Simple Strategies for Managing Missing Emissions Data
November 16, 2023
By: Daniel McDermott
What do you do when you find you are missing data for an EI/GHG report that is due around the corner?
Read about Huco’s best practices for preventing this situation in the first place by implementing streamlined report preparation processes and delegating data collection to operations throughout the year.
If you are missing a piece of data for the year, don’t panic. The important thing is to identify these missing data points as soon as possible so you can select the best strategy for managing the situation.
Assess alternative calculation methods
First, review the different calculation methodologies for a given source. Required data is calculation-method specific, so if you are missing one piece of information, it is often possible to check an alternate method against the data you have available. For instance, there are 4 methods of calculation for amine units, dependent on the data you collect:
- Method 1: CEMS
- Method 2: CO2 composition in vent/stack gas
- Method 3: CO2 composition in inlet/residue gas and amine throughput volume
- Method 4: Simulation software
Employ missing data procedures
When the greenhouse gas rules were first released, facilities and suppliers had the option to use the Best Available Monitoring Method (BAMM) to determine emissions from specific sources because it was not always feasible for a facility to acquire, install, and operate all of the required monitoring equipment by the required date.
This changed in 2017, however, and BAMM is no longer an accepted method. Instead, missing data procedures must be utilized for all sources moving forward. This requires you to communicate the following within the Subpart W Spreadsheet:
- What piece of data was estimated?
- At what frequency is the data usually measured?
- How many times were measurements missed?
- What procedure was used to estimate the missing data?
If there is still a lack of data after assessing alternative calculation methods, you will need to employ missing data procedures. These procedures include:
- Standards set by the rule, such as using an emission factor,
- The average of other measurements,
- Best engineering estimates, or
- A value that was used in the previous year.
Verify recordkeeping procedures
Beyond resolving instances of missing data, it is critical to ensure your data is being properly recorded. Operations are required to maintain records on-site that document how the data provided in their annual GHG reports were developed. These records include a monitoring plan describing where and when samples were collected, methods used to analyze samples, and the procedures used for quality assurance and quality control.
Verifying data is collected and maintained as required (for example, records must be kept for at least 3 years following the respective reporting period in a format that is readily available for inspection and review) improves the quality of your reports and will help prevent future data gaps.