xvEPA
United States •
Environmental Protection
Agency 4*^
TIT
Reducing SF6 Emissions
Means Better Business
for
PG&E Case Study
Pacific Gas and Electric Company (PG&E) serves an
area of 70,000 square miles in central and northern
California. With a workforce of 21,800 people, PG&E
provides gas and electric services for approximately one of
every 20 Americans. In 2002, the Company met their goal to
reduce their 1998 baseline emissions of sulfur hexafluoride
(SF6) by half. SF6 is a gaseous dielectric used by electric
utilities primarily in high voltage circuit breakers and gas-insu-
lated substations. When released to the atmosphere, SF6 is a
highly potent and persistent greenhouse gas that contributes
to global climate change. The experience of PG&E can help
other utilities in meeting their environmental and operational
goals through cost-effective solutions to reduce SF6 loss.
The SF6 Emission Reduction Partnership for Electric Power Systems
is a voluntary program between the Environmental Protection Agency
(EPA) and electric power companies. Its goal is to identify and imple-
ment cost-effective operational and technical solutions to reduce SF6
emissions. By reducing SF6 emissions where feasible, the electric
power industry can play a key role in addressing climate change.
This Partnership is one of several EPA voluntary programs working
with specific industries that emit potent greenhouse gases.
\ SR Emission Reduction
Partnership for Electric Power Systems
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Benefits of Reducing SF6 Gas Loss
and Joining the SF6 Partnership
Pacific Gas and Electric Company chose to join
the Partnership for three reasons:
• to respond to the issue of climate change;
• to learn SF6 management and emission
reduction techniques from other utilities; and
• to manage the escalating cost of SF6 gas
purchases.
Participation in the Partnership has led to a
productive dialog between PG&E, the EPA
and other utility partners, with benefits for all.
For example, at EPA's 2002 SF6 Conference,
PG&E not only presented its successes to other
utility partners and potential partners but also
learned of an innovative new method for drain-
ing low pound/pressure SF6-containing equip-
ment such as circuit switches. The Company is
currently investigating this new technique.
Company Achievements
In 1999, PG&E set a three-year goal of
reducing annual SF6 emissions by 50 percent
from a 1998 baseline. The Company achieved
this goal by implementing several key policies
and procedures resulting in more efficient and
cost-effective use of SF6. The savings in avoided
gas purchases totaled about $400,000; the
cost to implement the policies and procedures
totaled about $100,000 (and yielded a net
savings of $300,000).
Figure 1. Annual SFg Emissions
i"
£ 10
CO
5
0
2000 2001
Year
2002
2007
In 2002, PG&E had one of the lowest SF6 gas
loss rates of all large partners, at 4 percent.
The Company has set a second goal of reduc-
ing annual SF6 emissions by 60 percent by
2007, compared to the 1998 baseline.
Key Policies and Procedures
Pacific Gas and Electric Company's success
in reducing SF6 emissions results from five
key actions:
• Corporate Support. PG&E senior
managers played a key role in initiating
and sustaining progress in reducing SF6
emissions. In 2003, corporate officials
recognized members of the SF6 Emission
Reduction Team for their contribution to
environmental protection. As an early
Partner, PG&E participated in discussions
with EPA and other industry representatives
to develop the SF6 Partnership.
• Getting the Right Mix of People. To
meet its emission reduction target, PG&E
established a team from its Electric
Transmission and Environmental Affairs
departments. Environmental Affairs and
Electric Transmission staff collaborated in
developing an SF6 handling policy, while
the Transmission department educated field
employees and implemented the newly
developed SF6 policy and procedures.
• SF6 Handling Procedures. The Company
had a corporate environmental policy prior to
joining the Partnership, but new SF6-specific
handling procedures were created to address
issues such as transfers of SF6 gas from
cylinders, evacuation of SF6 from circuit
breakers, and leak detection procedures.
These procedures provided additional
guidance to field personnel.
• Controlling SF6 Purchases. PG&E
selected a single full-service vendor to
replace multiple SF6 suppliers, with the
understanding that the Company and vendor
Reducing SF6 Emissions
SF6 Partnership Case Study
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would work together in achieving the goal of
tracking all SF6 transactions and compiling
an accurate SF6 inventory. The vendor sup-
plies SF6, removes SF6 for recycling off-site,
conducts an annual SF6 cylinder inventory and
coordinates leak detection activities with a sub-
contractor. As a result, SF6 costs are no longer
hidden at the local facility level. Separating SF6
purchases, inventory and recycling from other
compressed gas purchases has allowed for
better tracking of SF6 usage. In addition, PG&E
is able to purchase its own recycled SF6 at a
reduced cost.
Improved Leak Detection and Mitigation
Measures. PG&E's leak detection strategy
involves tracking "topping off" events logged
for circuit breakers. When a leaking breaker is
identified, the Company first attempts to find
the leak by spraying the breaker with a soap
and water solution or by using a hand-held
halogen gas detector. If these efforts fail to
locate the leak, or if the equipment must
be kept energized, a laser camera is used.
PG&E's original SF6 leak detection policy was
to survey all SF6 equipment with the laser
camera. This policy was revised based on the
realization that leaks could be more readily
identified by whether or not the equipment
required topping off. As a result, more selective
use of the camera has reduced the originally
estimated costs for the program and enabled
the Company to focus on a smaller population
of breakers. With increased awareness of SF6
issues, field personnel also identified leaks in
equipment that were previously overlooked,
such as gas carts and gauges.
Before undertaking these leak detection and
mitigation measures, the Company was losing
roughly 20,000 to 30,000 pounds of SF6 per
year. Now the loss rate is down to about 11,000
pounds per year (approximately 4 percent of the
Company's total nameplate capacity).
Additional Benefits
More Money Saved in the Future. PG&E
estimates that it can save an additional
$50,000 to $100,000 annually over the next
10 years through improved SF6 handling.
These savings assume continuation of the
aggressive leak mitigation measures, replace-
ment of older SF6-filled circuit breakers,
SF6 recycling and inventory reductions and
extended warranties from equipment
manufacturers.
Eliminated Cylinder Rental Fees
and Cleaned Up Maintenance Yards.
Previously, a limited sense of "ownership"
for stored SF6 cylinders existed at substation
maintenance yards. This led to occasional
failures in returning leased cylinders, which
then incurred unnecessary rental fees and
cluttered the gas storage areas. Now (through
tight inventory control), old cylinders have been
removed, new cylinders are closely tracked
and rental fees have been eliminated.
Reducing SF6 Emissions
SF6 Partnership Case Study
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Reduced Maintenance. Facility operators like
getting rid of old leaky breakers, as it reduces
maintenance demands, improves equipment
reliability and allows crews to focus on higher
priority activities.
Improved Safety. Filling (topping off)
breakers less frequently also improves
worker safety, since operators have to handle
the 250-pound cylinders less often, thus
reducing the risk of injury.
SF6 Management Linked to Other
Environmental Concerns. PG&E is a
charter member of California's Climate Action
Registry and is on its Technical Advisory
Committee. The SF6 emission reduction
strategy is one component of the Company's
overall climate protection program.
Leaks = Lost Money
More Leaks Than You Think. Efforts to
reduce SF6 emissions at PG&E resulted in
discovering that more equipment was leaking
than was previously thought. Such leaks mean
that more money was spent to purchase addi-
tional SF6 gas. The improved leak detection
program, including use of a laser camera to
identify leaks, more than paid for itself through
cost savings gained by leak reductions.
Tracking SF6 Usage Saves Money. By track-
ing actual SF6 used, the Company was able to
identify numerous areas where SF6 purchases
could be reduced, such as purchasing its own
recycled gas at a reduced rate and eliminating
cylinder rental fees. The Company now recycles
at least 90 percent of its SF6 gas from decom-
missioned equipment. Reduced SF6 loss has
led to fewer purchases of SF6 and resulted in
significant cost savings.
Pacific Gas and Electric Company's SF6 pro-
gram has been a "win-win" situation, resulting
in less SF6 usage, lower emissions of a potent
greenhouse gas and cost savings for the com-
pany and its ratepayers. Management is con-
vinced of the value of the program's cost-effec-
tiveness and the operating staff appreciate the
reduced workloads gained from implementing
more efficient practices. Electric utility efforts
such as those undertaken by PG&E in reducing
SF6 emissions can help create a better environ-
ment for the customers they serve.
For more information on the SF6 Partnership
goto:
Office of Atmospheric Programs
www.epa.gov/electricpower-sf6
April 2006
EPA430-F-06-011
Reducing SF6 Emissions
SF6 Partnership Case Study
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