Electricity generation and biofertilizer on a dairy farm using anaerobic biodigesters

Abstract

This study aimed at conducting a technical study and verifying the economic feasibility of implementing anaerobic digesters to treat waste from a dairy farm with 2,200 animals, aimed at scaling for power generation and production of biofertilizer, thus providing reduction of the environmental impact on the property and savings in production costs. The farm currently has a demand of energy 50.000 kWh month(-1) and comprises 875 ha exclusively for milk production. Calculations were carried out to establish how many digesters would be required, and from the project was established installer with flowchart, mass balance, and graphical design. Revenues were calculated with the use of biogas and biofertilizer to shoot down spending, respectively, electricity and chemical fertilizers. It was performed an economic analysis to verify the feasibility of the project. The planning horizon was 10 years, with four scenarios: 1) scenario 1: to establish the digesters considering an the average of a year production of biogas and biofertilizer; 2) loss of 50% in biogas production of scenario 1; 3) loss of 30% of the net income (milk production), which will affect the biogas, biofertilizer production, and energy generation; 4) loss of 40% of net income keeping the same conditions of scenario 3. It is concluded that about 39 tons of waste arising from the dairy property cease to be launched daily in the soil; through the process of anaerobic digestion for the generation of a clean and sustainable energy, bringing revenue to the transformation of biogas into electricity; the residue of the process of digestion gives rise to biofertilizer, reducing production costs, the study proved to be economically viable under the conditions of three scenarios, with a fall of 37% of net revenue (scenario 4), the project was not viable.