The Southern Illinois Power Cooperative plans to shutter its largest coal-fired generator this fall, which is expected to save it $125 million over a decade but cost 26 workers their jobs.

President and CEO Don Gulley said the tentative decision to close Unit 4, as it is known, was based on more competitive energy prices on the open market and a need to diversify the cooperative’s energy sources.

The tentatively approved plan awaits final regulatory approvals which are expected by late July. A formal board decision is to follow.

“It was — and is — a difficult decision,” Gulley said. “But my responsibility is to ensure the long-term viability of SIPC to benefit our member-owners, which ultimately benefit those 80,000 members. And the savings of $125 million over the next 10 years is significant and important to those 80,000 members.”

Up to 26 of the plant’s 82 employees will likely face layoffs, Gulley said.

According to Gulley, retiring Unit 4 will reduce total carbon emissions at the Marion plant by 50%.