Technoeconomic assessment for the viable exploitation of biomass residues by an innovative pyrolysis-anaerobic digestion processing plant.

In Greece, there is no organized practice in agricultural and animal wastes management. Their exploitation is still set aside, due mainly to economic reasons and lack of incentives for their efficient utilization. Therefore, in the present work a technoeconomic assessment for the environmentally friendly useful exploitation of biomass residues produced in the Prefectures of Ilia and Achaia (Western Greece) for the generation of energy by an integrated anaerobic digestion (AD)-pyrolysis processing plant was carried out. The processed biomass of the AD unit is corn residues and cattle manure, while the feedstock of pyrolysis unit is olive tree prunings. The residues will be transferred to collection areas by field tractors. Then an integrated harvester is used and afterwards, the residues are discharged from the lifting bin of the harvester to trucks and are transported to the processing unit. The total fixed capital for a capacity of 328,716 t/y is equal to 11.5 M€, while the initial working capital is equal to 2.1 M€. The total operational cost of this investment is estimated at 18.3 M€/y, the projected revenues amount to 21.4 M€/y and the net profit is equal to 3.1 M€/y. The return on investment is estimated at 23% and the payback period becomes equal to 4.4 years. From the sensitivity analysis becomes apparent that the capacity, the incentive cost, the fuel price, the products price and the total fixed capital affect significantly the investment characteristics of the proposed AD-pyrolysis processing unit. The amount of the expected profit is considered quite significant, and the evaluation criteria (return on investment and payback period) advocate for a more detailed examination of the investment plan, in the direction of undertaking the project.