Energy Imbalance Market Background

An energy imbalance market is a voluntary market that provides a sub-hourly economic dispatch of participating resources for balancing supply and demand every five minutes. This market is security-constrained, meaning transmission and reliability constraints would be honored.

Selling surplus energy and capacity in the western markets is essential to keeping BPA's rates low. BPA must adapt its business model as these markets change. Our analysis shows that participating in the Western EIM will provide valuable experience as BPA helps shape more elaborate day-ahead markets being considered throughout the region and beyond.

Benefits accessible through EIM membership

  • Congestion management functions that are more economically efficient than present curtailment and bilateral redispatch capabilities. 
  • Optimized day-to-day operation of the power system.
  • Transmission expansion investment decisions.

BPA's decision process

Prior to joining the Western EIM on May 3, 2022, BPA conducted a five-phase decision process beginning in 2018. BPA began by exploring the feasibility and possible benefits of joining the EIM. This launched Phase I of BPA's decision process. On Sept. 26, 2019, BPA signed an EIM Implementation Agreement with the market operator, the California Independent System Operator. BPA also signed the EIM Policy Record of Decision (ROD) in a move toward joining the EIM. With the EIM Implementation Agreement in place, BPA began work on EIM-specific projects identified in the Grid Modernization Roadmap and developed a detailed project plan with the CAISO to ensure the necessary systems, processes and training are in place before the proposed go-live date. The EIM Implementation Agreement and EIM Policy ROD concluded Phase II of the decision process.  

Phase III commenced in October 2019 with discussion of policy issues that could involve rate or tariff changes. These discussions were held during the pre-rate and tariff case workshops. BPA issued the EIM Phase III Final Decision Document on Oct. 30, 2020, covering four issues that could be decided outside of the rate and tariff proceedings. This document ended the third phase of the decision process.

The BP-22 Rate Case and TC-22 Terms and Conditions Tariff Proceeding marked Phase IV of the process. These proceedings, which concluded on July 28, 2021, included important rate and tariff decisions that would enable BPA's participation in the Western EIM. 

BPA made its final decision to join the Western EIM on Sept. 27, 2021, when it released the Final EIM Close-out Letter. This letter concludes the extensive assessment and public process conducted through all five phases of the EIM decision process. On May 3, 2022, BPA joined the Western EIM.  BPA will continue to conduct implementation workshops and other engagements with customers and constituents as BPA participates in the market.


EIM Workshops

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Decision Documents