POWER October 2013 - 28

TOP PLANTS
Cliffside Steam Station Unit 6,
Cliffside, North Carolina
Owner/operator: Duke Energy
Courtesy: Duke Energy
With a mandate to cut emissions, improve efficiency, and increase output, Duke
set out to replace the four World War II-era units at Cliffside Steam Station with a
modern, state-of-the-art supercritical plant. The result was one of the cleanest, most
efficient coal plants in the country, with twice the output and half the emissions of
its predecessor.
Thomas Overton
D
uke Power's deep roots in North
Carolina go especially deep in the
Appalachian Mountain range in the
western part of the state, where Duke-then
Catawba Power Co.-got its start building
hydroelectric generating stations to power
the state's nascent industrial sector.
One of its first fossil fuel plants was the
Cliffside Steam Station, which broke ground
in January 1939. Its first 80-MW unit came
online the following July. The new plant was
located along the Broad River about 50 miles
east of Charlotte, with the intent of taking
advantage of its proximity to the Appalachian
coal fields to power North Carolina's
growing textile industry. Three more units,
ultimately totaling 198 MW, came online
during the 1940s. Unit 5, located about half a
mile from the original four-unit building, was
completed in 1972 and added 556 MW to the
plant's capacity.
But by the 2000s, it had become clear that
28
the oldest units were reaching the end of their
useful life, and the Cliffside station would be
unable to meet rapidly growing electricity
demand in the area, while complying with
increasingly stringent state and federal emissions
regulations, without a major upgrade.
In mid-2006, Duke filed an application with
the North Carolina Utilities Commission to
retire and replace Units 1 through 4. Though
Duke had originally hoped to add two 800MW
supercritical units to the site, the commission
ultimately approved only one of
them in early 2007.
Construction
The Shaw Group was selected build the plant.
Duke and Shaw created an integrated team to
address design, specifications, and pricing
for the project, instead of using a fixed-price
engineering, procurement, and construction
contract. Permission to begin construction
was issued in January 2008, and ground was
www.powermag.com
broken shortly afterward. The permit included
an additional project installing a wet flue
gas desulfurizer (WFGD) on Unit 5.
Although the air permit issued by the state
included a first-of-its-kind carbon mitigation
plan, the proposal to build a large new coal
plant on the site sparked strenuous opposition
from area environmental groups. Plant
opponents were concerned primarily about
mercury emissions from the new Unit 6, even
though replacing the old units would result in
a dramatic net reduction. Much of the dispute
centered around what emissions levels were
mandated under the Clean Air Act and state
regulations, a determination that was complicated
by the Environmental Protection Agency's
delay in finalizing Maximum Available
Control Technology rules for new plants.
Opponents were unsuccessful in stopping
the project despite a series of lawsuits and
administrative actions, as well as sporadic
episodes of civil disobedience. Duke agreed
POWER | October 2013
http://www.powermag.com
POWER October 2013

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