Underground CO2 Sequestration

This process is called solubility trapping, and the concentration of dissolved HCOs depends on pH and Pco2- pH increases when ground water interacts with 

NaAlSi30g (Na-feldspar) + H2CO3 - - 5H2O Na+ -f l/2Al2Si205(0H)4 + 2H4S104 

In the dissolution of carbonates, CO2 changes to HCO3 according to the reaction  

If the ground water becomes over-saturated with carbonates, then dissolution results in the precipitation of the carbonates according to the following reactions  

through this mineral trapping, CO2 can be trapped almost permanently underground. 

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Several types of nature-humans interactions with respect to materials and energy include resources, waste and global environmental problems (Fig. 6.1). In this Chapter we focus on the global environmental and waste problems such as acid rain, CO2 emission, underground CO2 sequestration, geological disposal of high level nuclear waste, and water and soil pollutions. 

Further, although humanity constitutes mily a small part of the biosphere, human activities have a marked influence the surface environment of the earth (atmosphere, hydrosphere, biosphere, soils). Consequently, the influence of humans on the other subsystems (atmosphere, hydrosphere, soils, rocks) through, for example, acid rain, pollution of surface water, geological disposal of nuclear waste, and underground CO2 sequestration are also examined (Chap. 6). 

CO2 Sequestration into Coal Seams. This project is directed at developing fundamental physicochemical descriptions of the coal/ supercritical CO2 interactions as well as the coal/rocl/water/C02 interactions. It will provide quantitative data which will form the basis for deciding what the critical environmental issues are regarding CO2 underground ... 

Conventional processes for hydrogen production are among major producers of CO2 emissions. It has been proposed recently that CO2 produced in steam reforming or partial oxidation proeesses eould be captured and sequestrated in the ocean or underground. In our work we estimated that the total energy consumption for CO2 sequestration (CO2 capture, pressurization, transportation and injection), will most likely exceed 5,000 kJ per kg of sequestrated CO2. Sinee about 80% of world energy production is based on fossil fuels, this eould potentially result in the production of 0.20-0.25 kg of CO2 per kg of sequestrated CO2. 

Carbon sequestration involves three steps—capture, transport, and disposal. The current estimated cost of capture and compression of CO2 to pipeline pressure (110 bar) is approximately US 30-50 per ton of CO2. Transport of CO2 adds US 1-3 per ton per 100 km. Disposal costs vary, but in some cases, they are quite low, e.g., US 4 per ton of CO2 for some forms of underground injection. 

Some of the caibon sequestration approaches under consideration are aimed at transferring some of the CO2 that would otherwise be released 10 die atmosphere to the sediments or underground deep-water reservoirs by direct injection of CO2 emitted by power plants. 

In Chap. 6, the influence of anthropogenic activities on the flux to the atmosphere, hydrosphere and soils and associated mass transfer mechanism are discussed. Geological disposal of high level nuclear disposal and CO2 underground sequestration are briefly presented. 

One way is to use carbon capture and sequestration (a.k.a. carbon capture and storage, CCS). This can involve removing CO2 from the chimney gases of a power station or factory, sometimes by reaction with a basic amine. Ultimately, these schemes depend upon storing the CO2 in underground cavities of porous rock (often worked-out oil fields) under a cap of impermeable rock. 

Will the creation of the carbon sequestration leadership forum and the stimulation of world wide research into how CO2 produced through burning fossil fuels can be captured at source and stored deep underground promote sustainable development (4)7... 

The risks of large-scale underground sequestration of CO2 are poorly understood, and there has been little or no systematic effort at risk assessment. The risks may be roughly divided into two kinds (1) the... 

During underground sequestration operations, supercritical CO2 will be injected into a deep aquifer and rise, as a result of buoyancy, until it reaches the overlying aquiclude where it will form a bubble . The presence of supercritical CO2 will result in chemical disequilibria and hence the initiation of reactions. It is important to understand the direction, rate and magnitude of such reactions, both in terms of their impact upon the ability of the aquifer to safely contain the injected CO2, and in terms of the longevity of CO2 containment. Three broad areas of reaction can be considered ... 

Safety aspects of the underground sequestration of CO2 in the deep geosphere... 

If sequestration of CO2 is most practicable within deep sandstone aquifers with no proven lateral seal, there is a need to ensure that the CO2 will remain safely underground and not return to the atmosphere on relatively short time-scales (thousands of years). The track record of purpose-designed underground storage of... 

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