Compressing a gas above compressor's discharge pressure

[ttt]

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?

 

[russ_watters]

The compressive uses more energy to pump up to a higher pressure, obviously. Some is lost as heat of compression and most of the rest is lost as inefficiency in regulating it back down to working pressure.