Does water electrolysis work efficiently under high pressure?

[arusse02]

One of the stages in hydrogen production after electrolysis is to run the hydrogen through a compressor and that can take a lot of energy. Would it be possible to run an electrolysis setup inside an already high pressure hydrogen tank so that the hydrogen being separated during the electrolysis immediately stays in the high pressure area instead of needing to be compressed?

Or does electrolysis use more and more energy the higher pressure the external environment is such that it would match the energy used during the compression stage?

I'm assuming there is some mechanism to separate both the oxygen and hydrogen into equally high pressure tanks such that the pressure was balanced.

 

[Bystander]

Or does electrolysis use more and more energy the higher pressure the external environment is such that it would match the energy used during the compression stage?

You got it; not as elegant a statement as a thermodynamicist would make, but it's all there.

 

[snorkack]

How efficient are the compressors? How big are the losses to heat in compressor operation?
The equilibrium voltage depends on hydrogen and oxygen partial pressures - slightly.
Balancing the pressures would be easy. Just use a separating barrier partway down. If you do not want the level of liquid to change, make the free areas on both electrodes side proportional to gas production.