Empire District Electric pursues coal retrofit, Riverton gas uprate

Under its latest integrated resource plan (IRP), filed Feb. 28 at the Arkansas Public Service Commission, Empire District Electric is installing new air emissions controls at the Asbury coal plant and pursuing an uprate of its gas-fired Riverton plant.

In order to comply with forthcoming and recent environmental regulations, Empire is taking actions to implement its compliance plan and strategy. This compliance plan is already in action and largely follows the preferred plan presented in the 2010 IRP, with an update to the IRP presented in 2012. This new IRP covers the 2013-2032 period.

The compliance plan calls for the installation of an SO2 scrubber, fabric filter, and powder activated carbon injection system at the Asbury plant (collectively referred to as the air-quality control system or AQCS) by early 2015 at a cost ranging from $112m to $130m.

The Asbury plant, located near Asbury, Mo., consists of two coal-fired units totaling 203 MW. Unit 1 (189 MW) was installed in 1970 and Unit 2 (14 MW) was installed in 1986. At the end of 2012 a new chimney and foundations for the project were in place. The addition of this air quality control equipment will require the retirement of Asbury Unit 2, a small 14-MW steam turbine that has been used for peaking purposes.

The compliance plan also calls for the transition of the Riverton Units 7 (38 MW) and 8 (54 MW) from operation on coal to full operation on natural gas. The transition to natural gas was accomplished in 2012 and the Riverton coal delivery/handling system has been retired.

As part of the compliance plan, Riverton Units 7 and 8, along with Riverton Unit 9, a small combustion turbine that requires steam from Unit 7 for start-up, will be retired upon the conversion of Riverton Unit 12, a recently installed simple-cycle combustion turbine, to a combined-cycle unit. The conversion of Riverton 12 is currently scheduled for the 2016 timeframe and was included as a committed resource for this IRP compliance filing.

Riverton Unit 12 conversion to start this year

Riverton Unit 12 is a natural gas-fired Siemens V84.3A2 combustion turbine that was installed at the Riverton power plant in Riverton, Kansas, in 2007. It is currently rated at 142 MW for the summer peak season and it is primarily used as a peaking unit. When this unit was originally constructed adequate natural gas piping and electrical transmission were designed and built to accommodate its conversion to a combined cycle unit at some point in the future. The Riverton 12 conversion project will add about 100 additional MW to the system, making the Riverton combined cycle around a 250 MW unit upon completion. A heat recovery steam generator (HRSG) will be installed along with a new steam turbine and a cooling tower to provide cooling water for the condenser. A new control room and control system will also be installed to operate the unit.

Empire concluded, and expressed to interested parties in a 2013 project review, that the Riverton 12 conversion is the lowest cost 2016 supply alternative and should continue to be treated as a committed resource in its 2013 IRP and that Empire would move forward with the Riverton combined-cycle project.

Empire worked with the engineering firm Black and Veatch (B&V) to develop a specification for the project to support the release of a request for proposal (RFP). The RFP was issued to six bidders in January 2013, and four bids were returned. Empire is in the final selection and negotiation process. Empire has begun acquiring the necessary permits for the construction and operation of the Riverton Combined Cycle unit. At this time, construction is expected to begin in the summer of 2014, with the unit available for service in mid-2016.

The Plum Point Energy Station is a 665 MW, sub-critical coal-fired facility located near Osceola, Ark. Empire is a joint owner of the unit at the 7.52%, or approximately 50 MW level. In addition, since September 2010, Empire has a 30-year power purchase agreement (PPA) for roughly an additional 50 MW of capacity from this unit and has an option to purchase an undivided ownership share of the 50 MW covered by the PPA in 2015. For purposes of this IRP, the Plum Point PPA was not converted to ownership in any of the plans studied.

During the IRP development process, Empire analyzed the option to purchase the 50 MW of Plum Point capacity currently under PPA. The analysis indicated that under certain circumstances the conversion to ownership was a low cost long-term supply-side option for Empire. The decision to exercise the purchase option also has to take into consideration undefined issues that were not reflected in the IRP modeling. While Empire intends to maintain an ownership interest in the plant for the life of the asset (i.e. well in excess of 30 years), risks of taking on an even larger ownership interest in the plant must be further analyzed, the IRP noted. Several risk factors including the plant ownership structure, availability of operating personnel, operation by a third party, plant equipment redundancy, and availability restrictions due to location, make this plant unique when compared to Empire’s other singly- and jointly-owned units.

Asbury air project due for completion in early 2015

The Asbury AQCS and turbine project is underway. In January 2012, Empire entered into a contract with a joint venture formed by Alberici Constructors and Stanley Consultants for the construction of the AQCS. Construction is in progress, and completion is anticipated in early 2015. Asbury Unit 2 will retire in late 2013 or early 2014 so that it’s generator step up transformer can be used to supply energy to the AQCS. In the 2014 outage to complete the AQCS tie-in, Empire will install upgraded turbine hardware that will increase the turbine output. This will partially compensate for the retirement of Unit 2 and the increased auxiliaries associated with the operation of the new AQCS equipment.

Empire contracted with Aquaterra to complete an ash impoundment study to determine potential locations and associated construction and operating and maintenance costs for a new Asbury and/or Riverton landfill to address Empire’s existing and future Coal Combustion Residuals (CCR). Based on Aquaterra’s report and further study, Empire has moved forward on development of a new CCR landfill at Asbury. A parcel of land adjacent to the plant property was purchased, and site investigations have begun. Assuming a favorable outcome on the permitting process, the landfill should be available to receive CCR in the third or fourth quarter of 2016.

Empire District Electric is an investor-owned, regulated utility company, based in Joplin, Mo., that provides electric, natural gas and water service, with approximately 215,000 customers (total electric, natural gas and water). The electric operation is engaged in the generation, purchase, transmission, distribution and sale of electricity to nearly 168,000 electric customers in parts of Missouri (88.8%), Kansas (5.8%), Oklahoma (2.8%) and Arkansas (2.6%).

About Barry Cassell 20414 Articles
Barry Cassell is Chief Analyst for GenerationHub covering coal and emission controls issues, projects and policy. He has covered the coal and power generation industry for more than 24 years, beginning in November 2011 at GenerationHub and prior to that as editor of SNL Energy’s Coal Report. He was formerly with Coal Outlook for 15 years as the publication’s editor and contributing writer, and prior to that he was editor of Coal & Synfuels Technology and associate editor of The Energy Report. He has a bachelor’s degree from Central Michigan University.