1、Study of the energy potential of the biogas produced by an urban waste landfill in Southern SpainMontserrat Zamora Jorge Ignacio Pe rez Pe rezb,Ignacio Aguilar Pave sc, A ngel Ramos RidaoaSection of Environmental Technology, Department of Civil Engineering, University of Granada, 18071 Granada, Spai
2、nSection of Construction Engineering, Department of Civil Engineering, University of Granada, Granada, SpainReceived 8 April 2005; accepted 5 May 2005AbstractSanitary landfills have been and continue to be one of the most common ways to dispose of urban waste although such landfills inevitably gener
3、ate waste management problems. Landfills are an important source of anthropogenic CH4 emissions. In this sense the European Union has passed regulations regarding the effective management of biogas within the framework of an EU policy for renewable energies. The sealed landfill analyzed in this stud
4、y is an example of energy recovery, but in this case the biogas generated by the landfill is being re-used to produce electrical energy. This article presents the results of the economic viability study, which was carried out previous to the construction of the installation. The results based on the
5、 use of empirical and theoretical models show the biogas to have a 45% proportion of methane and an overall flowrate ranging from 250 to 550 N m3/h. It is presently being used to produce electricity amounting to approximately 4,500, 000 kW h/year. The economic viability of the installation was estim
6、ated by means of the Internal Recovery Rate (IRR) for an exploitation period of 7 years.Keywords: Landfill gas; Energy recovery; Renewable energy; Economic analysisContents1. Introduction11.1. Environmental impacts of landfill gas11.2. Landfill gas as a renewable energy source21.3. Legal questions21
7、.3.1. Directive 96/61/CE regarding the integrated prevention and control of pollution31.3.2. Directive 99/31/CE on landfilling of waste31.3.3. Resolution 97/C76/01 on an EU waste management strategy31.3.4. Communication regarding a strategy for the reduction of methane emissions42. An urban waste la
8、ndfill in Granada (Spain)52.1. Profile of the landfill52.2. Production and characterization of wastes62.3. Quantification of the theoretical production/yield of biogas62.3.1. Empirical estimate of biogas72.3.2. Theoretical and actual production of biogas83. Installation design103.1. Collection and e
9、xtraction system103.2. Energy recovery system114. Economic viability115. Conclusions126. References121. Introduction1.1. Environmental impacts of landfill gasWaste disposal in landfills can generate environmental problems such as water pollution, unpleasant odors, explosion and combustion, asphyxiat
10、ion, vegetation damage, and greenhouse gas emissions 13. Different methods are presently being used to evaluate these problems in order to find solutions for them 47.Landfill gas (LFG) is a naturally occurring by-product of the decomposition of organic waste in sanitary landfills, and is produced du
11、ring the microbially mediated degradation of the organic portion of waste. An example of the conversion of a biomass into usable energy can be seen in sanitary landfills that produce an amount of biogas of about 0.350 N m3/kg of solid urban waste 8,9.Landfill gas is generated under both aerobic and
12、anaerobic conditions. Aerobic conditions occur immediately after waste disposal due to entrapped atmospheric air. The initial aerobic phase is short-lived and produces a gas mostly composed of carbon dioxide.Since oxygen is rapidly depleted, a long-term degradation continues under anaerobic conditio
13、ns, thus producing a gas with a significant energy value that is typically 55% methane and 45% carbon dioxide with traces of a number of volatile organic compounds (VOC) 1012. Most of the CH4 and CO2 is generated within 20 years of landfill completion, whereas emissions may continue for 50 years or
14、more.There are two possible solutions for the problem of LFG emissions. One solution is the extraction and flaring of the LFG, a method often used in the past to reduce the pressure of the LFG as well as its odor. The other solution is to reuse LFG for other purposes. Since its total chemical energy
15、 is sufficient to sustain the operation of a gas turbine, it is evidently a valuable energy resource. In fact, it can be used as a supplementary or primary fuel to increase the production of electric power, as a pipeline quality gas and vehicle fuel, or even as a supply of heat and carbon dioxide fo
16、r greenhouses and various industrial processes 1,13.The use of biogas as a fuel source is environmentally sound because it contributes to a reduction of fossil fuel use and mitigates the greenhouse effect. In particular, the emissions of CH4, one of the two greenhouse gases emitted, are almost 21 times more dangerous than carbon dioxide for the greenhouse eff
