Green hydrogen | Traditional AWE systems Dynamic AWE systems
Figure 1. Traditional AWE systems suffer from large shunt currents that significantly reduce cell efficiency, especially with decreasing load. The result is a limited dynamic range and increasing costs of hydrogen production. Source: Verdagy white paper, Dynamic Alkaline Water Electrolysis, the pathway to hydrogen achieving fossil fuel cost parity
assemblies); but this lowers system reliability and manufacturing yields.
PEM electrolysers suffer from lower durability of membranes, which significantly increases operational costs and decreases availability. Like filter-pressed, traditional AWE systems, PEM electrolysers also do not have the ability to be digitally monitored at the component level. This means that degradation is not monitored or controlled at the component level and the only option to deal with significant degradation is to replace entire electrolyser stacks, leading to significant operational expenses and lost productivity.
Figure 2. The low shunt currents of Dynamic AWE systems maximise hydrogen production efficiency and ensure high hydrogen production rates, resulting in lower energy capital costs relative to traditional AWE and PEM systems. Source: Verdagy white paper, Dynamic Alkaline Water Electrolysis, the pathway to hydrogen achieving fossil fuel cost parity
Dynamic AWE systems are based on a single- cell, zero-gap architecture in which individual electrolytic cells are electrically connected but chemically isolated. Dynamic AWE systems incorporate cell designs that confer several advantages:
They achieve current densities up to 400% higher than those of traditional AWE electrolysers. These high current densities, coupled with large cell areas, allow dynamic AWE systems to achieve very high rates of hydrogen production in compact footprints. Dynamic AWE systems achieve the widest dynamic operating ranges in the industry,
Comparison chart of low temperature electrolysis technologies
irrespective of technology type, to enable seamless coupling with intermittent energy sources, which leads to high utilisation factors, lower hydrogen production costs, and the lowest carbon intensities. The pairing of single- cell architecture also ensures an efficiency loss of only 0.1% – 2% from shunt currents throughout the entire operating range (see Figure 2).1
Cell area (cm2 )
Traditional AWE 3000 –30 000
Temperature (°C) 65–100 Pressure Atm – 30 bar Efficiency (%HHV*) 60 – 80 Electrolyte
Supply chain maturity
Electrode–membrane configuration
Current density (A cm-2
) Serviceability Dynamic AWE
➝ 3000 –30 000 ➝ 65–100
➝ Atm – 30 bar ➝ 70 –95
Mature
20 –40 wt.% KOH ➝ 20 – 40 wt.% KOH ➝ Mature
Fixed gap Operating conditions Steady state 0.2–0.6 Ramp time (minutes) 15–60 Stack replacement
*HHV = higher heating value, based on 1.481 V ^PFSA = perfluoro sulfonic acid
Zero gap
Steady state and dynamic
0.1–2 1–2 During operation PEM 100 – 3000 70 –90 30–80 bar 44–65 PFSA^ Commercial Zero gap
Steady state and dynamic
0.8–2.5 ~1 Stack replacement
➝Arrows in table demonstrate how Dynamic AWE can leverage system benefits of Traditional AWE with operational benefits of PEM, while also having differentiated features from either system with continued serviceability.
The single-cell architecture of Dynamic AWE systems (see Figure 3) eliminates the need for stack replacements, a significant expense inherent in PEM and traditional AWE electrolysers (see Figure 4). Equally importantly, digital monitoring of individual electrolytic cells facilitates performance upgrades to maximise plant revenues and profitability and proactive maintenance to maximise plant utilisation. Dynamic AWE systems build on several decades of experience in the chlor-alkali industry to enable robust, low-cost, highly reliable systems optimised for hydrogen electrolysis. The capital expenditure/first cost required for Dynamic AWE systems is significantly lower than that of PEM electrolysers, and comparable to those of traditional AWE electrolysers, while offering higher productivity, higher electrolytic (or conversion) efficiency, field upgradable performance, and significantly smaller footprints and installation costs.
Verdagy’s Dynamic AWE Verdagy has designed and optimised its refinery- grade, Dynamic AWE eDynamic electrolysers for industrial scale applications. They have the highest current densities and hydrogen production rates of any alkaline electrolysers. They also provide real-time load matching to intermittent energy sources such as renewables and can accommodate varying electrical grid prices in order to maximise asset utilisation. They also completely eliminate stack replacements and offer dramatically reduced operating costs thanks to the use of electrolytic cells that have lifetimes of over 20 years. In addition, modular design enables them to offer the lowest installation costs and commissioning times.
32 | April 2025|
www.modernpowersystems.com
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