It operates as a closed system with no moving classical mechanical parts, requires no input of fuel, and creates no exhaust.
Each stage consists of a working fluid chamber that a copper lined membrane electrode assembly (MEA) bisects.
After passing through the PEM, the protons recombine with the electrons to produce low pressure hydrogen gas that flows out to the compression stage.
In the compression stage, electrical potential is applied across the MEA and forces protons to flow through the PEM to produce high pressure hydrogen.
The amount of energy available to the external load is the difference in electrical potential between that needed to compress hydrogen at low-temperature and that which expanding it at high temperature generates.