Electrochemical hydrogen compressor
Encyclopedia
An electrochemical hydrogen compressor is a hydrogen compressor
where hydrogen is supplied to the anode, and compressed hydrogen
is collected at the cathode with an exergy efficiency
of 70 to 80% for pressures up to 10,000 psi or 700 bars.
(MEAs) separated by proton exchange membrane
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 protons and electrons.
This type of compressor has no moving parts and is compact. With electrochemical compression of hydrogen a pressure of 5000 psi is achieved. Pressure is believed to go beyond 10,000 psi to the structural limits of the design. Water vapor partial pressure
, current density
, operating temperature
and hydrogen
back diffusion due to the pressure gradient
have an effect on the maximum output pressure.
Hydrogen compressor
A hydrogen compressor is a device that increases the pressure of hydrogen by reducing its volume. Compression of hydrogen gas naturally increases its temperature, due to Charles' Law....
where hydrogen is supplied to the anode, and compressed hydrogen
Compressed hydrogen
Compressed hydrogen is the gaseous state of the element hydrogen kept under pressure. Compressed hydrogen in hydrogen tanks at 350 bar and 700 bar is used for mobile hydrogen storage in hydrogen vehicles...
is collected at the cathode with an exergy efficiency
Exergy efficiency
Exergy efficiency computes the efficiency of a process taking the second law of thermodynamics into account.-Motivation:...
of 70 to 80% for pressures up to 10,000 psi or 700 bars.
Principle
A multi-stage electrochemical hydrogen compressor incorporates membrane-electrode-assembliesMembrane electrode assembly
A membrane electrode assembly is an assembled stack of proton exchange membranes or alkali anion exchange membrane , catalyst and flat plate electrode used in a fuel cell.-PEM-MEA:...
(MEAs) separated by proton exchange membrane
Proton exchange membrane
A proton exchange membrane or polymer electrolyte membrane is a semipermeable membrane generally made from ionomers and designed to conduct protons while being impermeable to gases such as oxygen or 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 protons and electrons.
This type of compressor has no moving parts and is compact. With electrochemical compression of hydrogen a pressure of 5000 psi is achieved. Pressure is believed to go beyond 10,000 psi to the structural limits of the design. Water vapor partial pressure
Partial pressure
In a mixture of ideal gases, each gas has a partial pressure which is the pressure which the gas would have if it alone occupied the volume. The total pressure of a gas mixture is the sum of the partial pressures of each individual gas in the mixture....
, current density
Current density
Current density is a measure of the density of flow of a conserved charge. Usually the charge is the electric charge, in which case the associated current density is the electric current per unit area of cross section, but the term current density can also be applied to other conserved...
, operating temperature
Operating temperature
An operating temperature is the temperature at which an electrical or mechanical device operates. The device will operate effectively within a specified temperature range which varies based on the device function and application context, and ranges from the minimum operating temperature to the...
and hydrogen
Hydrogen
Hydrogen is the chemical element with atomic number 1. It is represented by the symbol H. With an average atomic weight of , hydrogen is the lightest and most abundant chemical element, constituting roughly 75% of the Universe's chemical elemental mass. Stars in the main sequence are mainly...
back diffusion due to the pressure gradient
Pressure gradient
In atmospheric sciences , the pressure gradient is a physical quantity that describes in which direction and at what rate the pressure changes the most rapidly around a particular location. The pressure gradient is a dimensional quantity expressed in units of pressure per unit length...
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 or to pressurize other working fluids (such as refrigerants) as demonstrated by winners of the global GE's Ecomagination awards for 2011. These electrochemical compressors are noiseless, scalable, modular and highly efficient without the use of CFC's.See also
- Guided rotor compressorGuided rotor compressorThe guided rotor compressor is a positive displacement rotary gas compressor. The compression volume is defined by the trochoidally rotating rotor mounted on an eccentric drive shaft with a typical 80 to 85% adiabatic efficiency.-History:...
- Hydride compressorHydride compressorA hydride compressor is a hydrogen compressor based on metal hydrides with absorption of hydrogen at low pressure and desorption of hydrogen at high pressure by raising the temperature with an external heat source like a heated waterbed or electric coil....
- Ionic liquid piston compressorIonic liquid piston compressorAn ionic liquid piston compressor, ionic compressor or ionic liquid piston pump is a hydrogen compressor based on an ionic liquid piston instead of a metal piston as in a piston-metal diaphragm compressor.-Principle:...
- Linear compressorLinear compressorA linear compressor is a gas compressor where the piston moves along a linear track to compress to minimize energy loss during conversion.-History:...
- Timeline of hydrogen technologiesTimeline of hydrogen technologiesTimeline of hydrogen technologies — A timeline of the history of hydrogen technology.-1600s:* 1625 - First description of hydrogen by Johann Baptista van Helmont...