Introduction:
An electrolyzer conducts electrolysis reactions and makes hydrogen. As hydrogen is a clean form of energy,
it can solve the world energy crisis, but as the electrolysis reaction requires huge amount of energy mostly
in form of electricity, to obtain truly clean hydrogen, this energy should come from green sources. The
slightly varying ways electrolyzers operate are mostly determined by the type of electrolyte used.
Electrolyzers can be categorized into
 Unipolar designs
 Bipolar designs
Unipolar designs
The unipolar cell design has each of the cell electrodes connected to the electric source. This means that
each electrode has the same polarity on its entire surface. The unipolar design often uses alkaline
electrolytes, the unipolar cell design is suitable for smaller and less intensive processes where the total
electric current flowing through the electrolyzer stack is not extremely high bipolar designs. Alkaline
electrolyte electrolyzers have following disadvantages:
 Can’t withstand fluctuating renewable energy sources like cloudy weather in case of solar power.
 Hydrogen is not compressed so an additional compressor is needed to compress it.
Bipolar design
In the bipolar design, the electric source is only connected to the two electrodes on the opposite ends of the
cell. These electrodes are designated as “terminal electrodes” the bipolar design uses a solid polymer
Electrolyte
Advantages are
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Pure hydrogen, no mixing of oxygen
Can withstand the inconsistent power
Provides compressed hydrogen
Disadvantages are
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Costly as membrane is gold, catalysts are platinum and iridium.
Anion exchange membrane
Advantages
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Low cost as membrane is anion solid polymeric membrane
Pure hydrogen
Compressed hydrogen
Efficient use of renewable energy
An electrolyzer cell configuration can also be gap or zero gap. In the zero-gap cell design, the porous
electrode materials are pressed on each side of the diaphragm, forcing the hydrogen and oxygen gases to
exit the electrodes at the back. This method differs from the gap design, in that it has the benefit of reducing
ohmic losses. This will enable the cell to operate at higher current densities
Performance specifications
H2 flow
O2 flow
Voltage(metered from electrode of cell stack)
Max input current
Technology employed
Stack diameter
Unit cell qty
Output pressure
Water consumption rate
Operating temperature
Exploded figures:
0-240ml/ min
0-120ml /min
DC 8v
DC 9A
Proton Exchange Membrane (PEM) Solid
Electrolyte Maintenance-Free and Caustic-Free
85mm
4
0-10bar
16cc/hr
90°C
This PEM electrolyzer cell is an advanced product, which is low voltage and higher efficiency, energysaving and of environmental protection, producing hydrogen and oxygen through the electrolysis of pure
water (without adding alkali).
Working:
The proton exchange membrane (PEM), which only allows water and positive ions to cross between
compartments. The membrane also serves as the electrolyte in the cell, eliminating the need for hazardous
liquid electrolytes such as concentrated potassium hydroxide. PEM water electrolysis simply splits pure
deionized water (H2O) into its constituent parts, hydrogen (H2) and oxygen (O2), on either side of this
membrane. When a DC voltage is applied to the electrolyzer, water fed to the anode, or oxygen electrode,
are oxidized to oxygen and protons, while electrons are released. The protons (H+ ions) pass through the
PEM to the cathode, or hydrogen electrode, where they meet electrons from the other side of the circuit,
and are reduced to hydrogen gas. The two reactions that occur in the cell are as follows:
2H2O -> 4H+ + 4e- +O2
4H+ + 4e- -> 2H2
The overall reaction becomes
2H2O(l) → 2H2(g) + O2(g)
Thus, the only possible components of the streams are hydrogen, oxygen and water moisture
Design decisions:
One of the main purposes of this design will be to put it into the micro-CT scan, available at the
collaborating group at HZDR, and be able to scan it with a high resolution. To achieve this there are several
things required for the design. The body needs to be made of a material which can easily be looked through
by the CT scan, the footprint of the part which needs to be scanned can’t be larger than 1x1cm and the
porosity of the electrodes needs to be as high as possible since CT scans cannot look well through metals.
Requirements:
• The gap is expected to be adjustable within the range [0, 0.5] mm and with accuracy in the order of
micrometers.
• Keep the concentration Hydrogen in Oxygen or Oxygen in Hydrogen below 4% outside of the electrolyte,
since the mixture will otherwise be explosive.
• The body has to be watertight.
• All materials used have to be chemically resistant to the electrolyte.
Preferences:
• The design has to be safe to use.
• Membrane, anode and cathode have to be replaceable.
• The container of the electrolyte has to be made of a transparent material.
• Make the porosity of the electrode as high as possible.
• Make it possible to do a batch experiment.
• The design has to be simple.
For the membrane, the Zirfon UTP 220 is used because this was the only one available on short time, since
it takes quite some time to deliver. This membrane has a porosity of 60 ± 10% and a thickness of 220 ±
30µm.
Constraints:
• The position of the anode and cathode have to be adjustable.
• The electrolyser makes use of alkaline electrolysis.
• Material suitable for CT scan.
Market competetors:

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Fuel Cell Store, Texas, USA
Evonik Industries
Phi Suea House Project
McPhy
Enapter
EcoScan
Simulation Results
Mesh analysis:
This analysis was done taking a standard mesh size under the given conditions.
Thermal analysis:
The alkaline water electrolyzer cell uses 30 wt.% KOH solution as electrolyte. The 8 V DC power source
supplies a voltage and current density of below 3.0 V and 300 A.m-2 respectively. The operating
temperature is maintained at 90°C, and the operating pressure, at 1.0 bar. Given that water molecules can
traverse the membrane to the other side, the alkaline electrolyte penetrates both the anode and cathode
regions on both sides. Water molecules in the electrolyte mix with electrons in the cathode part of the cell
to make hydrogen and hydroxide ions, and in the anode region, the hydroxide ions lose electrons to form
oxygen and water. This process occurs when the cell is powered by the supply of electric current. The
membrane keeps the generated hydrogen and oxygen gases separated for collection through their separate
channels.
Stress analysis:
Stress simulations on the modelled components were performed by subjecting the components to the load
of the pressure acting within the electrolyzer system, maintained at 1.0 bar (0.1 MPa). Again, the results of
the stress simulations are shown. The stress distribution over the components evaluated using Von Mises
stress highlights regions of the components that are highly stressed and the regions that experience minimal
stress. The maximum stress values of 0.143 MPa and 0.138 MPa (PTFE plastic), as well as 0.126 MPa and
0.157 MPa (PP plastic), for the endplate and spacer respectively, are well within the safe limits for the
chosen materials. The yield strength of polytetrafluoroethylene (PTFE) and polypropylene (PP) plastics are
35 MPa, and 24 MPa respectively.
References:
 Y. Tang, “BEP proposal ”zero-gap” electrolyser.”
 Agfa, “Technical Data Sheet ZIRFON UTP 220 Product description,” pp. 1–2, 2021.
 Eriks, “Chemical resistance guide.” [Online]. Available: https://o-ring.info/en/tools/ chemicalresistance-guide/#c-1213,1889
 P. C. F. Picolog, F. Picolog, and R. P. Os, “TC-08,” 1820. [Online]. Available: https://nl.rsonline.com/web/p/data-loggers/4925105?cm_mmc=NL-PPC-DS3A-_
-google-_3_NL_NL_Test+%26+Measurement_Data+Loggers_Exact-_-Pico+ Technology+-+4925105++TC-08-_-tc+08&matchtype=e&aud-813230962291: kwd-306225632062&gclid=CjwKCAjw8qVBhANEiwAfjXLrl2Tb