Advancements in waste-to-hydrogen technologies across Asia: A critical review of thermal conversion process on hydrogen

The increasing energy demand and escalating waste generation in Asia have driven the exploration of sustainable waste-to-hydrogen (WtH) technologies. Hydrogen production via thermochemical waste treatment-particularly gasification, pyrolysis, and plasma-assisted process, offers a promising pathway to convert municipal solid waste, agricultural residues, and industrial waste byproducts into a clean energy carrier. Despite numerous studies on WtH, a comprehensive assessment linking process performance, techno-economic feasibility, and policy frameworks across Asian countries remains limited. This review bridges the gap by systematically examining over 200 recent publications to evaluate advancements, challenges, and prospects of hydrogen production through thermal treatment in the Asian context. Findings reveal substantial variations in feedstock composition, process efficiencies, hydrogen yields (30–65 %), and national policy frameworks. Plasma-assisted gasification demonstrates superior performance, with hydrogen contents reaching up to 50 vol% in syngas and notable reductions in CO₂ emissions, though high capital intensity remains a barrier. Economic assessments indicate a levelized cost of hydrogen between 2 and 6 USD/kg H₂, while environmental evaluations suggest reductions of 2–30 kg CO₂-eq per kg H₂ produced. Policy analysis highlights both enabling drivers, such as feed-in tariffs and renewable portfolio standards in Japan, Korea, and China, and persisting barriers related to financing, infrastructure, and regulatory inconsistencies. Overall, this review underscores that advancing WtH technologies in Asia requires coordinated efforts in pilot-scale validation, demonstration projects, and cross-sectoral collaboration. By overcoming technical and policy challenges, WtH can play a critical role in achieving Asia's net-zero and circular economy targets.