E3 has completed studies for more than 10 utilities on the costs and benefits of participating in the western energy imbalance market (EIM), a regional 5-minute balancing market that became operational in 2014. The EIM aims to lower costs for consumers and assist states in meeting renewable energy goals through more-efficient dispatch, which reduces the need to carry costly reserves and curtail renewable generation. For each study, we ran a production simulation grounded in a detailed representation of the utility’s system. Our work has informed decisions by PacifiCorp, Arizona Public Service, NV Energy, and other utilities to join the EIM, as well as Chelan County Public Utility District’s decision not to participate. Consistent with E3 findings, the California ISO estimated that participants saved more than $85 million in the 20 months after the EIM became operational. Several more studies for utilities are under way.