Mitsubishi Heavy Industries Technical Review Vol. 49 No. 1 (March 2012)37

Large-scale Carbon Dioxide Capture
Demonstration Projectat a Coal-fired Power Plant in the USA
MASAKI IIJIMA*1

TATSUTO NAGAYASU*2

TAKASHI KAMIJYO*3SHINYA KISHIMOTO*4SHINSUKE NAKATANI*4

Economically less-burdensome and drastic carbon dioxide (CO2) reduction methods arerequired to mitigate global warming and facilitate sustainable social activities. CO2 capture andstorage (CCS) technologies provide an answer to reduce CO2 emissions from coal-fired thermalpower plants, which have the highest level of CO2 emissions in the power-generation sector.
Large-scale CCS projects are being planned for implementation in developed countries. Mitsubishi
Heavy Industries, Ltd. (MHI) and Southern Company, a major U.S. electric power company, havejointly constructed the world’s largest CO2 recovery demonstration plant at an existing coal-fired
thermal plant located in Alabama. The CCS demonstration plant has the capacity to capture 500
metric tons of CO2 per day, and has recently begun operation. In this paper, we present the current
operational status of the CO2 recovery demonstration plant in U.S., and the test program
scheduled for the plant.

|1. Introduction
Because of its promise as an environmental countermeasure for reducing greenhouse gas
emissions, CO2 capture and storage (CCS) has attracted global attention in recent years. According
to the World Energy Outlook 2009 issued by the International Energy Agency (IEA), world energy
demand in 2030 is predicted to be 1.4 times that in 2007. Furthermore, the use of fossil fuels isexpected to increase and will continue to be the primary energy source of the future. The continueduse of fossil fuels, however, leads to further production of greenhouse gases.
In anticipation of the expected increase in CO2 emissions, the IEA announced two CO2
reduction scenarios to be implemented in the power sector by 2050. In the first scenario, which iscalled the Act Scenario, the IEA suggested that by making practical use of existing and/or
under-development technologies, CO2 emissions by 2050 could be curbed to 2005 emission levels.
In the other scenario, called the Blue Scenario, the IEA suggested that cutting CO2 emissions to the2005 level might be insufficient to curb global warming, and instead recommended that the 2050
target should be reduced to half of the current CO2 emission level.
Figure 1 shows the breakdown of CO2 emission reductions in these two scenarios. As
illustrated by the figure, CCS technologies are critical to the success of CO2 reduction in thepower-generation sector; CCS accounts for 21% of the CO2 reduction in the Act Scenario and asmuch as 26% in the Blue Scenario.
CCS includes separation and recovery of CO2 from large-scale CO2 emissions sources, suchas power plants; transportation of the CO2 through pipelines or similar; and storage of the CO2 insubterranean aquifers. Figure 2 shows a conceptual illustration of CCS. Candidate sites for CO2
storage include depleted oil fields, depleted gas fields, and underground or seabed aquifers.
*1

Engineering Headquarters*2

Group Manager, Environmental & Chemical Plant Project Management Division, Engineering Headquarters*3

Engineering Manager, Environmental & Chemical Plant Project Management Division, Engineering Headquarters*4

Environmental & Chemical Plant Project Management Division, Engineering Headquarters

Mitsubishi Heavy Industries Technical Review Vol. 49 No. 1 (March 2012)38

For the purpose of CO2 emission reductions from coal-fired thermal power plants, large-scale
CCS demonstration projects backed by government initiatives, especially in Europe and North
America, are now being planned. In addition, European governments have announced plans toimpose a CO2 Capture Ready duty on new power plants to ensure space for retrofitting CO2
recovery facilities and to present prospective beds for CO2 storage. Prior to these moves,
Mitsubishi Heavy Industries, Ltd. (MHI), Southern Company, and the Electric Power ResearchInstitute (EPRI) jointly constructed a large-scale CO2 recovery demonstration plant with a capacityof 500 metric tons of CO2 per day at a coal-fired flue gas plant in Alabama. The demonstration
plant has begun verification operations.

Figure 1

IEA CO2 reduction scenarios in the power-generation sector by 2050

Figure 2

Conceptual illustration of CO2 underground storage|2. Overview of the Demonstration Project in U.S.
An overview of the demonstration project undertaken by MHI and Southern Company isshown in Table 1, and an exterior view of the plant is shown in Figure 3. The demonstration plant
was constructed at Alabama Power’s Plant Barry (Figure 4). Alabama Power is an electric powercompany under the umbrella of Southern Company that supplies electricity to 1.40 million
households, offices, and workplaces across approximately two thirds of Alabama. Alabama Powerplans to conduct the various tests for CO2 recovery at the plant.
A portion of the flue gas from the stack-gas desulfurization unit downstream of the existingcoal-fired thermal Barry Power Plant is introduced into the demonstration plant, and its CO2 gas isrecovered. The recovered CO2 is then dehydrated, compressed, transferred via pipeline to theinjection location 18km away, where it is injected into a saline aquifer and safely stored.
The demonstration test operation began in 2011, and is scheduled to be conducted for fouryears. Mitsubishi Heavy Industries America (MHIA) and Southern Company Service (SCS)Mitsubishi Heavy Industries Technical Review Vol. 49 No. 1 (March 2012)39

oversee the CO2 recovery, compression, and dehydration processes, and the Southern Regional
Carbon Sequestration Partnership (SECARB) manages the storage process. SECARB receives asubsidy from the United States Department of Energy, and is conducting geological surveys of CO2storage and CO2 injection experiments in the southeastern region of the U.S.
The demonstration plant utilizes the KM CDR Process® (described in Section 3), which was
jointly developed by MHI and The Kansai Electric Power Co. Inc., and which has the following
requirements: CO2 recovery capacity of 500 metric tons per day, CO2 recovery ratio of 90 percent,and capacity to process flue gas from the power plant equivalent to about 25 MW. Energy saving
points for process modification and the effect of impurities contained in the coal-fired exhaust gas
on the CO2 recovery plant and its absorption solvent will be studied during the demonstration
operation. With the aim of ensuring development of large-scale CCS demonstration andcommercial plants, the behavior of impurities will be understood and countermeasures for theimpurities-related difficulties will be validated.
Table 1 Overview of the CO2 recovery
demonstration plant in U.S.
Item
Location
Bucks, Alabama
SouthernCompany
Customer(Alabama Power)
Process
KM CDRTM process
Absorbing solution
KS-1TM Solvent
OutputEquivalent to 25 MW
Flue gas quantity
73 ,800 SCFM (116 ,800 Nm3/h)
CO2 recovery ratio
90 %500
metricton/day
CO2 recovery capacity(150 ,000 metric ton /year)
CO2 concentration in
10.1 mol.% -wetflue gas

Figure 4

Figure 3 Exterior view of the 500
metric tons per day CO2 recovery
demonstration plant in U.S.

Location of the Plant Barry

Locations of coal-fired thermal power plants owned by Alabama Power under the umbrella of Southern
Company are shown in the figure. At the Plant Barry, continuous demonstration tests for CO2 recovery andunderground storage are conducted.

|3. MHI’s CO2 Recovery Process
As noted above, the demonstration plant has adopted the KM CDR Process®.Note MHI andKansai Electric Power Co. Inc. have worked on the development of a process for CO2 recovery
from combusted flue gas since 1990, and the first commercial plant was delivered in 1999.
Note : The KM CDR Process® is an MHI trademark registered in Japan, the U.S., the European
Community (CTM), Norway, Australia, and China.

(1)

Process Flow of the Demonstration Plant
Figure 5 contains a schematic flow diagram of the MHI CO2 recovery plant. The flue gas
containing CO2 is introduced into the flue gas quencher, cooled therein, and then pressurized byMitsubishi Heavy Industries Technical Review Vol. 49 No. 1 (March 2012)40

the blower, which is installed downstream of the quencher and delivered into the CO2 absorber.
The flue gas delivered into the bottom section of the absorber makes contact with the alkaline
absorption solvent KS-1TM, which was jointly developed by MHI and Kansai Electric PowerCo. Inc., and CO2 is absorbed into the absorption solvent. After CO2 is absorbed, the flue gas
exhausts into the atmosphere as a clean flue gas. On the other hand, the absorption solvent, now
rich in CO2, is discharged into the regenerator, in which CO2 is stripped by steam, resulting inregeneration of the absorption solvent. In the regeneration process, the latest energy-saving
process developed by MHI is used, which enables the greatest possible reduction in the amountof steam required. The regenerated absorption solvent is circulated back to the absorber andreused.

Figure 5

Process flow diagram of MHI’s CO2 recovery process (KM CDR Process®)(2)

Commercialization Track Record
MHI has implemented the CO2 recovery process for flue gas from natural gas-fired
boilers and gas turbines, and has thus far supplied 10 commercial plants (with another onorder). The first plant was delivered to Malaysia in 1999 and had a capacity of 200 metric tons
per day of CO2. The recovered CO2 has been used to increase the production of urea, and theplant has been in operation for more than ten years. Additional commercial plants have been
supplied for chemical production use and/or general use all over the world. For example, a CO2
recovery plant (400 metric tons of CO2 per day) was delivered to Abu Dhabi in 2009. At theAbu Dhabi plant, the first energy-saving regeneration system was introduced (described below),which allowed the plant to reduce energy consumption per unit of CO2 recovered compared toother conventional regeneration systems.
(3) Pilot Plant for Coal-fired Flue Gas
Flue gas from coal-fired power plants typically contains large quantities of impurities,
such as sulfur oxides, nitrogen oxides, and solid particulates. Therefore, it is necessary to
precisely understand the effects of these impurities on CO2 recovery technologies. Prior toimplementation of the MHI/Southern Company large-scale CCS demonstration project, MHI
conducted demonstration tests using various small pilot plants. Table 2 contains a list of thedemonstration test plants.
Table 2Demonstration plants for CO2 recovery from coal-fired flue gas

Location

CO2 recovery
capacity

Customer

Flue gas source

Start of operationJapan
MHI R&D center1 metric ton/day-Coal-fired boiler

April 1999

Electric Power
10 metric ton/day Development Co. Coal-fired boiler(J-Power)
U.S.A.
Southern
500 metric ton/day
Coal-fired boiler
Southern Company Plant BarryCompanyJapan
Matsushima Power Plant

July 2006June 2011

Mitsubishi Heavy Industries Technical Review Vol. 49 No. 1 (March 2012)41

As a first step, MHI fabricated a demonstration pilot plant in its research center with acapacity of one metric ton of CO2 per day, and began demonstration tests on CO2 recovery fromcoal-fired flue gas.
Subsequently, with the support of the Research Institute of Innovative Technology for theEarth (RITE) and the cooperation of the Electric Power Development Co., Ltd., MHI
constructed a pilot plant with a capacity of ten metric tons of CO2 per day in an existingcoal-fired thermal power plant in Matsushima, Nagasaki Prefecture, and conducteddemonstration tests from 2006 to 2008. In long-run demonstration tests in Matsushima, MHI
achieved continuous operations of more than 5,000 hours, acquired operational expertise,investigated the effects of impurities in flue gas upon the pilot plant, validated thecountermeasures, and collected data for medium-scale CO2 recovery from coal-fired flue gas.

|4. Operational Results of the Demonstration Plant
The operational status of the CO2 recovery demonstration plant in U.S. is described below.
Course of the Operation from Startup
The CO2 recovery demonstration plant in U.S. began receiving feed gas in June 2011. It
has achieved stable operation for 1,612 hours in total by August 2011. Total CO2 recovery forthis period is approximately 28,680 tons.
(2) Trend of CO2 Recovery Ratio and Capacity
Figures 6 and 7 show the 72-hour operational trends for the CO2 recovery capacity andCO2 recovery ratio, respectively. The demonstration plant stably achieves the rated operational
conditions: CO2 recovery capacity of 500 metric tons per day and CO2 recovery ratio of 90 %.

(1)

Figure 6

CO2 recovery capacity

Figure 7

CO2 recovery ratio(3)

Energy-saving Performance
The demonstration plant adopted MHI’s energy-saving process, which was proved toexhibit much higher energy saving performance than conventional processes. For reference, theenergy-saving process is the same as at the Abu Dhabi commercial plant, for which the process
was adopted for the first time. But because of further improvements implemented at the CCS
demonstration plant in U.S., the demonstration plant achieves even lower steam consumption(Figure 8).

Mitsubishi Heavy Industries Technical Review Vol. 49 No. 1 (March 2012)
42Figure 8

Steam consumption(4)

Behavior of Trace Components
Trace components in flue gas that accumulate within the system have the potential tocause corrosion and degradation of the solvent. Due to the high quantities of impurities
contained in coal-fired flue gas, it is essential to investigate the effects of impurities and todesign and implement countermeasures against corrosion. Since its startup, however, theMHI/Southern Company CCS demonstration plant for CO2 recovery from coal-fired flue gas
has never exhibited negative effects caused by trace components in the flue gas. Instead, theplant continues to operate in a stable manner. Thus, MHI’s CO2 recovery technologies have
proven practical for implementation on a commercial scale, even for feed gas from coal-fired
power plants.
During the demonstration operations, various futher testing programs (described below) areplanned, including tests with the aim of further reducing both the energy consumption per unit of
CO2 recovery and the consumption of absorption solvent.

|5. Future Testing Program
Demonstration operations at the MHI/Southern Company CCS plant are planned for fouryears from startup. The demonstration plant continues to be in stable operation since its startup,
despite the fact that the feed gas contains a lot of impurities. MHI and Southern Company haveplanned a comprehensive testing program on the CO2 recovery system for this period. An exampleof the testing program is shown below.
(1) Acquisition of material and heat balance(2) Flue gas and wastewater component measurements
Measurement of the trace components of treated flue gas and wastewater are planned.
(3) Accuracy improvements
Tests will be conducted with varied operating conditions to accumulate meaningful datawith the aim of improving the accuracy of simulation tools.
(4) Optimization of operation conditions
In an effort to determine optimized conditions, the operational costs will be measured forvarious operational conditions.
(5) Load-following operation test
The system, which automatically controls the operating load of the CO2 recovery plant inresponse to load fluctuations from the existing power plant, will be verified.
(6) Long-term reliability of plantThrough long-term operation, along with monitoring the effect of impurities contained in
the flue gas from coal-fired power plant, the reliability of the impurity countermeasures thathave been undertaken will be validated.
(7) Test operation with high-particulate concentration
The type of coal burned will be varied in order to change the particulate concentration in
the feed gas flowing into the CO2 recovery plant. The effect of high particulate concentration
upon the CO2 recovery plant will be investigated, and the effectiveness of countermeasures willbe verified.

Mitsubishi Heavy Industries Technical Review Vol. 49 No. 1 (March 2012)
43|6. Conclusion
MHI and Southern Company have completed construction of the world’s largest CO2
recovery demonstration plant, with a capacity of 500 metric tons of CO2 per day, at the Plant Barryin Alabama. Demonstration operations were begun in Jun 2011. The demonstration plant has
achieved both the rated CO2 recovery capacity and ratio, and also exhibited lower steam
consumption by adopting the MHI energy-saving process. In addition, the plant has been operating
in a stable manner since startup, demonstrating the high reliability of MHI’s technologies for CO2
recovery.
Through application of know-how gained at the demonstration plant into a comprehensive
design review of the CO2 recovery process, MHI is advancing the development of optimized CO2
recovery technologies. This process will enable the realization of larger-scale CO2 recovery
projects at commercial coal-fired thermal power plants.

References
1.
2.
3.

International Energy Agency, World Energy Outlook, 2009
The European CCS Demonstration Network, CO2 Capture and Storage
Endo, T. et al., Current Status of MHI CO2 Capture Plant technology, Large Scale Demonstration project
and Road Map to Commercialization for Coal Fired Flue Gas Application, GHGT-10