JUNE 6 — Green hydrogen has become the darling of the net-zero world. Politicians love announcing “gigafactories.” Energy executives call it the “Swiss Army knife” of decarbonisation. But if you strip away the glossy PowerPoint slides and the subsidy promises, you’re left with a brutal engineering reality: we are not yet very good at making the stuff affordably or efficiently. That is precisely why a recent review is so refreshingly necessary. It is not another cheerleading session for a hydrogen economy. Instead, it reads like a sober field manual — one that quietly confirms what many insiders fear but few say aloud: the road to green hydrogen is paved with good intentions, thermodynamic limits, and very expensive membranes.
The authors systematically walk through the three main technological pathways for green hydrogen: alkaline electrolysis (AEC), proton exchange membrane (PEM) electrolysis, and solid oxide electrolysis (SOEC). Their analysis is technically sound, but the implicit message is unmistakable.
AEC is the old workhorse — mature, relatively cheap, but sluggish and difficult to pair with the wild intermittency of solar and wind. PEM is the flashy young contender: fast response, high current density, and perfectly suited for renewables. But it remains stubbornly dependent on iridium and platinum — metals that are scarce, geopolitically concentrated, and brutally expensive. SOEC offers mind-bending efficiencies at high temperatures, yet it wilts under cycling and still struggles with long-term stability. What the authors clearly imply is this: there is no single electrolyzer technology ready to dominate at scale. Anyone claiming otherwise is selling something. The real breakthrough will not be a silver bullet technology. It will be a systems integration miracle.
Here is where the review quietly drops a bombshell that most hydrogen advocates prefer to ignore: green hydrogen is intensely water-intensive. Producing 1 kg of hydrogen requires about 9 kg of ultrapure water. In a world where hundreds of millions already face water scarcity, where exactly do we plan to site these gleaming electrolysis plants? Placing green hydrogen production in arid, sun-rich regions — the very places that seem ideal for solar-powered electrolysis — is an act of environmental trade-off politics. Desalination adds cost and complexity. Pumping water inland adds more. The review’s call for “hybrid system optimisation” is, in this light, a quiet indictment of back-of-the-envelope hydrogen economics that ignore water infrastructure entirely.
Most reviews list hybrid systems as a polite afterthought. These authors do the opposite: they elevate system integration to the central challenge. And they are right. A PEM electrolyzer paired directly with a solar farm without intelligent buffering — batteries, supercapacitors, or grid-smoothing algorithms — is a recipe for degraded membranes and frustrated operators. The authors argue convincingly that optimal green hydrogen production is not an electrolysis problem. It is a control systems problem: forecasting renewable output, managing thermal loads, balancing hydrogen storage with battery state-of-charge, and doing it all in real time.
The most provocative finding is that the levelised cost of green hydrogen is far more sensitive to capacity factor and system design than to electrolyzer efficiency alone. In plain English: running a decent electrolyzer at 60 per cent capacity factor with smart hybrid storage beats running an excellent electrolyzer at 25 per cent capacity factor with dumb controls. That runs directly counter to the marketing narratives obsessed with record-breaking cell efficiencies.
The authors stop short of saying this outright. But the article strongly suggests that green hydrogen may never be cheap enough for routine uses like heating buildings or passenger cars. The review’s emphasis on optimisation, water constraints, and rare metal dependence all point to a future where green hydrogen is a premium molecule — essential for steel, ammonia, and long-duration shipping, but not a universal fuel.
That is not failure. That is focus. And focus is what the hydrogen conversation desperately needs. The authors have done the field a real service. They have reminded us that before we fantasise about a hydrogen-powered world, we should first figure out how to make a single kilogram of green hydrogen reliably, cheaply, and sustainably — without breaking the grid, the water budget, or the bank. Their review is not an endpoint. It is a much-needed reality check, disguised as a technical paper. Now the hard work of hybrid optimisation begins.
* The author is affiliated with the Tan Sri Omar Centre for STI Policy Studies at UCSI University and is an Adjunct Professor at the Ungku Aziz Centre for Development Studies, Universiti Malaya. He can be reached at [email protected].
** This is the personal opinion of the writer or publication and does not necessarily represent the views of Malay Mail.
