Evaluation of multi–hydrogen production for Afyon biogas plant from excess methane and by–product hydrogen sulfide through desulfurization process

Abstract

This study presents a detailed computational simulation of a hybrid hydrogen production system that integrates steam methane reforming (SMR) and hydrogen sulfide (H₂S) electrolysis, coupled with waste heat recovery, at the Afyon Biogas Power Plant (ABP). The plant operates with a capacity of 4000 kW and an exhaust gas temperature of approximately 767 K, converting 55 % of the biogas to energy, constrained by the limitations of both the turbine and biogas plant operations. Despite these constraints, a methane yield of up to 75 % from biomass is achievable. The surplus methane is converted into blue hydrogen via SMR, while H₂S, a byproduct of biogas production, undergoes electrolysis to generate green hydrogen. Additionally, gray hydrogen is separated and stored during the biogas production process. The system achieves a hydrogen production rate of 0.061 kg/s through optimization, comprising 91.4 % blue hydrogen, 8.18 % gray hydrogen, and 0.41 % green hydrogen. The energy and exergy efficiencies of the primary system are calculated to be 26.23 % and 22.99 %, respectively. The integration of waste heat recovery enhances these efficiencies to 76.21 % and 42.96 %. A techno-economic analysis indicates that the cost of electricity is 0.04644 $/kWh, while the average hydrogen production cost is 2.05 $/kg. The total investment cost (TIC) amounts to 21,177,230 $, with an estimated annual revenue of 4,702,000 $, yielding a payback period of 4.405 years. This study demonstrates the efficiency and economic feasibility of hydrogen production from waste products at the biogas plant, underscoring the viability of the proposed investment.