OS21D-1197
An Earth System Model Ensemble Assessment of Potential Liquefied CO2 injection Sites in the Deep Ocean
Anthropogenic CO2 can be sequestered by means of the injection of CO2 into the ocean, either as liquid CO2 or by pre-reacting with the mineral CaCO3 to neutralize the acidity prior to injection. One of the greatest uncertainties in this approach concerns the time scale over which the carbon will remain sequestered and where it will outgas, and to what degree it will be 'naturally' neutralized by CaCO3 in deep-sea sediments. Social and economic constraints, e.g., where carbon dioxide is produced, also provide a practical constraint in identifying the optimal locations for potential CO2 injection projects. In this study we perform an ensemble of tracer release experiments using an Earth System Model (GENIE) to examine the fate of injected CO2. We analyze the fraction of injected CO2 'leaked' to the atmosphere on a series of time-frames (1, 10, 100, 1000 years). We also assess the benefits of artificial pre-neutralization as well as the role of natural reactions with CaCO3.
OS21D-1198
Underwater CO2 Sequestration Program in Korea
In Korea an interdisciplinary project on underwater CO2 sequestration has been started. One of the main potential sites for the sequestration is the ¢®¡ÆDolGoRae (Dolphin)¢®¡¾ gas field located over the southwestern part of the East/Japan Sea. We plan to deliver CO2 captured from the largest steel company in Korea (POSCO) to this site through pipe lines. To meet this end, chemical engineers study the behavior of CO2 hydrates, mechanical engineers design the pipe lines and injection systems, geologists and geological engineers survey the geological structure of the potential sites, and oceanographers assess the environmental effects. From a preliminary study, we find that we can store captured CO2 to the gas filed safely. In case the CO2 leaks from the storage site it would move to the north along the Korean coast on the average.
OS21D-1199
Risk Assessment for CO2 Sequestration in Under Water Geological Structures
Ocean uptake of CO2 will help moderate future climate change, but the subsequent hydrolysis of CO2 in seawater increases the hydrogen ion concentration. In addition, dissolved CO2 itself can influence the physiology and biochemistry of marine organisms by decreased pH of body fluid during exposure. To mitigate the impact of the future atmospheric CO2 increase, CO2 sequestration into sub-seabed structures such as gas reservoir or saline aquifer has been proposed recently. Here we proposed a preliminary framework for the risk assessment of CO2 leakage during transportation, injection and/or storage process in Korea. Our framework has three compartments: (1) the assessment of leakage probability during operational process and from the storage site, (2) the prediction of the fate of released CO2 and (3) the assessment of risk posed to the marine organisms during exposure to elevated CO2 concentration in seawater. For the effect assessment of dissolved CO2 in seawater, we have tried to develop 'no-effect level of CO2' for most of marine organisms during acute and chronic exposure period. So we have conducted a series of bioassay using representative marine species including bioluminescent bacteria, harpacticoid copepod, benthic amphipod, fish and sea urchin.
OS21D-1200
Particulate Organic Carbon (POC) in the North Atlantic: Spatial and Temporal Variability
We have used the recently derived remote sensing algorithm (Stramski et al., 2008) to estimate surface concentration of POC in the North Atlantic. Our estimates are based on Level 3 standard mapped images (SMI) of daily normalized water leaving radiances at 443, 490, and 555 nm with a nominal 9 km x 9 km resolution from the ten years of SeaWiFS ocean color. In this presentation we discuss characteristic patterns of seasonal and geographic POC variability. We demonstrate that the large scale interannual trends in POC concentration are relatively small. POC variability is compared with patterns in primary productivity (PP) and export (PE). Mixed layer depth (MLD) climatology and optical depth estimates are used to derive estimates of POC reservoir in the North Atlantic surface waters.
OS21D-1201
Development of monitoring strategy for the assessment of Carbon Dioxide Capture and Storage (CCS)
CO2 storage into the ocean and/or the seabed geological formations has being studied as one of possible options to limit the accumulation of anthropogenic CO2 into the atmosphere. To investigate the validity of CO2 storage into the ocean, research of behaviors of the CO2 in the ocean environment is important. In addition, impacts on the ocean environment including marine ecosystem should be assessed. Therefore, development of new cost-effective monitoring technique is essential to understand dissolution and diffusion of stored CO2 into the ocean. Newly developed high response and precision in-situ pH/pCO2 sensor is measurement technology for stored CO2 into the ocean environment. Towing multi-layer monitoring system is observation technology for diffusion behavior of stored CO2 in the ocean. Bottom-installed acoustic tomography is detection technology for emission of liquid CO2 and/or CO2 gas bubble from seafloor. Several sensors installed AUV was applied for automatic detection and monitoring of CO2 leakage from seafloor. The performance of these technologies was confirmed by natural analogue in seafloor hydrothermal systems. The in-situ pH/pCO2 sensor measured dissolution of liquid CO2 into the ambient seawater while ascending of hydrothermal CO2 droplet and detected small pH depression in the ambient environment. The low pH plume derived from hydrothermal liquid CO2 was detected in 100m high and 200m wide areas above the summit of the submarine volcano. The result of CO2 gas bubbles mapping survey showed localized pH depression below 120m depth.
OS21D-1202
Effects of suspension pH and mineral dissolution on carbon dioxide hydrate formation
CO2 sequestration as a form of hydrate into geological formations could be significantly affected by soil mineral heterogeneity potentially contributing to the stochastic behavior of hydrate formation. In this study, we controlled the pH of soil mineral suspensions (Na-montmorillonite, kaolinite mixture, and pyrite) by the addition of 2M/10M NaOH and 2M/10M HCl before the dissolution of CO2. The soil mineral suspensions were prepared in deionized water (DIW) and NaCl (3.5 %) solutions. The formation of mass of CO2 hydrates was observed in most of the soil mineral suspensions at 30 bar and 0.3„aC. In montmorillonite and kaolinite mixture suspensions with and without NaCl near neutral (pH 6~8) suspension pHs can provide the fastest hydrate formation kinetics followed by basic (~pH 12.0) and acidic (pH 2.0) suspension pHs. Acidic suspension pH gives the fastest kinetics in pyrite suspensions without NaCl followed by neutral and basic pHs, while no hydrate formations were observed in basic and near neutral pyrite suspensions with NaCl. The experimental results suggest that different types of soil mineral structures and chemical species can form under different suspension pHs, significantly affecting the hydrate formation time. Chemical species (e.g. Al+3) that could potentially affect hydrate formation times were identified by a chemical equilibrium modeling software, PHREEQC. The results obtained from this research could provide promising avenues for hydrate formation mechanism studies.
OS21D-1203
High CO2 Retained Fraction in Ocean Sequestration Estimated by a High Resolution Model
In the CO2 ocean sequestration, CO2 retained fraction is one of the most important topics. It shows how long CO2 injected into the ocean is isolated from the atmosphere. The retained fraction of the injected CO2 calculated in previous studies are around 70 percent in average after 200 years (IPCC report) which are calculated by relatively coarse resolution models with the horizontal resolution larger than one degree. Since the time scale of deep ocean circulation is about 2000 years, 30 percent leakage into the atmosphere after 200 years seems to be too large. We considered that distribution of a point-source tracer as in the CO2 ocean sequestration depends on whether a model resolves mesoscale eddies. We estimated the CO2 retained fraction using a high resolution model with the horizontal resolution of 0.1 degree. The fine grid mesh explicitly represents effects of mesoscale eddies on CO2 transport and dilution. As expected, the injected CO2 is kept in a smaller ocean volume than that obtained from coarse resolution models. Only 0.4 percent of the injected CO2 is leaked into the atmosphere after 200 years, although about half of the injected CO2 is horizontally transported to the outside of the narrow model domain. We supposed that the difference in the retained fraction between high and coarse resolution models is caused by difference in horizontal CO2 transport. As shown in previous studies, CO2 leakage occurs mostly in around the equator and the Antarctic Ocean. If CO2 is kept in a small ocean volume, it takes a long time before attaining these regions. Difference in simulated western boundary current regions also may effect on the difference of the retained fraction. Now, we are extending the model domain to prevent the horizontal CO2 transport outside of the model domain. Results of the new model will be shown in the meeting.