Behavior Analysis of Discharged DIC Concentrated Seawater through Towed Pipe Injection from Ship

Abstract

Climate change is a very vital issue that can be no longer avoided. Korea has been a top-level country Iin dealing with carbon dioxide emissions since 1960. Many studies have been conducted to suppress or eliminate carbon dioxide emissions, which account for a large portion of greenhouse gases. Carbon Capture and Storage (CCS), the most practical method of them, plays a significant role. However, these methods have the disadvantage of the limits of geographical distribution and high possibility of re-emission into the atmosphere. Recently, ocean storage has been studied using Accelerated Weathering of Limestone (AWL), a technique for storing carbon dioxide in the ocean as an alternative to CCS, an underground storage. AWL is a method of converting carbon dioxide into concentrated water in the form of bicarbonate ion and discharging it to the ocean to dilute and store it. It does not cause re-emission to the atmosphere, and the discharged concentrated water increases the alkalinity of the ocean to prevent marine acidification. The objective of this study was to understand the behavior of DIC (Dissolved Inorganic Carbon) including carbon dioxide during the ocean discharge of bicarbonate ion concentrated water in AWL method. This study area was set near Ulleung-do where sufficient water depth and operational efficiency were secured. CORMIX model was used to calculate the material diffusion by submerged discharge using ship.

Fig. 1 Relationship between carbon species and pH

Fig. 2 Schematic of near field zone, NFR

Fig. 3 Location of study area

Fig. 4 Observed current & sea surface temperature sources : Korea Hydrographic and Oceanographic Agency

Fig. 5 Averaged wind speed(2015-2017) at Ulleung buoy(after KMA, 2018)

Fig. 6 Vertical profiles of temperature, salinity and density with respect to water depth

Fig. 7 Schematic of the towed pipe DIC discharge scenario

Fig. 8 3-D mixing visualization of discharge scenario

Fig. 9 Hydrate particle release image from a stationary source in a strong cross flow(after Chow, 2009)

Fig. 10 Summary of concentration vs downstream distance in summer season, effluent velocity is 0.5m/s

Fig. 11 Summary of concentration vs downstream distance in summer season, effluent velocity is 1.0m/s

Fig. 12 Summary of concentration vs downstream distance in winter season, effluent velocity is 0.5m/s

Fig. 13 Summary of concentration vs downstream distance in winter season, effluent velocity is 1.0m/s

Fig. 14 Summary of dilution vs downstream distance is summer season

Fig. 15 Summary of dilution vs downstream distance in winter season

Fig. 16 Summary of concentration excess iso-lines in summer season

Fig. 17 Summary of concentration excess iso-lines in winter season

Table 1 Characteristics of bicarbonate seawater according to concentration of bicarbonate

Table 2 Summary of air and seawater conditions at the study area

Table 3 Conditions of bicarbonate concentrated seawater