Japan Geoscience Union Meeting 2015

Presentation information

Oral

Symbol H (Human Geosciences) » H-RE Resource and Engineering Geology

[H-RE28] CCUS (Carbon Dioxide Capture, Utilization, and Storage) for Climate Mitigation

Mon. May 25, 2015 2:15 PM - 4:00 PM 105 (1F)

Convener:*Tomochika Tokunaga(Department of Environment Systems, University of Tokyo), Ziqiu Xue(Research Institute of Innovative Tech for the Earth), Masao Sorai(Institute for Geo-Resources and Environment, National Institute of Advanced Industrial Science and Technology), Chair:Ziqiu Xue(Research Institute of Innovative Tech for the Earth)

3:45 PM - 4:00 PM

[HRE28-19] A method for assessing the impacts of leaked CO2 on the marine environment

*Keisuke UCHIMOTO1, Yoshimasa MATSUMURA2, Jun KITA1, Yuji WATANABE1 (1.Research Institute of Innovative Technology for the Earth, 2.Institute of Low Temperature Science Hokkaido University)

Keywords:marine environmental impacts, Carbon dioxide Capture and Storage, numerical model, database of marine biological impacts

Carbon dioxide (CO2) capture and storage (CCS) is promising technology that mitigates the global warming. Captured CO2 from industrial processes is transported to a reservoir in the deep geological formations. Storage sites are selected so deliberately that CO2 is believed to be stably stored in the reservoir. However, in case of a worst-case scenario, we should assess the impacts of leakage. In Japan, CO2 will be stored under the seabed, so that CO2 would leak out into the sea if unexpected leakage should occur. Therefore, we should assess the potential impacts on the marine environment. In this talk, we will introduce a method of the assessment that we have been developing. The method consists of two tools; a numerical model and a database of marine biological impacts. A numerical model predicts dispersion, i.e. distribution and concentration, of leaked CO2 in the sea. Since leaked CO2 is advected and diffused by ocean flow, the model should properly represent flow, temperature, and salinity fields in the sea. In addition, seasonal variation in the sea could be important for the simulation. Stratification in the sea strengthens in summer and weakens in winter, so that leaked CO2 would be more likely to be mixed vertically in winter than in summer. We have been developing an ocean model for simulating leaked CO2, taking consideration of those factors above. The model is based on a non-hydrostatic ocean model, called kinaco, developed by Matsumura and Hasumi (2008). In general, numerical cost of a non-hydrostatic model is very expensive. In kinaco, numerical cost is improved greatly, which enables a simulation in a relatively large area and of a relatively long period, as a simulation with a non-hydrostatic model. With this model, we conducted a numerical simulation in a gulf-like topography. A passive tracer, which is regarded as TCO2 (total dissolved inorganic carbon) originating from leaked CO2, is injected near the bottom. In order to represent seasonal variation, sea surface temperature (SST) is restored to temporally variable temperature from observational data, and temperature and salinity on a lateral boundary are also restored to observational data. Wind velocity data given at the sea surface, which are converted to wind stress in the model and drive the model ocean, are daily mean observational data. In order to access the potential impacts of leaked CO2 on the marine organisms, we make use of a database of marine biological impacts of CO2 concentration that RITE has been compiling. The biological impacts of CO2 in the ocean are referred to not TCO2 but partial pressure of CO2 (pCO2), and so the calculated TCO2 in the simulation should be converted to pCO2. With the resulting pCO2 values and the database, we can estimate the potential area where marine organisms might be impacted.