CO2 sequestration

CO₂ sequestration or "storage" is the storage of carbon dioxide (usually captured from the "atmosphere") in a solid material through biological or physical processes. [http://www.neo.ne.gov/statshtml/glossarys.htm] CO₂ can also be captured as a pure by-product in processes related to petroleum refining (upgrading) and power generation. [http://www.pointcarbon.com/article.php?articleID=3774&categoryID=147] CO₂ sequestration can then be seen as being synonymous with the "storage" part of carbon capture and storage, a term which refers to the large-scale, permanent artificial capture and storage (sequestration) of industrially-produced CO₂ using subsurface saline aquifers, reservoirs, ocean water, or other sinks. It has been proposed as a way to mitigate the accumulation of greenhouse gases in the atmosphere released by the burning of fossil fuels.

In September 2008, a coal-fired power plant in Spremberg eastern Germany, became the world's first coal using plant to capture and store carbon dioxide. [http://abcnews.go.com/Technology/story?id=5844357&page=1]

Methods

Methods of CO2 sequestration include:
* Adsorption [http://www.netl.doe.gov/publications/proceedings/01/carbon_seq/3b3.pdf]
* Amine extraction
* Metal-organic framework [http://www.azom.com/details.asp?newsID=4484] [ http://www.greencarcongress.com/2005/12/metalorganic_fr.html]
* Mineral storage
* Calcium oxide: Carbon Dioxide reacts with quicklime (calcium oxide), to form limestone (calcium carbonate). [http://www.sciencedaily.com/releases/2002/04/020412080812.htm]
* Serpentine: The metamorphic mineral serpentine (magnesium silicate hydroxide), is composed of magnesium, silicon and oxygen.
* Regenerative Carbon Dioxide Removal System (RCRS)

The RCRS on the space shuttle Orbiter uses a two-bed system that provides continuous removal of CO2 without expendable products. Regenerable systems allow a shuttle mission a longer stay in space without having to replenish its sorbent canisters. Older lithium hydroxide (LiOH)-based systems, which are non-regenerable, are being replaced by regenerable metal-oxide-based systems. A system based on metal oxide primarily consists of a metal oxide sorbent canister and a regenerator assembly. It works by removing carbon dioxide using a sorbent material and then regenerating the sorbent material. The metal-oxide sorbent is regenerated by pumping air heated to around 400°F at 7.5 scfm through its canister for 10 hours. [ http://www.hamiltonsundstrand.com/hsc/proddesc_display/0,4494,CLI1_DIV25_ETI5338_PRD776,00.html]

Ovivine: [http://www.sciencedaily.com/releases/2004/09/040903084832.htm] [ http://www.tececo.com/sustainability.tececo_kiln.php]
* Molecular Sieve
* Polymer membrane gas separators [http://www.medal.airliquide.com/en/membranes/carbon/index.asp] [ http://www.medal.airliquide.com/en/membranes/carbon/coal.asp]
* Porous carbon
* Reversing heat exchangers

On February 9, 2007 Sir Richard Branson offered a $25 million prize to anyone who develops a workable means to remove a billion (10⁹) tonnes of carbon dioxide per year from the atmosphere. [ http://green.itweek.co.uk/2007/02/bransons_climat.html]

Benefits of CO2 sequestration

It was recently noted that the CO₂ from fossil fuel emissions is almost entirely depleted in radiocarbon, or ¹⁴C, and so could be used to produce food products containing little or no radiocarbon. [cite web | url=http://dx.doi.org/10.1007/s10311-007-0100-7| title=Williams, C.P. Recycling greenhouse gas fossil fuel emissions into low radiocarbon food products to reduce human genetic damage. Environmental Chemistry Letters. 2007 May 23 (online). DOI: 10.1007/s10311-007-0100-7| accessdate=2007-07-03] Humans and animals raised on such food could be spared billions of lifetime chromosomal damage events normally caused by radiation in food and the environment. This could reduce rates of spontaneous cancer or birth defects, or even slow their aging. This use for CO₂ could increase incentives for carbon capture in general, and particularly in those methods which would allow the recovery and reuse of low radiocarbon CO₂ for sequestration in soils for producing safer food.Fact|date=July 2008 This would have the added advantage of inducing terra preta formation, one of the richest soils on the planet and the only one known to regenerate itself.

CO₂ has been used extensively in enhanced crude oil recovery operations in the United States beginning in 1972. There are in excess of 10,000 CO₂ wells in the state of Texas alone. The gas comes in part from anthropogenic sources, but principally from large naturally-occuring geologic formations of CO₂. It is transported to the oil-producing fields through a large network of over 5,000 kilometers of CO₂ pipelines. The use of CO₂ for enhanced oil recovery (EOR) methods in heavy oil reservoirs in the Western Canadian Sedimentary Basin (WCSB)has also been proposed. [http://www.dailyoilbulletin.com/issues/article.asp?article=dob%2F080415%2FDOB2008%5FAF0019%2Ehtml] However, cost of transport remains an important hurdle. A similar CO₂ pipeline system to that of Texas does not yet exist in the WCSB that could connect most of the sources for CO₂ in Canada associated with the mining and upgrading operations in the Athabasca oil sands, with the subsurface heavy oil reservoirs that could most benefit from CO₂ injection hundred's of kms to the south.

References

External links

* [http://www.geos.ed.ac.uk/sccs/ Scottish Centre for Carbon Storage Research] Carbon Capture and Storage Research in Edinburgh, Scotland.
* [http://www.co2storage.org.uk UK Carbon Capture and Storage Consortium] Overview of the UK academic consortium focused on researching issues related to Carbon Capture and Storage.
* [http://www.physorg.com/news65284632.html Sieves put a lid on greenhouse gas]
* [http://www.osti.gov/bridge/servlets/purl/10192734-xc1wDZ/webviewable/10192734.pdf www.osti.gov] The capture, utilization and disposal of carbon dioxide from fossil fuel-fired power plants.