The Western EIM took on BPA and Tucson Electric Power as new participants, marking the market’s largest single expansion since its founding.

The Bonneville Power Administration is on target to enter the Western EIM in early May after executives made a final determination on its market readiness.

A CAISO market report says high natural gas prices drove a 50% run-up in electricity costs in Q4 2021, hitting the Western Energy Imbalance Market as well.