Biogas from anaerobic co-digestion of food waste and primary sludge for cogeneration of power and heat

Computational models of biogas production and a combined heat and power (CHP) system were developed using Aspen Plus software. Results indicated that a mixing ratio of 1:2 and mass flow of 132.42 tonnes/day, the maximum specific methane production obtained was 270 and 205 ml CH4/ gVS at thermophilic and mesophilic conditions respectively. The power production with the aforementioned values were 188.42 and 137.79 kW for both thermal conditions. Finally, an economic analysis for both scenarios was carried out using Ecuadorian renewable energy tariffs. A positive NPV values of £147,580 and £186,307 with a discounted payback period of 20.97 and 17.33 years were obtained for both scenarios respectively, assuming that the interest rate was 4.89% and a lifetime of 25 years.