Effectiveness Of CO2 Sequestration Research Articles

Insights into carbon dioxide sequestration into coal seams through coupled gas flow-adsorption-deformation modelling

Injecting carbon dioxide (CO2) into coal seams may unlock substantial carbon sequestration potential. Since the coal acts like a carbon filter, it can preferentially absorb significant amounts of CO2. To explore this further, desorption of the adsorbed gas due to pressure drop is investigated in this paper, to achieve an improved understanding of the long-term fate of injected CO2 during post-injection period. This paper presents a dual porosity model coupling gas flow, adsorption and geomechanics for studying coupled processes and effectiveness of CO2 sequestration in coals. A new adsorption−desorption model derived based on thermodynamics is incorporated, particularly, the desorption hysteresis is considered. The reliability of the proposed adsorption-desorption isotherm is examined via validation tests. It is indicated that occurrence of desorption hysteresis is attributed to the adsorption-induced pore deformation. After injection ceases, the injected gas continues to propagate further from the injection well, while the pressure in the vicinity of the injection well experiences a significant drop. Although the adsorbed gas near the well also decreases, this decrease is less compared to that in pressure because of desorption hysteresis. The unceasing spread of CO2 and drops of pressure and adsorbed gas depend on the degree of desorption hysteresis and heterogeneity of coals, which should be considered when designing CO2 sequestration into coal seams.

Effects of carbon-sequestering coral aggregate on pore structures and compressive strength of concrete

CO2 sequestration/storage shows considerable impacts on the pore structures and compressive strength of concrete. This paper presents a study in which coral aggregates were presoaked in Ca(OH)2 slurries with different solid-to-liquid ratios (i.e. 0.2, 0.4, and 0.6 g/mL) followed by accelerated carbonation. The effects of CO2 sequestration on the particle size distribution, cylinder compressive strength, water absorption, and apparent density of coral aggregate were investigated. The evolution of pore structures in coral aggregate concrete after CO2 sequestration was also studied. Additionally, the effect of CO2 sequestration on the development of compressive strength of coral aggregate concrete was explored. The results showed that CO2 sequestration affected the properties of coral aggregate. Moreover, the porosity of CaCO3 formed by CO2 sequestration was the highest in the concrete. With the increase of solid-to-liquid ratio, the porosity of cement pastes and the CaCO3 increased, and more big pores existed in the cement pastes and CaCO3. Furthermore, the compressive strength of coral aggregate concrete when the solid-to-liquid ratio was 0.2 g/mL increased compared with that before CO2 sequestration, but the compressive strength reduced when the ratio increased to 0.6 g/mL.

Effects of CO2 sequestration on lipid and biomass productivity in microalgal biomass production

The study is focused on the technology and manipulation of production strategies for the cultivation of biomass from four strains of microalgae. Species of microalgae studied are: Chlorella vulgaris, Dunaliella, Scenedesmus quadricauda and Synechococcus spp. The effects of the rate and amount of CO2 removal from the atmosphere and sequestration with dissolved oxygen on lipid production from accumulated biomass were studied. Also, the rate of sequestration of both total and dissolved carbon was investigated. Daily measurements of total, organic and inorganic carbon sequestrated, optical densities, proximate analysis and kinetic parameters of the growing and cultivated microalga were monitored and carried out during the two phases of cultivation: dark and light phases. The values of maximum rate of carbon (IV) oxide removed, rmax varied from 11.73mgL−1min−1 to 18.84mgL−1min−1 from Chlorella vulgaris to Synechoccocus spp. Important parameters such as biomass productivity, maximum pH values obtained at cultivation, lipid content of the produced biomass and the hydraulic detection time for all four strains of microalgae were considered and presented in comparison and with their individual and collective effects. The ratios of the rate of CO2 absorption constant and the constant for the CO2 desorption rate (k1/k2) occurred highest in Dunaliella suggesting that with a high uptake of CO2, the algal strain is more effective in CO2 sequestration. The best biomass producer in this study was the C. vulgaris (Xmax=5400mgL−1 and Px=35.1mgLh−1) where biomass productivity is Px and the maximum cellular concentration is Xmax. C. vulgaris has the highest lipids productivity of 27% while Synechoccocus has the least (11.72%). In general, biomass productivity may be inversely related; this fact may be explained by greater metabolic involvement of lipid biosynthesis. This pioneer study may be advanced further to developing models for strategic manipulation and optimisation approach in micro algal biomass cultivation.

Effect of CO2 sequestration on soil liquefaction in geological pits

Effect of CO2 sequestration on soil liquefaction in geological pits

Physical and structural effects of carbon dioxide storage on vitrinite-rich coal particles under subcritical and supercritical conditions

The effects of CO2 sequestration on the chemical and physical properties of coal have been shown to be influenced by the coal's maceral composition. Whilst inertinite-rich coal particles have insignificant changes upon exposure to subcritical CO2 conditions for extended time periods (6months), vitrinite-rich coal particles had changes in the structure and physical properties. In the present paper, changes in the structural and physical characteristics of a South African vitrinite-rich dry coal were studied after exposure to subcritical (42bar, 25°C), and supercritical (125bar, 35°C) CO2 conditions for 6months. The samples were characterised pre- and post-CO2 exposure. The characterisation techniques used were: CO2 adsorption capacity (using a custom built high pressure volumetric system), surface area and pore size distribution analysis using both N2 and CO2 gas and the Brunauer–Emmett–Teller method (BET) and Fourier-Transform Infrared Spectroscopy (FTIR). Structural and physical changes in the coal were observed; these changes differed for subcritical and supercritical conditions. It was found that the surface area and number of micro-pores decreased sharply for the supercritical treated coal sample when compared to the untreated and subcritical treated coal sample. The adsorption capacity of the supercritical treated coal was also reported to be lower than the subcritical treated coal over the same period.

Modeling of CO2 storage in aquifers

Storage of CO2 in geological formations is a means of mitigating the greenhouse effect. Saline aquifers are a good alternative as storage sites due to their large volume and their common occurrence in nature. The first commercial CO2 injection project is that of the Sleipner field in the Utsira Sand aquifer (North Sea). Nevertheless, very little was known about the effectiveness of CO2 sequestration over very long periods of time. In this way, numerical modeling of CO2 injection and seismic monitoring is an important tool to understand the behavior of CO2 after injection and to make long term predictions in order to prevent CO2 leaks from the storage into the atmosphere. The description of CO2 injection into subsurface formations requires an accurate fluid-flow model. To simulate the simultaneous flow of brine and CO2 we apply the Black-Oil formulation for two phase flow in porous media, which uses the PVT data as a simplified thermodynamic model. Seismic monitoring is modeled using Biot's equations of motion describing wave propagation in fluid-saturated poroviscoelastic solids. Numerical examples of CO2 injection and time-lapse seismics using data of the Utsira formation show the capability of this methodology to monitor the migration and dispersal of CO2 after injection.

96/04352 Effectiveness of CO 2 sequestration in the post-industrial ocean

96/04352 Effectiveness of CO 2 sequestration in the post-industrial ocean

96/02045 Effectiveness of CO 2 sequestration in the oceans considering location and depth

96/02045 Effectiveness of CO 2 sequestration in the oceans considering location and depth