As seen from Figure , both the data from Hendriks et al. and the data from the present study show a decreasing levelised cost from the lowest to the highest flow. However, there are also noticeable differences. While the data from shows a smooth monotonically decreasing levelised cost as a function of increasing mass flow compressed, the model of the present study is not monotonic. At certain mass flows the levelised cost increases despite an increase in mass flow. This occurs when the cost function adapted in the present study reaches the upper limit of the validity. The implemented compressor cost model has a maximum applicable power of 25 MW. If the required power is higher than this, the mass flow is assumed to be split in two proportionally smaller compressors to avoid exceeding this limit. Due to economics of scale built in to the cost function this results in an in-crease in cost (smaller units have a higher cost per kW). The cost model in ref. does not have an upper limit of this kind despite the power exceeding 60 MW at the highest CO 2 flows. Such a large single unit compressor is not considered realistic, and it gives a good explanation why the present model has higher levelised cost from 70 kg/s and above compared to the model of Hendriks et al. . At mass flows below 60 kg/s, the model of Hendriks et al. shows higher levelised cost than the present study. The main reason for this is the power law exponents used in to account for economy of scale, which is between 0.3 and 0.4 independent on the compressor capacity / power whereas in the present study such exponents are 0.9 at power up to 7,000 kW and 0.71 for higher compressor power. . They studied CO 2 compression from 1 bar up to the critical pressure followed by pumping to a final pressure of 150 bar. Input and calculated output are summarised in Table . As seen from the table, the two different approaches compare very well in terms of levelised cost, with the present study predicting slightly higher levelised cost. This minor difference is partly due to the present study predicting slightly higher annualised CAPEX and also slightly higher variable O&M costs. The latter is directly related to the applied cost of electricity and the predicted power requirement. Since the electricity cost is the same, apparently the study of McCollum and Ogden predicts lower power consumption, most likely due to a simplified single equation power model. It is also interesting to note that the variable O&M cost related to power requirement is the dominating factor in the levelised cost (60%), but obviously very sensitive to the choice of electricity cost.