Grid innovation

The Extended Day‑Ahead Market helps balancing authority areas across the West plan and schedule electricity one day ahead using a shared market system. Instead of each participant or utility planning mostly on its own, EDAM helps the region meet electricity demand using the lowest‑cost mix of power plants and transmission using a larger pool of power plants and transmission that isn’t available to each utility individually. 

EDAM builds on the Western Energy Imbalance Market, which runs every 5 and 15 minutes. Balancing authority areas that participate in the EDAM still balance in real time through WEIM, making sure the amount of electricity is being produced matches the amount customers are using.  

PacifiCorp chose to join the EDAM because it is expected to lower overall power supply costs and support reliability for customers. The decision was based on several factors:  

• WEIM has a 14-year proven track record of delivering savings and reliability benefits.  
• PacifiCorp helped shape EDAM’s design over several years to make sure it works for customers. 
• Independent research commissioned by PacifiCorp found EDAM could provide substantial customer benefits. 

PacifiCorp joined EDAM early to help create a strong, shared energy market to reduce costs for customers. Experience from the WEIM showed that once a market is established, other utilities are more likely to join. As more utilities participate, the market becomes more efficient and delivers greater savings and reliability benefits to customers. 

EDAM helps lower costs by improving how generation resource schedules and transmission use is planned across the West. When the grid can be scheduled more efficiently in advance, it reduces production costs and can reduce expensive last-minute purchases. Those savings show up over time through lower net power costs in customer rates. 

Since 2014, WEIM has provided over $1.1 billion in benefits to PacifiCorp customers and over $8.6 billion to participants across the West. EDAM is designed to build on that success with day-ahead coordination. 

EDAM helps utilities coordinate resources across a larger region before a storm or heat wave occurs, allowing participants to better prepare to meet expected demand and manage changing conditions.

Participation in EDAM is voluntary, and utilities across the West continue to make their own decisions about how they plan generation resources, maintain reliability and achieve savings for customers. Also, transmission service providers maintain their responsibilities for balancing their respective service areas and maintaining back-up generation resource capacity to resolve reliability events. So, while the EDAM expands day-ahead market participation into states beyond California, utilities retain their autonomy and are still subject to state policies. EDAM will provide savings and reliability benefits for all participating customers without imposing California energy regulations. 

Market oversight is changing to reflect broader regional input. Through collaboration from state regulators and market participants, known as the West-Wide Governance Pathways Initiative (Pathways), major governance changes have been adopted and planned for. Starting in 2025, the Western Energy Markets Governing Body, whose members are selected by market participants in the WEIM and EDAM, took decision-making authority over market-related matters. The decision-making authority used to be with the California Independent System Operator Board of Governors, whose members are selected by the California governor.  

Pathways also led to the passage of California Assembly Bill 825, which updated California state law so California utilities can participate in a market governed by an independent entity. Under the law, decision-making authority can transfer to an independent entity after certain steps are completed to ensure the independent entity offers a level playing field for all market participants and does not favor any state’s authority over another. The independent entity, known as the Regional Organization for Western Energy, is expected to take decision-making authority on market rules and federal tariff matters starting in 2028. 

In preparing to go-live in the EDAM, PacifiCorp thoroughly evaluated its processes to determine what would need to change for successful market participation and has worked to implement those changes. PacifiCorp will be planning to meet electricity demand, the day before the operating day, using a larger pool of generation resources from across the EDAM footprint. This impacts many operational processes, including how PacifiCorp schedules generation resource capacity to meet electricity demand, schedules transmission use, and manages the flow of electricity on its transmission system.

The EDAM is designed to optimally schedule generation resources while respecting transmission rights and the grid’s physical limits. The market applies transmission line and pathways limits so energy flows don’t create reliability issues. Transmission rights holders can use their existing rights similarly to how they use their rights today, and the market fairly distributes revenues so that the value of the transmission rights is sustained.