Mandatory GHG Reporting - Asset Controlling Supplier
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Background
An asset-controlling supplier (ACS) is a specific type of electric power entity (EPE) approved and registered by CARB under the Regulation for the Mandatory Reporting of Greenhouse Gas Emissions (MRR). An ACS owns or operates interconnected electricity generating facilities or serves as an exclusive marketer for these facilities even though it may not own them. Each ACS must be approved by CARB and is assigned a system emission factor for the wholesale electricity procured from its system and imported into California. Once approved by CARB, ACS specified source power can be reported using CARB-approved emission factors, subject to the requirements to claim specified source power.
ACS System Emission Factors
For each reporting year, CARB publishes emission factors for all approved ACSs pursuant to section 95111(b)(3). These emission factors provide electricity purchasing and selling entities information regarding the carbon intensity of power sourced from ACS systems for MRR reporting purposes. These emission factors can be used to report specified source electricity from ACS systems under MRR, subject to the requirements to claim specified source power.
EPEs may only claim power from an ACS when the specified source requirements in MRR have been met. Specifically, in order to claim specified source ACS power, the EPE must have a specified source power contract, comply with seller warranty provisions in section 95111(a)(4), and meet all other applicable requirements. More information on the requirements for claiming specified source and ACS power can be found in the Electric Power Entity Reporting Requirements Frequently Asked Questions document.
Data Year 2025 - ACS Emission Factors:
For transactions of ACS power delivered during calendar year 2025, CARB has approved two asset-controlling suppliers: Bonneville Power Administration (BPA) and Tacoma Power. CARB approval was based on CY2023 reported data submitted by the applicants and independently verified pursuant to section 95111(f) of MRR. Emissions associated with these factors will be reported by June 1, 2026. The 2025 assigned system emission factors for the approved ACSs are provided below:
Asset-Controlling Supplier System Emission Factors for Data Year 2025 (Reported in 2026) - Date Posted: October 10, 2024
| Asset Controlling Supplier | CARB-Assigned Emission Factor |
|---|---|
| Bonneville Power Administration (BPA) ARB ID #4000 | 0.0451 MT CO2e per MWh |
| Tacoma Power ARB ID #104567 | 0.0314 MT CO2e per MWh |
Data Year 2024 - ACS Emission Factors:
For transactions of ACS power delivered during calendar year 2024, CARB has approved two asset-controlling suppliers: Bonneville Power Administration (BPA) and Tacoma Power. CARB approval was based on CY2022 reported data submitted by the applicants and independently verified pursuant to section 95111(f) of MRR. Emissions associated with these factors will be reported by June 2, 2025. The 2024 assigned system emission factors for the approved ACSs are provided below:
Asset-Controlling Supplier System Emission Factors for Data Year 2024 (Reported in 2025) - Date Posted: November 6, 2023
| Asset Controlling Supplier | CARB-Assigned Emission Factor |
|---|---|
| Bonneville Power Administration (BPA) ARB ID #4000 | 0.0160 MT CO2e per MWh |
| Tacoma Power ARB ID #104567 | 0.0230 MT CO2e per MWh |
Archive – ACS Emission Factors for Data Years 2012-2022:
The table below shows the ACS emission factors assigned by CARB in previous data years 2012-2023.
| Data Year | Asset Controlling Supplier | CARB-Assigned Emission Factor | Date Posted |
|---|---|---|---|
| 2023 (Reported in 2024) | Bonneville Power Administration (BPA) ARB ID #4000 | 0.0174 MT CO2e per MWh | 11/16/2022 |
| 2023 (Reported in 2024) | Tacoma Power ARB ID #104567 | 0.0218 MT CO2e per MWh | 11/16/2022 |
| 2022 (Reported in 2023) | Bonneville Power Administration (BPA) ARB ID #4000 | 0.0160 MT CO2e per MWh | 11/5/2021 |
| 2022 (Reported in 2023) | Tacoma Power ARB ID #104567 | 0.0203 MT CO2e per MWh | 11/5/2021 |
| 2021 (Reported in 2022) | Bonneville Power Administration (BPA) ARB ID #4000 | 0.0211 MT CO2e per MWh | 11/13/2020 |
| 2021 (Reported in 2022) | Tacoma Power ARB ID #104567 | 0.0337 MT CO2e per MWh | 11/13/2020 |
| 2020 (Reported in 2021) | Bonneville Power Administration (BPA) ARB ID #4000 | 0.0117 MT CO2e per MWh | 11/19/2019 |
| 2020 (Reported in 2021) | Powerex ARB ID #3101 | 0.0342 MT CO2e per MWh | 11/19/2019 |
| 2020 (Reported in 2021) | Tacoma Power ARB ID #104567 | 0.0168 MT CO2e per MWh | 11/19/2019 |
| 2019 (Reported in 2020) | Bonneville Power Administration (BPA) ARB ID #4000 | 0.0129 MT CO2e per MWh | 11/5/2018 |
| 2019 (Reported in 2020) | Powerex ARB ID #3101 | 0.0233 MT CO2e per MWh | 11/5/2018 |
| 2019 (Reported in 2020) | Tacoma Power ARB ID #104567 | 0.0200 MT CO2e per MWh | 11/5/2018 |
| 2018 (Reported in 2019) | Bonneville Power Administration (BPA) ARB ID #4000 | 0.0120 MT CO2e per MWh | 12/19/2017 |
| 2018 (Reported in 2019) | Powerex ARB ID #3101 | 0.0254 MT CO2e per MWh | 12/19/2017 |
| 2018 (Reported in 2019) | Tacoma Power ARB ID #104567 | 0.0155 MT CO2e per MWh | 12/19/2017 |
| 2017 (Reported in 2018) | Bonneville Power Administration (BPA) ARB ID #4000 | 0.0193 MT CO2e per MWh | 12/19/2016 |
| 2017 (Reported in 2018) | Powerex ARB ID #3101 | 0.0205 MT CO2e per MWh | 12/19/2016 |
| 2017 (Reported in 2018) | Tacoma Power ARB ID #104567 | 0.0249 MT CO2e per MWh | 12/19/2016 |
| 2016 (Reported in 2017) | Bonneville Power Administration (BPA) ARB ID #4000 | 0.0195 MT CO2e per MWh | 12/13/2015 |
| 2016 (Reported in 2017) | Powerex ARB ID #3101 | 0.0469 MT CO2e per MWh | 12/13/2015 |
| 2016 (Reported in 2017) | Tacoma Power ARB ID #104567 | 0.0329 MT CO2e per MWh | 12/13/2015 |
2015 | Bonneville Power Administration (BPA) ARB ID #4000 | 0.0221 MT CO2e per MWh | 12/23/2014 |
2015 | Powerex ARB ID #3101 | 0.0355 MT CO2e per MWh | 12/23/2014 |
2014 | Bonneville Power Administration (BPA) ARB ID #4000 | 0.0192 MT CO2e per MWh | 12/18/2013 |
2014 | Powerex ARB ID #4000 | 0.0216 MT CO2e per MWh | 12/18/2013 |
2013 | Bonneville Power Administration (BPA) ARB ID #4000 | 0.0249 MT CO2e per MWh | 12/20/2012 |
2013 | Powerex ARB ID #3101 | 0.0293 MT CO2e per MWh | 12/20/2012 |
2012 | Bonneville Power Administration (BPA) ARB ID #4000 | 0.0856 MT CO2e per MWh* | 1/1/2012 |
*The 2012 emission factor for BPA was calculated following the 2010 MRR, which states that “[C]ARB will assign BPA a default system emission factor equal to 20 percent of the default emission factor for unspecified sources” for years where a previously verified GHG report submitted to CARB was not available at the start of the data year. The emission factor is not a reflection of the emissions profiles of BPA’s generation portfolio for that year. All other posted values are verified ACS emission factors. (footnoted 2/8/2021)
Asset Controlling Supplier Registration
Pursuant to section 95111(f) of MRR, electric power entities (EPE) may register with CARB as an Asset Controlling Supplier (ACS). For entities applying to be an ACS, submit your application to CARB by May 1st of the year preceding the data year for which the entity intends to be an ACS. Submission by this date is needed to ensure sufficient time to process and review the application for the upcoming reporting year.
For questions, please contact Tess McDermott, (916) 272-0049.