Wiki - All about hydrogen

Updated on 1 June 2024

Electrolyzer comparison

The field of water electrolyzers is rapidly developing, with an increasing number of models and manufacturers emerging in the market. This growth is driven by advancements in technology and a rising demand for efficient hydrogen production methods. As a result, there is a diverse range of electrolyzer options available, each offering unique features and benefits. The table below provides a simple comparative overview of various electrolyzer technologies, highlighting key data such as efficiency, operating conditions, and scalability, to assist in making informed decisions based on specific needs and applications. Our team and our partners are here to support you with your project at any time.

Alkaline electrolyzerPEM electrolyzerSOEC electrolyzerAEM electrolyzer
Typical pressureAtmospheric up to 30 bar(g)Atmospheric to pressureized up to 40 bar(g)Pressurized at 20 to 50 bar(g)Pressurized up to 35 bar(g)
Power consumptionFrom 50-70 kWh/kgH2From 52-57 kWh/kgH2From 37-45 kWh/kgH2From 53 kWh/kgH2
Water purity< 5 μS/cm Highest requirements< 20 μS/cm  
Characteristics– Modular
– Robust
– Slower ramp up / ramp down
– Compact when pressurized
– Modular
– Requires ultra pure water
– Quick ramp up / ramp down
– Compact
– Typically contains scarce materials like iridium
– Typically built for special projects
– Requires high temperatures (600 °C or more)
– Typically built for special projects
– Requires high temperatures (600 °C or more)
– Slower ramp up / ramp down
– Combined use for production / combustion of hydrogen possible
– Quick ramp up / ramp down
– Compact
LifetimeUp to 80’000 hoursUp to 60’000 hoursRealistic lifetime not fully knownUp to 60’000 hours
Waste heat recoveryPossible, depending on manufacturerPossible, depending on manufacturer, usually 50-60 °CPossible, depending on manufacturerPossible, depending on manufacturer
An alkaline electrolyzer installed at a facilitiy together with a GRZ DASH buffer storage and an UPSOM methanation reactor.

In addition to the above-summarized technologies, there are others. Chlor-alkaline electrolyzers are among the most widespread water electrolyzers and have been used in industrial applications for decades. They are ideal for situations where there is a steady demand for hydrogen and a continuous supply of electricity, typically in applications exceeding 5 MW. On the other hand, photoelectrochemical (PEC) electrolyzers are still in the very early stages of development and are not yet commercially available. Steam methane reforming (see also this article) is a common method for producing hydrogen from methane gas, primarily in the oil industry; however, this process releases about 10 kg of CO₂ for every 1 kg of hydrogen produced, making it highly polluting unless CO₂ is captured. Steam methane reforming is typically used in larger installations that resell hydrogen for transportation. Additionally, there are emerging methods such as the pyrolysis of biomass, waste-to-hydrogen conversion, and photovoltaic (PV) systems with built-in electrolyzers, all contributing to the evolving landscape of hydrogen production technologies.

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