As seen from Figure (A) there is a clear tradeoff between the compression and liquefaction (refrigerant compressor) power requirement. At lower liquefaction/pumping pressure, the power demand for liquefaction is high and relatively low for compression, and vice versa at higher liquefaction/pumping pressure. This trade-off is as expected and also in agreement with the findings of Dlamini et al. . Around and just above the critical pressure, there is a peak in the pumping power requirement, which is also seen in the discharge temperature of the pump in Figure . This is due to the relatively high temperature of the compressor discharge temperature of 38 • C (above the critical temperature) leading to a lower density and higher compressibility, sub-optimal for pumping applications. It is interesting to note that the minimum power requirement of 32.7 MW is for the case of compression up to a pressure of 72.5 bar, just below the critical pressure, followed by pumping to the final pressure. For comparison, the power required for the case of compression/liquefaction at 15 bar and compression only is 37.7 and 33.8 MW respectively. Actually, there is a power requirement valley for a range of liquefaction/pumping pressures from approx. 40 bar to the critical pressure where the total power requirement is generally low. Dlamini et al. concluded that a liquefaction pressure of 45 bar leads to a minimisation of the total power, although their analysis did not extend up to the critical pressure only from 15 to 45 bar. Also the starting pressure (5.7 bara) was different compared to the present study. In their study they also found that a pure compression case with 8 stages/sections was slightly more energy-efficient compared to the compression/liquefaction/pumping scenario with 3 compression stages, which is opposite to the results shown here. One reason may be the lower applied inter-stage pressure drop of 0.1 bar compared to the 0.3 bar applied in this study or that they consider impure CO 2 .