Systematic review of green hydrogen and e-fuel integration in large-scale sector-coupled energy system models

The transition towards renewable energy has accelerated interest in green hydrogen and e-fuels as scalable solutions for decarbonising hard-to-electrify sectors. This paper presents a critical appraisal of the existing literature, supported by a systematic review of 271 peer-reviewed energy systems modelling studies that analyse the integration of green hydrogen and e-fuels into large-scale energy system models. The review applies a dual lens, assessing (i) the coverage of key supply-chain elements and (ii) the coverage of sectors and cross-sector flexibility options. It critically discusses the computational techniques used and the scope of the studies. The analysis shows a methodological concentration centred around the use of linear optimisation models. Across the literature, green hydrogen and e-fuel chains are typically modelled partially, with several cost- and loss-driving stages omitted or treated implicitly. The power sector is consistently well represented, whereas heating, transport, and industry are often simplified or omitted, and flexibility portfolios, such as thermal storage, electric-vehicle flexibility, and industrial demand response, are included in only a minor subset of studies. The potential consequences of these findings are discussed, and an evidence-based suggestion for hybrid modelling frameworks is provided to address the identified challenges and more effectively support robust strategic policymaking.