Waste-to-Hydrogen Technology: A Sustainable Approach to Waste Management

Abstract

This review provides a comprehensive analysis of waste-to-hydrogen (WtH) pathways for the conversion of various types of WtH, focusing on hydrogen generation, energy efficiency, environmental implications, and economic viability. The result shows that feedstock characteristics influence each pathway’s feasibility and performance. Thermochemical treatment, particularly gasification, demonstrates high hydrogen yield and the processing versatility of heterogeneous wastes. Hydrogen concentrations of 10–45 vol% can be obtained by dry gasification, while 35–55 vol% H2 and 70–90% carbon conversion can be obtained by plasma-assisted gasification. Hydrothermal gasification converts 45–70% of the energy in the feedstock, suitable for wet feedstocks. Pyrolysis produces H2-rich gas along with bio-oil and char, while plasma-assisted pyrolysis could enhance H2 production by up to threefold compared with conventional catalytic systems. Biological pathways are more suitable for wet and biodegradable wastes. Dark fermentation provides lower H2 recovery than thermochemical routes, whereas sequential dark and photo-fermentation improves substrate utilization, achieving hydrogen yields of 4.44–4.96 mol H2/mol glucose and hydrogen production efficiencies of 45.31–82.67%. Among the evaluated feedstocks, plastic waste achieved a hydrogen production rate of 189.6 kg H2/h, but also generated up to 4.3 kg CO2-eq/kg H2. Mixed plastic waste achieved 0.29 kg H2/kg waste at a levelized cost of hydrogen (LCOH) of 3.41 USD/kg H2. Integrated systems demonstrated performance improvements, including 71.3% energy efficiency for anaerobic digestion and gasification with heat recovery, 61.6% for gasification coupled with electrochemical CO2 reduction, and more than 99% CO2 capture in the latter configuration. The LCOH from investigated pathways vary from 0.3 to 13.37 USD/kg H2 for different feedstock, conversion technology, system configuration, and carbon management requirements. Overall, gasification appears promising for heterogeneous and energy-dense wastes, as well as biological routes for wet biodegradable fractions, while integrated configurations offer a promising strategy for balancing hydrogen recovery, energy efficiency, economic performance, and environmental impacts.