engleski

Technical and Economic Analysis of Integrating Anaerobic Digestion with Sugar Production

The aim of this study is to investigate technical and economic aspects of integrating anaerobic digestion with sugar industry to replace natural gas used for heat and electricity taken from the grid for small-scale sugar beet processing. In 245 days when the sugar beet is not processed (March-October), riverbank residue grass and animal manure are daily utilised in the amount of 100 tonnes to produce 8, 000 Nm3/day of biogas. 21% of the produced biogas is stored on-site, while the rest is utilised for combined production of heat and electricity which are sold on the markets. Power of the biogas plant has been estimated on 474 kWel, while the optimum amount of biogas fed to Combined Heat and Power unit has been estimated on 4, 160 Nm3/day. In the period when the sugar beet processing starts, a part of biogas to cover energy demands for sugar beet processing is produced from sugar-beet by- products and animal manure. 63% of stored biogas is consumed, while the other part is considered for burning in a boiler, for achieving the required amount of biogas for optimum operation of heat and power unit at the biogas plant. Capital investment in the building of a biogas plant with compressor and storages is estimated on € 1, 940, 000. Economic analysis has shown that the payback period of the investment is around 5.7 years, while the internal rate of return is 16%. The net present value of the investment, using the discount rate of 10%, has been estimated on ca. € 600, 000 in the time frame of 14 years. Sensitivity analysis has shown that the price of generated electricity in cogeneration that is sold on the market plays the most important role in achieveing the economic feasability of the proposed system.

Sugar ; Anaerobic Digestion ; Heat ; Electricity ; Biogas ; Storage

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