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Publikācija: Optimization Model of Biogas Use in Landfills in Latvia

Publication Type Conference paper
Funding for basic activity Unknown
Defending: ,
Publication language English (en)
Title in original language Optimization Model of Biogas Use in Landfills in Latvia
Field of research 2. Engineering and technology
Sub-field of research 2.7 Environmental engineering and energetics
Authors Ģirts Kuplais
Dagnija Blumberga
Elīna Dāce
Francesco Romagnoli
Keywords Biogas, Landfill, Optimization, Feed-in tariff
Abstract Utilization of landfill biogas in Latvia is based on energy production in power station placed close to landfill for different reasons. One of the most important reasons is financial state support of small scale power stations (4 MWe) from renewable energy resources. Such kind of support prevents both, development of waste sorting and utilization of refuse derived fuel in cement production, and biogas improvement to cover needs transportation sector or to connect to natural gas grid. Paper presents analysis of possibilities to utilize landfill biogas for electricity production in one of Latvia’s landfills. Analysis is based on selection of criteria and methodology for optimization of biogas utilization for energy production. The objective of the paper is to model optimal parameters of biogas utilization in Latvia’s landfills. Optimization refers to finding the values of decision (or free) variables, which correspond to and provide the maximum or minimum of one or more desired objectives. In this paper criteria and methodology for optimization of biogas utilization for energy production have been selected. Optimization target function includes engineering, greenhouse gas and economical parameters which are applied to foresee potential of landfill biogas utilization. Optimization model for biogas utilization in landfills includes four modules and is based on technological, climate and economical sub models. Economical sub model is based on investment costs, operational and maintenance expenses from one side, and on feed-in tariff, which depends on state energy policy, from the other side. Technological sub model includes different factors of small scale cogeneration units, which present installed capacity, operation hours, electricity and thermal energy relation and others. Climate sub model includes emission trading components based on green investment scheme, losses of green house gases and other parameters. Model of power production in landfill shows that feed-in tariff stated as financial support today in Latvia allows to reach economically feasible projects even in case if cogeneration unit is operated in power station regime (generates only electricity). Results show that state policy needs corrections to improve energy efficiency of biogas utilization for energy production. Results of economical optimization show that in case of low biogas quality (4 kWh/m3) the optimal installed capacity is 2.2MW. In case of biogas quality of 5 kWh/m3, optimal installed capacity is 2.8MW, and 3.4MW – in case of high biogas quality (6 kWh/m3). Results of technological optimization show that, the higher the installed capacity, the shorter the operation time of equipment. If assumed that operation time of the equipment could be 5 up to 10 years, then the installed capacity can be 0,5MW and higher. Results of the climate sub model show that the higher is installed capacity, the greater the reduction of greenhouse gas emissions. Besides that, it is not possible to reach extremum by using two objective functions (heat value of biogas and installed capacity), which have been used in case of economical and technological sub models, and it is necessary to introduce another objective functions. Conclusions of the paper are; 1. The analysis of three optimization sub models: technological, economical and climate presents that target function of optimization depends from the large number of independent variables (multi objective optimization models), however after their analysis only two of the independent parameters have been chosen: quality of biogas is characterized by heat value, whereas technological equipment is characterized by electrical capacity. 2. The economical optimization of biogas utilization in existing landfills shows that maximum value of benefits depends on quality and installed capacity of power station. Lower installed capacity and lower quality of biogas allows to reach lower benefits and savings. Whereas, higher installed capacity and higher quality of biogas allows to reach higher benefits and savings.
Reference Kuplais, Ģ., Blumberga, D., Dāce, E., Romagnoli, F. Optimization Model of Biogas Use in Landfills in Latvia. In: Book of Abstracts of the 7th International Conference “Organic Resources in the Carbon Economy” (ORBIT 2010), Greece, Heraklion, 29 Jun-3 Jul., 2010. Thessaloniki: Grafima Publ., 2010, pp.115-115.
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