research watch: will ocean storage of co2 get a lift?
TRANSCRIPT
Research Watch
Will ocean storage of C02
get a lift? Burning fossil fuels releases large quantities of C0 2 to the atmosphere-more than 4 million metric tons daily in the United States alone. Because this contributes significantly to buildup of greenhouse gases, scientists have been trying to find ways to sequester these emissions and prevent their release (see Environ. Sci. Technol. 1998, 32 (1), 20A-24A; 1999, 33 (3), 66A-70A; and 2000, 34 (7), 176A-182A, 184A-187A).
One suggested approach for addressing the greenhouse gas buildup problem is discussed in this issue (see figure below) by a team of Japanese scientists. Takayuki Saito of Shizuoka University Takeo Kajishima of Osaka University and Ryuichi Nagaosa of the
National Institute for Resources and Environment, in Tsukuba, Ibaraki, propose using an inverse-J pipeline system set in die ocean at depths of 200-3000 m, with gas initially injected into the J section of die pipeline at a target depth around 400 m. With this arrangement, die pumping (gas-lift) effect produced by die natural buoyancy of dissolving CO, bubbles can be used to transport C02-rich seawater through the pipeline system to greater depths.
The scientists claim that this can be done cost-efficiently with low energy consumption. However, it takes almost as much energy to inject gaseous C0 2 to the target depth as it would to liquefy it, and compared to some proposed approaches, the process adds considerable complexity.
The death of Milankovitch? Strong evidence is accumulating that there are serious flaws in the Milankovitch dieory which is used by scientists to account for the timing of the Earth's ice ages. Data taken from several sources indicate that the penultimate ice age was virtually complete about 135,000 years ago. This is thousands of years earlier dian die theory predicts it could have occurred.
Concept and principle of proposed system Conceptual diagram and principle of the GLAD system: (A) fired power plant, (B) compressor, (C) underwater gas pipeline, (D) GLAD system, (F) drainpipe, (G) dissolution pipe, and (H) drainpipe. C02 gas is pumped to the GLAD system (E) from the fired power plant (A) through the underwater pipeline (C). The gas is injected into the dissolution pipe (G) at a depth between 200 and 400 m. The buoyancy of the bubbles in the dissolution pipe generates gas-lift effect (pumping effect). The C02 bubbles dissolve into seawater while rising. The C02-rich seawater is transported in the drainpipe (F) or (H) by the gas-lift effect and the density difference between the C02-rich seawater and the ambient one. It is released into the deep ocean at 1000-3000 m in depth.
Source: Environ.Sci. Technol.nm, 34(19),4140-4145.
Ice age occurrences are proving to be difficult to explain.
According to Daniel Karner and Richard Miller, physicists at the University of California-Berkeley, there are no simple answers that can reconcile the data with the theory, which is based on changes in the Northern Hemisphere summer insolation (incident solar radiation). In a perspective article that appeared in Science (2000 288 (5474) 2143-2144), they suggest that the disparity poses a significant problem for paleocli-
matologists virtually all published timescales used in their research suspect as a result of these findings
The summer insolation could not have triggered the ice age's end, Karner and Muller assert. As if this were not enough to confound researchers, the scientists also suggest that there is reason to believe other
4 1 8 A • OCTOBER 1, 2000 / ENVIRONMENTAL SCIENCE & TECHNOLOGY / NEWS