Background

The worldwide focus on clean power generation and carbon capture has   increased the importance of the associated technologies, which involve two   distinct approaches, namely pre-combustion and post-combustion carbon   capture.

In pre-combustion CO₂ capture, fuel is gasified by applying heat   under pressure in the presence of steam and air and/or oxygen to form synthetic   gas (Syngas). CO₂ is then captured from the Syngas, before being   mixed with air in a combustion turbine, resulting in the CO₂ being   relatively concentrated and at a high pressure.

In post-combustion CO₂ capture, mainly, pulverized coal is burnt   in air to raise steam. CO₂ is exhausted in the flue gas at   atmospheric pressure and concentrations of 10-15% v/v. This process is more   challenging due to the low pressure and dilute CO₂ concentration   resulting in a high volume of gas having to be treated. Also trace impurities in   the flue gas tend to reduce the effectiveness of the CO₂ absorbing   processes and compressing the captured CO₂ from atmospheric pressure   to pipeline pressure represents a large parasitic load.

Another post-combustion capture technology, oxy-combustion, involves   combustion of the fuel with near pure oxygen resulting in a flue gas stream of   higher CO₂ concentration. This technology relates more to combustion,   and is not discussed further in this paper.