California ISO, which operates the power grid in California and parts of Nevada, said it would add Puget Sound Energy to the Energy Imbalance Market (EIM).

The EIM uses technology to find the most efficient resources over a larger geographical area. This will reduce electricity costs and enhance reliability by providing a larger pool of resources for system operators to use in managing the grid, the California ISO said.

Apart from Puget Sound, Berkshire Hathaway Energy unit NV Energy of Las Vegas is expected to begin participating in the market, which currently includes the ISO and Portland, Oregon-based PacifiCorp, another Berkshire Hathaway Energy unit, in October 2015.

Berkshire Hathaway Energy is a unit of Warren Buffett's Berkshire Hathaway Inc.

The EIM will encompass seven western states -- California, Oregon, Washington, Nevada, Utah, Idaho and Wyoming -- by year-end, the ISO said.

(Reporting by Arpan Varghese in Bengaluru)