KNOXVILLE — For the fifth time in the past two years, the Tennessee Valley Authority is buying a financially distressed gas-fired plant to help meet its growing demand for peak power.

TVA announced Thursday it has agreed to pay $466.3 million to buy and take over a bankrupt gas plant in Southaven, Miss. The three-unit, 810-megawatt combined-cycle combustion turbine facility was built for $490 million five years ago by Southaven Power LLC, a subsidiary of Cogentrix Energy LLC, which filed for bankruptcy in 2007. Pending approval of the U.S. Bankruptcy Court in Charlotte, N.C., and the Federal Energy Regulatory Commission in Washington, D.C., TVA will take over the plant in time to help meet expected summer power peaks.

“The good news is that we were able to bid on and buy this plant for substantially less than what it would cost to build such a unit,” TVA President Tom Kilgore told the utility’s board Thursday. “The bad news is that we are about out of places where we can go buy these distressed assets.”

TVA previously has bought plants or plant sites for other natural gas plants in Gleason and Brownsville, Tenn.; Columbus, Miss.; and Marshal County, Ky.

As a combined-cycle plant, the Southaven facility reuses heat produced during the initial gas burn to achieve greater efficiency and operate at a lower cost. Both the combined-cycle and the simple-cycle gas turbines rely upon natural gas, which is often twice as expensive as either coal or nuclear fuel.

Although the gas-fired plants generate power only a few weeks a year and cost more to operate than what TVA charges for power, they help meet power peaks for less than buying the power from other utilities or independent power producers, agency officials said.

TVA bought more than $1.4 billion of power from other utilities last year. But TVA’s strategic plan calls for the agency to cut that share of outside power by producing more of its own power.

“This is a great outcome for TVA and its customers, and it is a natural fit with the goals of our strategic plan,” TVA Chief Operating Officer Bill McCollum said in a prepared statement. “We continue to diversify our fleet through acquisitions of natural gas plants such as Southaven, and by adding nuclear capacity with the restart of Browns Ferry Unit 1.”

Since 2000, the power generating capacity added to TVA’s fleet contributes less than 27 percent as much in carbon dioxide emissions linked with global warming as TVA’s other plants, Mr. Kilgore said.

“These plants are reducing our carbon footprint,” he said.