2. Outlines:
- Introduction.
- CO2 Capture Technologies.
- CO2 Separation methods.
- CO2 Transportation.
- CO2 Geological Storage.
- Challenges of CCS
- Conclusion.
- References.
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3. 3
Introduction:
Different approaches are considered and adopted by various countries to reduce and prevent their
CO2 emissions from release into the atmosphere, including:
• Reduce demand for energy services
• Increase energy efficiency
• Renewable energy (e.g wind, solar, ….. etc)
• Nuclear power
• Enhancing natural carbon sinks (e.g planting trees)
• CO2 Capture and Storage (CCS): can reduce CO2 emissions (typically 85–90%) from large point
emission sources, such as power production utilities.
4. Carbon Capture Storage System:
System designed to accomplish this in three steps:
- CO2 Capture.
- CO2 Transportation.
- CO2 Storage.
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5. CO2 Capture Technologies: Three main capturing systems
1- Post-combustion capture system:
• Applied in Coal- fired and gas-fired plants.
• This process removes CO2 from the flue gas after combustion
has taken place.
• This technology is the preferred option for retrofitting
existing power plants. The technology has been proven at
small-scale with CO2 recovered at rates up to 800 tons/day .
• The cost of electricity would increase by 32% and 65% in gas
and coal-fired plants, respectively.
• 2 of 16 large scale integrated CCS projects (currently
operating or under construction) are post-combustion
technology.
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Source: http://www.claverton-energy.com/download/137/
Process the flue gas goes through to remove the
carbon dioxide.
6. 6
Advantages:
- Technology more mature than other alternatives.
- Can easily retrofit into existing plants.
Disadvantages:
- Low CO2 Concentration affects the capture efficiency.
- Energy penalty has been relatively high.
- Solvents are degraded by oxygen and impurities.
1- Post-combustion capture system:
7. 7
2- Pre-Combustion Capture System:
This process applied in coal-gasification plants, the coal is pre- treated before combustion:
Gasification process conducted in a gasifier under low oxygen level forming a syngas which consists mainly of CO and H2, and
is mainly free from other pollutant gases.
The syngas will then undergo water gas shift reaction with steam forming more H2 while the CO gas will be converted to CO2
CH4 can be reformed to syngas containing H2 and CO. The content of H2 can be increased by the water gas shift reaction.
8. 8
Advantages:
- High CO2 Concentration enhance sorption efficiency.
- Deployed at the required scale in some industrial sectors.
- Opportunity for retrofit to existing plants.
Disadvantages:
- Energy penalty has been relatively high.
- Solvents are degraded by oxygen and impurities.
2- Pre-Combustion Capture System:
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3- Oxy-Fuel Combustion Capture System:
• This applied in coal-fired and gas-fired plants; it reduces the
amount of nitrogen present in the exhaust gas and that affect the
separation process; with the use of pure oxygen for the
combustion, the major composition of the flue gases is CO2 (80–
98% depending on fuel used), water, particulates and SO2. High
SO2 Concentration lead to corrosion problems which can be
removed by conventional electrostatic precipitator and flue gas
desulphurization methods.
http://www.oresomeresources.com/resource
/oxyfuel-combustion-process/
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Advantages:
- Very high CO2 concentration that enhance absorption efficiency.
- Reduce volume of gas to be treated.
Disadvantages:
- Only tested at a small scale.
- High cost of oxygen production.
3- Oxy-Fuel Combustion Capture System:
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CO2 Separation Technologies :
This describes the main CO2 separation technologies that can be applied to isolate the CO2 from the
flue/fuel gas stream prior to transportation.
1- Absorption.
2- Adsorption.
3- Chemical looping combustion
4- Membrane separation.
5- Hydrate-based separation.
6- Cryogenic distillation .
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CO2 Transportation:
• Once CO2 is separated from the rest of the flue gas components it needs to be transported to the storage
site or to the facilities for its industrial utilization.
• CO2 is transported in 3 states: Gas- Liquid- Solid.
• The means of transportation depending on the volumes, ranging from road tankers to ships and
pipelines.
• Pipelines are considered to be the most efficient and viable method for onshore transport of high volume
of CO2 through long distances specially with a power plant which life time is longer than 23 years.
• For shorter period road and rail tankers are more competitive.
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• The typical range of pressure and temperature for a CO2 pipeline
is between 85 -150 bar, and between 13- 44oC to ensure a stable
single- phase flow through the pipeline.
• Larger diameter pipelines allow lower flow rates with smaller
pressure drop and therefore a reduced number of recompression
stations.
• The presence of water concentration above 50 ppm may lead to
the formation of carbonic acid inside the pipeline and cause
corrosion problems.
Specification for Transportation of CO2 in pipelines:
Pipeline infrastructure, Alaska, USA.
https://www.co2captureproject.org/co2_transport.html
Pipelines have been used for this
purpose in the USA since the 1970s.
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CO2 Geological Storage:
The subsurface of the earth is the largest carbon reservoirs where the vast majority of world’s carbon
held in coal ,oil, gas organic rich shells, and carbonate rock. There different geological settings:
1- Enhanced oil recovery (EOR) in oil and gas reservoirs:
CO2 can be injected into depleted oil/gas reservoirs to
increase their pressure and provide the driving force to
extract residual oil and gases.
2- Unmineable coal bed storage:
CO2 can be injected into deep coal bed store cover
methane which is trapped in the porous structure of coal
seams.
3- Storage in saline aquifers:
Deep aquifers at 700–1000 m below ground level. These
saline aquifers have no commercial value but can be
used to store injected CO2 captured.
https://www.brgm.eu/activities/geological-storage-of-co2/does-geological-
storage-of-co2-mean
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At depths greater than 3 km, CO2 will be
liquefied and sunk to the bottom due to its
higher density than the surrounding sea water.
Injecting large amounts of CO2 directly into our
oceans may affect the sea water chemistry
causing ocean acidification, which may lead to
disastrous consequences to the marine eco
system.
4- Deep ocean storage :
http://theliquidgrid.com/2018/07/22/ocean-storage-of-co2/
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CCS Challenges:
• Leakages: There are two possible sources of CO2 leakage; CO2 transport facilities or the
storage area (such as acidification and pollution).
• Monitoring: The monitoring strategy includes pre-injection, during injection and post-
injection to assure the integrity of the reservoir, the absence of leakages, the quantification
of the volumes of the stored CO2 and to verifying the project’s aim.
• Infrastructure needs: Large and long-term investments required for transportation and
separation.
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Conclusions
1. Using the Carbon dioxide Capture and Storage method to mitigate our
climate change is a realistic and possible method.
2. Drawbacks in capture are cost and inefficiency to plant.
3. Drawbacks in storage are possible leakage and environmental effects.
4. The challenges against the CCS is about the cost, it really need to reduce it.
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References
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39(2014) 426–443.
2. IPCC. Special report on emissions scenarios: a special report of working group III of the Intergovernmental Panel on
Climate Change. New York: Cambridge University Press; 92-9169-1135.
3. de Visser E, Hendricks C, Barrio M, Molnvik MJ, de Koeijer G, Liljemark S, et al. Dynamics CO2 quality
recommendations. IntJ Greenh Gas Control 2008;2:478–84.
4. OlajireAA.CO2 capture and separation technologies for end-of-pipe application – a review.Energy2010;35:2610–28.
5. Bhown AS, Free man BC. Analysis and status of post-combustion carbon dioxide capture technologies.
EnvironSciTechnol2011;45:8624–32.