The Netherlands-based HyET BV (Hydrogen Efficiency Technologies), has achieved a milestone in electrochemical hydrogen compression, reaching for the first time a single-stage pressure increase of more than 400 bar.
Building on this promising result, the Netherlands-based company now plans to develop hydrogen purifiers and compressors for several automotive and industrial applications. HyETs hydrogen compressor contains no moving parts, can be produced at low cost, in high volume and is three times more efficient than existing mechanical compressors.
In general, electrochemical cells feature a ion-conductive membrane sandwiched between two reactant chambers. At one side of the membrane a hydrogen-containing molecule (e.g., water or molecular hydrogen) is converted to form protons, electrons, and optionally other gases, using a catalytic material. The protons are transported through the membrane, while the electrons are removed through an electrode present on the membrane.
The electrons are passed through an external circuit, and fed to an electrode present on the other side of the membrane where they react with protons, and optionally other components like oxygen, to form molecular hydrogen, water, or other compounds, depending on the application.
|Electrochemical hydrogen compression. Source: HyET BV. Click to enlarge.|
Electrochemical cells can also be utilized to pump and compress hydrogen from one side of a cell to another. By applying an electric potential between the electrodes in this type of electrochemical cell, hydrogen is catalytically dissociated at one electrode (anode) to produce two protons which pass through the membrane to the second electrode of the cell (cathode), where they are rejoined by two electrons to form a hydrogen molecule again. The electrochemical compression of hydrogen consumes DC power.
HyET says that its working principle offers the potential of reaching 700 bar or more.
An electrochemical hydrogen compressor offers advantages compared to a mechanical compressor:
It is highly efficient due to the practically isothermal process that is used.
It is a silent, solid state device without moving parts and with low maintenance requirements.
Instead of contaminating hydrogen with trace lubricants, as is often the case with mechanical compressors, electrochemical hydrogen compression will purify the hydrogen feed stream.
Despite these advantages electrochemical hydrogen compression has until now found limited practical use. Efforts by other research groups in the past have proven that is difficult to reach single-stage pressure increases of more than 100 Bar using conventional materials and construction principles.
The new materials and designs developed by HyET now allow much higher pressure levels for the first time.
In the last three months we have managed a tenfold increase in the compressor’s performance. At this rapid rate of development we are confident that HyET will raise the Bar in hydrogen compression even further.—Head of Process Design Wiebrand Kout
HyET develops high pressure electrochemical hydrogen compressors suitable for use in hydrogen filling stations, electrolyzers and hydrogen home refuelers. When coupled to a natural gas reformer or bio-hydrogen generator, HyETs technology can simultaneously purify and compress the hydrogen gas. Part of this research portfolio is the technology to compress hydrogen electrochemically “on-board” a hydrogen vehicle. This “self- filling tank” can partially regain the compression energy if the polarity is switched when hydrogen flows out of the tank.