Abstract
Abstract Green hydrogen is emerging as a pivotal energy carrier in the global transition toward decarbonization, offering a sustainable alternative to fossil fuels in sectors such as heavy industry, transportation, power generation, and long-duration energy storage. Despite its potential, large-scale deployment remains hindered by significant economic, technological, and infrastructure challenges. Current production costs for green hydrogen range from USD 3.8 to 11.9/kg H2, significantly higher than gray hydrogen at USD 1.5–6.4/kg H2, due to high electricity prices and electrolyzer capital costs exceeding USD 2000 per kW. This review critically examines the key bottlenecks in green hydrogen production, focusing on water electrolysis technologies, electrocatalyst limitations, and integration with renewable energy sources. The economic viability of green hydrogen is constrained by high electricity consumption, capital-intensive electrolyzer costs, and operational inefficiencies, making it uncompetitive with fossil fuel-based hydrogen. Infrastructure and supply chain challenges, including limited hydrogen storage, transport complexities, and critical material dependencies, further restrict market scalability. Additionally, policy and regulatory gaps, disparities in financial incentives, and the absence of a standardized certification framework hinder international trade and investment in green hydrogen projects. This review also highlights market trends and global initiatives, assessing the role of government incentives and cross-border collaborations in accelerating hydrogen adoption. While technological advancements and cost reductions are progressing, overcoming these challenges requires sustained innovation, stronger policy interventions, and coordinated efforts to develop a resilient, scalable, and cost-competitive green hydrogen sector.