Green, grey, blue, turquoise, pink: what the hydrogen colours leave out
Five colour names, one identical molecule. The colour tells you what a kilogram of hydrogen was made from and what powered it, and nothing else. Certification schemes have already moved past the colours to the number underneath them.
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Storing hydrogen: four routes, and what each one charges
A kilogram of hydrogen occupies about 11 cubic metres at ambient conditions, which is why it is never stored that way. Every method of shrinking it charges a fee, and the fee is paid in a fraction of the hydrogen's own energy.
Read →Who actually makes water electrolysers in 2026
Once you know how water electrolysis works, the next question is who builds it. This is a map of the manufacturers by technology, and a reading of what the list itself tells you about where the industry is.
Read →Fuel cell or electrolyser: the same stack, run backwards
They share a three layer cell, a catalyst vocabulary and even the technology names. One consumes hydrogen to make electricity, the other consumes electricity to make hydrogen. Why that single reversal changes almost every design decision.
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What water electrolysis is, and the four numbers that describe any electrolyzer
Water electrolysis is one reaction with a fixed price. Thermodynamics sets the floor for the energy, Faraday's law sets the charge, and stoichiometry sets the water. Everything a supplier can influence is the gap between those floors and the machine you buy.
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Alkaline water electrolysis: a century of industrial use, and the two limits that remain
Alkaline electrolysis is the only water electrolysis technology with a hundred years of industrial operation behind it, and it reached that position without a single noble metal. What separates it from the membrane technologies is not the chemistry but the separator, and almost every limit people attribute to alkaline electrolysis comes back to that one component.
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PEM water electrolysis: what the acidic membrane buys, and what it costs
PEM electrolyzers do things a liquid alkaline plant cannot: hold a large pressure difference, follow a variable power input, and deliver hydrogen that is already pure. All of it follows from one decision, a solid acidic membrane, and so does the bill that comes with it.
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Solid oxide electrolysis: what running at 800 °C actually changes
Solid oxide electrolysis does not beat the other technologies by being a better cell. It changes the accounting, paying for part of the reaction with heat instead of electricity. Whether that is an advantage depends entirely on where the heat comes from.
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Hydrogen generators: how to size one, and what the specification has to tell you
A hydrogen generator makes hydrogen where it is used, from water and electricity, instead of having it delivered. Sizing one is not a matter of picking a model. It is a matter of turning what you consume into a rate, and then checking five numbers against your site.
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The ionomer: the polymer inside the catalyst layer, and why its amount decides performance
Two polymers do different jobs in the same cell. The membrane separates the gases. The ionomer sits inside the catalyst layer and carries ions the last few micrometres to the catalyst surface. Too little and the layer has no ion path. Too much and the gas has no way out.
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What a catalyst does, and why the electrolyte decides which one you can use
A catalyst does not split water. The current does. What it changes is the voltage the reaction needs, and whether your electrolyte is acidic or alkaline decides which materials are available to do it.
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What an electrolysis system is, and why its efficiency is not the stack's
A stack splits water. It does not make hydrogen you can use. Between the two sits the balance of plant, and that is where the numbers you actually buy are decided: energy per kilogram, purity and pressure.
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AEM water electrolysis explained: what changes when the membrane is anionic
Alkaline electrolysis is inexpensive but slow. PEM is fast but tied to iridium and PFAS. AEM keeps the solid membrane and moves it into an alkaline environment, and this is what that changes, what it has not solved, and where the technology stands measured.
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Alkaline, PEM or AEM: how to choose an electrolysis technology
There is no best electrolysis technology, only the one whose limits your project can live with. This is the set of questions that decides the answer, and what each of the three technologies is actually chosen for.
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Electrolyzer efficiency: what the number means and how to compare it
Two electrolyzers quoted at 75% and 64% can be the same machine. Efficiency figures move with the heating value basis, the measurement boundary, the current density and the age of the stack, and this is how to read one properly.
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What is an electrolyzer stack, and what decides how well it works
A stack is cells in series, held at the right pressure and fed the same electrolyte. Most of what separates a good stack from a bad one is not the chemistry inside the cells but the mechanical engineering between them.
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What is an MEA, and why it decides an electrolyzer's performance
The membrane electrode assembly is the layer stack where water is actually split. It sets the efficiency ceiling of everything built around it, and most of its performance is decided at the interfaces rather than by the ingredients.
Read →Measured data
Technical notes cover our own measurements and the conditions they were taken under.
Technical notes and news