How western EIM works
How western EIM works video

Western Energy Imbalance Market (EIM)

The Western EIM is a real-time wholesale energy market, the first of its kind in the western United States. It allows participating balancing authority areas to buy and sell the final few megawatts of power to satisfy demand within the hour it’s needed. Since its launch in 2014, the ISO’s western EIM has enhanced grid reliability and generated cost savings for participating utilities in eight states. The EIM also advances renewable energy integration, leading to a cleaner, greener power system.

Western EIM highlights


Latest developments


Technical reports and studies

  • Greenhouse gas emissions tracking report
    This report includes an accounting of GHG emissions for the ISO balancing authority area (BAA), including ISO internal resources, net imports, and transfers from Energy Imbalance Market entities into the ISO BAA. This report also reflects the ISO assessment of GHG reductions associated with EIM operations.
  • EIM quarterly benefits reports
    These reports quantify the estimated gross benefits from EIM operations.