Regulators have approved a settlement that prohibits Duke Energy from passing on to consumers all the costs the company will incur building a coal-gasification plant in southwestern Indiana.

Costs for the plant in Edwardsport have increased substantially since it was proposed in 2007, and the latest estimate is $3.5 billion. Under the new agreement, Duke’s customers will pay nearly $2.6 billion for the plant, while the utility will be forced to absorb nearly $900 million in cost overruns.

The plant will turn coal into synthetic gas, and has met significant opposition in Indiana over the past several years. Many argue it’s not cost effective, especially when natural gas prices are at an all-time low.

A spokeswoman for Duke says the company is reviewing the order.