Abstract
•Proposal of a novel MSW-fueled cogeneration system for power and hydrogen production•Comparison of proton exchange membrane and alkaline electrolyzers•Tri-objective optimization based on exergy efficiency, product cost, and CO2 emission•Better performance of alkaline electrolyzer in terms of levelized product cost
Efficient conversion of Municipal Solid Waste (MSW) into useful energy by anaerobic digestion is a sustainable method which received growing interest, particularly for small-scale decentralized energy systems. This paper aims at development of an efficient combined cogeneration cycle for production of electricity and hydrogen from biogas generated using anaerobic digestion of MSW. When it comes to the topping cycle, the proposed system makes use of a micro gas turbine, whose waste heat is converted to electricity by an absorption power cycle. This additional electricity is provided to a water electrolyzer, which uses it to generate hydrogen. Two types of electrolyzers, including the Proton Exchange Membrane Electrolyzer (PEME) and the Alkaline Electrolyzer (AE) are considered, and their performances (as a component of the overall suggested combined systems) are compared from economic and thermodynamic viewpoints. The CO2 emission index is also addressed, and tri-objective optimization based on exergy, cost, and emission indices is carried out to compare the two systems. Obtained results indicated important outcomes, including that the system integrated with PEME is superior in terms of exergetic performance and emissions, whereas the system with AE is superior in terms of economics. The former has a 3.0% greater efficiency and a 3.3% lower emissions at optimal point established by tri-objective optimization, while it has a 9.3% higher levelized product cost.