Meta-study and environmental techno-economic assessments (eTEAs) of blue hydrogen processes

Blue hydrogen, produced by retrofitting conventional hydrogen technologies with carbon dioxide (CO₂) capture (CC) systems, offers a low-carbon alternative to gray hydrogen and a transitional pathway alongside green hydrogen, which is generated through renewable-energy-powered water electrolysis. While studies indicate that cradle-to-plant-exit emissions for blue hydrogen can approach those of green hydrogen, inconsistent assumptions in techno-economic and life-cycle assessments, such as variations in plant location, feedstock type, and production scale, complicate direct comparisons and hinder the development of standardized benchmarks. This work addresses these challenges by conducting a systematic literature review of recent environmental techno-economic assessments for blue hydrogen production. A key contribution is the application of a consistent set of assumptions, system boundaries, and definitions to harmonize and standardize the reported data. By providing a unified framework for evaluating blue hydrogen technologies, this study resolves discrepancies in prior assessments and facilitates more accurate comparisons across studies. Implementing CC technologies on conventional hydrogen production can reduce life cycle CO₂ emissions by around 60 % (comparable to that of green hydrogen) with a cost increase of only 30 % compared to unabated gray hydrogen. Producing green hydrogen results in costs up to three times higher than gray hydrogen and more than double that of blue hydrogen. These results offer valuable insights for policymakers and industry stakeholders to support the adoption and optimization of low-carbon hydrogen technologies.