Simulation of the combined oxy-fuel combustion and electrolyte alka-line electrolysis for production of hydrogen

Carbon dioxide emissions and municipal solid waste are globally increasing, affecting the thin balance on Earth. Oxy-fuel combustion thermal power plants effectively reduce carbon dioxide emissions in the energy sector. However, carbon capture processes have a low over-all efficiency, which is a common disadvantage of this strategy. This thesis investigates the modelling using Aspen Plus of the Vantaan Energia waste-to-energy thermal power plant, taken as a reference case, to its retrofitting into a municipal solid waste oxy-fuel combustion thermal power plant with alkaline electrolysis cells. The simulation results report that the proposed design is not electrically self-sustainable, which requires an additional supply of 365.5 MWel. The electrical demand might be fulfilled by involving wind park design, which should have a nominal installed power of 1100 MW in order to smooth wind production fluctuations. The wind park installation could result in a higher cost of the system. Nevertheless, the simulation indicates the economic feasibility of the proposed municipal solid waste oxy-fuel combustion system owing to a massive produc-tion of thermal power for district heating purpose equal to 191.1 MW. The alkaline electroly-sis cells produce 278 MW of hydrogen fuel power. The oxy-fuel combustion system has an overall efficiency of 26.21%. The simulated retrofitted thermal power plant produces hydro-gen with a levelized cost of 0.851 EUR/kg. The simulated thermal power plant produces hydrogen and carbon dioxide with a ratio of 2.48:1 (H2-CO2), close to methanol production stoichiometric reaction. The reduction in hydrogen cost consecutively results in the eco-nomic feasibility of a methanol power plant, which would have a methanol selling price break-even cost of 0.221 EUR/kg. The exploitation of municipal solid waste effectively re-duces the cost of hydrogen. The proposed design is a promising strategy to cope with climate changes, by achieving carbon neutrality, as well as to produce cheap and clean hydrogen.