# Systematic Analysis of the Hydrogen Value Chain from Production to Utilization
## 6 Challenges to the Implementation of a Green Hydrogen Economy  
[PERSON] et al. [112] conducted a comparative analysis of world trends in hydrogen production. The study used the information presented in the IEA database, which considered information on hydrogen projects completed, ongoing, or in the planning phase until October 2021, and expanded it to October 2022. In total, 789 projects across 61 countries were considered. Most projects were established in Europe, with electrolysis as the dominant production method (722 projects). Completed projects were mostly experimental and laboratory installations, presenting a delay in the transition to industrial implementation. While electrolysis leads the future planning, most configurations are power-to-X with unspecified uses, and no new projects using alkaline or solid oxide electrolysis are planned post-2028, likely due to limited industrial-scale research.  
The previous study highlights the early-stage maturity of the green hydrogen economy, which remains largely focused on localized case studies, often limited to laboratory-scale implementations. There is a delay in scaling up the green hydrogen economy to achieve the energy objectives for hydrogen and strengthen the role of this energy vector as one of the cornerstones of the planned energy transition. The main challenges that condition this scale-up process are as follows:  
* The investment needed to support the transition from conventional hydrogen production methods to renewable methods, as green hydrogen production technologies require high initial capital expenditures [113].
* The complexity and expenditure of the storage process resulting from hydrogen's low volumetric density [92]. Physical-based storage is energy intensive and requires high-strength materials to handle the high-pressure values and/or cooling systems capable of achieving and maintaining low-temperature values [113; 114]. Although material-based storage has shown some potential to tackle this limitation, the technology remains at a low TRL.  
Figure 15: Schematic representation of hydrogen use in 2022 by sector and the projected hydrogen use for 2030 according to the Net Zero Emissions by 2050 scenario ([8]).  
* The development of hydrogen transporting infrastructure requires significant upfront investment [92]. The existing natural gas pipeline systems cannot be directly converted to transport pure hydrogen [114].
* The fragmentation of the current hydrogen market, which is lacking infrastructure and a consolidated regulatory framework [113]. Effective development of hydrogen economies also requires coordination and collaboration among the different players across the value chain. A purely free market approach may not foster such collaborations and could increase the risk of underinvestment in early-stage hydrogen projects and research activities, as these areas typically offer medium to long-term financial returns [113].
* The public perception of hydrogen safety may affect its acceptance [115].  
To overcome the main challenges pointed out and strengthen the advantages of building hydrogen value chains, future research should prioritize improving production, storage, and transportation technologies' efficiencies, reducing costs through technological innovations, and developing robust infrastructure solutions. This technological improvement should be accompanied by a greater focus on industrial-scale applications. At the same time, long-term policy and strategic frameworks should be developed to define clear pathways to design and deploy hydrogen value chains, offer certainty to investors, and promote cooperation between different stakeholders [55,115]. Public education on the advantages and safety and security features of green hydrogen is also essential to increase public acceptance and foster public-private partnerships [55].