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AEM electrolysis passes 1,250-hour pilot with Repsol
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Power to Hydrogen and Repsol completed a multi-day pilot that ran for more than 1,250 hours to exercise a commercial-scale anion exchange membrane (AEM) electrolyser under realistic, variable renewable inputs. The pilot, run through Repsol’s All4Zero innovation hub, combined parametric and durability testing and confirmed system operation below 50 kWh/kg with repeated cycling between 40% and 100% load. As first reported by Energies Media, Power to Hydrogen used Repsol-specific inputs and a U.S. Department of Energy H2A-Lite framework to produce levelized cost of hydrogen figures referenced in the test summary.
Key takeaways
- Pilot duration: Power to Hydrogen ran an AEM electrolyser pilot for more than 1,250 hours at Repsol’s All4Zero hub.
- System efficiency: The AEM system operated below 50 kWh/kg at the system level during the pilot.
- Load‑following test: The pilot included repeated cycling between 40% and 100% load to simulate variable renewable supply.
- Projected costs: Using H2A-Lite inputs, P2H2 reported a levelized cost of hydrogen of about €3.86/kg, and an optimized scenario estimate of €2.82/kg.
Table of contents
What the 1,250‑hour pilot actually tested and what passed
The pilot targeted three practical questions for scaling AEM: sustained stack durability, efficiency under varying power, and real-world flexibility. Over more than 1,250 hours the system ran parametric sweeps and extended duty cycles to reveal how the hybrid AEM stack responds to prolonged operation and frequent load changes. Repsol’s All4Zero test protocol supplied site-specific inputs and simulated renewable profiles so the stack saw repeated swings between partial and full output.
Test outputs reported by Power to Hydrogen included steady operating points, degradation trends within the monitored window, and a set of key-performance indicators the company judged to meet or exceed its targets for efficiency, flexibility and durability. These outcomes are the basis for P2H2 calling AEM a credible lower-cost route to industrial hydrogen production. The paragraph-level finding that the project ran “1,250 hours of parametric and durability testing” is central to claims about long‑duration operation.
How AEM stacks behaved: efficiency and load‑following
AEM electrolysis splits water using an anion exchange membrane and avoids precious-metal catalysts; that material difference is why developers pitch AEM as lower cost. During the pilot P2H2 reported system-level energy use below 50 kWh/kg, a figure that positions this AEM implementation competitively against other electrolysis types when measured at the stack-to-system scale.
Equally important was the stack’s response to variable power. The All4Zero protocol placed the electrolyser through repeated cycles between 40% and 100% load to mirror renewables-driven intermittency. Power to Hydrogen reported the hardware sustained these swings while maintaining operating efficiency and showing manageable short-term performance drift, supporting the company’s argument that the stack has meaningful load-following capability.
Cost signals and the near‑term commercial picture
For its economic estimates, Power to Hydrogen combined Repsol-supplied assumptions with the DOE H2A‑Lite modeling framework to produce a central LCOH figure of roughly €3.86/kg. The company characterized that outcome as approximately a 16% improvement versus incumbent electrolysers on the same assumptions, and said that stronger renewable inputs and hybrid contract arrangements could push the estimate down to about €2.82/kg.
Those figures are model outputs tied to the pilot’s measured efficiency and assumed capital, power and balance-of-plant costs; they are not independently audited in the public domain. If the reported stack durability and sub-50 kWh/kg energy use hold up at scale, the economics would narrow the gap between green hydrogen and established industrial alternatives, but that depends on deployment scale, local power costs and financing.
| Item | Metric | Value / note |
|---|---|---|
| Pilot duration | Runtime | more than 1,250 hours |
| Reported efficiency | System energy use | below 50 kWh/kg |
| Load cycling | Range tested | 40%–100% load |
| LCOH (reported) | Central case | €3.86/kg (≈16% reduction vs incumbents) |
| LCOH (optimized) | Optimized renewables case | €2.82/kg |
How the pilot could and could not shift deployment odds
The case for
- If long‑duration degradation rates remain low beyond 1,250 hours, project operators can plan for longer service intervals and lower replacement costs.
- Sub-50 kWh/kg system energy use materially improves LCOH in regions with moderate renewable prices, making commercial projects closer to bankable thresholds.
The case against
- The pilot’s time window is limited; unseen failure modes or accelerated degradation after the tested hours would raise lifecycle costs and undermine the reported LCOH.
- Published cost outcomes depend on Repsol-specific inputs and H2A-Lite assumptions; different local power prices or capex profiles could push actual LCOH higher than the reported €3.86/kg.
What to be careful about
- Pilot duration does not equal multi‑year field performance; stack degradation beyond the test window could change lifecycle economics.
- Modelled LCOH relies on assumptions (power price, CAPEX, stack lifetime) that are not fully disclosed in the summary and may not generalise across sites.
- Scale-up may reveal balance‑of‑plant complexities or supply‑chain limits for non‑precious materials used in commercial AEM stacks.
The bottom line
The All4Zero pilot gives AEM electrolysis a substantive endurance test: more than 1,250 operational hours, repeated cycling between 40% and 100% load, and a reported system energy use under 50 kWh/kg. Those results underpin the company’s LCOH figures of €3.86/kg and a lower optimized case of €2.82/kg, but the business case rests on whether those efficiency and durability gains persist beyond the pilot window and across diverse power markets. The next step for the technology to affect deployment decisions will be published long‑duration degradation data and an independently verifiable commercial reference site.
What to watch
- Watch for Power to Hydrogen’s publication of the full test dataset and stack degradation curves; no date has been set.
- Watch for a P2H2 announcement of the next field deployment or commercial reference site following the All4Zero pilot; no date has been set.
Frequently asked questions
What did the pilot demonstrate about AEM durability?
The Power to Hydrogen pilot ran in excess of 1,250 hours of combined parametric and durability trials conducted to Repsol’s protocol; Power to Hydrogen reported that the stack met or exceeded the project’s durability targets within that testing window, while noting that longer-duration trials or published degradation curves would be required to confirm multi‑year durability.
How energy efficient was the tested system?
The company reported system-level energy use below 50 kWh/kg during pilot operation, a metric measured at the stack-to-system boundary rather than a raw cell figure and used to calculate levelized cost outcomes.
What LCOH figures did P2H2 publish from the pilot data?
Power to Hydrogen applied Repsol’s input assumptions together with the Department of Energy H2A‑Lite methodology and calculated a levelized cost of hydrogen (LCOH) of about €3.86 per kilogram — which the company said represents roughly a 16% reduction compared with incumbent electrolysers — and presented an optimized scenario in which LCOH falls to €2.82/kg.
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