Colorado Ongoing Basin Emissions Study (COBE)
Summary:
This is an environmental project that serves to support the Colorado Department of Public Health and Environment (CDPHE), Air Pollution Control Division (APCD) in facilitating the state of Colorado’s efforts to enact greenhouse gas (GHG) reduction measures with the goal of limiting future climate warming. CSU will develop a measurement-informed inventory for methane emissions from the statewide upstream O&G segment utilizing site-level aircraft measurements. This project will support the implementation of the Intensity Verification Rule enacted by the Colorado Air Quality Control Commission (AQCC) in July 2023.
CSU (in collaboration with aerial survey participants and research participants) shall conduct a series of aerial surveys to scan upstream O&G facilities and quantify observable methane emissions throughout the state of Colorado. Emission observations collected from the aerial survey participants shall be sent to the Contractor for attribution of emission sources to specific facilities. CSU will share these emission observations with O&G operators who agree to participate in non-disclosure agreements for bi-directional data sharing. The sharing of emission observations with O&G operators is needed for assessment of maintenance operations occurring on site at the time of observation. The emissions data collected by the aerial survey participants as well as operational metadata collected from O&G operators for each measurement campaign shall be analyzed by the CSU and its partners to create a statistical model to develop measurement-informed emission factors for a series of classes of O&G facilities throughout the state from the data collected by aerial survey participants. The resulting model shall assess the total methane emissions from the upstream O&G segment in comparison to the state Oil and Natural Gas Annual Inventory Emission Report (ONGAIER) database for use within the development of the state default factor(s) for the implementation of the Intensity Verification Rule.
Objectives:
Goal: To improve and protect the air quality in Colorado through the development and implementation of cost-effective and efficient air pollution control measures that are consistent with the requirements of state and federal law.
Objective: Collect site-level aircraft measurements performed at a subset of facilities to develop a measurement-informed inventory of methane emissions from the upstream O&G sector throughout the state of Colorado.
Project Plan:
- Broad multi-basin sampling with many hours of aircraft time
- Repeat sampling, as funding allows, to help with persistence numbers
- Aircraft have ‘context cameras’ to help identify activities on facilities
- Establish a ‘pipeline’ to allow participating operators to review aircraft detections:
- Identify plumes from maintenance actions
- React to / correct fugitive emitters
- Establish a dialog about what & why
- Use data from (2) to identify maintenance emissions
- Note that matching aircraft plumes to maintenance does not indicate that the maintenance emissions were reported accurately.
- Use data from (1)-(3) to estimate emissions for major gas basins in Colorado
Why Does Maintenance Impact Estimates?
- Common scaling method for aircraft detections:
- Sum up plumes: Estimated size X <some estimate of persistence>
- Above sum = emission rate of basin
- Basin rate is implicitly scaled to 24×7 emissions
- Common scaling works if:
- Emitter duration is similar for all sources, and persistence assumption is correct
- Sampling is unbiased to times with more/fewer emitters
- But …
- Aircraft resampling too infrequent to identify persistence (duration) of maintenance releases
- Aircraft sampling is biased to daylight weekday periods
What does operator/CSU participation look like in COBE?
- Agree to participate: CSU/Operators covered by an NDA.
- CSU only releases results based on aggregation and anonymization
- Expect operators to join in stages as more hear about project
- NDA will define how information will be exchanged – depends on legal counsel’s recommendations
- Operators provide email and phone contact for POC for CSU to send detections on their facility
- CSU provides window of flight campaigns (few months span but operators will not be informed of exact flight plans)
- CSU sends detections to POC using our best estimate of who owns the facility
- Operator returns best estimate of cause – maintenance, known problem – to CSU …sometimes reiteration needed here
- CSU/Operators have regular working group meetings
- CSU provides all aggregated and anonymized data in reports to CDPHE; scientific analysis reported in peer-reviewed journals
Data Pipeline
- Multiple flight windows from 2024 (Spring/Summer/Fall).
- Operators won’t be pre-informed of flight plan – logistially impossible and sampling needs to be random
- CSU will use GHG reporting data from 2022 (and other sources) to target flight paths
Before:
| CSU/operator signs NDA | Optional - operator provides shape files/asset map |
During:
| Aircraft flight occurs (operator not pre-informed) | → | CSU receives data, sorts to individual facilities/operators | ← → (probably some back and forth here) | Operators receive shorted data, respond with event data | → | CSU/study team anonymize data; creates scaling model separating fugitives from activities | → | CDPHE receives emissions report (annon, aggregated data) |
Schedule:
Project timeline:
March 2024 – June 2025
Flight campaigns:
1. Campaign 1: Spring 2024
2. Campaign 2: Summer 2024
3. Campaign 3: Fall 2024
Results:
The Colorado Ongoing Basin Emissions (COBE) project was jointly developed between teams at Colorado Department of Public Health and Environment (CDPHE)’s Air Pollution Control Division (APCD) and Colorado State University (CSU)’s Methane Emissions Technology Evaluation Center (METEC) to help inform the 2026 Colorado greenhouse gas (GHG) Intensity Verification Rule. The project is also intended to help inform the implementation of the GHG Intensity Verification Rule for calendar year 2026 and beyond. COBE had three primary objectives:
- Collect representative measurements of methane emissions from upstream oil and gas facilities throughout the state of Colorado via anonymous aerial campaigns.
- Develop measurement-informed inventory (MII)s using the aerial emissions data.
- Compare the MIIs to operator-reported emissions in the Oil and Natural Gas Annual Emission Inventory Reporting (ONGAEIR) to provide recommended ratios of modeled total emissions to reported emissions.
To collect aerial measurements, the project worked with Bridger Photonics, Inc. (Bridger), GHGSat, and Insight M. METEC formed a scientific modeling team with Colorado School of Mines (CSM). METEC’s modeling approach used a discrete event simulation tool via the Mechanistic Air Emissions Simulator (MAES). MAES is intended to first match a reported inventory, here ONGAEIR [1], and then add in any measurements of emissions that are determined to not be included in the reported emissions. MAES allows understanding of emissions at the emitter level (most often, equipment level). CSM concurrently developed a statistical model that relied only on the emissions detections by the measurement technologies, using a data set of continuous monitoring system data to inform emissions below the detection limits of the aerial companies. Both models developed emissions totals and estimated ratios of total modeled emissions to reported emissions. These ratios were further split out by major basins and major facility classification. The CSM statistical model predicted higher state-wide emissions totals and ratios than the MAES model: 160,250 mt/y and a ratio of 3.08 vs 60,087 mt/y and a ratio of 1.19. More work will be done after the project end data of June 30, 2025, for COBE by the science team to determine causes for the discrepancies in model results. The team will report findings to the APCD team, via peer-reviewed journal articles and, as appropriate, through an update to this current report.
Opportunities to Participate:
Operators interested in participating, please contact Anna Hodshire.
