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 is an electrode of a polarized electrical device through which conventional current enters the device. This contrasts with a cathode, an electrode of the device through which conventional current leaves the device. A common mnemonic is ...

, and

compressed hydrogen Compressed hydrogen (CH2, CGH2 or CGH2) is the gaseous state of the element hydrogen kept under pressure. Compressed hydrogen in hydrogen tanks at 350 bar (5,000 psi) and 700 bar (10,000 psi) is used for mobile hydrogen storage in hydrogen vehicles ...

is collected at the cathode with an

exergy efficiency 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 efficiency of an actual system ...

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 membrane A proton-exchange membrane, or polymer-electrolyte membrane (PEM), is a semipermeable membrane generally made from ionomers and designed to conduct protons while acting as an electronic insulator and reactant barrier, e.g. to oxygen and hydrogen ...

s (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 , H+, or 1H+ with a positive electric charge of +1 ''e'' elementary charge. Its mass is slightly less than that of a neutron and 1,836 times the mass of an electron (the proton–electron mass ...

s and

electron The electron ( or ) is a subatomic particle with a negative one elementary electric charge. Electrons belong to the first generation of the lepton particle family, and are generally thought to be elementary particles because they have no kn ...

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 gas ...

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 ar ...

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 the chemical element with the symbol H and atomic number 1. Hydrogen is the lightest element. At standard conditions hydrogen is a gas of diatomic molecules having the formula . It is colorless, odorless, tasteless, non-toxic, an ...

back diffusion due to the

pressure gradient In atmospheric science, the pressure gradient (typically of Earth's atmosphere, 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 particu ...

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−). The term is applied loosely. At one extreme, all compounds containing covalently bound H atoms are called hydrides: water (H2O) is a hydride of oxygen, ammonia is a hydride of ...

or to pressurize other working fluids (such as

refrigerants A refrigerant is a working fluid used in the refrigeration cycle of air conditioning systems and heat pumps where in most cases they undergo a repeated phase transition from a liquid to a gas and back again. Refrigerants are heavily regulated due ...

) as demonstrated by Xergy Inc. winners of the global GE's

Ecomagination General Electric Company (GE) is an American multinational conglomerate founded in 1892, and incorporated in New York state and headquartered in Boston. The company operated in sectors including healthcare, aviation, power, renewable ener ...

awards for 2011. These electrochemical compressors are noiseless, scalable, modular and highly efficient without the use of CFC's. {{Clear, left

References

Gas compressors Hydrogen technologies

Principle

Applications

See also

References