While a few sources have called this a coal plant, it was actually to be Petroleum Coke fueled plant. That is the solid leftovers from crude oil after all the available liquid/gas fuels have been removed from it.
From Corpus Christi Caller-Times:
Although financial conditions played a role in the decision, Freysinger said the project was the victim of an insurmountable regulatory framework erected by the U.S. Environmental Protection Agency, which has in recent years enacted stiffer carbon-based fuel permitting requirements while tightening standards on petroleum coke emissions.
The (Las Brisas Energy Center) is a victim of EPAs concerted effort to stifle solid-fuel energy facilities in the U.S., including EPAs carbon-permitting requirements and EPAs New Source Performance Standards for new power plants, he said. These costly rules exceeded the bounds of EPA authority, incur tremendous costs, and produce no real benefits related to climate change.