PEM Electrolyzer Animation: How to Explain Stack Technology
A good PEM electrolyzer animation explains the stack by following one water molecule through the cell: in at the anode, split into oxygen, protons and electrons, protons across the membrane, hydrogen out at the cathode. Build the film around that single path, then peel back the layers (membrane, catalysts, porous transport layers, bipolar plates) so engineers and buyers see why each one exists.
That is the short answer. The rest of this post sets out the physics an accurate animation has to respect, a six-beat storyboard you can adapt, and the communication problems that make PEM stack technology hard to explain with slides alone.
What a PEM electrolyzer animation has to show
The U.S. Department of Energy describes an electrolyzer as an anode and a cathode separated by an electrolyte. In a proton exchange membrane (PEM) electrolyzer, that electrolyte is a solid plastic material that only lets hydrogen ions (protons) through. The chemistry is two half-reactions:
Anode: 2H₂O → O₂ + 4H⁺ + 4e⁻
Cathode: 4H⁺ + 4e⁻ → 2H₂
DC voltage drives the split at the anode. Electrons travel through the external circuit, protons cross the membrane, and the two meet again at the cathode to form hydrogen gas. DOE notes that PEM electrolyzers typically run at about 70–90 °C. Any animation that shows electrons crossing the membrane, or hydrogen forming on the oxygen side, is wrong in a way a technical audience will notice immediately.
The layers inside a PEM stack, explained for the camera
A 2025 review in ACS Applied Energy Materials (García-Salaberri et al.) describes the cell cross-section as bipolar plates, porous transport layers, catalyst layers and the membrane at the centre. Each layer gives the animator something concrete to show:
Layer | What it does | How to show it |
Membrane (typically a PFSA polymer such as Nafion) | Conducts protons, separates the gases | A translucent sheet that lets only small charged particles through |
Anode catalyst layer (iridium-based) | Splits water and releases oxygen | Oxygen bubbles nucleating on dark catalyst particles |
Cathode catalyst layer (platinum-based) | Combines protons and electrons into hydrogen | Smaller hydrogen bubbles forming on the opposite face |
Porous transport layers (titanium on the anode, carbon paper on the cathode) | Carry water in, gas out and current through | A cutaway of the porous structure with water and gas moving in opposite directions |
Bipolar plates and flow fields | Distribute water, collect gas, connect cells in series | Zoom out from one cell to a repeating stack |
The materials are where the story becomes interesting. The review explains that the anode side sees high potentials and low pH, which is why it relies on precious-metal catalysts and corrosion-resistant titanium transport layers, often coated with platinum. It also names passivation of anode transport layers as a major challenge. DOE's technical targets note that iridium in the anode accounts for much of the platinum group metal content in a PEM electrolyzer. Those two facts give a film a natural "why it costs what it costs" moment without anyone quoting a price. (For the buyer-side comparison of the two main technologies, see H2Hub's PEM vs alkaline electrolyzer guide.)
Why membrane thickness and current density belong in the film
Buyers compare stacks on performance, so the animation should make the key trade-off visible. The review notes that ohmic resistance largely depends on membrane thickness, citing Nafion 117 at 180 μm and Nafion 115 at 125 μm. A thinner membrane lowers resistance, which is why an animator can show voltage losses shrinking as the membrane thins, while flagging that durability has to keep up.
DOE's PEM stack targets put numbers on the same story. Its 2022 status is 2.0 A/cm² at 1.9 V per cell; the 2026 target is 3.0 A/cm² at 1.8 V per cell. Multiplying current density by cell voltage gives a simple, illustrative power figure per square centimetre of cell:
DOE stack metric | Current density × voltage | Power per cm² (illustrative) |
2022 status | 2.0 A/cm² × 1.9 V | 3.8 W/cm² |
2026 target | 3.0 A/cm² × 1.8 V | 5.4 W/cm² |
Ultimate target | 3.0 A/cm² × 1.6 V | 4.8 W/cm² |
Moving from the 2022 status to the 2026 target means about 42% more power through each square centimetre at a lower cell voltage. That is a strong visual: the same cell area, more current, less voltage. The ultimate target trades a little power density for efficiency, which is itself a useful point for a technical audience. DOE also lists stack degradation (4.8 mV per 1,000 hours in 2022, with a 2026 target of 2.3) and a stack lifetime of 40,000 operating hours in 2022, rising to 80,000 in the target years.
A six-beat PEM stack animation storyboard
This is an original outline any PEM electrolyzer or component maker could adapt. Each beat is one idea.
The single cell. Start on one water molecule entering the anode flow field. Label nothing yet; just follow it.
The split. At the iridium-based catalyst, the molecule splits. Oxygen bubbles away; protons and electrons go separate ways. Show the anode half-reaction once, briefly.
The crossing. Protons move through the membrane while electrons take the external circuit. This is the beat that explains "proton exchange membrane" in a few seconds.
The cathode. Protons meet electrons on the platinum catalyst, and hydrogen bubbles form and leave through the cathode transport layer.
The exploded view. Pull the cell apart into its layers, then highlight the one your company makes or improves: the membrane, a coating, a transport layer, a plate design.
The stack. Pull back as cells repeat into a stack, with the performance metric that matters to your buyer (current density, efficiency or degradation) shown as a clear comparison, sourced on screen.
The communication problem PEM stack makers face
A PEM stack is a sandwich of layers measured in micrometres, inside a sealed steel assembly. Nothing important is visible from outside, and the best photograph of a stack still shows a box with pipes. Slide decks fall back on cross-section diagrams that make sense to electrochemists but lose procurement teams, investors and project developers.
Three things usually go wrong:
Scale is invisible. Viewers cannot tell a membrane from a plate unless motion and zoom show the difference.
Trade-offs get flattened. Thinner membranes, lower iridium loading and higher current density all interact. A static chart rarely shows how.
Claims outrun evidence. Marketing films that skip the physics lose engineers in the first minute. Films that cite DOE-style metrics on screen keep them watching.
Animation solves the first two because it can move through layers and change one variable at a time. The third is about editorial discipline: every number on screen should trace to a datasheet, a test report or a public source.
Examples of ReneEnergy technical explainers
ReneEnergy makes evidence-based explainers that follow this approach. Two examples from the channel:
How Grey Hydrogen Is Made, and Where the Carbon Goes, a process explainer that follows the molecule through a plant.
How Hydrogen Gas Turbines Work: Burning Hydrogen for Power, a component-level look at what changes inside the machine.
Frequently asked questions
How long should a PEM electrolyzer animation be?
For a website or trade-show loop, the six beats above fit a short film. A sales or investor version can run longer, adding a beat on durability or manufacturing. Length should follow the audience, not the other way round.
Should a stack animation show real performance numbers?
Yes, if they are sourced. Show the metric your buyer compares, such as current density at a stated cell voltage, and put the source on screen. Avoid numbers that cannot be traced to a test report or datasheet.
Is animation better than filming the real stack?
For the inside of a cell, yes, because the important parts cannot be filmed. Live footage works well for factory, assembly and installation scenes, and many films combine both.
Related reading
Planning a PEM stack explainer?
If your team needs to explain a membrane, coating, transport layer or full stack to buyers and investors, ReneEnergy produces evidence-based technical animation for electrolyzer, fuel-cell and clean-energy companies. See ReneEnergy's technical video services, or email contact@reneenergy.com.
Sources
U.S. Department of Energy, Hydrogen and Fuel Cell Technologies Office, "Hydrogen Production: Electrolysis": energy.gov/eere/fuelcells/hydrogen-production-electrolysis
U.S. Department of Energy, "Technical Targets for Proton Exchange Membrane Electrolysis": energy.gov/eere/fuelcells/technical-targets-proton-exchange-membrane-electrolysis
García-Salaberri, P. A., et al. (2025). "Materials Engineering for High Performance and Durability Proton Exchange Membrane Water Electrolyzers." ACS Applied Energy Materials 8(18), 13050–13121. pmc.ncbi.nlm.nih.gov/articles/PMC12458485
Fact-checked November 11, 2026.
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