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Hydrogen - How does an industrial electrolyzer work?
Mis à jour le
January 28, 2026
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In the intermittent renewable energy sector, terms like “electrolysis,” green hydrogen ” and “hydrogen electrolyzer” are gaining momentum. Considered essential for the ecological transition, hydrogen production is tending towards a process that is more and more environmentally friendly.
While many governments and investors are pinning their hopes on the implementation of green hydrogen, how it is produced is still unknown to the general public.
In this article, SirEnergies explains the industrial electrolyzer and its main uses. The time will also come to question the future for the production ofhydrogen by electrolysis?
Hydrogen electrolyzer: what is it?
THEhydrogen electrolyzer Is simply a fuel cell inverted. Unlike the fuel cell, which produces electricity from oxygen and Hydrogen, this device produces these using electricity. For the less scientific among you, here is a simpler explanation.
An electrolyzer is a device composed of a water container in which there is an electrolyte. It also includes two electrodes: an anode or positive pole and a cathode or negative pole.
Once an electric current passes through it, the electrolyser induces a chemical reaction on both sides of the electrolyte: it is electrolysis. This reaction gradually breaks down compound substances into other compound or singular substances.
Result? Oxygen is released at the anode and hydrogen is created at the cathode. The latter can then be transformed into liquid hydrogen using a liquefier.
To be sustainable in the long term, The electrolysis of water must be based on sustainable energy. Among others, we can mention:
You can use other energy sources to produce hydrogen by electrolysis. However, the result cannot be considered as green hydrogen.
What are the main types of electrolysers?
The production of hydrogen by electrolysis is a well-established principle. However, there are several systems to achieve this, the main ones of which are the PEM electrolyzer and the alkaline electrolyzer.
The PEM electrolyzer
THEproton exchange membrane electrolyzer or PEM electrolyzer works like a filter. The polymer membrane that equips this device only allows hydrogen ions to pass through.
During the electrolysis reaction, hydrogen ions and electrons formed at the anode pass through the wall to reach the cathode. They are transformed into hydrogen at the cathode. We can summarize chemical reactions with the following equations:
Anode: H2O → H2 + ½ O2 + 2e
Cathode: 2 h+ + 2e → H2
The PEM electrolyzer has the particularity of be able to operate under pressure. It can therefore be smaller than the alkaline electrolyzer. However, you must take into account the particular requirements it requires to produce hydrogen under very acidic conditions.
The alkaline electrolyzer
This device makes it possible to produce hydrogen from an alkaline liquid electrolyte. You can use sodium hydroxide or potassium hydroxide, as these compounds have long been known for their good results.
During the chemical reaction in an alkaline electrolyzer, the water contained in the electrolyte is subdivided into hydrogen and hydroxide ions at the cathode. They then come into contact with a membrane before being oxidized to oxygen and water at the anode.
We can summarize the results of the reactions to two poles of the alkaline electrolyzer by the following equations:
Cathode: 2 h 2 O + 2e → H2 + 2 OH -.
Anode: 2 OH - → ½ O2 + 2e- + H2O.
Balance: H2O → H2 + ½ O2.
Here are some figures to give you a better overview of the conditions necessary for this reaction to take place. It takes approximately:
- 235 kJ/mol of renewable electricity per mole of water,
- 50 kJ/mol of heat,
- Between 40 and 90°C.
The main advantage of the alkaline electrolyzer is the high availability of electrolytes necessary for its functioning. However, it uses bulky cells whose current density is relatively low.
What are the prospects for the industrial electrolyzer?
THEindustrial electrolyzer is of no interest if it cannot be used over the long term to cover the planet's energy needs. Several companies have committed themselves in this direction to set up infrastructures capable of meeting the challenges of tomorrow.
The production of carbon-free hydrogen with Air Liquide
The largest membrane electrolysis unit was created in Quebec. Inaugurated in January 2021 in Bécancour by Air Liquide, this power plant has 4 distinct units. It works on the principle of a proton exchange membrane. Its total power of 20 MW makes it a global reference.
What is the particularity of this industrial electrolyser? La production of carbon-free hydrogen : it works with renewable energy to 99%! In addition, the installation can produce up to 8.2 tons of low-carbon hydrogen per day. To give you an idea of its potential, you should know that this quantity is enough to power 16,000 forklifts or even 230 large trucks!
McPhy's high-pressure electrolysis
The McPhy CEOG project is an innovation that offers hope to the storage of intermittent renewable energies. This hydrogen production platform will avoid the emission of around 39,000 tons of CO2 each year compared to a fossil power plant.
The ingenious mechanism behind this project? The combination between alkaline electrolysis at a pressure of 30 bar and high current density electrodes. The platform has a capacity to produce around 860 tons of green hydrogen per year for a total capacity of 16 MW.
Genvia high-temperature electrolysis
Created in March 2021, the joint project between CEA and the multinational Schlumberger aims at the production of hydrogen on a large scale. The technology used is under development. However, it is promising because it is based on high-temperature electrolysis.
Genvia extends over 600 m² in Béziers in Hérault. The site will host advanced equipment to manufacture the components that make up power stacks. It is a repeated stacking of the reaction core (electrochemical cell) and a metal sheet. The expected return? 99% higher calorific value (PCS)!
The industrial electrolyzer thus operates on the principle of separating chemical compounds from an electrolyte to produce hydrogen. La need for synthetic fuels, the size constraints of the cells and those related to their current density constitute obstacles to the development of this manufacturing process.
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Pourquoi la France a-t-elle exporté un volume record d'électricité en 2025 ?
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Ce record de 92,3 TWh s'explique par la conjonction de trois facteurs :
- Le redressement du parc nucléaire : Après les problèmes de corrosion sous contrainte de 2022, la production nucléaire a retrouvé une forte disponibilité (373 TWh).
- L'essor des renouvelables : Une capacité installée en hausse (solaire et éolien) et une production hydraulique solide.
- Une consommation intérieure atone : La demande française reste inférieure de 6 % à la moyenne historique, créant un surplus massif disponible pour nos voisins.
Pourquoi mon contrat est-il en kVA et ma consommation en kWh ?
Le kVA mesure la capacité maximale que votre compteur peut supporter à un instant T, tandis que le kWh mesure la quantité d'énergie consommée sur une durée.
Is Bellenergie Business electricity really green?
Yes. The supplier guarantees an offer 100% renewable via the official Guarantees of Origin (GO) mechanism.
For the most demanding companies, the offer GREENVOLT+ ensures very low carbon intensity electricity, sourced exclusively from independent French producers (hydraulic, wind, solar).
How to optimize the taxes and contributions of a community?
Communities are subject to taxes such as TICFE or TICGN. Sirenergies analyzes invoices, identifies exemption possibilities and fixes possible errors to reduce the tax burden.
Comment l'eau est-elle transformée en électricité ?
Le processus repose sur l'utilisation de la force de l'eau (énergie cinétique) issue des courants, des chutes d'eau ou des dénivelés. Le fonctionnement suit trois étapes clés :
- Le barrage retient l'eau et l'oriente vers des conduites.
- La pression de l'eau fait tourner une turbine, créant de l'énergie mécanique.
- Une génératrice (alternateur) transforme cette énergie mécanique en électricité, laquelle est ensuite adaptée par un transformateur pour le réseau
Qu'est-ce que le cosinus phi
C'est l'indicateur d'efficacité d'un appareil électrique ; il représente le ratio entre la puissance active (utile) et la puissance apparente (totale).
What are the PP1 and PP2 alert days?
These are signals sent by RTE during periods of tension on the electrical network. The Sirenergies tool informs you in real time to anticipate your uses.
How to properly define your subscribed power?
The subscribed power must be calculated according to the consumption profile and uses (heating, industrial processes, tertiary equipment). One fine analysis makes it possible to ensure the adequacy between real need and contract.
What are the challenges for tertiary companies?
Tertiary companies must manage their energy costs while guaranteeing the comfort of users (offices, shops, services). Consumption is often linked to heating, air conditioning and lighting, which requires precise monitoring to avoid budgetary excesses.
What taxes are particularly relevant to manufacturers?
The industry is concerned by TICFE, TICGN and other contributions that may represent an important part of invoices. Sirenergies identifies cases of exemption and accompanies the procedures to benefit from them.
Quel est l'impact réel de la rénovation de l'éclairage public ?
C'est le levier le plus rapide pour obtenir des résultats visibles. L'éclairage représente environ 40 % de la consommation d'électricité d'une commune.
Passer au LED avec pilotage intelligent permet de réduire la facture de 50 à 80 %, avec un retour sur investissement (ROI) rapide, souvent estimé à 2 ou 3 ans.
Quel est l'impact de ces exportations sur le prix de l'électricité pour les entreprises ?
L'abondance de production française tire les prix du marché de gros vers le bas.
En vertu du mécanisme de l'Ordre de Mérite (Merit Order), les centrales les moins coûteuses (nucléaire, renouvelables) couvrent la demande plus souvent, évinçant les centrales à gaz ou charbon plus onéreuses.
Cela multiplie les épisodes de prix bas, voire négatifs, sur le marché spot.
How do I read an electricity or gas bill?
One invoice consists of several elements: consumption, supplier share, taxes and contributions. The analysis of each line makes it possible to identify possible errors and to check the consistency with the signed contract.
How do I get a tax exemption?
Some businesses may obtain a partial or total exemption from the TICFE or the TICGN, depending on their activity and energy intensity. The support of an expert makes it possible to identify the eligibility criteria and to put together the file.
What are the customer reviews on bellenergie Business's customer service?
In 2025, the supplier had a NPS (Net Promoter Score) of +16 and a note of 4,17/5.
Satisfaction is based on a “zero solicitation” model and 100% in-house customer service in Toulon, guaranteeing proximity and responsiveness that cannot be found with major historical suppliers.
Quelle est la différence concrète entre le transport et la distribution d'électricité ?
Le transport (RTE) correspond aux "autoroutes" de l’électricité. Il s’agit de transporter de très grandes quantités d'énergie sur de longues distances, depuis les centrales de production (nucléaires, barrages, parcs éoliens offshore) vers les régions de consommation.
La distribution (Enedis) s'apparente aux "routes départementales" et aux rues. Elle récupère l'électricité à la sortie du réseau de transport pour la livrer directement chez le client final, en abaissant la tension pour qu'elle soit utilisable par vos appareils.
Qu'est-ce qui remplace l'ARENH depuis le 1er janvier 2026 ?
Le dispositif ARENH a laissé place au VNU (Versement Nucléaire Universel).
Ce changement structurel expose davantage les entreprises aux prix de gros, rendant la gestion des risques plus complexe qu'auparavant.
Il devient alors indispensable de définir une stratégie d'achat d'électricité avec Sirenergies pour lisser l'impact de la volatilité des marchés sur votre budget.
What are the consequences of overpowering?
Exceeding capacity leads to financial penalties and can impact the size of the contract. Adjust the correctly subscribed power makes it possible to avoid these additional costs.
Why launch an energy tender?
Un appel d’offres permet de mettre en concurrence plusieurs fournisseurs d’électricité et de gaz afin d’obtenir des conditions contractuelles optimisées. C’est une démarche transparente qui permet de choisir l’offre la plus adaptée aux besoins budgétaires et techniques de l’organisation.
L'hydroélectricité est-elle une énergie "propre" ?
Oui, elle est considérée comme une énergie renouvelable à faibles émissions de gaz à effet de serre.
De plus, l'eau ne subit aucune transformation chimique durant le cycle de production et réintègre son milieu naturel en aval.
Cependant, la construction de barrages nécessite des mesures pour protéger les écosystèmes (débit minimum, passes à poissons).
What is the difference between €/MWh and kWh?
The €/MWh is a price unit used in wholesale markets, while kWh is the unit visible on your bills.
What is the point of following Spot & Forward prices?
This makes it possible to choose the right time to contract, secure your budgets and anticipate increases.
What are the main taxes applicable?
Among the taxes include TICFE, TICGN, CTA, CJA and TURPE. They represent a significant part of the bill and vary according to consumption profiles. Understanding them well is essential to optimize costs.
How to optimize taxes and contributions?
Tertiary companies are concerned by taxes such as TICFE or TICGN. Sirenergies checks the accuracy of invoices, identifies possible exemptions, and helps correct errors to sustainably reduce costs.
Quel est le nouveau record 2025 d'exportation d'électricité de la France ?
En 2025, la France a atteint un solde exportateur net de 92,3 TWh, battant le précédent record de 2024 (89 TWh).
What is energy sourcing?
Sourcing consists in identifying and analysing the offers of several electricity and gas suppliers. This approach makes it possible to obtain contracts adapted to the consumption profile and budgetary constraints of the company.
What are the electricity offers offered by bellenergie Business?
The range E @sy is available in four pricing structures to adapt to each risk profile:
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Which taxes are particularly relevant for farms?
Farms are subject to taxes such as TICFE or TICGN. Sirenergies verifies their application, identifies cases of exemption and accompanies the procedures to reduce the tax burden.
Pourquoi le kVA est-il crucial pour les entreprises ?
Parce que la puissance souscrite en kVA détermine le prix de l'abonnement et que tout dépassement peut entraîner des surcoûts importants.
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