Life Cycle Assessments of Energy From Solid Waste (PDF)

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7.5.5 Summary A final summary of the ranking of the waste management options in the scenario with medium transports and transports by passenger car, for the whole system, is given in Table 7.20. Table 7.20 The ranking of the waste management options for the whole system for each impact category. When the three recycling alternatives are ranked in sequence they are reported as one. Rec/d is the recycling alternative where food waste is anaerobically digested, this alternative may be split in (he) where heat and electricity is generated from the biogas collected and (f) where the biogas is used for fuelling buses. Rec/c is recycling combined with composting, Inc is incineration and Lf landfilling. In this scenario there are two incineration alternatives and when they are not ranked in sequence they are both reported, Inc/t for only medium transport and Inc/c for additional passenger car use. Impact category Ranking Total energy Rec < Inc < Lf Non-renewable energy Rec < Lf < Inc Abiotic resources Rec < Lf < Inc Non-treated waste Rec < Lf < Inc Global warming Rec < Inc < Lf Photo-oxidant formation max Inc/t < Lf < Rec < Inc/c Acidification (excl. SO x and NO x) Rec/d < Inc < Lf < Rec/c Aquatic eutrophication (excl. NO x) Rec < Inc < Lf SO x Rec < Inc/t < Lf < Inc/c NO x Rec/d (he) < Rec/c < Lf < Rec/d (f) < Inc NH 3 max Inc < Rec/d < Lf < Rec/c E-tox EDIP Inc/t < Lf < Inc/c < Rec E-tox USESmin Inc < Lf < Rec E-tox USESmax Lf=Inc/t < Rec < Inc/c H-tox EDIP Inc/t < Lf < Rec < Inc/c H-tox USESmin Inc/t < Lf < Rec < Inc/c H-tox USESmax Inc/t < Lf < Rec < Inc/c Ecotax98 / EDIP Rec < Inc/t < Lf < Inc/c Ecotax98 / USESmin Rec < Inc < Lf Ecotax98 / USESmax Inc/t < Lf < Rec < Inc/c Eco-indicator 99 Rec < Inc < Lf 7.6 Results Scenario Natural gas for heat production 7.6.1 Introduction In this scenario natural gas is assumed for the production of heat which is avoided by incinerating waste and combusting gas from digestion or landfilling. In the base scenario this avoided heat is produced from forest residues. Differences between this scenario and the base scenario are in general that the incineration, but also the landfilling and anaerobic digestion processes, are credited avoidance of a non-renewable fuel instead of a renewable. This is an advantage if focus is on abiotic resources and global warming. However, in other cases natural gas seems to be a more preferable alternative than forest residues from an environmental point of view. With the characterisation and weighting methods used here this may be said for the categories photo-oxidant formation, aquatic eutrophication (excl NO x ), acidification (excl SO x and NO x ), SO x , NO x , NH 3 , non-treated waste and the toxicological impact categories. The substances emitted from forest residues incineration with the largest toxicological effects modelled are different metals ending up in the ashes, which are spread in the forest and thereby emitted to soil. NMVOC is a major contributor to photo-oxidant formation and also to human toxicological impacts mainly in the Ecotax 98/USESmax case. A comparison between the two heat production alternatives are shown in Table 7.21, identifying which impact categories that are affected more by which alternative and also which substance is responsible for the major part of the impact. 118
Table 7.21 Heat from forest residues and natural gas respectively are compared. For each impact category the process with the highest value is marked and the substance contributing the most to the category is stated. Impact category Heat from forest residues Heat from natural gas Substance contributing the most to the category Abiotic resources X Natural gas Non-treated waste Global warming X CO 2 Photo-oxidant formation max X CO, NMVOC Acidification (excl SO x and NO x) X NH 3 Aquatic eutrophication (excl NO x) X NH 3 SO x X NO x X NH 3 max X Eco. tox. EDIP X Cd, Zn to soil Eco. tox. USESmin X Zn, Cr to soil Eco. tox. USESmax X Ni, Cu, Zn, Cr to soil Hum. tox. EDIP X As to soil Hum. tox. USESmin X NMVOC to air Hum. tox. USESmax X NMVOC to air Ecotax 98/EDIP X Category: abiotic resources Ecotax 98/USESmin X Category: global warming Ecotax 98/USESmax (X) very narrow X Category: abiotic resources (natural gas), E-tox and H-tox (forest residues) Total Eco-indicator 99 (X) very narrow X Category: abiotic resources -fossil fuels (natural gas), E-tox and human health – carcinogenic (forest residues) Results for the different categories and total weighted results are shown in Tables 7.22 – 26 for the whole system, food waste, newspaper and PET. Figures are shown both for the base scenario as a reference and for the natural gas scenario. 7.6.2 Energy, abitoic resources and non-treated waste Only very marginal changes in the total energy balance compared to the base scenario occur when substituting forest residues with natural gas. When focusing on the non-renewable part of the energy more discernible changes can be seen. Incineration will for this impact category be ranked as the most preferable alternative for the whole system, because of the avoided heat production from natural gas. The non-renewable energy balance for landfilling is also improved, but not enough to become a better alternative than recycling. For PET the ranking in the case of non-renewable energy is incineration before recycling before landfilling. For newspaper, recycling is still ranked highest, but the difference compared to incineration is small. Landfilling is also for this fraction the least preferable option. Concerning food waste the ranking of waste management options will also be altered for this impact category. Incineration is the most preferable, followed by digestion with heat and electricity generation. Digestion with recovered gas used as bus fuel and landfilling is contributing equally to avoidance of non-renewable energy use, whereas the composting alternative still gives rise to a net use, since no heat production is avoided using this option. The impact category abiotic resources consists to the larger part of the non-renewable energy sources and consequently the same changes appear for this category. The amounts of nontreated waste are only marginally altered compared to the base scenario. 119
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Life Cycle Assessments of Energy fr
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ISBN 91-7056-103-6 ISSN 1404-6520,
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Ekvall, T. and Finnveden, G. (2000)
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Summary We live in a changing world
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fractions are included. In Figures.
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Contents PREFACE ABSTRACT SUMMARY C
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Nutrients content in digestion resi
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7.6.6 Summary 125 7.7 RESULTS SCENA
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USES VOC YLD YLL Uniform system for
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discussed. Another question is wher
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2 Methodology 2.1 General LCA metho
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geographical coverage, and consiste
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Weighting is and has always been a
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2.2.2 Open-loop recycling Open-loop
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often assumed to replace virgin pap
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the differentiation between biotic
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composting of the food waste. Sourc
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2.3.7 Landfills as a carbon sink In
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et al (1998) (recycling of PET), He
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3 Scenarios and major assumptions 3
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of the incinerator capacity. If, ho
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Finally, in the long transport scen
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Table 3.4 Vehicles and distances wi
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3.9.2 Medium transports scenario Th
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4 Household waste composition 4.1 I
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Table 4.4 Composition of the fracti
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defined composition of newspaper. T
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5. Processes 5.1 Introduction The w
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WASTE PAPER ADDITIVES EL. TRANSPORT
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Combining testliner and wellenstoff
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The first step in the recycling pro
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involves PET-resin production from
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PE as described in section 5.2. Thi
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The original inventory data for ana
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5.3.3 Avoided production of fertili
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FOOD WASTE TRANSPORT ENERGY INCL EL
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The heat released in the kiln is ca
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Aluminium, CaCO 3 , clay, crude oil
Page 80 and 81: Emissions formed during landfill fi
Page 82 and 83: energy used for purification is ass
Page 84 and 85: 5.7.2 Exceptions Marginal electrici
Page 86 and 87: Combustion of biomass is not consid
Page 88 and 89: 6.2.5 Stratospheric ozone depletion
Page 90 and 91: Table 6.2 Some emissions lacking a
Page 92 and 93: Table 6.4 Some emissions lacking a
Page 94 and 95: Non-treated waste All waste that ha
Page 96 and 97: Table 6.6 continued… Impact categ
Page 98 and 99: 6.4.4 Additions For some substances
Page 100 and 101: categories for the substances found
Page 102 and 103: For PET most energy is saved in the
Page 104 and 105: Table 7.2 The table shows weighted
Page 106 and 107: The results for the food waste frac
Page 108 and 109: for both alternatives. Most of this
Page 110 and 111: 7.2.13 Undefined substances As disc
Page 112 and 113: Table 7.4 The results for all impac
Page 114 and 115: 7.3.1 Energy, abiotic resources and
Page 116 and 117: 7.3.3 Toxicological effects Medium
Page 118 and 119: 7.3.5 Summary A final summary of th
Page 120 and 121: 7.4.2 Non-toxicological impacts For
Page 122 and 123: 7.4.4 Total weighted results Change
Page 124 and 125: Table 7.16 Comparison between a sce
Page 126 and 127: The categories acidification (excl
Page 128 and 129: 7.5.4 Total weighted results When u
Page 132 and 133: Table 7.22 Weighted results for the
Page 134 and 135: A similar pattern results for SO x
Page 136 and 137: Table 7.25 Weighted results for hum
Page 138 and 139: Table 7.27 The ranking of the waste
Page 140 and 141: Table 7.29 Weighted results for the
Page 142 and 143: Table 7.31 Weighted results for hum
Page 144 and 145: 7.8.2 Non-toxicological impacts The
Page 146 and 147: Opposite to the USESmin results, no
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Page 150 and 151: Table 7.39 Weighted global warming
Page 152 and 153: 7.10 Results Scenario Plastic Palis
Page 154 and 155: Table 7.43 The ranking of the waste
Page 156 and 157: In category human toxicology there
Page 158 and 159: 7.12 Results Qualitative discussion
Page 160 and 161: Table 7.49 The 100 year perspective
Page 162 and 163: Table 7.50 Continued Different time
Page 164 and 165: (MJ/ton) 0.0E+00 -1.0E+04 -2.0E+04
Page 166 and 167: materials in the base scenario (sec
Page 168 and 169: In general anaerobic digestion is p
Page 170 and 171: 8.4 Limitations and need for furthe
Page 172 and 173: separation of fractions to be incin
Page 174 and 175: CEPI and BIR (1999). European List
Page 176 and 177: Finnveden, G., and T. Ekvall (1998)
Page 178 and 179: Johansson, S. (1998). Förstudie av
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Tukker, A. (1999a). Life Cycle Asse
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Additives Active pesticide Record:
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HCl (100%) B250 - (Hydrochloric aci
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NaClO 3 - (Sodiumchlorate) Record:
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Inputs from technosphere: Potato S
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natural gas, coal, water, silver an
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Energy - heat Heat diesel B250 Reco
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MJth gas energy Record: IVAM Refere
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of the coal and efficiency losses.
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MJel oil NL Record: IVAM References
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Gaslinetransport NL Record: IVAM Re
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Other Wastew. Treatment industry Re
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Chauvel & Lefebvre (1989) Chauvel &
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LCA-landbouw LCA-landbouw Database
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Remmerswaal (1996) J.Remmerswaal, F
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VNC Vereniging Nederlandse Cementin
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