Mississippi Power now says that its Kemper County integrated gasification combined cycle (IGCC) power plant could enter service at the end of June. Even so, the utility says that major systems need to be redesigned for the plant to achieve long-term sustained operations.
The utility says the latest schedule shift stems from maintenance work done during May. Those repairs extended the time needed to establish sustained, integrated operation of both of the project’s gasifiers for syngas production used to produce electricity.
The Kemper project has achieved periods of integrated operation of both gasifiers and combustion turbines. It also has been producing sulfuric acid and ammonia, and has captured and transferred carbon dioxide. Altogether, the project has operated for around 200 days using lignite as a fuel.
The utility also says that it is not filing for a full rate review to recover the project’s costs at this time. The company and the Mississippi Public Utilities staff have been discussing the status of the project and the nature and timing of a rate filing.
The portion of the Kemper project currently being recovered in rates includes a portion of the project’s combined cycle generating plant, which has been supplying approximately one-third of the electricity used by Mississippi Power customers since August 2014. The plant has primarily been using natural gas as fuel, but has also been using syngas from the project’s gasifiers as they have been tested and operated.
IGCC technology turns coal into synthesis gas, a combination of hydrogen and carbon monoxide. The syngas can then be cleaned of impurities, and burned to drive a turbine. Excess heat goes to power a steam turbine.
Kemper is years behind schedule and well over the $2.2-billion cost estimate given in 2010 when construction began. (Read "Kemper County and the Perils of Clean Coal Technology.")
During May, Mississippi Power says it completed work to repair a leak in one of the particulate control devices for gasifier “A.” It also modified each gasifier’s ash removal systems, and repaired the plant's "sour water" system.
The plant also experienced leaks in the syngas coolers on gasifier “B.” These leaks required a repair outage and to make modifications to the syngas coolers on both gasifiers.
The utility says that after gaining experience through startup and operational testing over nearly 200 days of coal operation, "achievement of long-term sustained operations is expected to require the redesign and eventual replacement of the syngas cooler superheaters sooner than originally expected." The utility says this is primarily a result of the leaks experienced. Redesign and replacement could take 18 to 24 months.
Long-term operations are also expected to require relocation of the ash loading process and other equipment. These additional capital projects are expected to be subject to the $2.88 billion cost cap established by the Mississippi PSC as they are undertaken over the next several years and may further negatively impact the Kemper IGCC's economic viability.
The utility says that further cost increases and/or extensions of the expected in-service date may result from factors that include:
- Difficulties integrating the systems required for sustained operations
- Sustaining nitrogen supply
- Continued issues with ash removal systems or syngas coolers
- Major equipment failure
- Unforeseen engineering or design problems including any repairs and/or modifications to systems, and/or operational performance (including additional costs to satisfy any operational guidelines adopted by the Mississippi PSC.
Additional improvement projects to enhance plant performance, safety, and/or operations may be completed after the remainder of the Kemper IGCC is placed in service.
The utility says that any extension of the in-service date beyond June 30 is currently estimated to result in additional base costs of approximately $25 million to $35 million per month, which includes maintaining necessary levels of start-up labor, materials, and fuel, as well as operational resources required to execute start-up activities.