Thermodynamic and thermoeconomic analysis and optimization of biogas usage in electricity and hydrogen productions from wastewater treatment systems

In this thesis, we perform thermodynamic and thermoeconomic analysis and optimization of biogas usage in electricity and hydrogen productions from wastewater treatment systems. The procedure and formulations of the analyses are provided and applied to an actual municipal wastewater treatment plant and a biogas engine powered cogeneration system located in Gaziantep, Turkey [GASKI] using actual operational and cost data. The plant treats nearly 222,000 m3/day of domestic wastewater and as a result of the sludge stabilization in the plant, daily biogas generation is 10,000-18,000 m3. The annual electricity production of the cogeneration is 8760 GWh and the total annual biogas consumption is 3,400,000 m3. The overall exergetic efficiency of GASKI WWTP including BEPC system is found to be 46.2%. The specific unit exergetic costs for the treated wastewater and electricity produced are obtained to be 3.804 ¢/m3 and 25 $/GJ, respectively. Seven hydrogen production models for the present municipal wastewater treatment plant are developed and thermodynamic and economic analyses of these models are performed using the actual data obtained from GASKI WWTP and BEPC.Key words: Wastewater treatment, Cogeneration, Thermodynamic, Thermoeconomic, Optimization, Hydrogen production.