Sequestration, the capture and storage of carbon dioxide, CO2, and other greenhouse gases, is necessary to control the concentrations of greenhouse gases, that unless controlled will, according to most engineers and scientists, lead to global warming. CO2 constitutes 81% of green house gases, followed with methane which represents another 9%. When any fossil fuel is burned this results in production of CO2. Since 86% of our energy comes from fossil fuels they release such large quantities of CO2 without imposition of controls, that global warming is inevitable. The concentration of CO2 in our atmosphere has increased dramatically since the start of the industrial revolution, increasing its concentration to 380 ppm in 2004, accompanied by a corresponding increase in the temperature of the atmosphere. By 2020 our energy requirements are forecast to increase by 40% and 86% of the energy will still come from fossil fuels, increasing CO2 concentration to even more dangerous levels. The exact point at which global warming will become excessive is not known, but it according to one report, when the atmospheric temperature is increased by another 2oC (3.6oF) and the CO2 level reaches 400 ppm we will have reached conditions of unacceptable global warming.
About 40% of our energy comes from coal, oil and gas each supply 24% and the other 12% is split between nuclear and renewables. Electrical generation contributes 39% of the CO2, transportation 32% and other sectors 30%.
Carbon can be reduced by using more renewable and nuclear energy, improvements in efficiency or by sequestration. Sequestration can be accomplished by storing CO2 in underground reservoirs, in trees, plants or algae, converting it to soil materials or dissolved it in deep oceans.
The above items are further elaborated in a presentation by the National Energy Technological Laboratory (NETL)