POWER October 2013 - 33

Top planTs
less water use, less solid waste generation,
and higher gross thermal efficiency than
a conventional pulverized coal plant with
modern emission controls. These benefits
increase when a plant burns high-sulfur
Midwestern coal, as Edwardsport does.
In fact, with IGCC, emissions of criteria
pollutants are generally an order of magnitude
cleaner than required by current
regulations. In general, the lower emissions
are possible because the pollutants
are removed before combustion rather than
post-combustion, as with a typical pulverized
coal plant. At Edwardsport, key pollutants
(particulates, sulfur, and mercury)
are removed between the gasifier and the
combustion turbines, when they are in a
more concentrated form and removal technologies
are much more efficient.
Additionally, and a prime reason Duke
chose this technology in the first place, an
IGCC plant can be designed from the start,
or retrofitted, to capture carbon dioxide prior
to fuel combustion.
The Edwardsport 2 x 1 IGCC uses a coal
gasification system to convert coal into a
synthesis gas (syngas) that fuels the combustion
turbines (CTs). Bechtel Corp. was
responsible for project design and construction
of the plant based on General Electric
(GE) gasification technology. GE provided
the process design and two separate trains
of its radiant quench gasification equipment.
The process-capable of using high-sulfur,
high-ash coals found in the Midwest-converts
the coal into a slurry and feeds it into
the gasifier along with oxygen, where it is
turned into raw syngas consisting of H2 and
CO. The raw syngas is next scrubbed of flyash,
mercury, chlorides, and sulfur before it
is burned in the CTs.
GE also supplied two 7FB IGCC syngas
CTs, each rated at 232 MW, the single
320-MW four-flow reheat steam turbine,
and the plant's Mark VIe distributed control
system. Exhaust gas from each CT
travels through a Doosan-supplied twopressure
heat-recovery steam generator to
produce steam that drives the steam turbine
(Figure 1). Air Products supplied the
air separation unit that produces oxygen
for the gasifier.
Development Speed Bumps
Duke received approval to construct Edwardsport
from the Indiana Utility Regulatory
Commission (IURC) on Nov. 20, 2007,
despite the earnest objections of many consumer
and environmental groups. When
proposed in 2006, the project cost estimate
was ~$2 billion, net of potential tax credits.
Construction began in March 2008 and two
months later the project cost estimate was increased
to $2.35 billion. The planned startup
date was the summer of 2011.
Duke's clout within the political process
was apparent during 2009. The proposed
American Clean Energy and Security Act of
2009 (ACES) was designed around the carbon
control blueprint written by US-CAP, an
advocacy group of which Duke Energy was
a founding member. The bill barely passed
its June 26, 2009, House vote but was later
defeated in the Senate. Edwardsport was well
under construction by this time, reportedly
30% complete in October 2009.
Projects costs continued to inch up during
2009-10. By November 2009, Duke officially
adjusted its cost estimate upward by ~6%
($150 million), followed by another increase
1. Complex arrangement. The air inlet filter to one of the two GE 7FB IGCC syngas
combustion turbines is shown on the far right, with the two-pressure heat recovery steam
generators are shown in the background. Courtesy: Duke Energy
of ~$530 million in April 2010. The plant
was reported to be 55% complete in July
2010. By November 2011, the cost estimate
had soared to nearly $3 billion.
The IURC capped the amount of recoverable
construction costs at $2.595 billion in
December 2012 as part of a 134-page settlement
agreement, although the additional
financing costs of $320 million are not included
in the cap. The project cost is now
estimated as ~$3.5 billion-$1.5 billion
over the original estimate-and the plant
was conservatively one year late entering
service. Duke Energy responded that the increased
costs were a result of the project's
" scale and complexity. "
Edwardsport was declared to be in commercial
operation on June 7, 2013, although
the plant was shut down for repairs six days
later, the Indianapolis Star reported. The outage
was reportedly caused by damage to fans
required by the two gasifiers. Since repairs,
the plant has been running intermittently. A
monthly compliance report filed with state
regulators revealed the plant operated with
~10% capacity factor in June.
Duke's declared in-service date has reignited
the passions of those opposed to the
project. A Duke Energy spokesperson confirmed
that the plant is expected to slowly
ramp up to its full capacity over the next 15
months, taking many industry observers by
surprise. Opponents suggest that Duke prematurely
declared the plant commercial to
take advantage of a loophole in the settlement
agreement: Capital repair costs that
occur subsequent to commercial operation
should come under the cost cap and could be
disguised as operation and maintenance costs
normally paid by ratepayers. A Duke spokesperson
disputes the accusation, noting, " it all
depends on the repair. " The IURC and other
advocacy groups will certainly closely scrutinize
repair costs incurred subsequent to commercial
operation.
The project team of Duke, Bechtel, and
GE will unquestionably do what is necessary
to get the plant running reliably in the coming
months, although the controversies surrounding
the project will likely not subside.
The best way to quiet critics will be with a
history of reliable operation.
For unilaterally taking a significant step
in developing IGCC technology with carbon
capture potential-a move that will
allow the use of domestic coal as a power
production fuel in the future-Edwardsport
Generating Station is recognized as a 2013
Top Plant. We look forward to reporting on
the plant's full-load and reliable operation
in 2014. ■
-Dr. Robert Peltier, PE, is POWER's
consulting editor.
October 2013 | POWER
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POWER October 2013

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