The figure below, from a paper by R. Stuart Haszeldine (see For more information for complete reference), illustrates the general stages of carbon capture and sequestration (CCS). Anthropogenic CO 2, formed as a consequence of fossil fuel combustion in electrical power generation (2 in figure), must be captured; there are several approaches CO 2 capture, with the post-combustion capture approach most advanced in its development. Captured CO 2 is compressed and transported by pipeline (3 in figure) to the site of sequestration. CO 2 is injected into sequestration sites (4 in figure), with the two principal possibilities being deep saline aquifers and depleted oil and gas fields. An alternative to these two options is a mature gas field, in which case injected CO 2 enhances oil recovery (1 in figure). Another section of this webpage addresses enhanced oil recovery (EOR).