Mississippi Power, a Southern Company subsidiary, has secured approval from the Mississippi Public Service Commission (PSC) for its new 582MW coal-fired plant planned to be built in Kemper County, US.

The PSC had voted for the power project again after the state Supreme Court asked more details last month on why the commissioners raised the cost of the plant to $2.88bn from $2.4bn.

The Sierra Club, which opposes the plant, brought the lawsuit that called a fresh look at the plant’s finances.

PSC commissioner and chairman Leonard Bentz said the commission clarified its original decision as requested by the Supreme Court.

"Fundamentally, the order today has not changed from the previous Order and decision of the Commission to approve the IGCC Kemper Plant," Bentz said.

"What we did today was clarify our original decision, as requested by the Supreme Court. They asked us for more detail, and we gave it today.

"If for some reason this plant doesn’t work or does not perform as advertised, the Ratepayer will not be responsible."

The Commission noted that the Kemper coal-gasification power project will serve as an alternative source to provide reliable energy, contributed by lignite currently, for the next several decades.

Commissioners said their approval does not raise the $2.88bn cost cap, which is meant to provide a 20% margin for overruns.

Earleir, commissioners approved the proposed project by Mississippi Power in 2010, limiting to $2.4bn that the company could recover from its 193,000 customers.

Operations of the Kemper plant are scheduled to commence in 2014.

Mississippi Power, a subsidiary of Southern Company, serves 188,000 customers in 23 southeast Mississippi counties.