Hydrogen production for a decarbonized future: a review of production technologies

Abstract

Hydrogen is increasingly viewed as an essential element in the global transition toward low-carbon and sustainable energy systems. This review systematically evaluates the major hydrogen production pathways, spanning mature fossil-based processes, steam methane reforming, dry methane reforming, catalytic methane decomposition, and coal gasification, to emerging renewable routes including biomass gasification, water electrolysis, photolytic methods, and biological/biochemical processes. Each technology is critically assessed through integrated techno-economic and environmental analyses, examining efficiency, carbon intensity, technological readiness levels, and scalability potential. Life cycle assessments reveal that conventional methods, while cost-effective ($1.25–2.27/kg H2), generate substantial CO2 emissions (9–20 kg CO2-eq/kg H2). Conversely, renewable pathways demonstrate significantly lower environmental impacts but face economic and technological barriers limiting commercial deployment. Key challenges identified include catalyst deactivation, high capital costs for electrolyzers, and low efficiencies in photolytic systems (∼5%). The review establishes strategic research priorities: developing durable, cost-effective catalysts; advancing high-temperature electrolysis technologies; integrating renewable energy systems; and scaling photobiological platforms. This analysis provides actionable insights for researchers, industry stakeholders, and policymakers to accelerate hydrogen technology development and deployment, supporting the transition toward a sustainable, hydrogen-based energy economy aligned with net-zero emission targets.