engleski

Utilization of biogas produced by anaerobic digestion of agro-industrial waste: energy, economic and environmental effects

Anaerobic digestion of agro-industrial waste is of increasing interest in order to facilitate a sustainable development of energy supply. Using of material and energy potentials of agroindustrial waste, in the framework of technical, ecological and economic possibilities, contributes in increasing share of energy generated from renewable energy sources. Enabling environment, which stimulates utilization of biogas as renewable energy source, represent significant contribution to achievement of objectives concerning the greenhouse gases (GHG) emission reduction. The paper deals with the benefits coming from the utilization of biogas produced by co- digestion of whey and cow manure. The experimental work of whey and cow manure co- digestion, performed in a series of laboratory batch experiments, has pointed out that one- stage batch process can be conducted efficiently under optimal conditions of substrate concentration, temperature and pH. The advantages of this process are the profitability of the plant and the convenience in realising an anaerobic digestion plant to produce biogas that is enabled by the benefits from the sale of electric energy at favourable prices. Economic aspects are related to the capital cost (2, 250, 000 €) of anaerobic digestion treatment in the biogas plant with a 300 kW power and 510 kW heat unit in a medium size farm (450 livestock units). Considering the optimal biogas yield of 20.7 dm3 kg-1 wet substrate and methane content in a biogas mixture that is 79%, the anaerobic process results with a daily methane production of 2, 500 kg, with the maximum power production that is 2, 160, 000 kWh y-1 and heat production that is 2, 400, 000 kWh y-1. The net present value (NPV), internal rate of return (IRR) and payback period for implementation of profitable anaerobic digestion process is evaluated. Ecological aspects related to carbon dioxide and methane emission reduction are assessed using methodology proposed by Intergovernmental Panel on Climate Change (IPCC).

Anaerobic digestion; agro-industrial waste; biogas; energy; environmental; economic

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