The suit was filed in July in Kane County Circuit Court in Geneva, Illinois, by nine residents of nearby Batavia. Defendants include five consultants to Batavia, part of the Northern Illinois Municipal Power Agency, which acquired an ownership stake in Prairie State.

St. Louis-based Peabody, the world’s largest privately owned coal company, began developing Prairie State more than a decade ago. The nearly $5 billion project also includes the nearby Lively Grove underground mine that supplies more than 6 million tons of high-sulfur thermal coal annually to the power plant. The plant’s twin 800-megawatt units went into commercial operation in 2012.

Peabody is not listed as a defendant in the litigation, but is among 19 other entities classified as “respondents in discovery.” Peabody sold 95% of the ownership — and financial risk — of the Prairie State complex to more than 200 municipalities in the Midwest, including Batavia, in 2007, according to the Institute of Energy Economics and Financial Analysis, a critic of the project.

An attorney for the plaintiffs said the suit seeks unspecified damages from the defendants. The suit also requests a jury trial.

Vic Svec, Peabody senior vice president of global investor and corporate relations, strongly denied accusations that the project was misrepresented to potential joint owners.

“Sound long-term forecasts show electricity costs from Prairie State will be extremely competitive with other fuels over the long term,” he said. “Prairie State also has been one of the most transparent projects of its kind. It is a generation company, with municipal corporations owning the power and working directly with their members to set retail rates.”

Eight of the Prairie State participants are public power and electric cooperatives “that bring to the table decades of experience in power planning,” Svec added. “After performing extensive research and investigating all options for new long-term power sources, they concluded that Prairie State was the right project and took an active role in the development of the facility.”

Svec continued that “when the scorecard is complete, we firmly believe Prairie State will continue to provide reliable, clean electricity for the benefits of millions of customers in multiple states.”

Raj Rao, president and CEO of the Indiana Municipal Power Agency (IMPA), is among the defendants in the suit, as is IMPA. “We will vigorously defend against the lawsuit and what are ultimately baseless allegations,” he said.