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[[File:Three methods for CCS.jpg|500px|Fig. 3—CO<sub>2</sub> capture overview of three optional processes.]]
[[File:Three methods for CCS.jpg|500px|Fig. 3—CO<sub>2</sub> capture overview of three optional processes.]]


'''Fig. 3—CO2 capture overview of three optional processes.'''<ref name="r8">Global CCS Institute. 2014. CO2 Capture Overview, http://www.globalccsinstitute.com/sites/default/files/pages/92241/4-co2-capture-overview.jpg (accessed 29 September 2014).</ref>
'''Fig. 3—CO<sub>2</sub> capture overview of three optional processes.'''<ref name="r8">Global CCS Institute. 2014. CO2 Capture Overview, http://www.globalccsinstitute.com/sites/default/files/pages/92241/4-co2-capture-overview.jpg (accessed 29 September 2014).</ref>


==Challenges==
==Challenges==

Revision as of 16:03, 29 September 2014

CO2 sequestration, also known as CO2 capture and storage (CCS), uses a range of technologies and approaches that isolate, extract, and store carbon dioxide emissions from industrial and energy-related sources in order to prevent the release of it into the atmosphere.[1]

Video courtesy of National Energy Technology Lab (NETL).

History

Carbon capture and storage technology involves the process of trapping and separating the CO2, transporting it to a storage location, and then storing it long-term so that it does not enter into the atmosphere.[2] It is not a new technology and has been used by petroleum, chemical, and power industries for decades.[3] In fact, carbon capture was first used in Texas in 1972 as a method to enhance oil recovery.[4]

Purpose

CO2 emissions from the burning of fossil fuels has been on the incline since the industrial era; and with more than 85% of the world’s energy coming from fossil fuels, it will remain an important energy source well into the future. As the demand for fossil fuels is growing, so is the volume of CO2 emitted each year. This has led to concerns over the impact of CO2 emissions on global climate change. CO2 sequestration is an option that is gaining interest to stabilize and reduce the concentration of CO2.[5]

Types

After CO2 is captured at the source, it then must be safely sequestered or stored away. There are three types of CO2 sequestration: terrestrial, geologic, and mineralization. More than 150 CO2 sequestration projects are in progress in North America alone.[6]

Fig. 1—Three types of CO2 sequestration.

Fig. 1—Three types of CO2 sequestration.[6]

Terrestrial sequestration

Terrestrial sequestration is the removal and storage of CO2 from the atmosphere by vegetation and soils on the earth’s surface through tree-planting, no-till farming, wetland restoration, and forestation.[6]

Geologic sequestration

Geologic sequestration is permanently storing CO2 in subsurface structures such as oil reservoirs, natural gas deposits, unmineable coal seams, deep saline formations, shale rich in oil or gas, and basalt formations.[6]

Mineral sequestration

Mineral sequestration is the formation of stable carbonate salts by the reaction of CO2 with dissolved calcium and magnesium. It is a natural process that happens slowly and produces limestone. A process that occurs faster than a natural reaction is when “dunite, or its hydrated equivalent serpentinite, reacts with carbon dioxide to form the carbonate mineral magnesite, plus silica and iron oxide (magnetite).”[6]

Features

Geologic carbon sequestration stands out, in particular, as a viable option because of its substantial storage capacity, which is estimated to be between 800 and 3,000 billion metric tons; the technology of separating and injecting CO2 underground has been used for more than 30 years; and the large CO2 sources such as power plants and refineries are conveniently located near many potential geologic storage sites across the US and Canada.[7]

Fig. 2—Geologic potential storage in the US.


Fig. 2—Geologic potential storage in the US. Courtesy of US Department of Energy, National Carbon Sequestration Database and Geographic Information System (NATCARB).

Process

CCS consists of two different yet connected steps. In the first step, CO2 from power plants and industrial plants is separated and concentrated, and then compressed and transferred through pipelines. In the second step, a dense, fluid state of the CO2 (known as supercritical) is injected into underground geologic formations. There are three methods for capturing and separating CO2:

1. Precombustion capture: Before the fuel is burned, the fuel is converted to syngas, and then the syngas to hydrogen and CO2. Next, the hydrogen is separated from the CO2 so the hydrogen can be used as fuel.

2. Post-combustion: After the fuel is burned, the CO2 is separated from the nitrogen using chemical sorbents such as monoethanolamine.

3. Oxyfuel combustion: Burning fuel in pure oxygen so no nitrogen is present in the captured gases.[7]

Fig. 3—CO2 capture overview of three optional processes.

Fig. 3—CO2 capture overview of three optional processes.[8]

Challenges

References

  1. CO2 Capture Project. 2008. What Is CO2 Capture & Storage?, http://www.co2captureproject.org/what_is_co2_capture_storage.html (accessed 2 September 2014).
  2. Ronca, D. 2014. How Carbon Capture Works, http://science.howstuffworks.com/environmental/green-science/carbon-capture1.htm (accessed 25 September 2014).
  3. Carbon Sequestration Leadership Forum. 2011. CO2 Capture—Does It Work? inFocus http://www.cslforum.org/publications/documents/CSLF_inFocus_CO2Capture_DoesItWork.pdf.
  4. Richey, S. 2013. Carbon Sequestration: Myth or Hope?, http://www.steverichey.com/writing-samples/climate-change/carbon-sequestration-myth-or-hope/ (accessed 23 September 2014).
  5. Ramharack, R.M., Aminian, K., and Ameri, S. 2010. Impact of Carbon Dioxide Sequestration in Gas/Condensate Reservoirs. Presented at the SPE Eastern Regional Meeting, Morgantown, West Virginia, USA, 13–15 October. SPE-139083-MS. http://dx.doi.org/10.2118/139083-MS.
  6. 6.0 6.1 6.2 6.3 6.4 The University of Utah, Department of Civil and Environmental Engineering. 2011. Carbon Capture and Sequestration, http://co2.egi.utah.edu/ (accessed 4 September 2014).
  7. 7.0 7.1 Cuff, D. and Goudie, A., eds. 2008. The Oxford Companion to Global Change. New York: Oxford University Press.
  8. Global CCS Institute. 2014. CO2 Capture Overview, http://www.globalccsinstitute.com/sites/default/files/pages/92241/4-co2-capture-overview.jpg (accessed 29 September 2014).

Noteworthy papers in OnePetro

Online multimedia

Finley, Robert J. 2011. Development of a Saline Reservoir Carbon Sequestration Project in the Illinois Basin, USA. http://eo2.commpartners.com/users/spe/session.php?id=6835

External links

See also