Duke says its revised $1.83 billion plan complies with the Indiana Utility Regulatory Commission's request to explain its costs and confine modernization projects to its grid. But the consumer watchdog group Citizens Action Coalition says it will keep fighting the revised plan.

The northern Indiana power plant is being shuttered in the face of more stringent federal air pollution rules.

Indiana regulators have approved a series of agreements that will allow Duke Energy to purchase 20 megawatts of power from four solar farms in the works around the state.