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Subpart UU—Injection of Carbon Dioxide

§ 98.470 Definition of the source category.

(a) The injection of carbon dioxide (CO2) source category comprises any well or group of 

wells that inject a CO2 stream into the subsurface.

(b) If you report under subpart RR of this part for a well or group of wells, you are not 

required to report under this subpart for that well or group of wells.

(c) A facility that is subject to this part only because it is subject to subpart UU of this 

part is not required to report emissions under subpart C of this part or any other subpart listed in 

§ 98.2(a)(1) or (a)(2).

§ 98.471 Reporting threshold.

(a) You must report under this subpart if your facility injects any amount of CO2 into the 

subsurface.

(b) For purposes of this subpart, any reference to CO2 emissions in § 98.2(i) shall mean 

CO2 received.

§ 98.472 GHGs to report.

You must report the mass of CO2 received.

§ 98.473 Calculating CO2 received.

(a) You must calculate and report the annual mass of CO2 received by pipeline using the 

procedures in paragraphs (a)(1) or (a)(2) of this section and the procedures in paragraph (a)(3) of 

this section, if applicable.

(1) For a mass flow meter, you must calculate the total annual mass of CO2 in a CO2

stream received in metric tons by multiplying the mass flow by the CO2 concentration in the 
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flow, according to Equation UU-1 of this section. You must collect these data quarterly. Mass 

flow and concentration data measurements must be made in accordance with § 98.474.

where:

CO2T,r = Net annual mass of CO2 received through flow meter r (metric tons).

Qr,p = Quarterly mass flow through a receiving flow meter r in quarter p (metric 

tons).

Sr,p = Quarterly mass flow through a receiving flow meter r that is redelivered to 

another facility without being injected into your well in quarter p (metric 

tons).

CCO2,p,r = Quarterly CO2 concentration measurement in flow for flow meter r in quarter 

p (wt. percent CO2, expressed as a decimal fraction).

p = Quarter of the year.

r = Receiving flow meter.

(2) For a volumetric flow meter, you must calculate the total annual mass of CO2 in a 

CO2 stream received in metric tons by multiplying the volumetric flow at standard conditions by 

the CO2 concentration in the flow and the density of CO2 at standard conditions, according to 

Equation UU-2 of this section. You must collect these data quarterly. Volumetric flow and 

concentration data measurements must be made in accordance with § 98.474.

where:

CO2T,r = Net annual mass of CO2 received through flow meter r (metric tons).

Qr,p = Quarterly volumetric flow through a receiving flow meter r in quarter p at 

standard conditions (standard cubic meters).

Sr,p = Quarterly volumetric flow through a receiving flow meter r that is redelivered 

to another facility without being injected into your well in quarter p (standard 

cubic meters).
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D = Density of CO2 at standard conditions (metric tons per standard cubic meter): 

0.0018682.

CCO2,p,r = Quarterly CO2 concentration measurement in flow for flow meter r in quarter 

p (vol. percent CO2, expressed as a decimal fraction).

p = Quarter of the year.

r = Receiving flow meter.

(3) If you receive CO2 through more than one flow meter, you must sum the mass of all 

CO2 received in accordance with the procedure specified in Equation UU-3 of this section.

where:

CO2 = Total net annual mass of CO2 received (metric tons).

CO2T,r = Net annual mass of CO2 received (metric tons) as calculated in Equation UU1 or UU-2 for flow meter r.

r = Receiving flow meter.

(b) You must calculate and report the annual mass of CO2 received in containers using 

the procedures specified in either paragraph (b)(1) or (b)(2) of this section.

(1) If you are measuring the mass of contents in a container under the provisions of § 

98.474(a)(2)(i), you must calculate the CO2 received in containers using Equation UU-1 of this 

section.

where:

CO2T,r = Annual mass of CO2 received in containers r (metric tons).

CCO2,p,r = Quarterly CO2 concentration measurement of contents in containers r in 

quarter p (wt. percent CO2, expressed as a decimal fraction).

Qr,p = Quarterly mass of contents in containers r in quarter p (metric tons).

Sr,p = Quarterly mass of contents in containers r that is redelivered to another 

facility without being injected into your well in quarter p (standard cubic 

meters).

p = Quarter of the year.
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r = Containers.

(2) If you are measuring the volume of contents in a container under the provisions of § 

98.474(a)(2)(ii), you must calculate the CO2 received in containers using Equation UU-2 of this 

section.

where:

CO2T,r = Annual mass of CO2 received in containers r (metric tons).

CCO2,p,r = Quarterly CO2 concentration measurement of contents in containers r in 

quarter p (vol. percent CO2, expressed as a decimal fraction).

Sr,p = Quarterly volume of contents in containers r that is redelivered to another 

facility without being injected into your well in quarter p (standard cubic 

meters).

Qr,p = Quarterly volume of contents in containers r in quarter p (standard cubic 

meters).

D = Density of the CO2 received in containers at standard conditions (metric tons 

per standard cubic meter): 0.0018682.

p = Quarter of the year.

r = Containers.

§ 98.474 Monitoring and QA/QC requirements.

(a) CO2 received. (1) You must determine the quarterly flow rate of CO2 received by 

pipeline by following the most appropriate of the following procedures:

(i) You may measure flow rate at the receiving custody transfer meter prior to any

subsequent processing operations at the facility and collect the flow rate quarterly.

(ii) If you took ownership of the CO2 in a commercial transaction, you may use the 

quarterly flow rate data from the sales contract if it is a one-time transaction or from invoices or 

manifests if it is an ongoing commercial transaction with discrete shipments.

(iii) If you inject CO2 from a production process unit that is part of your facility, you may

use the quarterly CO2 flow rate that was measured at the equivalent of a custody transfer meter 
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following procedures provided in subpart PP of this part. To be the equivalent of a custody

transfer meter, a meter must measure the flow of CO2 being transported to an injection well to 

the same degree of accuracy as a meter used for commercial transactions.

(2) You must determine the quarterly mass or volume of contents in all containers if you 

receive CO2 in containers by the most appropriate of the following procedures:

(i) You may measure the mass of contents of containers summed quarterly using weigh 

bills, scales, or load cells.

(ii) You may determine the volume of the contents of containers summed quarterly.

(iii) If you took ownership of the CO2 in a commercial transaction, you may use the 

quarterly mass or volume of contents from the sales contract if it is a one-time transaction or 

from invoices or manifests if it is an ongoing commercial transaction with discrete shipments.

(3) You must determine a quarterly concentration of the CO2 received that is 

representative of all CO2 received in that quarter by following the most appropriate of the 

following procedures:

(i) You may sample the CO2 stream at least once per quarter at the point of receipt and 

measure its CO2 concentration.

(ii) If you took ownership of the CO2 in a commercial transaction for which the sales 

contract was contingent on CO2 concentration, and if the supplier of the CO2 sampled the CO2

stream in a quarter and measured its concentration per the sales contract terms, you may use the 

CO2 concentration data from the sales contract for that quarter.

(iii) If you inject CO2 from a production process unit that is part of your facility, you may

report the quarterly CO2 concentration of the CO2 stream supplied that was measured following 
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procedures provided in subpart PP of this part as the quarterly CO2 concentration of the CO2

stream received.

(4) You must assume that the CO2 you receive meets the definition of a CO2 stream 

unless you can trace it through written records to a source other than a CO2 stream.

(b) Measurement devices. (1) All flow meters must be operated continuously except as 

necessary for maintenance and calibration.

(2) You must calibrate all flow meters used to measure quantities reported in § 98.476 

according to the calibration and accuracy requirements in § 98.3(i).

(3) You must operate all measurement devices according to one of the following. You 

may use an appropriate standard method published by a consensus-based standards organization 

if such a method exists or an industry standard practice. Consensus-based standards 

organizations include, but are not limited to, the following: ASTM International, the American 

National Standards Institute (ANSI), the American Gas Association (AGA), the American 

Society of Mechanical Engineers (ASME), the American Petroleum Institute (API), and the 

North American Energy Standards Board (NAESB).

(4) You must ensure that any flow meter calibrations performed are National Institute of 

Standards and Technology (NIST) traceable.

(c) General. (1) If you measure the concentration of any CO2 quantity for reporting, you 

must measure according to one of the following. You may use an appropriate standard method 

published by a consensus-based standards organization if such a method exists or an industry

standard practice.
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(2) You must convert all measured volumes of CO2 to the following standard industry

temperature and pressure conditions for use in Equation UU-2 of this subpart: standard cubic 

meters at a temperature of 60 degrees Fahrenheit and at an absolute pressure of 1 atmosphere.

(3) For 2011, you may follow the provisions of § 98.3(d)(1) through (2) for best available 

monitoring methods rather than follow the monitoring requirements of this section. For purposes 

of this subpart, any reference to the year 2010 in § 98.3(d)(1) through (2) shall mean 2011.

§ 98.475 Procedures for estimating missing data.

A complete record of all measured parameters used in the GHG quantities calculations is 

required.

(a) Whenever the monitoring procedures for all facilities that used flow meters covered 

under this subpart cannot be followed to measure flow, the following missing data procedures 

must be followed:

(1) Another calculation methodology listed in § 98.474(a)(1) must be used if possible.

(2) If another method listed in § 98.474(a)(1) cannot be used, a quarterly flow rate value 

that is missing must be estimated using a representative flow rate value from the nearest previous 

time period.

(b) Whenever the monitoring procedures of this subpart cannot be followed to measure 

quarterly quantity of CO2 received in containers, the most appropriate of the following missing 

data procedures must be followed:

(1) Another calculation methodology listed in § 98.474(a)(2) must be used if possible.

(2) If another method listed in § 98.474(a)(2) cannot be used, a quarterly mass or volume 

that is missing must be estimated using a representative mass or volume from the nearest 

previous time period.
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(c) Whenever the monitoring procedures cannot be followed to measure CO2

concentration, the following missing data procedures must be followed:

(1) Another calculation methodology listed in § 98.474(a)(3) must be used if possible.

(2) If another method listed in § 98.474(a)(3) cannot be used, a quarterly concentration 

value that is missing must be estimated using a representative concentration value from the 

nearest previous time period.

§ 98.476 Data reporting requirements.

If you are subject to this part and report under this subpart, you are not required to report 

the information in § 98.3(c)(4) for this subpart. In addition to the information required by § 

98.3(c)(1) through § 98.3(c)(3) and by § 98.3(c)(5) through § 98.3(c)(9), you must report the 

information listed in this section.

(a) If you receive CO2 by pipeline, report the following for each receiving flow meter:

(1) The total net mass of CO2 received (metric tons) annually.

(2) If a volumetric flow meter is used to receive CO2:

(i) The volumetric flow through a receiving flow meter at standard conditions (in 

standard cubic meters) in each quarter.

(ii) The volumetric flow through a receiving flow meter that is redelivered to another 

facility without being injected into your well (in standard cubic meters) in each quarter.

(iii) The CO2 concentration in the flow (volume percent CO2 expressed as a decimal 

fraction) in each quarter.

(3) If a mass flow meter is used to receive CO2:

(i) The mass flow through a receiving flow meter (in metric tons) in each quarter.
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(ii) The mass flow through a receiving flow meter that is redelivered to another facility

without being injected into your well (in metric tons) in each quarter.

(iii) The CO2 concentration in the flow (weight percent CO2 expressed as a decimal 

fraction) in each quarter.

(4) The standard or method used to calculate each value in paragraphs (a)(2) through 

(a)(3) of this section.

(5) The number of times in the reporting year for which substitute data procedures were 

used to calculate values reported in paragraphs (a)(2) through (a)(3) of this section.

(6) Whether the flow meter is mass or volumetric.

(b) If you receive CO2 in containers, report:

(1) The mass (in metric tons) or volume at standard conditions (in standard cubic meters) 

of contents in containers in each quarter.

(2) The concentration of CO2 of contents in containers (volume or weight percent CO2

expressed as a decimal fraction) in each quarter.

(3) The mass (in metric tons) or volume (in standard cubic meters) of contents in 

containers that is redelivered to another facility without being injected into your well in each 

quarter.

(4) The net total mass of CO2 received (in metric tons) annually.

(5) The standard or method used to calculate each value in paragraphs (b)(1), (b)(2), and 

(b)(3) of this section.

(6) The number of times in the reporting year for which substitute data procedures were 

used to calculate values reported in paragraphs (b)(1) and (b)(2) of this section.
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(c) If you use more than one receiving flow meter, report the net total mass of CO2

received (metric tons) through all flow meters annually.

(d) The source of the CO2 received according to the following categories:

(1) CO2 production wells.

(2) Electric generating unit.

(3) Ethanol plant.

(4) Pulp and paper mill.

(5) Natural gas processing.

(6) Gasification operations.

(7) Other anthropogenic source.

(8) Discontinued enhanced oil and gas recovery project.

(9) Unknown.

(e) Report the following:

(1) Whether the facility received a Research and Development project exemption from 

reporting under 40 CFR part 98, subpart RR, for this reporting year. If you received an 

exemption, report the start and end dates of the exemption approved by EPA.

(2) Whether the facility includes a well or group of wells where a CO2 stream was 

injected into subsurface geologic formations to enhance the recovery of oil during this reporting 

year.

(3) Whether the facility includes a well or group of wells where a CO2 stream was 

injected into subsurface geologic formations to enhance the recovery of natural gas during this 

reporting year.
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(4) Whether the facility includes a well or group of wells where a CO2 stream was 

injected into subsurface geologic formations for acid gas disposal during this reporting year.

(5) Whether the facility includes a well or group of wells where a CO2 stream was 

injected for a purpose other than those listed in paragraphs (e)(1) through (4) of this section. If 

you injected CO2 for another purpose, report the purpose of the injection.

§ 98.477 Records that must be retained.

(a) You must follow the record retention requirements specified by § 98.3(g). In addition 

to the records required by § 98.3(g), you must retain quarterly records of CO2 received, including 

mass flow rate or contents of containers (mass or volumetric) at standard conditions and 

operating conditions, operating temperature and pressure, and concentration of these streams. 

You must retain all required records for at least 3 years.

(b) You must complete your monitoring plans, as described in § 98.3(g)(5), by April 1 of 

the year you begin collecting data.

§ 98.478 Definitions.

Except as provided below, all terms used in this subpart have the same meaning given in 

the Clean Air Act and subpart A of this part.

CO2 received means the CO2 stream that you receive to be injected for the first time into 

a well on your facility that is covered by this subpart. CO2 received includes, but is not limited 

to, a CO2 stream from a production process unit inside your facility and a CO2 stream that was 

injected into a well on another facility, removed from a discontinued enhanced oil or natural gas 

or other production well, and transferred to your facility.