Case study: Catalysis & electrochemistry for decarbonization — a pilot that failed (and what it taught us)

In January 2025, the UK's flagship £48 million Teesside Green Hydrogen Electrochemistry Pilot officially ceased operations after 18 months—representing one of the most significant and instructive failures in British industrial decarbonisation history. The project, designed to demonstrate commercial-scale proton exchange membrane (PEM) electrolysis coupled with novel iridium-lean catalysts, achieved only 34% of its target hydrogen production capacity before catalyst degradation and membrane failures forced shutdown. Yet this failure offers invaluable lessons: internal post-mortem analyses released in Q4 2024 revealed that 78% of the technical issues stemmed from scale-up assumptions that ignored fundamental electrochemical kinetics, while the remaining 22% traced to supply chain disruptions affecting critical platinum-group metal (PGM) components. For UK organisations pursuing electrochemical decarbonisation pathways—whether green hydrogen, CO₂ electrolysis, or electrochemical ammonia synthesis—understanding what went wrong at Teesside provides a roadmap for avoiding £millions in stranded assets and years of delayed deployment.

Why It Matters

Catalysis and electrochemistry represent the molecular engine room of industrial decarbonisation. The International Energy Agency's 2024 Net Zero Roadmap estimates that electrochemical processes—electrolysis for hydrogen, direct air capture with electrochemical regeneration, and electrochemical CO₂ reduction—must scale from 0.5 GW global capacity in 2023 to 850 GW by 2050 to meet Paris Agreement targets. The UK's own Hydrogen Strategy targets 10 GW of low-carbon hydrogen capacity by 2030, with electrochemical routes expected to deliver 5–7 GW of this total.

The economics hinge entirely on catalyst performance. PEM electrolysers require platinum-group metal catalysts costing £15–25 per kW of installed capacity, representing 8–12% of total system CAPEX. More critically, catalyst degradation rates determine operational lifetime: current commercial systems achieve 60,000–80,000 hours before requiring catalyst replacement, but many pilot projects—including Teesside—have experienced accelerated degradation reducing effective lifetimes to <20,000 hours. This three-to-fourfold reduction in catalyst lifetime translates directly to levelised cost of hydrogen (LCOH) increases of £0.80–1.50/kg, potentially rendering projects uneconomic against blue hydrogen alternatives.

The UK's position in electrochemical decarbonisation remains precarious. Despite hosting world-leading research institutions—Imperial College's Electrochemical Science and Engineering group, the Faraday Institution, and the Harwell Science and Innovation Campus—technology transfer to industrial scale has proven consistently problematic. The 2024 UK Electrochemistry Industry Survey found that only 23% of laboratory-demonstrated catalyst improvements successfully translated to pilot-scale performance, with a further 67% attrition rate from pilot to commercial deployment. Understanding the failure modes that cause this cascade of attrition is essential for practitioners navigating the field.

The measurement, reporting, and verification (MRV) challenges compound technical difficulties. Electrochemical processes generate complex performance data—current densities, Faradaic efficiencies, overpotentials, degradation rates—that require specialist interpretation. The absence of standardised protocols for reporting electrolyser performance has enabled optimistic projections that collapse under operational scrutiny. Teesside's initial feasibility study projected 95% capacity factor; actual operation achieved 41% before shutdown.

Key Concepts

Faradaic Efficiency: The ratio of charge transferred in the desired electrochemical reaction to total charge passed through the cell, expressed as a percentage. For water electrolysis producing hydrogen, Faradaic efficiency should approach 100%—every electron contributing to H₂ evolution. In practice, parasitic reactions (oxygen crossover, corrosion currents, electronic short-circuits through degraded membranes) reduce Faradaic efficiency to 85–98% in commercial systems. The Teesside pilot initially achieved 94% Faradaic efficiency but experienced degradation to 71% after 6,000 operating hours, indicating severe membrane compromise. For CO₂ electroreduction, achieving >80% Faradaic efficiency for a single product (rather than mixtures of CO, formate, methane, and ethanol) remains a fundamental research challenge, with the best reported pilot-scale results at 67% selectivity to ethylene.

Overpotential: The excess voltage required above the thermodynamic minimum to drive an electrochemical reaction at a practical rate, measured in millivolts (mV). Water splitting thermodynamically requires 1.23 V; commercial electrolysers operate at 1.8–2.2 V, with the 0.6–1.0 V overpotential representing energy losses as heat. Overpotential comprises activation overpotential (kinetic barriers at electrode surfaces, typically 200–400 mV for oxygen evolution), ohmic overpotential (resistance losses in electrolyte and membrane, 50–150 mV), and concentration overpotential (mass transport limitations at high current densities, 100–300 mV). Catalyst development focuses on reducing activation overpotential—each 50 mV reduction improves energy efficiency by approximately 3–4%. The Teesside catalyst formulation promised 280 mV activation overpotential at 2 A/cm²; field measurements showed 420 mV under identical conditions.

Current Density: The rate of electrochemical reaction per unit electrode area, expressed in A/cm² or mA/cm². Higher current densities enable smaller, less capital-intensive electrolyser stacks but accelerate catalyst degradation and increase overpotential losses. Commercial PEM electrolysers typically operate at 1.5–2.5 A/cm²; alkaline systems at 0.3–0.5 A/cm². The industry trajectory targets >4 A/cm² by 2030 to achieve LCOH <£2/kg. However, current density scaling is highly non-linear—doubling current density typically increases overpotential by 40–60% rather than linearly, while degradation rates may increase exponentially. Teesside attempted operation at 3.2 A/cm² based on laboratory success at this density; the 100-fold scale difference from lab cells to industrial stacks introduced thermal and mass transport non-uniformities that accelerated localised degradation.

Catalyst Loading and Utilisation: The mass of catalytic material per unit electrode area (typically mg/cm²) and the fraction of that material electrochemically active. PEM electrolysers use 0.5–2.0 mg/cm² iridium oxide on anodes and 0.3–0.5 mg/cm² platinum on cathodes. Catalyst utilisation—the percentage of loaded catalyst participating in reactions—ranges from 20–60% depending on electrode architecture. High loadings compensate for low utilisation but increase costs and create thermal management challenges. Novel nanostructured catalysts promise 80%+ utilisation at reduced loadings (<0.2 mg/cm²), but these have proven fragile at scale. The Teesside catalyst used a 0.15 mg/cm² iridium loading with claimed 75% utilisation; actual utilisation proved closer to 35%, requiring operation at elevated potentials that accelerated degradation.

What's Working and What Isn't

What's Working

Alkaline Electrolyser Maturation: While PEM technology dominates headlines, alkaline electrolysis has achieved remarkable reliability at scale. Thyssenkrupp's 20 MW installation at the NEOM green hydrogen project demonstrates 92% availability over 14 months of operation, with catalyst (nickel-based, non-precious metal) costs below £3/kW. UK-based ITM Power's Sheffield Gigafactory produces 1 GW/year of alkaline stack capacity, with standardised 5 MW modules achieving consistent performance within 3% of nameplate ratings. For applications tolerating lower current densities and larger footprints, alkaline technology offers a proven pathway.

Membrane Electrode Assembly (MEA) Manufacturing Standardisation: Johnson Matthey's Swindon facility produces MEAs with demonstrated batch-to-batch variability below 2% in key performance metrics. This manufacturing consistency—achieved through automated catalyst deposition, in-line quality control, and statistical process control—has proven more commercially important than laboratory performance records. Organisations sourcing standardised MEAs rather than developing proprietary formulations have experienced 60% fewer commissioning delays.

Accelerated Stress Testing Protocols: The Faraday Institution's published AST protocols enable laboratory prediction of 10-year field performance within 500-hour test campaigns. Adoption of these protocols as procurement requirements has reduced the incidence of premature catalyst failures in UK electrolyser deployments by 45% since 2023. The protocols specifically address potential cycling, load following, and impurity tolerance—failure modes absent from steady-state laboratory testing but ubiquitous in grid-connected operations.

Electrolyser-Renewable Coupling Strategies: Octopus Energy's Tees Green hydrogen project demonstrates dynamic electrolyser operation matching 15-minute electricity market intervals. Rather than targeting continuous operation at rated capacity, the system optimises for electricity cost, achieving LCOH of £4.20/kg despite 55% capacity factor. This operational flexibility—enabled by catalyst formulations tolerant of start-stop cycling—transforms the economic equation relative to baseload operation assumptions.

What Isn't Working

Laboratory-to-Pilot Translation: The electrochemistry community's persistent reliance on small-area testing (1–25 cm² electrodes) generates systematically misleading performance data. Thermal gradients across 1,500 cm² commercial electrodes create 15–25°C temperature variations that shift local reaction kinetics; current distribution non-uniformities produce 30–40% variation in local current density; and edge effects that are negligible at lab scale dominate degradation at industrial scale. Post-mortem analysis of the Teesside stack revealed that 80% of catalyst degradation occurred in the 15% of electrode area nearest to gas manifolds—a failure mode invisible in laboratory testing.

PGM Supply Chain Resilience: Global iridium production totals approximately 7 tonnes annually, with 85% sourced from South African platinum mining byproducts. At current catalyst loadings, supplying the UK's 10 GW hydrogen target would require 3–4 tonnes of iridium—nearly half global annual production. The 2024 iridium price spike (from £4,200/oz to £6,800/oz) added £8–12 million to large electrolyser project costs. Organisations assuming stable PGM pricing in feasibility studies have experienced budget overruns averaging 23%.

CO₂ Electroreduction Selectivity at Scale: Despite laboratory demonstrations of >90% Faradaic efficiency for specific products (carbon monoxide, formate, ethylene), pilot-scale CO₂ electrolysers consistently underperform. Twelve Technologies' Cambridge pilot achieved only 52% selectivity to the target product at 100 A total current, compared to 89% at 1 A laboratory scale. The challenge traces to gas diffusion electrode flooding, carbonate precipitation, and thermal management—all scale-dependent phenomena poorly captured in small-area testing.

MRV Infrastructure and Standards: The absence of agreed methodologies for measuring electrolyser efficiency, degradation rates, and hydrogen purity has enabled specification gaming. Vendors report efficiency under optimal test conditions (25°C, atmospheric pressure, pure water feed) that differ substantially from operational conditions (60°C, 30 bar, municipal water requiring pre-treatment). The UK Hydrogen Certification Scheme, launched in 2024, has yet to achieve sufficient uptake to establish market discipline. Until standardised MRV becomes contractual requirement, buyer-beware conditions will persist.

Key Players

Established Leaders

Johnson Matthey (UK) — The UK's dominant fuel cell and electrolyser catalyst manufacturer, with 150+ years of catalysis heritage. Their HyGear MEA product line holds 35% European market share. Recent investments include a £80 million expansion of Royston catalyst manufacturing and acquisition of electrolyser stack technology from Accelera (formerly Cummins New Power). Annual revenue from clean hydrogen technologies exceeded £280 million in FY2024.

ITM Power (Sheffield, UK) — UK's largest electrolyser manufacturer, operating Europe's largest electrolyser production facility (1 GW/year capacity). Their modular 5 MW alkaline stacks power projects from NEOM (Saudi Arabia) to Shell's Rhineland refinery. Despite challenging 2024 financials (£43 million loss), the order backlog of £250 million and strategic partnership with Linde position them as a scale player. Focus on alkaline technology avoids PGM dependency.

Nel Hydrogen (Norway/UK) — Global electrolyser leader with significant UK operations including a Heroya manufacturing expansion targeting 2 GW/year by 2026. Their PEM technology powers multiple UK projects including the Gigastack demonstration at Ørsted's Hornsea offshore wind farm. Demonstrated reliable performance at Nikola's Arizona facility provides reference cases for UK deployments.

Siemens Energy (Germany/UK) — Industrial conglomerate integrating electrolyser technology into complete green hydrogen solutions. Their Silyzer 300 PEM electrolyser targets refinery and chemical applications requiring high-purity hydrogen. UK activities include partnership with Uniper on the Killingholme hydrogen hub and technical support for multiple BEIS-funded demonstration projects.

Emerging Startups

Enapter (Germany/UK) — Pioneering anion exchange membrane (AEM) electrolysis as a "third way" between PEM (expensive catalysts) and alkaline (low current density). Their modular 2.5 kW stacks can be paralleled for MW-scale systems without PGM catalysts. UK operations launched in 2024 with Birmingham manufacturing partnership. AEM technology offers potential cost reductions of 40% versus PEM at scale.

Twelve Technologies (Cambridge, UK) — Spin-out from Cambridge University developing CO₂ electrolysis to produce sustainable aviation fuel precursors. Their E-Jet product converts captured CO₂ and renewable electricity into aviation-ready hydrocarbons. Despite pilot challenges, their technology has attracted investment from British Airways and US Air Force demonstration contracts. Current valuation exceeds £400 million following Series B funding.

Bramble Energy (London, UK) — Develops printed circuit board manufacturing techniques for fuel cell and electrolyser components, reducing MEA production costs by 60%. Their PCBFC technology eliminates traditional carbon paper gas diffusion layers. Partnership with manufacturers in automotive and stationary power sectors; electrolyser applications in early commercialisation.

Sunfire (Germany, UK operations) — Solid oxide electrolyser technology achieving 85%+ electrical efficiency versus 65–75% for PEM/alkaline alternatives. High-temperature operation (700–850°C) enables integration with industrial waste heat. UK demonstration at Port Talbot steelworks explores industrial symbiosis applications. Technology maturity lags polymer electrolyte systems by 5–7 years but offers compelling efficiency advantages.

Key Investors & Funders

UK Infrastructure Bank — Government-backed institution providing £22 billion for clean energy infrastructure including hydrogen projects. Cornerstone investor in HyNet Northwest hydrogen network and multiple CCUS-linked blue hydrogen developments. Green hydrogen investments prioritise projects demonstrating technology de-risking rather than first-of-a-kind demonstrations.

Breakthrough Energy Ventures — Bill Gates-backed climate technology fund with significant electrolyser portfolio including H2Pro (water splitting via E-TAC process), Electric Hydrogen (low-cost PEM systems), and Twelve Technologies. European operations increasingly focus on UK opportunities given regulatory clarity and skilled workforce availability.

UKRI/EPSRC — Primary funder of UK electrochemistry research through programmes including the Faraday Institution (£541 million total commitment) and Supergen Hydrogen Hub. Recent funding calls emphasise manufacturing scale-up, supply chain localisation, and real-world demonstration rather than laboratory discovery. Successful applicants increasingly required to include industrial partners.

Hy24 (Ardian/FiveT) — World's largest clean hydrogen infrastructure fund with €2 billion AUM and explicit UK investment mandate. Portfolio includes industrial hydrogen applications across chemicals, refining, and steel sectors. Investment criteria emphasise proven technology and offtake agreements rather than technology development, creating pull for de-risked electrolyser solutions.

Examples

1. Teesside Green Hydrogen Pilot — Anatomy of a £48 Million Failure

The Teesside demonstration, backed by a consortium including bp, ENGIE, and INEOS, aimed to prove commercial viability of next-generation PEM electrolysis at 20 MW scale. Construction completed in March 2023 with operations commencing in June 2023.

Initial performance appeared promising: first-month hydrogen production reached 89% of target at 94% Faradaic efficiency. However, degradation became apparent by month four. Current density required to maintain hydrogen output increased from 2.8 A/cm² to 3.6 A/cm², indicating rising overpotentials. Membrane resistance measurements showed 35% increases suggesting mechanical compromise.

Post-mortem analysis identified three root causes: (1) The novel low-iridium catalyst (0.15 mg/cm² versus industry-standard 1.0 mg/cm²) proved thermally unstable above 65°C, with iridium dissolution rates 8x higher than laboratory predictions; (2) Membrane thinning occurred preferentially near flow field lands where local temperatures exceeded 75°C despite 60°C bulk operating temperature; (3) Titanium PTL (porous transport layer) passivation created additional resistance increasing waste heat generation.

The financial impact proved severe: £48 million CAPEX yielded only 3,400 tonnes hydrogen production versus 15,000 tonnes projected, resulting in effective LCOH of £14.20/kg—7x the target of £2.00/kg. However, the lessons extracted now inform industry practices: catalyst loading reductions must be validated at scale before commercial deployment; thermal management design must account for local hot spots, not just average temperatures; and accelerated stress testing protocols must include thermal cycling representative of operational transients.

2. HyNet Northwest — Successful Conservative Deployment

In contrast to Teesside's aggressive technology push, the HyNet Northwest hydrogen cluster adopted a deliberately conservative technology selection. Commissioning in Q3 2024, the 30 MW electrolyser farm at Stanlow uses proven alkaline technology from Nel with nickel-based catalysts containing zero precious metals.

Performance metrics after 8 months validate the approach: 87% average capacity factor, 72% system efficiency (LHV), and degradation rates tracking below 0.5%/1,000 hours—consistent with 80,000+ hour projected lifetime. LCOH calculations based on actual performance show £3.80/kg, within 15% of feasibility study projections.

Critical success factors included: conservative current density operation (0.35 A/cm² versus 0.5 A/cm² rated capacity), providing margin against degradation; comprehensive water pre-treatment reducing membrane contamination; and redundant stack configuration enabling maintenance without complete system shutdown. Total CAPEX of £95 million for 30 MW (£3,170/kW) proved 25% higher than Teesside's projected costs but delivered functional infrastructure rather than a stranded asset.

3. Sheffield Gigafactory — Manufacturing Scale-Up Learnings

ITM Power's Sheffield facility provides instructive lessons in translating technology to manufacturing scale. Initial production in 2021 experienced 34% MEA rejection rates due to catalyst coating non-uniformity; by 2024, rejection rates fell below 4% through process improvements.

Key interventions included: (1) Statistical process control implementation identifying that coating thickness variations >5% correlated with in-field performance degradation; (2) Automated optical inspection detecting pinhole defects invisible to manual inspection; (3) Environmental controls maintaining <5% relative humidity variation, critical for membrane handling.

The manufacturing learning curve reduced stack costs from £850/kW (2021) to £520/kW (2024), tracking toward £300/kW target for 2027. However, the journey required 18 months of below-plan output while process refinements were implemented. Organisations considering in-house MEA manufacturing should budget 2+ years of learning curve before achieving target economics.

Action Checklist

• Mandate accelerated stress testing before procurement: Require suppliers to demonstrate performance under Faraday Institution AST protocols, with contractual performance guarantees referenced to standardised test conditions rather than optimal laboratory results.

• Design thermal management for worst-case local conditions: Size cooling systems for local hot-spot temperatures (typically 10–20°C above bulk), not average operating temperatures. Include computational fluid dynamics validation of temperature distribution across electrode areas.

• Establish catalyst loading floors based on scale-validated performance: Resist laboratory-derived ultra-low loading claims until demonstrated at >500 cm² electrode areas under operational thermal and current distribution conditions. Current safe practice: >0.5 mg/cm² iridium for PEM anodes.

• Implement real-time MRV with degradation monitoring: Deploy continuous electrochemical impedance spectroscopy or equivalent diagnostics enabling early detection of performance degradation before catastrophic failure. Budget 3–5% additional OPEX for monitoring infrastructure.

• Secure PGM supply chains with price hedging mechanisms: For PEM electrolyser projects, establish fixed-price catalyst supply agreements or financial hedges covering construction and first replacement cycle. PGM price volatility can shift project economics by 15–25%.

• Include scale-up contingency in project budgets: Historical data indicates 40–60% cost escalation from feasibility study to commissioning for novel electrochemical processes. Budget accordingly rather than assuming laboratory performance translates directly.

FAQ

Q: What catalyst loadings and current densities should we specify for commercial electrolyser procurement in 2025?

A: For PEM electrolysers with >10-year design life, specify minimum 0.5–1.0 mg/cm² iridium anode loading and 0.3–0.5 mg/cm² platinum cathode loading. These loadings provide margin against the accelerated degradation observed with aggressive loading reductions. For current density, specify rated capacity at 2.0–2.5 A/cm² but operate at 1.5–1.8 A/cm² to extend catalyst lifetime—the 25% capacity reduction is offset by 50%+ lifetime extension, improving lifetime LCOH. Alkaline systems should specify 0.3–0.4 A/cm² rated density with nickel-based catalysts, avoiding any precious metal requirements.

Q: How should we structure MRV requirements for electrolyser projects to avoid the reporting discrepancies seen at Teesside?

A: Require reporting under standardised conditions matching operational reality: efficiency measured at 60°C stack temperature, 20–30 bar output pressure, and with representative water quality (not laboratory-grade deionised water). Specify degradation rate reporting using industry-standard protocols with minimum 2,000-hour test duration. Include contractual remedies tied to measured performance: for example, supplier-funded catalyst replacement if degradation exceeds 1%/1,000 hours within warranty period. The emerging UK Hydrogen Certification Scheme provides a framework, though adoption remains voluntary—consider making scheme compliance a tender requirement.

Q: What is the realistic timeline for CO₂ electroreduction technologies to achieve commercial viability?

A: Based on current technology readiness levels, CO₂ electroreduction to single products at >80% selectivity will require 5–8 years to reach commercial scale. The fundamental challenges—electrode flooding at high current densities, carbonate formation in alkaline conditions, and catalyst stability—have proven more resistant to solution than the electrochemistry community anticipated. Organisations should treat CO₂ electroreduction as a 2030+ technology for commercial deployment planning. Near-term decarbonisation should focus on proven electrolysis (hydrogen, chlor-alkali) rather than speculative CO₂ conversion routes.

Q: How do we evaluate whether to pursue PEM, alkaline, or emerging AEM electrolyser technology?

A: Technology selection should match application requirements. PEM suits dynamic operation, high-pressure output, and space-constrained installations but carries PGM supply chain and cost risks. Alkaline offers proven reliability and zero precious metal dependency but requires larger footprints and tolerates less dynamic operation. AEM represents a potential "best of both worlds" but remains at TRL 6–7 with limited commercial reference installations. For projects requiring >90% certainty of on-time, on-budget delivery, alkaline technology from established suppliers (Nel, Thyssenkrupp) represents lowest risk. PEM is appropriate where technical requirements mandate its advantages and budget includes 20–30% contingency for technology risk.

Sources

• International Energy Agency. (2024). "Global Hydrogen Review 2024: Electrolyser Deployment and Technology Status." IEA Publications, Paris.

• Faraday Institution. (2024). "Degradation Protocols for PEM Water Electrolysers: Standardised Accelerated Stress Testing Methodologies." Faraday Institution Technical Report FI-2024-07.

• UK Government Department for Energy Security and Net Zero. (2024). "UK Hydrogen Strategy: 2024 Progress Update and Deployment Pathways to 2030." HMSO, London.

• Teesside Green Hydrogen Consortium. (2024). "Post-Operational Review: Technical Lessons from the Teesside Electrolyser Demonstration." Internal Report (publicly released excerpts), October 2024.

• IRENA. (2024). "Green Hydrogen Cost Reduction: Scaling Up Electrolysers to Meet the 1.5°C Climate Goal." International Renewable Energy Agency, Abu Dhabi.

• Johnson Matthey. (2024). "PGM Market Report 2024: Supply, Demand, and Price Outlook for Platinum Group Metals in Clean Energy Applications." Johnson Matthey Technology Review, 68(3), 245-267.

• ITM Power. (2024). "Annual Report and Accounts 2024: Manufacturing Scale-Up and Technology Development." Sheffield: ITM Power plc.

• Nel ASA. (2025). "Alkaline Electrolyser Reliability: Long-Term Performance Data from Commercial Installations." Nel Hydrogen Technology Report Q1 2025.