Reducing CO2 emissions from the use of fossil fuel is the primary purpose of carbon dioxide capture and storage (CCS). Two basic approaches to CCS are available.1,2 In one approach, CO2 is captured directly from the industrial source, concentrated into a nearly pure form, and then pumped deep underground for long-term storage (see Figure 1). As an alternative to storage in underground geological formations, it has also been suggested that CO2 could be stored in the ocean. This could be done either by dissolving it in the mid-depth ocean (1–3 km) or by forming pools of CO2 on the sea bottom where the ocean is deeper than 3 km and, consequently, CO2 is denser than seawater. The second approach to CCS captures CO2directly from the atmosphere by enhancing natural biological processes that sequester CO2 in plants, soils, and marine sediments. All of these options for CCS have been investigated over the past decade, their potential to mitigate CO2 emissions has been evaluated,1 and several summaries are available.1,3,4
Carbon Dioxide Capture and Storage
