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Our mercury expert, Ed Swain, suggested use the emission factor published by the Electric Power Research Institute (EPRI 1996) for natural gas combustion: 8.0 E-10 lb/MMBtu. This value could be used for both controlled and uncontrolled emissions. The emitted mercury would be elemental vapor, so it would not be captured by control equipment.
Citation:
Electric Power Research Institute, 1996. Mercury in the Environment - A Research Update; EPRI
Ed contacted with Anne Pope in Jan. 2007. EPA does not include mercury from natural gas combustion in the NEI as emission factors generated in late 80s/early 90s are suspect due to source tests problems.
Ed also checked with Bill Maxwell (see the following e-mail). Looks like the EPA doesn't know how much mercury is in natural gas. Therefore, Ed worked up a factor to use.
Chun Yi
-----Original Message----- From: Maxwell.Bill@epamail.epa.gov [mailto:Maxwell.Bill@epamail.epa.gov] Sent: Monday, January 08, 2007 8:26 AM To: Pope.Anne@epamail.epa.gov Cc: Swain, Edward; Wayland.Robertj@epamail.epa.gov; Eddinger.Jim@epamail.epa.gov; kirchgessner.david@epamail.epa.gov Subject: Re: FW: natural gas emission factor for mercury
Anne --
We do not have a "defensible" emission factor for mercury from natural gas. There are a couple of...probably lame...reasons for this --
1 -- Natural gas is presumed...by nearly everyone...to be "clean" in almost all aspects and certainly cleaner than the alternatives of coal and oil. Therefore, it has not received the testing "attention" necessary to develop such factors; the presumption was that there was no reason to look.
2 -- Antidotal information from industry was that any mercury that may have been in raw natural gas had to be removed at the well-head because of problems encountered with down-stream equipment. However, I've never really been able to pin this down.
I would suggest checking with David Kirchgessner, ORD, who did a study on mercury in oil and gas ("Mercury in Petroleum and Natural Gas: Estimation of Emissions from Production, Processing, and Combustion," EPA-600/R-01-066, September 2001). However, I don't know whether true emission factors were developed during this study.
Thanks.
Deliberative Document -- FOIA Exempt
Bill Maxwell Energy Strategies Group Sector Policies and Programs Division D243-01 U.S. EPA Research Triangle Park, NC 27711 Phone: 919-541-5430
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