Seven electricity providers plan to join CAISO western energy imbalance market

Seven electricity providers have announced plans to join the California Independent System Operator’s (CAISO) western energy imbalance market (EIM) over the next several years, which dispatches electricity-generating resources more frequently than other Western markets.

Most markets in the West dispatch generation hourly. The CAISO EIM, however, awards bids for 15-minute intervals and dispatches generating units every five minutes.

This increases responsive, enables improved integration of distributed energy resources and can lower generation costs.

PacifiCorp became the initial cooperating entity in the EIM in 2014. Since then, three more balancing areas, NV Energy, Arizona Public Service and Puget Sound Energy, have joined.

Six additional U.S. balancing authorities have announced plans to participate through 2020. Powerex, a subsidiary of the Canadian balancing authority BC Hydro, announced plans to join in 2018 and will become the first non-U.S. entity to join.

The EIM now balances systems that supply 55 percent of electricity sales in the western grid of the lower 48 states. The addition of the six new U.S. authorities will increase the system’s reach to cover another 16 percent of electricity sales in the western United States.

As membership in the EIM has grown, cost savings have increased as well as new members have added supply resources, demand and transmission to the market. The system’s expansion also improves integration of distributed energy resources, which may need to be reduced if excess generation can not be stored or exported.