Περιβαλλοντική και οικονομική αποτίμηση μιας μονάδας αναερόβιας χώνευσης μικρής κλίμακας: εμπειρική ανάλυση
Environmental and economic valuation of a small scale anaerobic digestion plant: empirical analysis
Μεζαρί, Λάουρα - Ειρήνη
The total amount of urban, agricultural and animal waste is constantly increasing. Yearly huge quantities are produced that must be legally and safely available without any negative impact on the environment. In addition, the availability of sufficient renewable energy is very important, as the environmental problems caused by the increased use of fossil fuels are rapidly contributing to the worsening of climate change. This dissertation deals with the application of anaerobic digestion for the processing of agricultural and animal waste with the aim of producing biogas. Anaerobic digestion is a process that aims to produce energy. Through the use of bacteria and in the absence of oxygen, the organic matter contained in organic waste is processed and biogas and organic compost (compost) are produced. A key advantage of this process is that organic wastes are not oxidized at high temperature (such as thermal methods), but they are processed between 38 and 42 °C. Biogas utilization avoids the release of methane (CH4), a gas with great contribution to the greenhouse effect. The compost produced is a first class organic fertilizer, both in liquid and solid form. With plant uptake through photosynthesis and the production of new biomass, it is ensured that the carbon dioxide (CO2) that is finally produced is captured in the biomass, so that the ecological balance is not disturbed. Unlike the process of burning garbage, biogas does not release dioxins and furans that burden the environment. The application of anaerobic digestion results in the minimization of organic waste for final disposal, avoids the emission of gases and odors, and the use of renewable energy. The use of anaerobic digestion plants can actively contribute to the achievement of European targets for Renewable Energy Sources (RES). By 2020, 20% of the energy demanded in the EU should be from RES. In this study, the economics of the anaerobic digestion of small scale anaerobic digestion will be approached. The fact that plants will be of small size, is helping to increase the self-sufficiency of agricultural businesses in terms of energy demand and to reduce the station's dependence on fluctuations in energy market prices. Energy production can be controlled and take place all day, irrespective of the weather conditions, which affect other types of power plants from RES. Our goal is to increase the security of the energy supply without any greenhouse gas emissions. Furthermore, the proper management and availability of raw materials will be a key objective of the study and will be related to changes in processes such as the production, collection, transport and availability of feedstock. We will study how to find the best solution about the Greek PPC (Public Power Corporation) and the possibilities of connecting the biomass stations per region with the Grid, from the HEDNO (Hellenic Electricity Distribution Network Operator). Finally, there will be a reference to ways of informing about the energy use of biogas and the effort to finance such stations. Project analysis requires Strategic Energy Management (SEM) with the key goal of achieving energy efficiency improvements through systematic and scheduled changes to installation, maintenance, and project behaviors. The aim of the study will be to find the optimum solution both economically and environmentally, with the main goal of achieving sustainability, depending on the needs of the project. The development and implementation of models, indicators, methods and strategies are necessary for the realization of future green projects. The economic and environmental assessment will be done through an integrated financial analysis method, taking into account environmental factors as well. With regard to the further environmental and economic study of the power plant using the project data of 500 kW, indicators will also be used to analyze project data. The feedstock (characteristics and potential) will be assessed and their impact on the size of the plant that was undertaken. The input design parameters will be defined and their influence on the major key output elements was evaluated. Based on input data and their impact on plant performance, significant economic figures will be estimated, such as the Total Capital Expenditure - CAPEX, the annual sales of the anaerobic digestion plant and the estimation of the Total Operating Cost – OPEX. Following a number of assumptions and the above economic figures, the key feasibility indicators of the anaerobic digestion will be evaluated (NPV, discounted pay-back, IRR). Finally, a decision-making process will be discussed, based on the economic analysis of the investment taking into account an evaluation of opportunities and risks. So, data analysis and presentation will be made through bar graphs and pie, the research methodology will be reported and empirical results will be made on the environmental and economic assessment of the energy use of an anaerobic digestion plant using 500 kW of organic raw materials.