An electrochemical hydrogen compressor is a

hydrogen compressor A hydrogen compressor is a device that increases the pressure of hydrogen by reducing its volume resulting in compressed hydrogen or liquid hydrogen. Traditionally, applications for hydrogen compressors included Chlorine electrolyser and many chem ...

where hydrogen is supplied to the

anode An anode usually is an electrode of a polarized electrical device through which conventional current enters the device. This contrasts with a cathode, which is usually an electrode of the device through which conventional current leaves the devic ...

, and compressed hydrogen is collected at the cathode with an

exergy efficiency In thermal engineering, exergy efficiency (also known as the second-law efficiency or rational efficiency) computes the effectiveness of a system relative to its performance in reversible conditions. It is defined as the ratio of the thermal effi ...

up to and even beyond 80% for pressures up to 10,000 psi or 700 bars.

Principle

Electrochemical Hydrogen Compressor Theory

A multi-stage electrochemical hydrogen compressor incorporates membrane-electrode-assemblies (MEAs) separated by proton exchange membranes (PEMs) in series to reach higher pressures, when a current is passed through the MEA protons and electrons are generated at the anode. The protons are electrochemically driven across the membrane to the cathode, after which they combine with the rerouted electrons to form hydrogen, which is fed to the hydrogen compressor to be oxidized at the anode of each cell to form

proton A proton is a stable subatomic particle, symbol , Hydron (chemistry), H+, or 1H+ with a positive electric charge of +1 ''e'' (elementary charge). Its mass is slightly less than the mass of a neutron and approximately times the mass of an e ...

s and

electron The electron (, or in nuclear reactions) is a subatomic particle with a negative one elementary charge, elementary electric charge. It is a fundamental particle that comprises the ordinary matter that makes up the universe, along with up qua ...

s. This type of compressor has no moving parts and is compact. With electrochemical compression of hydrogen a pressure of 14500 psi (1000 bar) is achieved, this world record was set by HyET from the Netherlands in 2011. Water vapor

partial pressure In a mixture of gases, each constituent gas has a partial pressure which is the notional pressure of that constituent gas as if it alone occupied the entire volume of the original mixture at the same temperature. The total pressure of an ideal g ...

current density In electromagnetism, current density is the amount of charge per unit time that flows through a unit area of a chosen cross section. The current density vector is defined as a vector whose magnitude is the electric current per cross-sectional ...

operating temperature An operating temperature is the allowable temperature range of the local ambient environment at which an electrical or mechanical device operates. The device will operate effectively within a specified temperature range which varies based on the de ...

and

hydrogen Hydrogen is a chemical element; it has chemical symbol, symbol H and atomic number 1. It is the lightest and abundance of the chemical elements, most abundant chemical element in the universe, constituting about 75% of all baryon, normal matter ...

back diffusion due to the

pressure gradient In hydrodynamics and hydrostatics, the pressure gradient (typically of air but more generally of any fluid) is a physical quantity that describes in which direction and at what rate the pressure increases the most rapidly around a particular locat ...

have an effect on the maximum output pressure.

Applications

Electrochemical hydrogen compressors have been proposed for use in hydrogen refueling stations to pressurize hydrogen gas for storage. They have also been applied into novel refrigeration systems to pressurize hydrogen for absorption into

metal hydrides In chemistry, a hydride is formally the anion of hydrogen (H−), a hydrogen ion with two electrons. In modern usage, this is typically only used for ionic bonds, but it is sometimes (and has been more frequently in the past) applied to all co ...

or to pressurize other working fluids (such as

refrigerants A refrigerant is a working fluid used in the cooling, heating, or reverse cooling/heating cycles of air conditioning systems and heat pumps, where they undergo a repeated phase transition from a liquid to a gas and back again. Refrigerants are ...

) as demonstrated by Xergy Inc. winners of the global GE's Ecomagination awards for 2011. These electrochemical compressors are noiseless,

scalable Scalability is the property of a system to handle a growing amount of work. One definition for software systems specifies that this may be done by adding resources to the system. In an economic context, a scalable business model implies that ...

, modular and highly efficient without the use of CFC's. {{Clear, left

References

Gas compressors Hydrogen technologies

Principle

Applications

See also

References