In a document filed Tuesday at a federal court in Nevada, the owner of Hawaii’s sole geothermal power plant denied allegations that it fraudulently obtained more than $130 million in federal grants.

Ormat Technologies Inc., a Nevada-based geothermal power developer, could face penalties of up to $400 million in a whistleblower lawsuit brought by two of its former employees.

At issue are federal grants Ormat received through the U.S. Treasury Department’s 1603 program, an initiative created under the so-called stimulus package in 2009. The plaintiffs allege that the company “knowingly and purposefully exploited” the program by filing fraudulent grant applications.

The Puna Geothemal Ventures plant on the Big Island.

Ormat Technologies Inc.

In its first answer to the plaintiffs’ complaint, Ormat — which owns Puna Geothermal Ventures, the operator of a geothermal power plant on the Big Island — categorically denied any wrongdoing.

“All accusations of an intent to defraud the Treasury or to obtain grants to which Ormat was not entitled are specifically rejected,” it wrote. “Ormat generally denies the allegations of wrongdoing in the complaint and affirmatively asserts that, at all times, Ormat and its officers acted reasonably and in good faith in light of all circumstances and in compliance with all applicable legal requirements.”

The lawsuit, filed in 2013, has been making its way slowly through the court. Ormat initially sought to dismiss it on technical grounds, but a federal judge rejected the move in March and forced the company to file its response this week.

It appears that both the plaintiffs and defendants are bracing for the long haul. In a joint filing last week, they asked the court to set the discovery process to last until June 30, 2016.