From electrolyzer tradeoffs to certified green hydrogen deployment through hydrogen valleys

Green hydrogen projects are not shaped by electrolyzer performance alone. Even a technically efficient system can be difficult to deploy if renewable supply, local infrastructure, or certification rules are poorly matched to it. This review considers these issues together. AEL, PEM, AEM, and SOEC are compared on a common 2030 basis using specific electricity consumption, minimum operating load, stack lifetime, and TRL. Min–max normalization, published techno-economic studies, and sensitivity analysis are used to examine the trade- offs. There is no single technology which excels in all aspects. SOEC has the lowest specific electricity consumption at 38 kWh kg −1 H 2 , while AEL and PEM are both at 50 kWh kg −1 H 2 and AEM at 55 kWh kg −1 H 2 . AEL stands out for maturity and durability, whereas PEM combines high maturity with greater flexibility under variable renewable input. The hydrogen-valley analysis shows a strong European concentration, frequent use of mixed renewable configurations, and predominantly multi-sector end uses, alongside persistent reporting gaps. Certification frameworks differ in greenhouse gas accounting, additionality, temporal and geographical correlation, traceability, market access, and bankability. Overall, the findings show that viable green hydrogen deployment depends on the combined fit between technology performance, territorial design, and regulatory eligibility.