California regional energy market to expand as new companies join

A California-run electricity market that allows utilities to make short-term energy purchases is expanding to South Dakota, its 12th state.

What happened: The California Independent System Operator announced Wednesday that two new companies will join its Western Energy Imbalance Market in May.

Black Hills Energy, based in Rapid City, South Dakota, operates natural gas and electric utilities and serves 1.35 million customers across eight states. PowerWatch in Great Falls, Montana, is an energy producer and grid operator owned by Berkshire Hathaway Energy.

“We are honored to welcome Black Hills Energy and PowerWatch into the WEIM,” CAISO President Elliot Mainzer said in a statement. “The continued growth of our markets delivers real economic benefits to market participants and their customers and is a proven strategy for improved reliability and affordability throughout the region.”