# Systematic Analysis of the Hydrogen Value Chain from Production to Utilization
## 1 Introduction
The present work aims to characterize the different hydrogen production, storage, transport and distribution technologies that compose the hydrogen value chain. Identifying the main advantages and disadvantages of each technology, as well as the main working parameters. This study is built on the extensive existing literature on hydrogen energy systems and the respective value chain. Typically, the studies available in the literature focus on individual phases of the value chain. In the production phase, [PERSON] et al. [13] analyzed the main hydrogen production technologies, assessing their respective cost, maturity, and environmental impact. [PERSON] et al. [14] reviewed the life cycle assessment performance of hydrogen production technologies. [PERSON] [15] analyzed and compared different commercially available water electrolysis systems, and [PERSON] et al. [16] explored the challenges and advancements in system designs and electrode materials engineered for seawater electrolysis for hydrogen production. Regarding storage and transportation, [PERSON] et al. [17] analyzed gaseous, liquid, and solid-state hydrogen storage systems, focusing on developments in hydrogen storage in metal hydrides. [PERSON] et al. [18] performed a systematic review to identify and assess the factors that influence the storage and transportation costs. [PERSON] et al. [19] explored the hydrogen strategies and roadmaps of different countries, highlighting the current maturity, challenges, and future directions of hydrogen storage and transportation technologies. In the end-use and hydrogen trends domain, [PERSON] et al. [20] reviewed and explored the developments, advantages and drawbacks of hydrogen economies and assessed the impact of these economies in various sectors, such as transport, industry, and power generation, while [PERSON] et al. [21] explored the role of hydrogen in decarbonizing the aviation and automotive industries. This research seeks to centralize information from all phases of the value chain within a single study and aims to update the technology readiness levels of each technology used in the different phases, in comparison to previous studies [22]. To achieve this, Section 2 analyses the main hydrogen production technologies, presenting the types of hydrogen produced, the technology efficiency, readiness level, and the respective levelized cost of hydrogen. Section 3 reviews the main hydrogen storage technologies, highlighting key characteristics, such as storage pressure and temperature, gravimetric and volumetric capacities, and TRLs. Section 4 presents the main hydrogen transportation and distribution technologies, highlighting the respective transportation costs. Section 5 introduces the four main sectors where hydrogen is expected to play a central role. Finally, Section 6 discusses the key challenges associated with the implementation of a large-scale green hydrogen economy. The conclusions obtained through this study should support researchers, decision-makers and the public in selecting hydrogen technologies, among the vast list of available technologies, that best fit the design of the specific hydrogen value chain for the case study at hand. Additionally, this study supports future research in addressing the specific challenges associated with scaling up the green hydrogen energy economy. Figure 1: Representation of hydrogen energy systems, with the respective production, storage, transport and distribution, and end-use phases.