Westar Energy Inc. said Friday it has agreed to buy a natural gas-fired power plant from Tulsa, Okla.-based ONEOK Inc. for $53 million.

The plant, located in Logan County, Okla., would be used only in the summer months when customer demand temporarily exhausted the utility’s electric capacity.

The news comes four days after the Topeka-based company told Kansas regulators it needed to raise electric rates by $84 million to continue recovering from financial problems it blamed on former Chief Executive Officer David Wittig.

Company officials said buying the ONEOK plant would be cheaper than building a new plant. The transaction requires federal approval and is expected to be completed next year.

The deal requires approval from the Federal Energy Regulatory Commission and is expected to be completed in 2006, Westar said.