Idaho Power plans to leave its Valmy coal plant in Nevada three years early and stop all its use of coal by 2030.

The investor-owned utility that serves most of southern Idaho and part of eastern Oregon will save its customers $3 million as it moves toward its goal to use only clean energy sources by 2045, said Jared Ellsworth, the utility’s transmission, distribution and resource planning director.

Only seven years ago, Idaho Power used coal for more than 40 percent of the power it generates for its 560,000 customers. But today, renewable energy and natural gas is cheaper than coal for power production. Economics, not environmental politics, has largely driven the utility industry’s dramatic shift toward wind and solar power.

Its costs have drop-ped dramatically, Ellsworth said.

“Every time a utility, not just Idaho Power, sharpens its pencil, coal closes faster,” said Ben Otto, an energy attorney for the Idaho Conservation League.

The decision to leave the Valmy plant early was made in Idaho Power’s Integrated Resource Plan, which was completed this month. The plan said leaving early will benefit customers.

“The plant sits idle for more than half the year due to high operating costs at the plant compared to more affordable sources like wind, solar and battery storage, including projects like Jackpot Solar near Twin Falls,” said Caleb Heeringa, of the Sierra Club in Seattle, in an email.

The utility hopes to make up for the lost power from the grid in Nevada and using the same transmission line into Idaho south of Twin Falls, Ellsworth said in a telephone interview.

“We can use those wires to purchase power from down there,” he said.

Oregon’s Boardman Coal Plant — 90 percent of which Portland General Electric owns, while Idaho Power owns the remaining 10 percent — closed Oct 15. Portland General Electric plans to replace most of its power with wind and solar projects and battery storage. That storage approach recently has become more competitive and makes wind and solar a more reliable energy option.

Idaho Power will decide by September whether it can rely on surplus power from the grid. If its not certain, it will put out a request for proposals that could include programs to manage demand, renewables or battery storage, Ellsworth said.

“That could be a part of it,” He said. “But we haven’t decided to do that yet.”

The Conservation League’s Otto prefers Idaho Power consider projects based in Idaho.

“We would like to see them prioritize Idaho markets and not play the markets in Nevada,” Otto said.

Idaho Power also included in its plan giving up its share of one of four coal-fired units of the Bridger coal plant in Wyoming in 2022. It would drop out of the second unit in 2026, the third in 2028 and finally pull out of all coal plants by 2030.

Those changes down the line are partially dependent on whether the utility completes its Boardman-to-Hemingway transmission line into Idaho. The line remains in regulatory limbo in Oregon. Otto said Idaho Conservation League has not decided whether to support the line yet.

“We care about climate and we care about landscapes, so transmission is a tough one,” he said.