Plum Point Energy Station

The Plum Point Energy Station (PPES) is a 665-megawatt (MW) energy facility located approximately five miles east of Osceola (Mississippi County). Owned by NRG Energy of Houston, Texas, the station began commercial production of electricity on September 1, 2010, serving members of the Missouri Joint Municipal Electric Utility Commission (MJMEUC) in the Arkansas communities of North Little Rock (Pulaski County), Osceola, and Piggott (Clay County), along with the Missouri communities of Carthage, Kennett, Malden, and Poplar Bluff, plus all thirty-five members of the Missouri Public Energy Pool No. 1 (MoPEP). The Empire District Electric Company, East Texas Electric Cooperative, and Municipal Energy Agency of Mississippi own smaller shares of the company.

Development and Construction
Spurred by recent economic setbacks in the community and surrounding areas, the city of Osceola, led by Mayor Dickie Kennemore, actively began to seek new industries that would create jobs and bolster the local economy. A result of this effort was the decision announced in January 2001 by LS Power of Chesterfield, Missouri, to construct a coal-fired generating plant near Osceola. The city’s proposal integrated a persuasive package of incentives totaling $3.5 million, including an offer of a 1,000-acre site with infrastructure improvements and twenty years of real estate tax abatement.

After several years of delay, the project groundbreaking ceremony took place on May 31, 2006. Among those present at the ceremony, U.S. congressman Marion Berry commented that “the Delta is moving forward like it hasn’t since cotton seed was first unloaded here. It’s like we just discovered the Mississippi River and all the wonderful things it brings and businesses just discovered it, too.”

The plant’s location in the New Madrid Fault Zone, as well as its proximity to the Mississippi River, posed significant geological and civil engineering challenges for its construction team, Plum Point Power Partners (a joint venture of Zachary Construction Corporation, Black & Veatch, and Gilbert Central Corporation). As a result, a series of specialized engineering and construction practices were utilized. Seismic issues were addressed with the use of a buckling resistance brace that serves as a structural shock absorber. This brace substantially reduced the amount of steel required to protect the facility from high seismic acceleration, thereby limiting potential damage from an earthquake over the following fifty years.

Excavation issues, complicated by the site’s shallow groundwater level, were solved with the installation of steel sheets underground, forming four sides of a water-tight box that was excavated to accommodate the deep rotary coal car dumper structure. Concrete grout was injected below grade to seal the bottom of the box. This allowed excavation of the area “in the dry.” When that step was finished, construction of the concrete substructure began.

The station’s first fire on coal took place on March 27, 2010. After seven months of testing, the project was effectively completed. The cost of building the plant, including change orders and addition in scope, was approximately $1,585 per kilowatt (kW).

Facility Profile
NAES Corporation, based in Issaquah, Washington, operates the facility, with an operations and maintenance staff of eighty permanent staff members on site, plus some contract personnel.

PPES is designated as a subcritical facility (a designation that refers to its operational temperatures, pressures, and efficiencies), utilizing pulverized coal boiler technology from the Japanese company IHI and advanced emission controls to provide steam at 2,520 pounds per square inch and 1,050° Fahrenheit to power a dual-flow four-exhaust Toshiba steam turbine. It has a design capacity of 1,330 MW. PPES burns Southern Wyoming Powder River Basin coal, emitting about twenty-five percent less carbon dioxide than some older coal-fired units still in operation.

The plant’s performance test demonstrated a heat rate that was lower than 9,100 Btu/kWh (British thermal unit to kilowatt hour). The unit’s actual generating capacity exceeded the guaranteed value of 665 MW by more than two percent. These figures were generated under test conditions just before commercial operation began in August 2010.

Flue gas treatment performance test results show that PPES emissions control systems exceed guaranteed removal rates. These technologies include a selective catalytic reduction system for nitrogen oxides control, a dry flue gas desulfurization system (scrubber) for sulfur dioxide removal, a carbon injection system for mercury removal, and a fabric filtration system (baghouse) for particulate material removal.

Economic Impact
PPES represents a $1 billion investment in northeastern Arkansas, with an annual payroll projected at $7 million. Significant tax revenues are generated by sales and use taxes and annual PILOT payments to local taxing districts (a PILOT payment is in lieu of taxes and compensates a local government for any loss of tax revenue). Over the four years of construction, 1,600 workers were employed during peak periods, representing a $200 million construction payroll. Hundreds of millions of dollars were spent on local goods and services to support the construction.

In a joint report published in December 2011 by the Environmental Integrity Project (EIP), EarthJustice, and the Sierra Club, PPES was ranked as the “dirtiest” power plant in the nation in terms of sheer pounds of toxic emissions. However, it was later learned that this designation was based on erroneous data reported by PPES to the Environmental Protection Agency. As a result, the EIP issued an erratum in a later publication, which acknowledged that PPES was not the top power plant toxic emitter as previously reported; it did not receive a new ranking after the correction.

Plans to construct a second unit on the site were withdrawn in 2011 as a result of a legal agreement between LS Power and the Sierra Club, which had actively fought development of the second plant as part of the environmental group’s “Beyond Coal” campaign launched in 2005.

For additional information:
Neville, Angela. “Top Plants: Plum Point Energy Station, Mississippi County, Arkansas.” Power: Business and Technology for the Global Generation Industry 155 (October 2011). Online at http://www.powermag.com/coal/Top-Plant-Plum-Point-Energy-Station-Mississippi-County-Arkansas_4048.html (accessed November 4, 2021).

“Plum Point Energy Station.” Power-Technology.com. http://www.power-technology.com/projects/plum-point-energy-station/ (accessed November 4, 2021).

“Power Plant to be Built near Osceola.” Blytheville Courier News, January 22, 2001, p. 1.

Wheeler, Brian. “Overcoming Obstacles at Plum Point.” Power Engineering, January 1, 2011. Online at http://www.power-eng.com/articles/print/volume-115/issue-1/departments/managing_the_plant/overcoming-obstacles-at-plum-point.html (accessed November 4, 2021).

Toney Butler Schlesinger
Granite Bay, California