RIVERTON, Kan. — The Riverton Power Plant, which provided hydro- and coal-fired electricity for the Tri-State Mining District more than a hundred years ago, is entering a new phase as the first combined-cycle power plant in Kansas.
To comply with new emission standards for mercury, sulfur dioxide and particulate matter set by the U.S. Environmental Protection Agency, Empire District Electric Co. has converted the plant from coal to natural gas, retiring two coal-fired units that had operated since the 1950s.
The construction of the combined-cycle power plant, which should become operational by the middle of next year, will have an estimated cost of $165 million to $175 million. Empire has filed a notice with the Missouri Public Service Commission that it will seek a rate increase to recover costs associated with the project.
The company is installing a steam turbine to capture the exhaust of its natural gas turbine and improve the efficiency of the latter by up to 67 percent. The combined cycle refers to running two such turbines together. The combined-cycle addition will replace the energy production capacity of the retired coal-fired units.
"The high efficiency of this configuration will help control fuel costs, lower emissions and ensure reliable energy for our customers,'' said Blake Mertens, vice president of energy supply and delivery operations. "We are proud to continue a tradition of innovative and economical power generation at Riverton dating back to 1905.''
In a way, the company is returning to a process at the plant that it first used a century ago. After the St. Louis World's Fair in 1904, Empire acquired "Old Kate,'' a steam generator that supplied power to the fair. In 1913, a 2,000-kilowatt, low-pressure turbine was installed to take steam from Old Kate's exhaust. It was one of the first combination installations in the country.
The natural gas unit that was installed at the plant in 2005 was designed to be converted into a combined-cycle unit. Plans call for the natural gas unit to be shut down next week to complete the conversion process. The tie-in outage could be two to three months. The power generated by the natural gas unit will be supplanted by electricity from other Empire power plants, Mertens said.
Though Empire relies heavily on coal, Mertens said the combined-cycle plant will help diversify Empire's energy mix. In addition to coal, the company gets energy from two wind farms and a hydropower plant. It also purchases about 2 percent of its power as needed. In 1997, the company acquired 93 percent of its power from coal-related sources. In 2014, coal-related sources accounted for 53 percent of the company's energy supply.
Ed Easson, plant manager, said as many as 160 people have been working at the site since the groundbreaking in 2013. In response to the Joplin tornado, temporary emergency storm shelters have been erected on the site.
Easson said a minor challenge with the site has been the discovery of old foundations and other features that were unknown to workers when the project started.
"Rarely do you see a site like this one where a plant has existed for so long and a new one is being built there,'' he said. "We had a few surprises, but nothing unusual.''
Burns & McDonnell is the engineering, procurement and construction contractor for the expansion.
Startup activities are planned for October. A steam blow, in which the pipes will be blasted with steam, will take place in early November. A company representative said it is possible that noise from the steam blow will be heard in the Riverton area. Steps will be taken to mitigate the noise. Performance testing of the unit will take place early next year.