Document ID: EPA-HQ-OAR-2003-0118-0049
Agency: epa
Document Type: Supporting & Related Material
Title: 
Posted Date: 2004-09-14T04:00Z

MEMORANDUM
To:
Erin
Birgfeld
Cc:
Bella
Maranion
From:
Sarah
Percy,
Mark
Wagner
Date:
September
10,
2003
Re:
Re­
evaluation
of
a
C­
6
Oxyfluorocarbon
(
trade
name
Novec
1230)
and
References
Deliverable
under
EPA
Contract
Number
68­
D­
00­
266,
Work
Assignment
2­
05
Task
03
Based
on
analysis
developed
by
ICF's
subcontractor,
Dr.
Don
Wuebbles,
please
find
a
revised
discussion
of
the
atmospheric
lifetime
and
Global
Warming
Potential
(
GWP)
for
C­
6
oxyfluorocarbon.
This
memorandum
presents
a
review
of
the
literature
that
supported
the
GWP
and
ALT
evaluation
conducted
in
January
of
2003.
Additionally,
a
revised
assessment
of
the
GWP
based
on
the
mass
of
C­
6
oxyfluorcarbon
and
CO2
is
provided.
Please
contact
Mark
Wagner
at
(
202)
862­
1155
if
you
have
any
questions.

Summary
Based
on
an
analysis
of
the
C­
6
oxyfluorocarbon,
derived
using
the
IPCC
recommended
approach
for
such
assessments,
it
was
determined
that
the
chemical
has
an
atmospheric
lifetime
of
up
to
two
weeks
and
a
GWP
of
between
0.6
and
1.8.

Discussion
of
Results
The
previous
examination
of
the
C­
6
oxyfluorocarbon,
trade
name
Novec
1230
(
CF3CF2C=
OCFCF3CF3),
was
conducted
in
October
2002
without
the
review
of
any
literature
that
could
directly
aid
in
the
determination
of
the
atmospheric
lifetime
or
radiative
forcing
on
climate
associated
with
this
compound.
Using
the
IPCC
approach,
it
was
concluded
that
absorption
of
solar
radiation
for
photodissociation
of
the
oxyfluorocarbon
would
likely
be
in
the
250­
350
nm
region,
implying
a
lifetime
of
days
up
to
as
much
as
a
year,
with
the
lifetime
most
likely
much
shorter
than
a
year.
Based
on
this,
the
concluded
100­
year
integration
GWP
for
the
C­
6
oxyfluorocarbon
would
range
from
a
value
of
6,
based
on
the
reaction
products
producing
six
carbon
dioxide
molecules,
up
to
100,
accounting
for
a
lifetime
as
long
as
one
year.

In
January
2003,
three
additional
papers
on
C­
6
oxyfluorocarbon
photolysis
were
reviewed.
The
first
of
these,
and
the
most
credible,
Taniguchi
et
al.
(
2003),
published
in
the
Journal
of
Physical
Chemistry
A,
deals
with
the
reaction
of
the
C­
6
oxyfluorocarbon
in
the
atmosphere
and
associated
reaction
products.
This
paper
concludes
that
photolysis
is
the
significant
reaction.
Taniguchi
et
al.
found
that
the
photolysis
quantum
yield
for
the
C­
6
oxyfluorocarbon
is
significantly
less
than
unity.
The
paper
concludes
that
the
atmospheric
lifetime
due
to
photolysis
will
be
1­
2
weeks,
and
suggests
the
need
for
further
study.
However,
the
authors
also
suggest
that
one
of
the
products,
CF3COF,
would
be
water
soluble
and
subject
to
rainout.
This
means
as
many
as
two
of
the
carbons
could
get
washed
out
and
not
become
carbon
dioxide
in
the
atmosphere.
The
other
four
carbons
would
likely
result
in
atmospheric
carbon
dioxide.
In
addition,
whatever
C­
6
oxyfluorocarbon,
and
therefore
CF3COF,
is
transported
into
the
free
troposphere
outside
of
cloud
regions
may
also
result
in
atmospheric
carbon
dioxide.
The
net
result
is
that
4+
carbons
in
the
C­
6
oxyfluorocarbon
would
eventually
result
in
carbon
dioxide
in
the
atmosphere.

The
second
paper,
Guschin
et
al.
(
1999),
makes
a
rough
estimate
of
the
atmospheric
lifetime
of
the
C­
6
oxyfluorocarbon
by
comparing
its
ultraviolet
and
visible
absorption
spectra
to
acetaldehyde,
and
suggests
that
this
comparison
implies
an
atmospheric
lifetime
for
the
C­
6
oxyfluorocarbon
of
5
days.
However,
this
is
only
a
crude
estimate
and
does
not
take
into
account
the
quantum
yields
measured
in
the
much
later
work
by
Taniguchi
et
al.
This
implied
5­
day
lifetime
was
then
used
in
a
paper
entitled,
Global
Warming
Potentials
of
3M
Novec
1230
Fire
Protection
Fluid,
author
unknown,
to
estimate
a100­
year
integrated
GWP
of
1.0.
Additionally,
this
paper
assigns
a
radiative
forcing
of
0.50
Wm­
2
ppbv­
1.

The
evaluation
of
the
radiative
forcing
is
based
on
the
approach
used
by
Pinnock
et
al.
(
1995).
However,
Pinnock
et
al.
assumes
a
constant
mixing
ratio
for
the
substance
in
both
the
troposphere
and
stratosphere,
which
would
most
certainly
not
be
the
case
for
the
C­
6
oxyfluorocarbon.
This
assumption
is
not
valid
for
C­
6
oxyfluorocarbon
and
the
radiative
forcing
would
likely
be
smaller.
This
implies
a
much
smaller
GWP
except
that
the
assumed
lifetime
is
too
small
based
on
the
analysis
of
Taniguchi
et
al.

In
conclusion,
the
new
information
found
in
the
literature
suggests
that
the
original
GWP
estimate
should
be
revised.
The
direct
GWP
for
a
100­
year
integration,
calculated
using
the
IPCC
approach
(
originally
developed
by
Dr.
Don
Wuebbles),
would
likely
have
a
value
of
1
or
less.
This
is
based
on
the
atmospheric
lifetime
of
up
to
two
weeks
(
instead
of
5
days),
but
with
the
radiative
forcing
likely
much
less
than
0.50
Wm­
2
ppbv­
1,
because
of
the
expected
rapid
fall
off
in
mixing
ratio
of
the
C­
6
oxyfluorocarbon
with
altitude.
In
addition,
however,
one
must
consider
and
add
in
the
GWPs
of
any
reaction
products
that
are
sufficiently
long­
lived.
As
stated
above,
4+
CO2
molecules
will
be
produced
and
enter
into
the
atmosphere
as
a
result
of
the
photodissociation
of
the
C­
6
oxyfluorocarbon.
By
definition,
the
GWP
of
each
of
these
is
1.
Therefore,
depending
on
the
exact
value
of
the
direct
GWP
of
the
C­
6
oxyfluorocarbon
and
the
amount
of
CF3COF
actually
rained
out,
the
total
GWP
for
the
C­
6
oxyfluorocarbon
and
its
products
will
be
greater
than
4
to
as
high
as
7.
In
accordance
with
its
definition,
the
GWP
has
been
further
revised
and
evaluated
to
account
for
mass1.
Multiplying
the
direct
and
indirect
GWP's
by
the
ratio
of
CO2
mass
to
C­
6
oxyfluorocarbon
mass
results
in
a
100
year
GWP
for
C­
6
oxyfluorcarbon
between
0.6
and
1.8.
The
total
GWP
is
comprised
of
a
direct
value
of
less
than
1
but
greater
than
zero
plus
an
indirect
GWP
of
0.56
to
0.84,
based
on
4
to
6
carbons
available
for
conversion
to
CO2.

1
The
definition
of
GWP
can
be
found
at
<
http://
yosemite.
epa.
gov/
oar/
globalwarming.
nsf/
content/
EmissionsNationalGlobalWarmingPotentials.
htm>
Finally,
although
it
has
not
yet
been
adopted
by
IPCC,
the
direct
GWP
for
short­
lived
gases
like
this
C­
6
oxyfluorocarbon
would
depend
on
where
and
when
the
emissions
occurred.
Thus,
the
direct
GWPs,
just
like
ODPs
for
short­
lived
gases
(
e.
g.,
see
Wuebbles,
et
al.,
2001),
would
depend
on
what
region
or
at
which
latitude
the
emissions
occurred.
This,
however,
should
have
a
very
minimal
effect
for
the
C­
6
oxyfluorocarbon,
in
question.

References
Guschin,
A.
G.;
Molina,
L.
T.;
and
Molina,
M.
J.
(
1999).
Atmospheric
Chemistry
of
L­
15381,
L­
15566
and
L­
14703
and
Integrated
Band
Strengths
of
L­
14374,
L­
14375,
L­
14752,
L­
13453
and
L­
14703.
Report
prepared
for
3M
Specialty
Chemicals
Division
Laboratory,
St.
Paul,
Minnesota.

Pinnock,
S.;
Hurley,
M.
D.;
Shine,
K.
P.;
Wallington,
T.
J.;
Smyth,
T.
J.
(
1995).
Radiative
forcing
by
hydrochlorofluorocarbons
and
hydrofluorocarbons.
J.
Geophys.
Res.,
100,
23227­
23238.

Taniguchi,
N.;
Wallington,
T.
J.;
Hurley,
M.
D.;
Guschin,
A.
G.;
Molina,
L.
T.
(
2003).
Atmospheric
Chemistry
of
C2F5C(
O)
CF(
CF3)
2:
Photolysis
and
Reaction
with
Cl
Atoms,
OH
Radicals,
and
Ozone.
J.
Phys.
Chem.
A.,
107(
15);
2674­
2679.

Wuebbles,
D.
J.;
Patten,
K.
O.;
Johnson,
M.
T.;
and
Kotamarthi,
R.
(
2001).
The
new
methodology
for
Ozone
Depletion
Potentials
of
short­
lived
compounds:
n­
propyl
bromide
as
an
example.
J.
Geophys.
Res.,
106,
14551­
14571.