https://en.m.wikipedia.org/wiki/Electrochemical_hydrogen_compressor https://en.m.wikipedia.org/wiki/Electrochemical_hydrogen_com... They're pretty efficient, c

https://en.m.wikipedia.org/wiki/Electrochemical_hydrogen_compressor https://en.m.wikipedia.org/wiki/Electrochemical_hydrogen_com... They're pretty efficient, compact, and also no moving parts and no noise.