A 2 stage compressor has a final delivery/discharge pressure of 250 bar. hydrogen is been compressed and stored in vessels. The pressure in the storage vessel reaches the delivery pressure(i.e.250 bar) and the compressor is still running ( vessel has a safety pressure of 450 bar) and the pressure increases above the discharge pressure of 250 bar( with the help of a no return valve). I want to know what effects this situation will have on the compressor's power consumption?(when the storage pressure is below and above discharge pressure) Would there be any energy losses?