The entry of Arizona Public Service and Puget Sound Energy into the Western Energy Imbalance Market went off without a hitch, according to CAISO.

Western energy execs discussed the growth of the EIM, a Western RTO, “Caliphopia” and how the Western Interconnection is likely to change.

Arizona Public Service and Puget Sound Energy began transacting in the Western Energy Imbalance Market (EIM) on Oct. 1, bringing the region’s only real-time market up to five members.

FERC approved the CAISO plan to for a new market mechanism for itself and the Western EIM designed to integration of variable renewable energy resources.

FERC rejected for a second time proposed rules by Arizona Public Service on external resources can use dynamic scheduling to participate in the EIM.

Western utility leaders at the CAISO annual stakeholder event said they welcome the operational benefits and increased regional cooperation of the EIM but remain wary of organizing the wider West under a CAISO-run RTO.

Arizona Public Service and Puget Sound Energy have met the milestones to participate in the CAISO-run Western EIM and will begin trading in the market on Oct. 1.

The newly established Western Energy Imbalance Market (EIM) governing body kicked off its first meeting last week by electing its leadership.

Berkshire Hathaway Energy affiliates NV Energy and PacifiCorp refunded nearly $95K to customers after FERC revoked their market-based rate authority.

CAISO last week began work on a plan to extend external resource participation in the western Energy Imbalance Market (EIM).