Sequestration of Carbon Dioxide Emissions

Background The world's oceans represent the largest potential sink for the carbon dioxide (CO 2) produced by human activities (anthropogenic CO 2). Already oceans contain the equivalent of an estimated 140,000 gigatons of CO 2. The ocean's natural carbon transfer processes span of thousands of years and will eventually transfer 80-90 percent of today's man-made CO 2 emissions to the deep ocean. This natural CO 2 transfer may already be adversely affecting marine life near the ocean surface and could also alter deep ocean circulation patterns. The effectiveness of ocean storage techniques depends largely on how long the CO 2 would remain in the deep ocean. Most studies indicate that if CO 2 can be injected into regions of deep oceanic water circulation, it will remain there for approximately 1,000 years. Direct injection of CO 2 into the ocean would reduce both atmospheric CO 2 concentrations and their sharp rate of increase. The purpose of this program is to investigate the technical, economic and environmental feasibility of CO 2 sequestration by injection of liquid CO 2 in the deep ocean. The purpose of R&D in ocean sequestration is to gain a better understanding of marine ecosystem dynamics at elevated CO 2 concentrations. Ocean sequestration is the injection of liquid CO 2 into the deep oceans for long-term storage. Key concerns about such an approach include the cost of delivering CO 2 500 meters or deeper below the ocean surface, the permanence of injected CO 2 , and possible negative effects on the deep ocean ecosystem. The advantage of this approach is the enormous potential storage capacity of the deep oceans. Although this extensive CO 2 storage capacity represents a considerable advantage compared to other CO 2 sequestration technologies, this approach to long-term CO 2 storage is not considered to be a viable option. Cost of transportation and compression of large amounts of CO 2 , together with the as yet to be determined impacts on the ocean ecosystems mitigate against a wide application of this CO 2 sequestration technology at this time. Therefore, the DOE will no longer sponsor research and development projects looking at carbon sequestration in the ocean once the existing projects are completed This figure illustrates the basic concept of Ocean Sequestration. Liquid CO 2 is injected into the Ocean at a depth of 500+ meters. At this depth and temperature, the CO 2 remains as a …