which is simply two and three 3 MMtonnes/year units in parallel, the discrepancy increases even more, suggesting that the OEM has factored in some synergies and discounts when ordering more of the same unit. This is not factored in with the applied cost model. For inline/barrel type centrifugal compressors, the cost model is compared to an in-house database of installed or quoted equipment costs. The results are shown in Figure . Error bars have been added to the calcu-lated values to visualise the ±30% accuracy suggested by Woods for the applied cost relations. As seen from the results, the majority of the compared cases are within the claimed accuracy of the cost relations. However, the data source is sparse, and solid conclusions can not be drawn. Nevertheless, it seems that the model tends to underpredict compressors in the lower driver power range, while the opposite holds for the higher end of the driver power range. While it is often claimed that integrally geared compressors have a lower CAPEX, the data presented in Figures does not appear to support a general conclusion on this matter. However, a secondary effect is that integrally geared compressors can achieve higher efficiencies. Thus, a lower driver power may be required for an integrally geared compressor compared to an in-line version, resulting in CAPEX savings.