst
and
NOx
emissions
are
being
reduced
by
80
percent.

8
Note
that
in
Table
5
of
the
NJ
SOTA
Manual
for
RICE,
the
NOx
efficiency
for
CI
diesel
and
dual­
fuel
engines
is
listed
as
greater
than
90
percent.
3
 
Requires
sulfur
levels
of
less
than
500
parts
per
million
(
ppm),
 
Fuel
penalty:
urea
consumption
approximately
4
percent
of
fuel
use,
 
Infrastructure,
 
Requires
engine
integration:
NOx
sensor
or
engine
NOx
map,
 
Ammonia
slip,
and
 
Possible
vanadium
emissions.

Emissions
Reductions
Selective
catalytic
reduction
is
capable
of
achieving
greater
than
90
percent
reduction
for
NOx,
a
0­
30
percent
reduction
for
particulate
matter
(
PM),
a
50­
90
percent
reduction
for
hydrocarbons
(
HC),
and
a
50­
90
percent
reduction
for
carbon
monoxide
(
CO)
(
with
oxidation
catalyst).

Costs
Information
from
the
Northeast
States
for
Coordinated
Air
Use
Management
(
NESCAUM)
and
from
Diesel
&
Gas
Turbine
Worldwide
was
used
to
estimate
the
costs
associated
with
the
purchase,
installation,
and
operation
of
SCR
on
an
engine.
The
information
from
NESCAUM
was
based
on
a
1,030
horsepower
(
hp)
diesel
engine
equipped
with
SCR
at
the
National
Steel
and
Shipbuilding
Company
in
San
Diego,
California.
The
total
capital
cost
including
installation
for
this
system
was
about
$
179,000.
The
total
annual
cost
was
about
$
44,000.
The
information
from
Diesel
&
Gas
Turbine
Worldwide
indicated
that
the
total
capital
cost
including
installation
for
an
SCR
system
applied
to
a
2,336
hp
engine,
achieving
a
90
percent
reduction
in
NOx
emissions,
was
$
160,000
with
annual
costs
of
about
$
67,000.
The
cost
information
from
both
sources
was
averaged
together
to
obtain
average
costs
per
hp.
Capital
costs
associated
with
SCR
were
estimated
to
be
$
121/
hp
with
an
annual
cost
estimated
to
be
$
36/
hp.
Costs
include
capital
recovery,
operation
and
maintenance,
fuel
penalty,
and
urea.
An
oxidation
catalyst
and
a
NOx
continuous
emissions
monitoring
system
(
CEMS)
can
help
to
reduce
ammonia
slip.
The
capital
cost
for
a
NOx
CEMS
is
$
158,000
with
an
annual
cost
of
$
43,000.

Cost
information
is
available
from
EC/
R's
update
on
NOx
control
technologies
report
which
was
obtained
from
a
vendor
who
calculated
costs
for
two
scenarios
involving
2,600
hp
natural
gas
fired
SI
engines.
For
the
first
scenario,
three
engines
each
operating
400
hours
were
used.
For
the
first
scenario,
capital
costs
were
calculated
at
$
187,000.
For
the
second
scenario,
one
engine
operated
2,000
hours
per
year.
The
capital
cost
for
this
scenario
was
calculated
at
$
68,000.
Capital
costs
include
catalyst,
urea
control,
injectors,
engine
map,
startup
assistance,
reagent
tank,
and
installation.
The
annual
costs
for
the
first
scenario
were
calculated
at
$
48,200
based
on
capital
recovery
(
equipment
life
of
7
years
and
10
percent
interest
rate)
and
reagent
costs.
The
annual
costs
for
the
second
scenario
using
the
same
assumptions,
except
that
an
equipment
life
of
5
years
was
used,
were
calculated
at
$
35,680.
Note
that
these
costs
do
not
include
all
cost
elements
typically
included
by
EPA.
For
example,
no
4
indirect
installation
costs
are
included
in
the
capital
costs.
Also,
operating
and
maintenance
costs
are
not
included
in
the
annual
costs.

The
RJM
Corporation,
a
provider
of
emission
control
technologies,
was
contacted
to
obtain
cost
information
about
their
SCR
products.
This
company
provided
SCR
technology
to
a
number
of
diesel
fired
engines
in
the
country.
The
product
RJM
installs
on
diesel
engines
for
NOx
control
is
the
RJM
ARIS
 
SCR
Technology.
The
capital
costs
for
the
SCR
system
for
a
2,336
hp
diesel
engine
range
from
$
140,000
to
$
160,000
depending
on
the
amount
of
control
(
50
to
90
percent
NOx
reduction).
The
cost
effectiveness
for
the
RJM
SCR
varies
depending
on
number
of
hours
of
operation
and
amount
of
control
desired.
For
90
percent
NOx
control
from
a
2,336
hp
diesel
engine
the
cost
effectiveness
is
$
3,130
per
ton
of
NOx
removed
based
on
1,000
hours
of
operation
and
ranges
to
$
738
per
ton
of
NOx
removed
based
on
8,000
hours
of
operation.
For
75
percent
NOx
control
from
a
2,336
hp
diesel
engine
the
cost
effectiveness
is
$
3,422
per
ton
of
NOx
removed
based
on
1,000
hours
of
operation
and
ranges
to
$
775
per
ton
of
NOx
removed
based
on
8,000
hours
of
operation.

Caterpillar
indicated
that
its
SCR
system
is
capable
of
reducing
NOx
emissions
by
90
percent
from
diesel
engines,
or
down
to
a
level
of
about
0.7
grams
per
horsepower­
hour
(
g/
hp­
hr)
from
a
7.0
g/
hp­
hr
engine.
The
cost
for
a
1.7
megawatt
(
MW)
(
2,278
hp)
diesel
genset
package
with
SCR
is
$
228,000,
or
$
130/
ekw.
Caterpillar
indicated
that
this
cost
includes
the
SCR
itself
for
$
133,000,
plus
the
urea
tank,
control
system,
connections,
and
packaging
for
$
95,000.
Caterpillar
also
provided
some
information
on
an
SCR
installation
at
EXAR,
a
semiconductor
manufacturer
in
Freemont,
California.
At
this
facility,
SCR
had
been
installed
on
Caterpillar
gas
engines
to
meet
2003
California
rules
on
NOx
emissions,
according
to
Caterpillar.
The
total
SCR
and
related
capital
costs
were
$
450,000,
or
$
473/
ekw,
for
a
plant
totaling
950
ekw
in
size,
according
to
Caterpillar.
These
costs
include
building
modifications,
civil
works,
fixed
piping
and
assembly.
According
to
Ralph
Renee
(
facilities
manager
at
EXAR),
the
actual
SCR
cost
was
about
$
230/
ekw.
Maintenance
costs
at
this
facility
were
estimated
at
about
$
0.01/
ekw­
hr,
with
the
assumption
of
a
urea
price
of
$
2­
5
per
gallon.
According
to
Caterpillar,
$
0.01/
ekw­
hr
would
probably
cover
the
total
SCR
system
over
time.

Experience
Information
from
EPA's
Alternative
Control
Techniques
(
ACT)
Document
identified
a
total
of
23
SCR
installations
with
lean
burn
engines
in
the
United
States.
A
total
of
nine
SCR
installations
with
diesel
engines
and
27
installations
with
dual­
fuel
engines
were
identified
in
the
United
States.
Note
that
EPA's
ACT
was
published
in
1993.

More
recent
information
from
EC/
R's
report
(
published
in
2000),
which
was
a
partial
update
of
EPA's
1993
ACT
indicated
that
at
least
44
engines
have
had
SCR
installed
since
1991.
Of
these,
38
are
compression
ignited
(
CI)
engines,
of
which
31
are
fired
with
diesel
fuel,
four
are
fired
with
distillate
fuel
oil
(#
2),
one
is
fired
with
5
residual
fuel
oil
(#
6),
and
one
dual­
fuel
engine
is
fired
with
diesel
and
natural
gas.
The
remaining
seven
engines
are
lean
burn
spark
ignited
(
SI)
engines
burning
natural
gas.

Information
was
received
from
catalyst
vendor
Miratech.
Miratech
indicated
that
there
are
basically
no
problems
applying
SCR
to
either
CI
or
SI
engines.
The
vendor
stated
that
worldwide
it
has
expertise
with
more
than
1,000
SCR
installations
on
engines
and
within
the
United
States
70­
80
SCR
installations
on
engines.

Information
regarding
SCR
was
requested
from
catalyst
vendor
Engelhard.
Engelhard
referred
the
request
to
Stephen
Frasch,
an
independent
consultant
and
distributor
of
emission
control
systems
who
has
used
Engelhard
products
for
the
last
10
years
and
who
is
also
hired
by
Engelhard
for
installation
and
warranty
work
in
the
western
United
States.
Stephen
indicated
that
they
have
successfully
installed
SCR
systems
on
both
diesel
and
lean
burn
natural
gas
engines
and
that
they
have
met
0.15
g/
bhp­
hr
for
NOx
for
both
fuel
types
with
10
ppm
or
less
ammonia
slip.
According
to
Stephen,
there
are
over
100
SCR
installations
on
engines
across
the
United
States.
Stephen
projects
to
install
10
or
more
SCR
systems
in
2004.

NOxTech
®
Emission
Control
System
According
to
EC/
R's
report,
NOxTech
Inc.
has
developed
the
NOxTech
®
emission
control
system,
which
involves
chemically
treating
exhaust
gases
with
a
nonhazardous
liquid
chemical.
The
system
can
be
applied
to
both
diesel
and
lean
burn
natural
gas
fired
engines.
It
replaces
the
exhaust
silencer
on
engines
with
a
reaction
chamber.
At
temperatures
between
1,400
to
1,500
°
F
the
non­
catalytic
chemical
reagent
is
injected
into
the
exhaust.
Nitrogen,
water
vapor,
and
CO
are
formed
from
the
reaction
between
NOx
and
the
injected
reagent.
There
is
no
toxic
waste
associated
with
this
process,
however,
there
are
trace
ammonia
emissions
of
less
than
2­
5
ppm
by
volume.
The
NOxTech
®
system
is
fully
automated,
installation
requires
no
major
modifications,
and
the
system
can
be
installed
in
2
to
3
weeks.
To
achieve
the
temperatures
required
for
the
reactions
associated
with
the
NOxTech
®
system,
the
exhaust
gas
must
be
heated.
A
heat
exchanger
is
placed
downstream
from
the
reactor
to
reclaim
and
reuse
this
heat
energy.
According
to
information
on
NOxTech
Inc's
website,
the
system
can
be
applied
to
both
retrofit
and
new
engines.
The
system
is
a
muffler­
size
device
made
of
sheet
metal
and
other
readily
available
materials
and
parts,
which
can
be
installed
easily.

Emissions
Reductions
Information
in
EC/
R's
report
indicated
that
according
to
NOxTech
Inc.,
the
emission
control
system
has
been
proven
to
remove
90­
95
percent
of
NOx
emissions,
60­
80
percent
of
PM,
90
percent
VOC,
and
50­
70
percent
of
CO
from
the
exhaust
of
the
4,000
hp
diesel
powered
generator
on
Catalina
Island.
According
to
NOxTech
Inc,
emissions
of
gaseous
organic,
PM,
and
CO
can
be
reduced
by
greater
than
80
percent.
6
Costs
According
to
literature
available
from
NOxTech
Inc.
website,
NOxTech
®
system
capital
costs
are
about
$
50­
150/
bhp­
hr
for
diesel
engines.
The
company
also
states
on
their
website
that
NOxTech
®
treatment
costs
are
not
expected
to
exceed
about
$
1,000/
ton
of
NO2
equivalent
NOx
reduction.
The
company
claims
that
the
NOxTech
®
system
can
provide
the
end
use
a
50
percent
cost
reduction
in
comparison
with
SCR
systems.

Experience
According
to
EC/
R's
report,
the
NOxTech
®
system
is
operating
on
several
diesel
generators
owned
by
Southern
California
Edison.
At
its
Catalina
Island
facility,
NOxTech
®
is
used
on
2.5
MW
(
3,350
hp)
and
3.8
MW
(
5,092
hp)
diesel
electric
generators.
At
its
Pebbly
Beach
generating
station,
NOxTech
®
is
used
on
1.5
MW
(
2,010
hp)
and
2.8
MW
(
3,752
hp)
diesel
generators.

On­
Engine
Control
Methods
Ceramic
Coating
Ceramic
engine
coatings
have
been
used
for
several
years
in
stationary
and
mobile
diesel
engines
to
reduce
PM
emissions.
Ceramic
engine
coatings
improve
combustion
by
reflecting
heat
away
from
coated
components
back
into
the
combustion
gas
path.

Emissions
Reductions
According
to
the
Manufacturers
of
Emission
Controls
Association
(
MECA),
testing
indicated
that
ceramic
engine
coating
combined
with
an
oxidation
catalyst
may
reduce
NOx
emissions
from
a
diesel
engine,
by
allowing
the
engine
timing
to
be
retarded,
by
40
percent.
According
to
MECA,
reductions
of
60
and
80
percent
for
nonmethane
hydrocarbons
(
NMHC)
and
CO,
respectively,
are
possible
with
an
oxidation
catalyst
and
engine
coatings.
One
manufacturer
of
ceramic
coatings
for
diesel
engines
stated
that
significant
HC
and
CO
reductions
can
be
achieved,
however,
an
estimate
of
the
percent
reductions
are
not
available.
More
tests
are
underway
to
better
determine
the
effect
of
ceramic
engine
coatings
on
diesel
as
well
as
gas
fired
engines.

Experience
According
to
MECA's
report
regarding
emission
control
technology
for
stationary
internal
combustion
engines
from
1997,
ceramic
engine
coatings
have
been
used
for
almost
5
years
in
well
over
200
stationary
and
mobile
diesel
engines.

Ignition/
Injection
Timing
Retard
7
Ignition
timing
retard
can
be
applied
to
all
new
or
existing
rich
and
lean
burn
engines.
This
method
delays
initiation
of
combustion
to
later
in
the
power
cycle,
leading
to
a
volume
increase
of
the
combustion
chamber
and
a
reduced
residence
time.
This
may
lead
to
reduced
NOx
formation.
The
extent
to
which
the
ignition
timing
can
be
retarded
to
reduce
NOx
emissions
varies
with
each
engine.
Ignition
timing
increases
exhaust
temperatures,
which
may
adversely
impact
exhaust
valve
life
and
turbocharger
performance,
and
extreme
levels
of
ignition
timing
retard
may
result
in
combustion
instability
and
a
loss
of
power.
Brake­
specific
fuel
consumption
(
BSFC)
increases.

Injection
timing
retard
applied
to
CI
engines
reduces
NOx
emissions
by
the
same
principles
as
those
for
SI
engines.
Injection
timing
can
be
adjusted
on
all
new
or
existing
CI
engines.
Retarding
the
injection
timing
leads
to
the
fuel
igniting
entirely
during
expansion
rather
than
igniting
initially
during
compression
and
then
mostly
igniting
during
expansion.
Lower
combustion
temperature
and
lower
thermal
NOx
is
the
result,
however,
this
also
causes
increased
fuel
consumption.
In
addition,
certain
engines
may
experience
problems
with
high
CO
and
soot
emissions
as
a
result
of
these
changes.

Ignition
and
injection
timing
retard
modifications
can
be
performed
with
a
very
low
capital
cost
and
may
also
require
a
few
hours
of
mechanics
time.
Some
additional
hardware
or
testing
is
often
recommended,
resulting
in
a
total
cost
of
a
few
thousand
dollars.
Similar
NOx
reductions
as
those
obtained
with
injection
timing
retard
can
be
achieved
with
ignition
timing
retard.
However,
SI
engines
are
typically
more
sensitive
to
timing
retard
than
CI
engines,
and
more
operational
problems
are
associated
with
SI
engines
when
applied.
Therefore,
the
level
of
NOx
reduction
achievable
for
SI
engines
can
be
more
limited
than
for
CI
engines.

Injection
timing
retard
adjustment
is
not
possible
on
all
engines.
Excessive
timing
retard
results
in
combustion
instability
and
engine
misfire.
The
BSFC
also
increases
with
increasing
levels
of
injection
timing
retard
for
both
diesel
and
dual­
fuel
engines.

Emissions
Reductions
The
NOx
reductions
from
applying
ignition
timing
retard
range
from
no
reduction
to
40
percent
for
rich
burn
engines
and
0­
20
percent
reduction
for
lean
burn
engines.
Ignition
timing
retard
has
little
effect
on
CO
and
HC
emissions.
For
CI
engines,
retarding
the
injection
timing
by
about
4
degrees
can
reduce
NOx
by
15­
30
percent,
however
achievable
NOx
reductions
are
engine­
specific.
There
is
no
definite
trend
for
CO
and
HC
emissions
for
moderate
levels
of
ignition
retard
in
diesel
engines
and
there
is
a
slight
increase
in
these
emissions
in
dual­
fuel
engines.

Costs
Costs
for
ignition
and
injection
timing
retard
were
provided
in
EPA's
ACT
from
1993.
For
rich
burn
engines,
the
capital
costs
associated
with
ignition
timing
retard
8
range
from
$
12,000
to
$
25,000
with
annual
costs
ranging
from
$
6,300
to
$
80,000.
For
lean
burn
engines,
the
capital
costs
are
similar,
estimated
to
range
from
$
12,000
to
$
24,000,
with
annual
costs
ranging
from
$
7,200
to
$
81,000.
To
obtain
and
maintain
effective
NOx
reduction
with
changes
in
engine
load
and
ambient
conditions,
it
is
required
that
the
engine
be
equipped
with
an
electronic
ignition
control
system
to
automatically
adjust
the
ignition
timing.
In
certain
cases,
the
ignition
system
is
standard
equipment,
in
which
case
no
purchased
equipment
is
required,
and
capital
costs
are
expected
to
be
about
$
4,000
or
less.
Annual
costs
associated
with
ignition
timing
retard
are
due
to
an
increase
in
maintenance
due
to
the
electronic
ignition
control
system,
an
increase
in
BSFC,
emission
compliance
testing,
and
capital
recovery.

For
diesel
engines,
injection
timing
retard
is
estimated
to
have
capital
costs
ranging
from
$
12,000
to
$
24,000
and
annual
costs
ranging
from
$
6,200
to
$
78,000,
based
on
varying
engine
sizes
between
80­
8,000
hp
operating
8,000
hours
per
year.
For
dual­
fuel
engines,
the
capital
costs
range
from
$
12,000
to
$
24,000,
with
annual
costs
ranging
from
$
10,000
to
$
57,000,
based
on
engines
from
700
to
8,000
hp
in
size
operating
8,000
hours
per
year.
It
is
anticipated
that
injection
timing
retard
will
require
an
automated
electronic
control
system
similar
to
ignition
timing
adjustment
for
SI
engines.
Capital
costs
are
estimated
on
the
same
basis
as
ignition
timing
retard
for
SI
engines.
Similarly,
annual
costs
for
injection
timing
retard
are
estimated
using
the
same
methodology
that
was
used
for
SI
engines
for
ignition
timing
retard.

The
Status
Report
on
NOx
Controls
developed
by
NESCAUM
presented
a
case
study
based
on
Tennessee
Gas
Pipeline's
facility
in
Mercer,
Pennsylvania.
Ignition
timing
retard
was
retrofitted
at
this
facility
on
six
1,100
hp
Cooper
GMV­
10
2­
stroke
natural
gas
fired
engines
to
meet
Pennsylvania
reasonably
available
control
technology
(
RACT)
requirements.
The
cost
of
the
retrofit,
including
commissioning
was
$
4,000
per
engine.
The
annual
cost
associated
with
this
project
was
estimated
at
about
$
21,200.

Water
Injection
Water
injection
as
a
control
method
can
be
used
on
any
engine,
but
has
been
applied
primarily
to
diesel
engines
for
the
reduction
of
NOx.
Only
a
few
engines
have
been
retrofitted
to
utilize
water
injection.
However,
several
engine
manufacturers
have
recently
offered
such
control
systems
as
techniques
on
their
new
engines.
Water
vapor
acts
as
a
heat
sink
to
reduce
peak
temperatures,
thereby
reducing
NOx
formation.

Emissions
Reductions
The
SOTA
Manual
for
RICE
developed
by
the
State
of
New
Jersey
Department
of
Environmental
Protection
stated
that
NOx
reductions
of
25­
35
percent
can
be
achieved
with
water
injection.

Exhaust
Gas
Recirculation
9
Exhaust
gas
recirculation
can
be
used
on
all
engine
types.
It
has
been
widely
used
on
gasoline
and
diesel
motor
vehicle
engines
for
NOx
reduction.
This
method
of
control
reduces
NOx
emissions
by
decreasing
peak
combustion
temperatures
through
two
mechanisms:
dilution
and
increased
heat
absorption.
Emissions
Reductions
The
SOTA
Manual
for
RICE
from
the
State
of
New
Jersey
stated
that
NOx
reductions
of
48­
80
percent
can
be
achieved
with
EGR
on
diesel
engines.

Under
Development
Add­
On
Controls
NOx
Adsorber
A
NOx
adsorber
is
a
catalyst
technology
for
removing
NOx
in
a
lean
exhaust
environment
for
diesel
and
gasoline
fired
engines.
The
technology
is
currently
on
the
market
for
mobile
gasoline
fired
engines,
but
still
in
the
research
and
development
phase
for
diesel.
It
is
expected
to
be
on
the
US
market
2007
at
the
earliest.
NOx
adsorbers
consist
of
ceramic
monolith
containing
parallel
channels,
coated
with
precious
metal
catalysts.
During
lean
operation,
NOx
is
stored
in
the
form
of
nitrates
produced
by
reactions
between
the
NOx
and
catalyst.
At
regular
intervals,
a
momentary
reducing
condition
(
switching
to
rich
burn)
is
produced
inside
the
monolith
by
injecting
reductant,
causing
the
nitrates
to
decompose
to
nitrogen.

Emissions
Reductions
A
NOx
adsorber
is
capable
of
achieving
greater
than
90
percent
NOx
reduction,
10­
30
percent
reduction
of
PM,
90
percent
reduction
of
HC,
and
90
percent
reduction
of
CO.
Ultra
low
sulfur
diesel
fuel
(<
15
ppm)
is
required
to
achieve
these
reductions.
This
is
the
technology
that
the
Office
of
Transportation
and
Air
Quality
(
OTAQ)
is
relying
on
for
nonroad
diesel
engines
to
meet
the
Tier
4
standards.
The
following
requirements
and
difficulties
are
associated
with
NOx
adsorbers:

 
Requires
sulfur
levels
of
less
than
15
ppm,
 
Sulfur
degradation
and
catalyst
durability,
 
Requires
engine
integration,
 
Requires
a
means
for
supplemental
fuel
injection,
 
Currently
have
no
information
on
fuel
penalty,
performance
penalty
or
costs,
 
Tremendous
system
complexity
&
packaging,
and
 
Costs
of
precious
metals.

Costs
Based
on
information
from
the
regulatory
impact
analysis
for
nonroad
diesel
engines
for
NOx
adsorber
system
costs,
EPA
developed
NOx
adsorber
costs
for
10
stationary
CI
engines.
These
costs
were
presented
in
the
memorandum
entitled
"
Control
Costs
for
NOx
Adsorbers
and
CDPF
for
CI
Engines,"
included
in
the
rulemaking
docket
(
Docket
ID
No.
OAR­
2005­
0029).
The
EPA
estimated
average
total
annual
control
costs
for
NOx
adsorbers
at
$
1/
hp
and
capital
control
costs
of
$
7/
hp.
For
example,
for
a
1,000
hp
engine,
annual
capital
control
costs
are
estimated
at
$
1,000
per
engine,
with
capital
control
costs
of
$
7,000
per
engine.

Experience
The
EMx
 
(
SCONOx
®
)
system
was
developed
by
Goal
Line
Technologies
(
now
Emerachem)
and
uses
a
single
catalyst
to
remove
NOx,
CO,
and
VOC
emissions.
The
system
was
originally
applied
to
gas
turbines,
but
has
now
been
developed
for
use
on
natural
gas
and
diesel
fired
engines.
The
EMxTM
process
uses
no
hazardous
materials
and
all
utilities
required
to
operate
the
system
(
natural
gas,
steam,
water,
ambient
air,
and
electricity)
are
often
available
at
the
site.
At
temperatures
between
300
and
700
°
F,
nitrogen
dioxide
(
NO2)
is
absorbed
onto
the
catalyst
surface
through
the
use
of
a
potassium
carbonate
coating,
which
reacts
with
the
NO2
to
form
potassium
nitrites.
Maximum
NOx
absorption
is
maintained
by
periodic
regeneration
of
the
EMxTM
catalyst.
The
catalyst
is
regenerated
by
passing
a
controlled
mixture
of
regeneration
gases
across
the
catalyst
surface
in
the
absence
of
oxygen.
Water
and
elemental
nitrogen
are
formed
by
the
reaction
between
the
regeneration
gases
and
nitrites.
The
regeneration
gas
contains
CO2
which
reacts
with
potassium
nitrites
to
form
potassium
carbonate,
the
absorber
coating
that
was
on
the
catalyst
surface
prior
to
the
oxidation
process.

Information
from
EC/
R's
report
indicated
that
the
vendor
tested
the
EMxTM
system
which
showed
that
NOx,
CO,
and
VOC
were
reduced
by
up
to
95
percent
in
lean
burn
engine
exhaust.
Three
EMxTM
systems
were
purchased
for
natural
gas
fired
engines
and
were
scheduled
to
go
on
line
in
May
2000.
Preliminary
testing
of
the
EMxTM
system
conducted
by
Cummins
Engine
Company
for
use
on
mobile
and
stationary
diesel
engines
showed
that
NOx
emissions
were
reduced
by
98.9
percent
down
to
0.4
g/
bhp­
hr.
Three
EMxTM
for
diesel
fired
units
have
been
sold
but
have
not
yet
been
commissioned.

Ozone
Injection
Ozone
injection
can
be
applied
to
all
engine
types.
This
control
technique
oxidizes
NOx
to
nitrous
pentoxide
(
N2O5).
A
water
or
caustic
scrubber
is
used
to
remove
the
N2O5
that
is
highly
water
soluble.
A
heat
recovery
steam
generator
and
economizer
are
typically
used
to
reduce
the
temperature
below
350
°
F.
Temperatures
below
350
°
F
inhibit
ozone
disassociation
and
ensure
that
the
efficiency
of
the
NOx
oxidation
is
optimal.

According
to
the
Status
Report
on
NOx
Controls,
technologies
such
as
electrocatalytic
oxidation
and
ozone
injection
are
emerging
and
offer
the
potential
for
high
NOx
emission
reduction,
as
well
as
reduction
of
emissions
of
other
pollutants.
However,
11
because
there
is
much
less
experience
with
these
technologies,
available
cost
information
is
limited.

Emissions
Reductions
The
SOTA
Manual
for
RICE
from
the
State
of
New
Jersey
stated
that
NOx
reductions
of
85­
95
are
achievable
with
ozone
injection.

Lean
NOx
Catalyst
Lean
NOx
catalysts
are
being
developed
to
reduce
NOx
emissions
in
the
oxygen­
rich
exhaust
of
lean
burn
engines,
particularly
diesel
engines.
There
are
two
types
of
lean
NOx
catalysts;
"
active"
and
"
passive"
lean
NOx
catalysts.
The
"
active"
lean
NOx
catalyst
injects
a
reductant
that
converts
NOx
contained
in
the
exhaust
gases
into
nitrogen
and
oxygen.
Diesel
fuel
is
typically
used
as
the
reductant.
The
presence
of
the
reductant
provides
locally
oxygen
poor
conditions
which
allows
NOx
emissions
to
be
reduced
by
the
catalyst.

Emissions
Reductions
According
to
OTAQ,
active
lean
NOx
catalysts
can
achieve
NOx
reductions
up
to
30
percent.
The
passive
lean
NOx
catalyst
does
not
employ
reductant
injection.
It
is
therefore
more
limited
in
its
ability
to
reduce
NOx
emissions.
Passive
lean
NOx
catalysts
are
able
to
reduce
NOx
emissions
less
than
10
percent.
OTAQ
noted
in
its
report
that
lean
NOx
catalysts
cannot
provide
the
significant
NOx
reductions
necessary
for
compliance
with
the
proposed
Tier
4
standards.

Information
from
the
Manufacturers
of
Emission
Controls
Association's
status
report
on
emission
control
technology
for
stationary
engines,
indicated
that
one
stationary
diesel
engine
was
equipped
with
a
lean
NOx
catalyst
and
NOx
emissions
were
being
reduced
by
80
percent,
CO
by
60
percent,
and
NMHC
emissions
by
60
percent.

According
to
the
SOTA
Manual
for
RICE
from
the
State
of
New
Jersey,
lean
NOx
catalysts
are
capable
of
achieving
NOx
reductions
of
90
percent
or
greater
for
CI
diesel
and
dual
fuel
engines.
12
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