A techno-economic assessment for replacement of conventional fossil fuel based technologies in animal farms with biogas fueled CHP units

In this paper, a case study applied to an animal farm in Iran, covering both technical and economic aspects of biogas production using manure from livestock to replace fossil fuel used for heat and electricity generation is presented. The mentioned farm has 3058 dairy cows. Biogas production followed by small-scale combined heat and power (CHP) units based on a new dual fuel internal combustion engine (ICE) have replaced conventional technology used today, namely electricity from the grid and diesel fuel for heating via boiler technology. Results from the techno-economic studies reveal that alternative technology using biogas as fuel are superior compared to the conventional one, both from economic and environmental point of view. By evaluating the proposed model, the annual cost saving, percentage of system profitability index, and payback period are calculated as 73,159.31 $, 60.99% and 28.5 month, respectively. Replacing the conventional technology by biogas based technology results in 529.65 tons per year annual CO2 emission reduction for this typical animal farm. Finally, a sensitivity analysis is elaborated in order to show how the profitability of biogas CHP plants would vary due to changes of some key parameters such as prices of diesel fuel, electricity and electricity buyback.