6. CO₂ Capture Transport and Storage, a Promising Technology for Limiting Climate Change

On a world-scale basis, fossil fuels are likely to remain the main sources for electricity generation in the twenty-first century, and many industrial processes that are also large CO₂ emitters will still be active for many decades. Therefore, carbon capture and storage (CCS) is generally considered a necessary option for reducing CO₂ emissions to the atmosphere. This chapter introduces the concept, which consists in the separation of CO₂ from energy-related and industrial gas streams, and its transport to a geological storage location where it is permanently and safely stored. The characteristics of the main capture processes: postcombustion, oxycombustion, and precombustion are summarized in terms of energy consumption and costs. Some other possible technological options are briefly described. The methods utilized for CO₂ transport are also presented with some cost estimates. The main formation for geological storage—depleted oil and gas fields, deep saline aquifers, and nonexploitable coal seams—are briefly described, with the mechanisms involved in storage operations. Storage capacity evaluations, methodologies for risk assessment and management, are also briefly summarized. The chapter discusses the 14 large-scale integrated CCS projects which are in operation or under construction today, with a rough total storage capacity of 33 million tons a year. This could indicate that provided public awareness, social acceptance, and economic drivers evolve favorably, CCS could play a very significant role in the transition to a future low emission energy use.