POWER May 2015 - 49

CARBON CAPTURE AND SEQUESTRATION
2. Cansolv. The Shell Cansolv process used at Boundary Dam's Unit 3 in Saskatchewan
employs a proprietary lean amine solvent formulation and removes both CO2 (upper half) and
SO2 (lower half) as SO3, which can be further processed to sulfuric acid. Courtesy: SaskPower
3. TRIG. The Kemper IGCC is based on the
unique circulating fluidized bed gasifier arrangement
known as a transport integrated gasification
(TRIG) reactor. Source: Southern Company
Presalter cyclone
Syngas
Standpipe
cyclone
Riser
Mixing
zone
Startup
burner
Coal
Seal leg
Air/O2
steam
J-leg
Standpipe
Ash
in the Global CCS Institute report for China is
a new 1,000-MW power plant with integrated
CCS and EOR, described as " newly identified. "
No other non-OECD countries in Asia
compared to conventional MEA, exhibits a
solvent loss and regeneration rate 10% that
of MEA, and a circulation rate that is 60%
lower than MEA.
The Worley Parsons report lists two sterically
hindered solvents, AMP (2-amino 2-methyl
1-propinol) and piperazine, a cyclical
diamine with molecular structure C4
H10
N2
.
They combine the higher reaction rates of
primary and secondary amines with the
lower regeneration energy of tertiary amines.
Simbeck notes that KS-1 is " the standard
today and likely the best real-world option, "
although the chemical industry continues to
seek better MEA solvents.
The Petra Nova scheme is unique because
an 80-MW gas-fired cogeneration unit is being
built along with the CCS to supply the
steam and electricity. In addition, the CO2
will be compressed to a pressure (2,115 psia)
that allows it to behave as a supercritical fluid-resembling
a liquid but expanding like a
gas-presumably to lower compression and
transport costs. Startup is scheduled for the
end of 2016. Cost of the facility is estimated
at $1 billion, $167 million courtesy of U.S.
taxpayers through the DOE Clean Coal Project
Initiative.
Petra Nova would qualify for a TRL of 7
after several years of operation. As an indication
of the scale-up this represents, MHI's
largest commercial KM CDR process installed
to date is ~450 tons/day CO2
recovery.
Petra Nova represents close to 4,000 tons/day
or approximately a 10:1 scale-up.
May 2015 | POWER
Projects Beyond North America
As mentioned earlier, the non-OECD countries
need to deploy CCS if it is to affect
global temperatures by 2050. Nowhere is
that need more urgent than China, where
coal-based electricity production continues
to grow. However, projects in that country
appear to be moving slowly.
Massachusetts Institute of Technology's
Carbon Capture and Sequestration
projects database lists only four projects
in China, all in the planning stages. The
Global CCS Institute's November 2014
report, The Global Status of CCS, notes
that there are 12 large-scale CCS projects
in that country. Four with EOR are furthest
along in planning.
Unfortunately, GreenGen, a project once
described as the centerpiece initiative to advance
near-zero emissions in China, involving
coal-fueled generation with hydrogen
production and CCS, appears to be moving
slowly. The first phase of that project, construction
of the 250-MW IGCC facility, has
been completed. According to an account
in Cornerstone magazine (a coal industry
publication), owner China Huaneng Group
has been wrestling with achieving continuous
operations. Phase II, construction of a
7% syngas slipstream CO2
capture facility,
reportedly began last year. Phase III, not expected
until after 2020, is the construction of
a 400-MW integrated IGCC CCS. The plant
processes subbituminous coal.
The other significant power-related project
www.powermag.com
are listed as having significant power-related
CCS activities.
As for the rest of the world, the only other
place with significant multi-project activity
is the United Kingdom. Five large-scale
projects are on the books, but all are in the
planning stage with start dates between 2018
and 2020. All are taking advantage of government
subsidies.
Other Challenges
Assuming commercial carbon capture options
were available today, CCS still presents
myriad challenges.
The flexibility of coal units with CCS will
be limited and, by extension, their value for
dispatch and cycling. The IGCC approach on
its own limits operating flexibility compared
to traditional boiler-based coal units. When
you have numerous interdependent process
unit operations, it is difficult for a plant to
respond to a dispatch command of, say, plus
or minus 100 MW at 10 MW/min. or to run at
30% of maximum continuous rating.
Permitting, monitoring, and liabilities
associated with sequestration sites have received
less attention than the carbon capture
processes; however, like nuclear waste (even
after reprocessing), sequestered CO2
has to
be managed forever. Geotechnical experience
with stored CO2
is limited. A key question is,
how long will it take to convince lawmakers
and the public that the approach is safe for
generations to come?
Although the correlation of gas frack49
Syngas

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POWER May 2015

Table of Contents for the Digital Edition of POWER May 2015