The Operating Costs are mainly determined by the selection of the pressure ratio across the membrane. That means the ratio between the feed pressure and the permeate pressure which are created by compression or by generating a vacuum. Realistic ratios are between 5 and 10. For higher pressure ratios the majority of the generated power is used for pressure change which obviously makes no sense. ​

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That means the Operating Costs are more or less fixed, because the only thing we are able to improve is the efficiencies of the compressor and the vacuum pump and these are well developed technologies.