TECHNICAL SUPPORT DOCUMENT FOR COKE
CALCINING: PROPOSED RULE FOR THE
GREENHOUSE GAS REPORTING PROGRAM
Office of Air and Radiation
U.S. Environmental Protection Agency
January 2022
CONTENTS
1. Industry Description................................................................................................................... 3
2. Total Emissions.......................................................................................................................... 4
3. Review of Existing Programs and Methodologies..................................................................... 5
3.1 Review of Existing Programs .......................................................................................... 5
3.2 Calculation Methodologies for Coke Calcining Processes .............................................. 6
4. Options for Monitoring Methods ............................................................................................... 8
4.1 CEMS Method ................................................................................................................. 8
4.2 Mass Balance and Combustion Methods ......................................................................... 8
5. References .................................................................................................................................. 9
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1. Industry Description
The coke calcining source category consists of processes that heat petroleum coke to high
temperatures in the absence of air or oxygen for the purpose of removing impurities or volatile
substances in the petroleum coke feedstock. The coke calcining source category includes, but is
not limited to, rotary kilns or rotary hearth furnaces used to calcine petroleum coke.
Calcined petroleum coke is a nearly pure carbon material used primarily to make anodes for the
aluminum, steel, and titanium smelting industries. The aluminum industry accounts for nearly 75
percent of the world's calcined coke consumption.
Table 1 includes a list of the coke calcining facilities based on available information (BP, 2008;
company [Oxbow and Rain Industries] websites; and Louisiana Department of Environmental
Quality, Electronic Document Management System). There are an estimated 5 operating coke
calcining companies in the US with 15 currently operating facilities with 29 coke calcining
process units. Most coke calcining facilities are located at or near a petroleum refinery. Oxbow is
the largest supplier of calcined petroleum coke in the world, with worldwide production capacity
of 2.34 million tons/year and US production capacity of 1.9 million tons/year (Calcining
(oxbow.com)). Rain Industries is also a significant producer of calcined petroleum coke, with
worldwide production capacity of 2.1 million tons/year and estimated US production capacity of
approximately 1.8 million tons/yr. (Carbon | Rain Industries Limited (rain-industries.com)).
Table 1. US Coke Calcining Facilities.
Facility Location Calciner Capacity† (tons/yr)
BP Cherry Point - #3 Blaine, WA 1 rotary hearth
BP Cherry Point - #1 & 2 Blaine, WA 2 rotary hearths
BP Wilmington Carson, CA 1 rotary kiln
RAINCII-Robinson Robinson, IL 2 rotary kilns 315,000
RAINCII-Lk Charles Lake Charles, LA 2 rotary kilns 350,000
RAINCII (ex-CII CARBON) Moundsville, WV 2 rotary kilns closed
RAINCII-Norco Norco, LA 1 rotary kiln 400,000
RAINCII-Gramercy Gramercy, LA 1 rotary kiln 400,000
RAINCII-Chalmette Chalmette, LA 1 rotary kiln 400,000
RAINCII-Purvis Purvis, MS 1 rotary kiln
Seadrift Port Lavaca, TX 1 rotary kiln
ConocoPhillips-Santa Maria Santa Maria, CA 1 rotary kiln closed
ConocoPhillips-Contra Costa Rodeo, CA 2 rotary kilns
ConocoPhillips Lake Charles Lake Charles, LA 1 rotary kiln
Oxbow-Lemont (formerly Lemont, IL 2 rotary kilns Production
Chicago Carbon Company) suspended in 2020
Oxbow-Port Arthur A Port Arthur, TX 3 rotary kilns 700,000
Oxbow-Port Arthur B Port Arthur, TX 1 rotary kiln
Oxbow-Enid Enid, OK 3 rotary kilns 500,000
Oxbow-Baton Rouge Baton Rouge, LA 4 rotary kilns 700,000
†
Based on company website or Title V air permit.
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2. Total Emissions
Conventional fuels are generally only used during startup to get the calcining kiln (or furnace) up
to the desired operating temperature. Once the desired calcining temperature is reached, process
gas consisting of volatile organics and sulfur-containing compounds driven from the coke are
used as the primary fuel to maintain kiln temperatures (see Figure 1). An afterburner is used to
convert excess process gas to carbon dioxide (CO2) and sulfur dioxide (SO2); a waste heat boiler
may be used to recover energy from this combustion process. The afterburner off-gas is emitted
to the atmosphere and is the primary source of greenhouse gas (GHG) emissions from this
process. The primary GHG emissions are CO2 emissions; the afterburner will also likely release
trace amounts of methane (CH4) and nitrous oxide (N2O) similar to other stationary combustion
devices.
Figure 1. Illustration of rotary hearth coke calcining process (from BP, 2008).
Many coke calcining facilities report to the Greenhouse Gas Reporting Program (GHGRP; 40
CFR part 98). Coke calcining processes co-located at petroleum refineries must calculate and
report emission from coke calciners following the methodologies specified in GHGRP Subpart Y
– Petroleum Refineries. Other facilities either do not report or report coke calcining emissions as
petroleum coke combustion under GHGRP Subpart C - Stationary Combustion Sources. Based
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on data reported to the GHGRP for Reporting Year (RY) 2019, the typical coke calcining facility
emits 150,000 metric tons (mt) CO2 per year. With 15 operating facilities in the US, it is
estimated that these facilities emit 2.2-million mt CO2 per year. As an alternative method to
project national coke calcining emissions, it is estimated that coke calcining capacity in the US is
about 5-million tons per year. Assuming 10 percent of the petroleum coke fed to the unit is
consumed during the coke calcining process, national emissions from coke calcining are
estimated to be 1.8-million mt CO2 per year.
3. Review of Existing Programs and Methodologies
3.1 Review of Existing Programs
In developing GHG monitoring and reporting options for coke calcining processes, a number of
existing programs and guideline methodologies were reviewed. Specifically, the following
resources were examined:
1. 2006 Intergovernmental Panel on Climate Change (IPCC) Guidelines for National
Greenhouse Gas Inventories. Volume 2, Chapter 2. https://www.ipcc-
nggip.iges.or.jp/public/2006gl/pdf/2_Volume2/V2_2_Ch2_Stationary_Combustion.pdf.
2. European Union (EU) 2021. Commission Implementing Regulation (EU) 2018/2066 of
19 December 2018 on the Monitoring and Reporting of Greenhouse Gas Emissions
Pursuant to Directive 2003/87/EC of the European Parliament and of the Council and
Amending Commission Regulation (EU) No. 601/2012. January. https://eur-
lex.europa.eu/legal-content/EN/TXT/PDF/?uri=CELEX:02018R2066-
20210101&from=EN.
3. International Aluminum Institute (IAI) 2006. The Aluminum Sector Greenhouse Gas
Protocol. October. https://ghgprotocol.org/sites/default/files/aluminium_1.pdf.
4. API (American Petroleum Institute) 2009. Compendium of Greenhouse Gas Emissions
Methodologies for the Oil and Natural Gas Industry. August.
https://www.api.org/~/media/Files/EHS/climate-
change/2009_GHG_COMPENDIUM.pdf
5. CARB (California Air Resource Board) 2019. Unofficial Electronic Version of the
Regulation for the Mandatory Reporting of Greenhouse Gas Emissions. April.
https://ww2.arb.ca.gov/mrr-regulation.
6. Environment and Climate Change Canada (ECCC) 2020. Canada’s Greenhouse Gas
Quantification Requirements. Version 4.0. December.
http://publications.gc.ca/collections/collection_2021/eccc/En81-28-2020-eng.pdf.
Each of these sources were reviewed to determine the types of emissions to be reported, the
facility reporting thresholds, the calculation methodologies, and the monitoring methodologies
recommended. The remainder of this section summarizes the key calculation methodologies. The
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reporting and monitoring options presented in Sections 4, 5, and 6 are consistent with the
methodologies used in these existing programs and guidelines.
3.2 Calculation Methodologies for Coke Calcining Processes
From the review of existing programs four basic calculation methodologies were identified. The
calculation methods are presented in terms of their relative accuracy, from most to least accurate.
Method 1. CEMS Method. Measure CO2 concentration and total exhaust gas flow rate using a
continuous emission monitoring system (CEMS) and calculate CO2 concentrations
from these measured values using Equation C-6 and, if necessary, Equation C-7 of
40 CFR 98.33(a)(4).
Method 2. Carbon Balance Method. This is a mass balance method using the carbon content of
the green and calcined coke. This method is based on the overall carbon balance
approach in IAI (Equation 5, IAI, 2006) and is used in the ECCC requirements for
petroleum refineries (Equation 11-22, ECCC, 2020). The equation as presented in
ECCC is provided below. This equation is the same as Equation Y-13 of 40 CFR
98.253(g)(2) used for coke calcining processes co-located at petroleum refineries.
Method 3. Methane in Green Coke Method. The methane in green coke uses a fixed methane
content in the coke of 0.035 mass fraction and uses mass reduction in the quantity
of coke fed to the process (corrected for moisture, volatile, and sulfur content) and
the quantity of coke leaving the process (corrected for sulfur content). This method
is based on the coke calcining approach in IAI (Equation 6, IAI, 2006) and is used
in the ECCC requirements for aluminum production (Equation 5-6, ECCC, 2020).
The equation as presented in IAI is provided below. It is expected that coke calcine
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operators could just as easily determine the carbon content of the green and calcined
coke and use the more direct carbon balance method.
Method 4. Vapor Combustion Method. This method is recommended by API (2009) for use for
coke calcining kilns (Table 2-9), although the method is presented specifically for
incinerators, thermal oxidizers, and vapor combustion units (Section 4.7, API,
2009). The method relies on analysis of carbon content of the gas stream inlet to the
vapor combustion unit. CO2 emissions are calculated assuming non-CO2 carbon is
combusted and converted to CO2 at the efficiency of the combustion system, and
assuming 100 percent of the CO2 in the inlet gas stream is emitted. The difficulty
with applying this method for coke calciners is collecting representative samples of
the process off-gas prior to the afterburner. There may be limited stack length prior
to the afterburner and the process gases are very hot in a reducing atmosphere, so
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sampling between the process and afterburner is dangerous. Additionally, the
process gas composition may be variable based on feedstock coke properties and
calciner operating conditions, requiring frequent sampling to get representative
concentrations.
Method 5. Coke Combustion Method. This method is based on the method that some non-
refinery facilities report emissions from coke calcining operations under 40 CFR
part 98, subpart C. This method can be applied using either the default high heat
values and CO2 emission factors in Table C-1 for petroleum coke (Tier 1 or 2) or
measured carbon content of the green coke (Tier 3) and attribute the mass reduction
of coke as petroleum coke combusted. This method does not correct for the fact that
the volatile matter has a lower carbon content than the green petroleum coke and so
is likely to produce CO2 emission estimates that are biased high. However, this
method is simple and relatively accurate.
4. Options for Monitoring Methods
4.1 CEMS Method
The CEMS method uses direct measurement CO2 concentration and total exhaust gas flow rate,
The CEMS monitoring requirements are outlined in 40 CFR 98.33(a)(4).
4.2 Mass Balance and Combustion Methods
All of the non-CEMS methods require monitoring of mass quantities of green coke fed to the
process, calcined coke leaving the process, and coke dust removed from the process by dust
collection systems.
The mass quantities can be determined using commercial weighing equipment meeting selected
accuracy requirements or can simply use of company records. Generally, most facilities would
follow the National Institute of Standards and Technology (NIST) requirements for weighing and
measuring devices (NIST, 2019). Measurements made following NIST requirements are
expected to be more accurate than measurements made not following NIST requirements.
The carbon balance method requires determination of carbon content of the green and calcined
coke. The Tier 3 coke combustion method also requires determination of carbon content, but
only for the green coke. The carbon content of the green and calcined coke is commonly
determined via ultimate analysis of the coke. Suitable methods include: 1
(1) ASTM D3176-15 Standard Practice for Ultimate Analysis of Coal and Coke
(2) ASTM D5291-16 Standard Test Methods for Instrumental Determination of Carbon,
Hydrogen, and Nitrogen in Petroleum Products and Lubricants.
(3) ASTM D5373-21 Standard Test Methods for Determination of Carbon, Hydrogen, and
Nitrogen in Laboratory Samples of Coal and Coke.
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These methods have been updated since the date the methods for GHGRP subpart Y were developed.
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It is expected that ultimate analyses composition will be available from purchase records of
green coke and from routine monitoring of feed material and product quality analyses. The
carbon content is not likely to vary significantly. These routine measurements are conducted to
verify that the impurities levels in the coke are less than those specified for the green coke input
or calcined coke product. The rule could specify a measurement frequency (weekly, monthly,
quarterly, or annually). Typically, the more measurements conducted, the more accurate the
average value will be. The methane in green coke method appears to require at least monthly
measurements (although focused on the content of impurities rather than the carbon content) and
applies the calculation monthly. The carbon balance method as implemented in subpart Y of the
GHGRP only requires that an annual average carbon content be determined. This requirement
could be met by a single annual analysis; however, it is expected that the annual average would
be determined based on a much greater number of measurements that are routinely determined
by the process operator.
The methane in green coke method requires proximate analysis of the coke to determine
moisture, volatile matter, and ash content. This is generally accomplished using:
• ASTM D3172-13(2021): Standard Practice for Proximate Analysis of Coal and Coke.
The percent sulfur requires additional analysis of sulfur in the ash using one of the following
methods.
(1) ASTM D3174-12 (Reapproved 2018): Standard Test Method for Ash in the Analysis
Sample of Coal and Coke from Coal.
(2) ASTM D5016-16: Standard Test Method for Total Sulfur in Coal and Coke Combustion
Residues Using a High-Temperature Tube Furnace Combustion Method with Infrared
Absorption.
(3) ASTM D4239-18: Standard Test Method for Sulfur in the Analysis Sample of Coal and
Coke Using High-Temperature Tube Furnace Combustion
As noted previously, the methane in green coke method requires these measurements at least
monthly. It is expected that coke calcining process operators may conduct many of these
analyses on a routine basis (more frequently than monthly).
There are a number of gas composition analysis methods available, such as those listed in 40
CFR 98.254(d). However, as noted in Section 3 of this document, collecting representative vapor
samples of the coke calciner process off-gas prior to the afterburner is expected to be difficult
and unsafe. Therefore, further review of gas compositional methods was not conducted.
5. References
2006 Intergovernmental Panel on Climate Change (IPCC) Guidelines for National
Greenhouse Gas Inventories. Volume 2, Chapter 2. https://www.ipcc-
nggip.iges.or.jp/public/2006gl/pdf/2_Volume2/V2_2_Ch2_Stationary_Combustion.pdf.
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British Petroleum (BP). 2008. NSPS Subpart J Applicability to BP Cherry Point Coke
Calciner. Presentation by BP Cherry Point Refinery to US EPA, circa 2008.
European Union (EU) 2021. Commission Implementing Regulation (EU) 2018/2066 of 19
December 2018 on the Monitoring and Reporting of Greenhouse Gas Emissions Pursuant to
Directive 2003/87/EC of the European Parliament and of the Council and Amending
Commission Regulation (EU) No. 601/2012. January. https://eur-lex.europa.eu/legal-
content/EN/TXT/PDF/?uri=CELEX:02018R2066-20210101&from=EN.
International Aluminum Institute (IAI) 2006. The Aluminum Sector Greenhouse Gas
Protocol. October. https://ghgprotocol.org/sites/default/files/aluminium_1.pdf.
API (American Petroleum Institute) 2009. Compendium of Greenhouse Gas Emissions
Methodologies for the Oil and Natural Gas Industry. August.
https://www.api.org/~/media/Files/EHS/climate-change/2009_GHG_COMPENDIUM.pdf
CARB (California Air Resource Board) 2019. Unofficial Electronic Version of the
Regulation for the Mandatory Reporting of Greenhouse Gas Emissions. April.
https://ww2.arb.ca.gov/mrr-regulation.
Environment and Climate Change Canada (ECCC) 2020. Canada’s Greenhouse Gas
Quantification Requirements. Version 4.0. December.
http://publications.gc.ca/collections/collection_2021/eccc/En81-28-2020-eng.pdf.
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