INDIANAPOLIS (AP): Environmental and citizens' groups are asking Indiana regulators to launch a formal investigation into problems and delays that have sharply limited the power output of Duke Energy's $3.5 billion coal-gasification plant.

The Indianapolis Star reports the groups say in a motion filed Thursday with the Indiana Utility Regulatory Commission that the southwestern Indiana plant has been plagued by failures and outages that have deeply reduced its power production.

The plant generated only 4 percent of its maximum capacity in January, and an average of 37 percent of maximum capacity from June to December.