Empire District Electric (NYSE: EDE), which has had the coal-fired Units 7 and 8 at its Riverton plant largely on economic shutdown since September 2011, plans to operate them entirely on natural gas after the summer of 2013 and permanently shut them in 2016 once a Riverton combined cycle project is completed.
Those are points made in July 6 testimony from Empire’s Manager of Strategic Planning, Todd Tarter, filed at the Missouri Public Service Commission in a rate case. In this case, the company is asking for an overall increase of $30.7m, or 7.6%, in its overall rates charged to Missouri customers.
Tarter noted that Riverton 7, installed in 1950, has 38 MW of total capacity, but can only operate at up to 24 MW (net) on coal. Unit 8 has 54 MW of capacity, but only up to 45 MW (net) on coal, and was installed in 1954. Both units can operate just on gas, or gas can be used in an overfire configuration along with coal to get them up to their rated capacities. After the summer of 2013, the utility plans to only operate them on natural gas. Both units, due to recent slumps in natural gas and purchased power prices, have mostly been on economic shutdown since September 2011.
Empire President and CEO Brad Beecher wrote in companion July 6 testimony that Riverton 9, a small combustion turbine that relies on Riverton 7 for steam at startup, will also be retired upon conversion of Riverton Unit 12 to combined cycle mode in 2016. Riverton 12 would be converted from a simple cycle combustion turbine (142 MW) to a combined cycle unit (250 MW).
Beecher also said that the company’s latest clean-air compliance plan calls for installation of an SO2 scrubber, fabric filter and powder activated carbon injection at the Asbury plant by early 2015, at a cost of $112m-$130m. The air plan also requires retirement of Asbury Unit 2, an 18-MW steam turbine that currently only operates for peaking purposes. In 2007, Empire completed installation of a selective catalytic reduction system at Asbury, reducing NOx emissions by about 90%.
Based in Joplin, Mo., Empire provides electric, natural gas (through its wholly owned subsidiary The Empire District Gas Co.), and water service, with approximately 215,000 customers in Missouri, Kansas, Oklahoma, and Arkansas. Asbury has 207 MW of capacity, while Riverton has a total of 279 MW (92 MW coal and 187 MW natural gas).
“Our Asbury Plant is fueled primarily by coal with oil being used as start-up fuel and [tire-derived fuel] being used as a supplement fuel,” said Empire’s Feb. 23 annual Form 10-K report. “In 2011, Asbury burned a coal blend consisting of approximately 86.9% Western coal (Powder River Basin) and 13.1% blend coal on a tonnage basis. Our average coal inventory target at Asbury is approximately 60 days. As of December 31, 2011, we had sufficient coal on hand to supply full load requirements at Asbury for 47-94 days, as compared to 56-70 days as of December 31, 2010, depending on the actual blend ratio.”
The Form 10-K added: “Our Riverton Plant fuel requirements are primarily met by coal with the remainder supplied by natural gas, petroleum coke and oil. Riverton Unit 12, a Siemens V84.3A2 gas combustion turbine installed in 2007, and three other smaller units are fueled by natural gas. During 2011, Riverton Units 7 and 8 burned an estimated blend of approximately 92.8% Western coal (Powder River Basin) and 7.2% petroleum coke on a tonnage basis. Our average coal inventory target at Riverton is approximately 60 days. We had sufficient coal as of December 31, 2011 to run 53 days on both units as compared to 40 days as of December 31, 2010. Our future plans are to transition Units 7 and 8 to natural gas and to convert Unit 12 to a combined cycle unit, which will make natural gas the primary fuel at our Riverton Plant.”
All of the Western coal used at Asbury and Riverton is shipped to Asbury by rail, a distance of approximately 800 miles, under a 6.5-year contract with the BNSF Railway and the Kansas City Southern Railway which began on June 30, 2010. The coal for Riverton is then trucked from Asbury.