Integrated techno-economic assessment of blue hydrogen production via steam methane reforming and autothermal reforming with carbon capture

Hydrogen is a key energy carrier in the transition toward low-carbon energy systems, with blue hydrogen representing an important bridging technology between gray and green hydrogen. This study presents, for the first time, a unified first-law Sankey-based framework combining rigorous reboiler modeling, thermodynamically consistent absorber-stripper column design, and techno-economic and environmental evaluation for steam methane reforming and autothermal reforming with amine- based carbon capture, providing quantitative guidelines for auxiliary boiler design and whether it can be completely eliminated through steam-to-reboiler integration. Gray hydrogen shows lower production costs, with 1.274 USD/kg for steam methane reforming and 1.634 USD/kg for autothermal reforming. For blue hydrogen, optimized capture designs yield 1.631 USD/kg for steam methane reforming and 1.875 USD/kg for autothermal reforming, including transport costs for a 200 km pipeline. Steam-to-reboiler integration reduces the energy penalty, boosting hydrogen efficiency by up to 8.84%, and eliminates auxiliary firing for autothermal reforming. Under grid electricity, blue steam methane reforming attains the lowest emissions at 3.98 kg CO 2 ,eq /kg H 2 , whereas under renewable electricity, blue autothermal reforming becomes the most carbon-efficient pathway at 3.33 kg CO 2 ,eq /kg H 2 . Blue steam methane reforming costs are primarily driven by natural gas price, while blue autothermal reforming is additionally sensitive to electricity price due to the air separation unit demand. The results highlight how reformer technology, heat integration, and capture design jointly shape the cost and carbon intensity of blue hydrogen.