CO2 sequestration

Overview

CO₂ sequestration is the storage of carbon dioxide (usually captured from the "atmosphere") in a solid material through biological or physical processes [1]. CO₂ can also be captured as a pure by-product in processes related to petroleum refining (upgrading) and power generation [2]. CO₂ sequestration can then be seen as being synonomous 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.

Methods

Methods of CO2 sequestration include:

• Adsorption [3]
• Amine extraction
• Metal-organic frameworks (MOFs) [4] [5]
• Mineral storage
• Calcium oxide: Carbon Dioxide reacts with quicklime (calcium oxide), to form limestone (calcium carbonate).

[6]

• 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. [7]

Ovivine: [8] [9]

• Molecular Sieve
• Polymer membrane gas separators [10] [11]
• 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. [12]

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. 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 source of 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.

The use of CO₂ for application in enhanced oil recovery (EOR) methods in heavy oil reservoirs is also being proposed [13]. Cost of transport remains an important hurdle. This application would represent a means of CO₂ sequestration that also has an economic return (increased recovery of viscous oil reserves).

External links

• Scottish Centre for Carbon Storage Research Current Carbon Capture and Storage Research being undertaken in Edinburgh, Scotland.

• UK Carbon Capture and Storage Consortium Overview of the UK academic consortium focused on researching issues related to Carbon Capture and Storage.

• Sieves put a lid on greenhouse gas

• www.osti.gov

the capture, utilization and disposal of carbon dioxide from fossil fuel-fired power plants(pdf) Template:WH Template:WS