Abstract:
Managing the build-up of carbon dioxide from fossil fuel consumption
Klaus Lackner, Professor, Columbia University, New York
The world must stop the accumulation of carbon dioxide in the atmosphere. At the same time, we must improve energy services to a growing world population that strives for a high standard of living. Carbon capture and storage technologies can avoid the stark choice between economic growth and a healthy environment. They allow continued access to abundant fossil fuels while eliminating the threat of climate change. The only other choice would be to eliminate all fossil fuels. Because of the worldwide rapid growth in energy demand, this could precipitate a major energy crisis. Among the options for carbon capture, capturing carbon dioxide directly from the air is particularly attractive, as it could be implemented without interfering with existing infrastructures. Air capture could deal with any emission source, and thereby provide a capture method of last resort. For large, concentrated sources of carbon dioxide, capture at the source would usually be preferable and more economic than air capture. However, in some instances, air capture, which can be accomplished far away from the source, may prove easier than retrofitting. Air capture could also economically address emissions from myriad small and distributed sources, like airplanes and cars, for which capture at the source is impractical. In addition, air capture can reduce the carbon dioxide concentrations in the atmosphere. Carbon dioxide removal from air has been practiced for special applications for more than half a century, but only our recent progress has made it cheap enough to consider large-scale, widespread application of air capture. Once collected, carbon dioxide must be either recycled into a new carbon- based fuel, or disposed of safely and permanently. Fuel recycling requires low-cost electric power from non-fossil sources to provide the energy for reducing carbon and hydrogen found in carbon dioxide and water. Today such electric power is rarely available. Until such sources are developed, carbon dioxide can be stored. Underground injection of carbon dioxide into geological formations and the production of solid mineral carbonates from mineral rock and carbon dioxide provide two avenues for safe and permanent carbon dioxide disposal. In order to achieve closure in the anthropogenic carbon cycle with carbon capture and storage technologies, it is necessary to provide a convincing methodology for a quantitative accounting of the carbon stored. This is easier in the case of mineral carbonation, but here we suggest an approach that could make quantitative inventories possible in either case. Thus, the technologies for a carbon-neutral fossil fuel -based energy system exist, and it is likely that these technologies will play an important role in satisfying the energy demand of the twenty-first century