*********** 021494B.ENV *********** Contributory Categories: CHM, ENG, ICE Country: Japan From: Japan Technology Highlights v. 5, no. 1 12 January 1994 KEYWORDS: Japan, Antarctica, Carbon Dioxide storage, Global Warming +++++ STORAGE OF CO2 IN SOUTH POLE Humans have regarded fossil fuel as an unlimited energy resource and have been consuming it indiscriminately. However, finally, the limit is on the horizon, and it is considered to dry up in the latter part of the 2lth century. While CO2 emitted from fuel combustion is a cause of global warming, recycling CO2 and storing it on a global scale would enable its reactivation once a technology is developed to convert it Carbon compounds efficiently as a post fossil fuel. While deep ocean bottom and pressure storage underground are being considered as a means of storage, the Government Industrial Research Institute of Osaka of the Agency of Industrial Science and Technology has announced at the Chemical Engineering Conference in October that it is feasible to store C02 emitted by the whole world in 10,000 years in the icecap of the South Pole. The world annual emission rate of CO2 is estimated to be 20 Billion tons. For the storage of CO2 many methods have been considered such as the deep ocean isolation method, application to recovering oil (EOR) from abandoned oil wells, pressure injec- tion into abandoned gas field and underground water table. However, none has been realized since the storage capacity is too small and the effect on the ocean water and the underground had not been investigated. In the deep ocean isolation method, C02 is liquefied, solidified, and isolated over 3000-m deep in the ocean. The dissolved CO2 lowers the pH and will possibly affect the environment of the living matters when it diffuses. In the method in which CO2 is injected into the underground water table, CO2 is injected into the water containing salt 2000 m underground. CO2 dissolved water turns to carbonate ions and diffuse through earth and rocks. The effect of C02 underground is not known and requires further research. In the EOR method, the storage capacity is only 63 Billion tons corresponding to CO2 emitted in three years. Even in the dried natural gas field storage method, the capacity is 180 tons corresponding to nine years' emissions. In the South Pole icecap storage method, according to T. Honjo of the Osaka Government Industrial Research Institute, "Storage in the South Pole is advantageous from the standpoint of storing recyclable CO 2." Technologically it is easy; it suffices to dig a hole in the icecap. CO2 is stored in the solid dry ice form. Since the sublimation temperature of dry ice is - 78 deg.C, an ice cavity that remains below the temperature is utilized. In the "wind hole of Mt. Fuji," ice exists even in summer. Since only the lowest temperature air remains in the hole in the winter, ice is preserved all year. The cavern points downwards and traps the highest (coldest) density air. In the winter, the coldest air enters the cavern and prevents invasion of warm light air in the summer. It selectively retains the coldest air regardless of the temperature fluctuations above. In the South Pole icecap, the lowest annual temperature easily reaches -78*C. Analogous to the "wind hole of Mt. Fuji," construction of downward caverns enables long term storage without a concern over sublimation. They are considering the icecap highlands in the interior of the South Pole. Those expanses are approximately 3 M km^2. The storage capacity enables collecting the annual world emissions of CO2 over 100 centuries; it is virtually unlimited. Unlike the ocean shore icecaps, the movement of the icecap of the highlands is extremely slow, approximately 1 m in several ten thousand years. In the excavation, they have experiences in excavating 700 m at the Japanese Mizuho base in the South Pole. There are no technological problems of excavating 200 m. The issue is how to transport the recycled C02 to the South Pole. While they are considering a dedicated tanker, they have not decided whether to transport in the liquid or the solid form. Also, while the scale is smaller, they are considering Greenland, that is much closer to the CO2 source, as a storage site. Comparison of Candidates for the Global CO2 Storage. LOCATION SITE DURATION PROBLEMS ================================================================= Deep ocean >6000 m depth 10^2 yrs? effect on bio environment, eggs on ocean bottom die at pH 3-4 EOR abandoned oil 3 years small scale, oil well recovery Dried Natural natural gas 10 years small scale, Gas Field field denitration of soil Water Bed 2000 m deep infinite? unknown behavior of CO2 in underground water Icecap South Pole infinite? transportability, good long term and large scale storage ================================================================= ************* END Msg B.ENV *************