Method and system for efficient hydrogen compression

A method for compressing hydrogen, the method comprising:

• delivering a flow of gaseous hydrogen from a hydrogen source to a mixing unit;
• delivering a flow of an additional gaseous component to the mixing unit;
• the additional gaseous component having an average molecular weight higher than hydrogen;
• mixing the gaseous hydrogen and the additional gaseous component in the mixing unit and forming a gaseous mixture at a first pressure;
• compressing the gaseous mixture at a second pressure, higher than the first pressure, in a compression unit;
• delivering the compressed gaseous mixture to a separation unit and separating a flow of compressed hydrogen and a flow of compressed additional gaseous component from one another;
• feeding the flow of compressed hydrogen through a compressed hydrogen delivery line;
• and
• expanding the compressed additional gaseous component at a third pressure, lower than the second pressure, recovering energy from the expansion of the compressed additional gaseous component and recovering thermal energy from the expansion of the additional gaseous component using expanded additional gaseous component as a chilling fluid in a heat exchanger.

A method for compressing hydrogen, the method comprising the following steps,

• delivering a flow of gaseous hydrogen from a hydrogen source to a mixing unit;
• delivering a flow of an additional gaseous component to the mixing unit;
• the additional gaseous component having an average molecular weight higher than hydrogen;
• mixing the gaseous hydrogen and the additional gaseous component in the mixing unit and forming a gaseous mixture at a first pressure;
• compressing the gaseous mixture at a second pressure, higher than the first pressure, in a compression unit the compressing comprising:
• compressing the gaseous mixture at an intermediate pressure in a first compressor;
• cooling the partially compressed gaseous mixture in an intercooler;
• further compressing the gaseous mixture in a second compressor;
• wherein heat is removed from the partially compressed gaseous mixture by heat exchange with expanded additional gaseous component;
• delivering the compressed gaseous mixture to a separation unit and separating a flow of compressed hydrogen and a flow of compressed additional gaseous component from one another;
• feeding the flow of compressed hydrogen through a compressed hydrogen delivery line;
• and
• expanding the compressed additional gaseous component at a third pressure lower than the second pressure, recovering energy from the expansion of the compressed additional gaseous component.