On August 1, 2023, the USEPA posted proposed changes to the greenhouse gas (GHG) reporting rules in 40 CFR 98 subpart W – Petroleum and Natural Gas Systems. The proposed rules affect most subpart W industry segments and emission source types. New emission source types and additional data and requirements for certain emission sources were proposed. For flares and enclosed combustion devices (ECD) the proposal expands the type and amount of data reported and changes the default combustion efficiency (also known as destruction and removal efficiency (DRE)).
These proposed rules will change the data used for flaring calculations, especially affecting future carbon dioxide (CO2) and methane (CH4) emissions reporting.
Several of the proposed requirements align subpart W with the proposed emission standards in 40 CFR 60 subpart OOOOb, Standards of Performance for Crude Oil and Natural Gas Facilities for which Construction, Modification or Reconstruction Commenced After November 15, 2021.
These are proposed regulations and still must go through the administrative rule making process which includes submission of comments by the regulated community and interested parties. The final rules could vary from the proposed rules.
Some key parts of the proposed rule changes that affects flares and ECDs include:
Well-Pad and Gathering and Boosting Facility Reporting Units
Currently flares are reported at the Basin level. Changes to this include:
- Reporting will be at the well-pad facility level and gathering boosting facility level.
- Reporters will need to assign an ID to each well-pad facility and gathering and boosting facility and report GHG emissions for the associated equipment.
- Each Flare ID will be reported with its associated well-pad facility ID or gathering and boosting (GB) facility ID.
- Storage tanks routed to a flare will be reported on the Flaring tab of the subpart W report.
No changes proposed for gas processing, LNG storage, and LNG import/export facilities which currently report flaring as the facility ID level.
Flare Types
Facilities must indicate the type of flare used. The listed flare types include:
- Open ground-level flare
- Enclosed ground-level flare
- Open elevated flare
- Enclosed elevated flare
The proposed rules do not define these terms used for flare types. The rules should include definitions for each type of flare.
Flare Assist
Facilities must indicate the type of flare assist used. The proposed options include:
- Unassisted
- Air-assisted with single speed fan/blower
- Air-assisted with dual speed fan/blower
- Air-assisted with variable speed fan/blower
- Steam-assisted
- Pressure-assisted
Pilot Flame and Combustion Flame
Pilot and combustion flame monitoring methods reporting include:
- Facilities must indicate whether the pilot flame or combustion flame was monitored continuously, visually inspected, or both.
- If the device is visually inspected, then report the number of inspections during the year.
- Indicate whether the flare has a continuous pilot or auto igniter.
- If the pilot flame was monitored continuously, report the number of times and hours the continuous monitoring device was out of service or otherwise inoperable for a period of more than one week.
This requires facilities to maintain records for the continuous monitoring and/or visual inspections.
Cimarron’s Sytelink360™ system can continuously monitor the pilot flame. Also, the system can track, store and report hours that a pilot flame was present for an ECD and flare system. Sytelink360TM also handles automated alerts to field operations so that corrective actions can be taken to minimize downtime.
Flare Metering
Facilities must indicate a method used to determine gas volume sent to the flare. For example, measured with continuous flow meter or based on parameter monitoring and engineering calculations.
Un-lit Flares
Un-lit flares result in venting CH4 to the atmosphere and will need to be quantified.
- Facilities must report the volume of gas sent to an un-lit flare (i.e., vented to the atmosphere).
- Requires monitoring data for flare pilot operation hours and the volume of gas sent to an un-lit flare is required. Visual inspections allowed.
- This data is used to calculate the reported amount of gas (i.e., methane) that is vented to the atmosphere by an un-lit flare.
- If conduct only visual inspections for presence of a flame, then must assume the pilot was un-lit since the last previous visual inspection and use this data for calculations.
- If do visual inspections every 30 days and find an un-lit pilot, then duration in hours for un-lit flare would be (30 days)(24 hours/day) = 720 hours
Flare combustion efficiency
The proposed rules specify a combustion efficiency (e.g., DRE) value to be used for calculating CO2 and CH4 emissions. This based on three tiers for the combustion efficiency to use in emission calculations as listed below:
- Tier 1: Use 98% DRE if monitor flare as specified in 40 CFR Subpart CC, §63.670 and 63.671. See link.
- Tier 2: Use 95% DRE if monitor flare as specified in proposed NSPS OOOOb, (§60.5417b(d)(1)(viii)). See link.
- Tier 3: Use 92% DRE if do not monitor flare as specified above.
NOTE: Currently most O&G operators use a default 98% DRE for flares reported under subpart W.
Below is a table showing data for vent gas flared at varying destruction and removal efficiency (DRE).
The requirements for using the Tier 1 DRE and the Tier 2 DRE for flares are listed below.
Tier 1: Rules in 40 CFR 63.670 and 63.671 require the operator to install, operate, calibrate, and maintain a continuous parameter monitoring system (CPMS) for the flare. The CPMS includes:
- Continuous monitoring for presence of a pilot flame.
- Daily visible emissions monitoring using USEPA test Method 22.
- As an alternative, a facility can use video surveillance to continuously record flares for visible emissions if video output is sent to an operator control room or other continuously manned location.
- Continuously measure the flow rate to the flare as well as any flare supplemental gas used.
- A flare gas composition (mole %, BTU/scf) monitoring system is required in some applications.
- Direct compositional or net heating value (BTU/scf) monitoring is not required for gas streams that have been demonstrated to have consistent composition.
- The net heating value of flare combustion zone gas required to be at or above 270 Btu/scf.
- If pre-mix assist air and perimeter assist are both used, the facility must separately measure the volumetric flow rate of premix assist air and perimeter assist air used.
- Use alarms to alert operators to problems such as high emissions or equipment failure.
- Maintain records of all monitoring activities and any deviations for 5 years.
Tier 2: The referenced proposed rules in NSPS OOOOb §60.5417b(d)(1)(viii) require:
Flare flares and ECDs, a continuous monitoring system that measures the operating parameters including:
- Continuously monitor for the presence of a pilot flame or combustion flame.
- Using a calorimeter, continuously determine the net heating value (BTU/scf) of the inlet gas to the enclosed combustor or flare.
- No continuous calorimeter monitoring is required if can demonstrate the flare inlet gas has a net heating value that exceeds 200 BTU/scf. This requires sampling/chemical analysis of inlet gas to determine the hourly net heating value for 10 consecutive days. At least 200 hourly samples are required to demonstrate the net heating value exceeds 200 BTU/scf. A detailed analysis of the data collected is specified in the proposed NSPS OOOOb rules.
Cimarron’s flare and enclosed combustion devices using our Sytelink360™ system can continuously monitor the pilot flame and record flow rate data from the flare meter. Also, the system can track, store and report hours that a pilot flame was present for an ECD and flare system. Sytelink360TM also handles automated alerts to field operations so that corrective actions can be taken to minimize downtime.
Cimarron’s Aftermarket Services group assists companies with troubleshooting and repair of flare and ECD systems.
Cimarron’s IQR team can manage any required sampling and chemical analyses of flare gas. This includes repairing un-lit flares, detecting and repairing open thief hatches and optical gas imaging (OGI) services.
Summary and Conclusions
The USEPA has proposed changes to the greenhouse gas (GHG) reporting rules in 40 CFR 98 subpart W – Petroleum and Natural Gas Systems. The proposed rules affect most subpart W industry segments and emission source types. For flares and enclosed combustion devices (ECD) the proposal expands the type and amount of data reported and changes the default combustion efficiency to use for emission calculations.
Some key parts of the proposed subpart W rule changes that affect flares and ECDs include:
- Reporting of emissions from flares and ECDs will be at the well-pad facility level and gathering and boosting facility level.
- Facilities must indicate the type of flare and the type of flare assist used.
- Pilot and combustion flame monitoring method reporting includes:
- Facilities must indicate whether the pilot flame was monitored continuously,
- Indicate whether the flare has a continuous pilot or auto igniter.
- Report the number of times and hours the continuous monitoring device was out of service or otherwise inoperable for a period of more than one week.
- Facilities must indicate whether volume gas sent to the flare is measured with continuous flow meter or based on parameter monitoring and engineering calculations.
- Facilities must report the volume of gas sent to an un-lit flare (i.e., vented to the atmosphere).
- The proposed rules specify a combustion efficiency (e.g., DRE) value to be used for calculating CO2 and CH4 emissions. The combustion efficiencies listed range from 92% (minimal monitoring); 95% (monitor according to proposed NSPS OOOOb); and 98% (monitor according to 40 CFR 63.670 and 63.671).
Cimarron – Who We Are
Cimarron’s vision is to work with our clients to create a cleaner environment. The company engineers and manufactures environmental, production and process equipment for the upstream, midstream and downstream energy industries, as well as environmental control solutions for biogas at wastewater facilities, digester tanks and landfills. Our flares and ECDs meet all federal and state environmental regulatory requirements for control efficiency and destruction efficiency.
Cimarron offers our customers the know-how and environmental expertise to meet the environmental standards of today and tomorrow. Cimarron is committed to bringing value to the Energy industry and their shareholders based on our financial strength, experienced personnel, and engineering capabilities.
As a company, we thrive every day to make a difference through innovation (e.g. ESG), customer focus, and operational efficiency. In addition to being present in all major regions in the US, Cimarron serves more than 45 countries around the world, ranging from offshore to desert. From key operational centers in the United States, Italy and the United Arab Emirates, Cimarron offers ongoing service and support through its own field service personnel and strategic third-party partners, creating a cleaner environment for our customers and their shareholders.
Since its founding in the mid-1970’s in Oklahoma, the company’s product offering has expanded from production equipment to include the largest line of environmental solutions that capture or incinerate fugitive vapors. With the acquisitions of HY-BON/EDI in 2019 and AEREON (including Jordan Technologies) in 2020, Cimarron has added strong brands, products, and services to its portfolio.
Please contact us to learn more about our products and services and about all our ESG solutions at sales@cimarron.com or visit our website cimarron.com.