Hydrogen production is provided via integrated closed-loop processing of landfill gas (LFG) and solid biomass feedstocks such as various agricultural wastes with minimal environmental impact. LFG is purified of harmful contaminants over a bed of activated charcoal (AC) and is catalytically reformed to synthesis gas, which is further processed to pure hydrogen via CO-shift and pressure-swing adsorption stages. Biomass is gasified in the presence of steam with production of a producer gas and AC. The producer gas is mixed with LFG and is processed to hydrogen as described above. High-surface area AC produced in the gasifier is used for the purification of both LFG and producer gas. An integrated processing of LFG and biomass offers a number of advantages such as a high overall energy efficiency, feedstock flexibility, substantial reduction in greenhouse gas emissions and production of value-added product-biocarbon that can be used as a soil enhancer.