Day-Ahead Markets & West-Wide GHG Reporting Initiative

February 2, 2024

Claire Halbrook



The Challenge Ahead: GHG Emissions Reporting and Expanding Electricity Markets

As electricity markets expand across the West, accurately accounting for and reporting greenhouse gas (GHG) emissions associated with generation will become more complex. This complexity is driven by increasingly overlapping boundaries for states, energy markets, and utility service territories.  At the same time, an increasing number of electricity market operators, state regulatory agencies, and clean energy buyers are relying upon GHG data to satisfy core functions, including:

  • Understanding the impacts of market design and operations decisions;
  • Tracking towards clean energy and climate goals; 
  • Assessing the emissions performance associated with clean energy procurement; and
  • Complying with new laws and regulations requiring companies to report their GHG emissions.


We can’t effectively reduce our industry’s carbon footprint if we can’t accurately count GHG emissions. Consistency in how GHG emissions are reported to interested stakeholders must be ensured to avoid double counting of emitting and non-emitting generation and to inform strategies to cut emissions. 


The Process

Gridworks led a six-month process to develop a list of minimum GHG reporting metrics for day-ahead markets across the West that can support the needs of key stakeholders. These metrics are intended to be consistent across the West, regardless of the day-ahead market operator as many stakeholders will need information from both the California Independent System Operator (CAISO) and the Southwest Power Pool (SPP). This initiative was carried out in partnership with the Western Resources Advocates (WRA), GridLab, the Clean Energy Buyers Association (CEBA), Renewable Northwest, and the Northwest Energy Coalition. The list of recommended GHG reporting metrics also reflect feedback from an Advisory Group composed of over 30 representatives from utilities, market operators, state agencies, clean energy buyers, and other interested stakeholders from across the West. Energy and Environmental Economics (E3) performed an evaluation of the final proposed recommendations. 


Recommended GHG Reporting Metrics 

The final deliverable for this project, located here, lists the minimum GHG reporting metrics required to satisfy the needs of market operators, state regulatory agencies, and clean energy buyers. Each metric is paired with a definition, proposed calculation, value proposition, and suggested reporting frequency/granularity. The project team recommends that CAISO and SPP include these metrics as outputs for their respective emerging day-ahead markets, EDAM and Markets+. The four metrics are: 

  • Market Total Average Emissions
  • Market Marginal Emissions Rate
  • Market Residual Emissions
  • Total Emissions 
Post by Claire Halbrook