How do they produce green hydrogen via electrolysis?

95% of the world’s hydrogen (over 60 million tons) is currently produced by steam methane reforming (SMR) process, which requires substantial energy input and emits a significant amount of CO₂. Using methane, the SMR process emits 5.5 kg of CO₂ per kilogram of hydrogen (H₂) produced.

Electrolysis produces H₂ that does not result in CO₂ emission. The industrial production of 1 kilogram of H₂ from 9 kilograms of water requires approximately 55 kilowatt-hours of electricity when the most efficient alkaline or PEM electrolysis processes are used. At a cost of $0.053/kWh for electricity, the cost of producing hydrogen by electrolysis is $3.32/kg-H₂.

Hydrogen production through electrolysis is sustainable if the electricity is generated from renewable sources such as hydropower, solar, and wind. Such produced hydrogen is called green hydrogen. In many regions with abundant hydropower, solar, and wind energy, the cost of renewable energy electricity can now be reduced to $0.037/kWh. This will make the electrolysis-based production of hydrogen competitive with the SMR hydrogen production coupled with carbon capture and storage processes.

Several companies are developing efficient and/or low-cost electrolysers that can inexpensively produce green hydrogen.


High cost of membrane-electrode materials hinders PEM electrolyser industrialization. Indeed, the protonic membrane, working at a very acidic condition (pH between 0.5 and 1), requires anti-corrosive platinum electrodes immersed in acidic electrolytes.

Enapter developed a safer and more cost-effective anion exchange membrane (AEM) electrolyser. It produces hydrogen electrolytically from an aqueous alkaline electrolyte. The diluted alkaline solution is present only in the anodic half-cell. The cathode is dry. The electrodes can use platinum free catalysts and steel bipolar plates.

Enapter AEM electrolyzer
Enapter AEM electrolyser.

Enapter has raised a total of $105.6M in funding over 8 rounds. Their latest funding was raised on May 25, 2022 from a Post-IPO Equity round. Enapter is registered under the ticker FRA:H2O. Enapter is funded by 3 investors.


Green hydrogen is not cost-competitive with fossil fuels at this time as a result of the high capital expenditure (CAPEX) and high operational expenditure (OPEX) of the present-day water electrolysis plants. The OPEX is by far the largest cost component, and it is dominated by the overall energy efficiency of the water electrolyser and the cost of the input renewable electricity used to power it.

Hysata developed a cost-effective alkaline capillary-fed electrolysis cell with high energy efficiency. The hydrogen- and oxygen-evolving electrodes come into contact with water via capillary-induced transport along a porous inter-electrode separator, resulting in bubble-free operation at the electrodes. The electrolysis cell has a 98% energy efficiency for water electrolysis, superior to commercial electrolysis cells. It consumes significantly less energy than commercial electrolysis cells.

The structure of a capillary-fed electrolysis cell of Hysata
The structure of a capillary-fed electrolysis cell of Hysata.

Hysata has raised a total of A$42.5M in funding over one round. This was a Series A round raised on Aug 1, 2022. Hysata is funded by 6 investors.

Paul Barrett is CEO.


H2Pro employs a revolutionary approach, E-TAC (Electrochemical-Thermally Activated Chemical), to produce hydrogen by electrolysis. They decouple these reactions by dividing the process into two steps: first, an electrochemical step that reduces water molecules to produce hydrogen at the cathode and oxidizes the anode, followed by a spontaneous chemical (non electrochemical) step that reduces the anode back to its original state by oxidizing water to generate oxygen simply driven by hot water. This method eliminates the most expensive and fragile component of an electrolyser, the membrane.

H2Pro prototype working principle.

H2Pro has raised a total of $107.2M in funding over 7 rounds. Their latest funding was raised on Mar 8, 2022 from a Venture-Series Unknown. H2Pro is funded by 18 investors. Doral Energy-Tech Ventures and Temasek Holdings are the most recent investors.

Talmon Marco is CEO.


Hydrogen pressures at the outlet of a traditional electrolyser do not exceed 80 bar, which is a minimum to be reached for storage and transportation. Compressing hydrogen with a mechanical compressor is costly.

Ergosup developed a membrane-free electrolyser that directly produces very highly pressurized hydrogen (over 80 bar) in a decoupled manner. This ground-breaking technology can be used for the decarbonized production and storage of hydrogen for clean transportation, industrial applications, and energy storage.

Ergosup electrolyser.

Ergosup has raised a total of €16.2M in funding over 2 rounds. Their latest funding was raised on Feb 18, 2019 from a Series B round. Ergosup is funded by 10 investors.

Christine George is CEO.

Advanced Ionics

There are two types of electrolysers: hot and cold. Cold electrolysers, such as alkaline and proton exchange membrane (PEM), use liquid water. Their operating temperature is typically limited to 100 ºC. Hot electrolysers, such as solid oxide electrolysis cells (SOEC), operate with superheated steam at 800 ºC, which increases reaction kinetics and decreases electrical energy needs.

Advanced Ionics develops electrolyser technology that utilizes industrial waste heat above 150 ºC (the majority of industrial processes operate between 200 and 600 ºC). Advanced Ionics’s electrolysers require 30% less electricity than alkaline or PEM systems. In addition, the technology of Advanced Ionics uses abundant and widely accessible materials to keep capital costs low – no costly platinum-group metals, no iridium, and no fluoropolymer membranes.

Advanced Ionics electrolyzer
Advanced Ionics electrolyser.

Advanced Ionics has raised a total of $7.1M in funding over 2 rounds. Their latest funding was raised on Apr 28, 2022 from a Seed round. Advanced Ionics is funded by 2 investors.

Chad Mason is CEO.

Battolyser Systems

The unpredictability and intermittent nature of renewable energy sources such as wind and solar requires energy storage facilities. Conventional batteries, such as those based on lithium, can store energy in the short-term, but when they’re fully charged they must release any excess or they will overheat and degrade. The green hydrogen production from water electrolysis powered by renewable energy may enable long-term energy storage in fuels and feedstock via chemical processes.

Battolyser Systems developed a low-cost, durable battolyser that integrates the functions of rechargeable battery and alkaline electrolyser. The battolyser provides electricity storage capacity, which is charged when there is a surplus of renewable electricity and discharged when there is an electricity deficiency. When the battery reaches its maximum capacity, hydrogen is produced from the excess electricity that exceeds the battery’s capacity. This makes the battolyser flexible with respect to energy insertion.

an image of a battolyser system and a diagram of the battolyser stack
An image of a battolyser system and a diagram of the battolyser stack.

Mattijs Slee is CEO.

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