Illustration of the potential for mitigation of greenhouse gas emissions from the waste sector in OECD countries and selected emerging economies; Utilisation of the findings in waste technology transfer

Study performed by:

ifeu-Institut für Energie- und Umweltforschung Wilckenstr. 3
69120 Heidelberg, Germany

Study completed in:

February 2015

Abstract

This study presents the greenhouse gas (GHG) mitigation potential of municipal solid waste (MSW) management in OECD countries as well as India and Egypt. Three detailed GHG balances for the USA, India, Egypt and one balance for the OECD countries are elaborated applying the life cycle assessment (LCA) method according to ISO 14040/14044 for waste management. For each balance the respective status quo is determined and compared with two scenarios to 2030. The methodology as well as the underlying data and assumptions were profoundly discussed at workshops with LCA experts and local stakeholders. A GHG calculation approach was developed, which uses harmonised emission factors to credit avoided emissions from material recycling. With regard to the status quo, the net results for the OECD countries, the USA, India and Egypt show that methane emissions from landfilling are the main contributor to the GHG burdens. Only OECD countries with little or no landfill of (organic) waste achieve a net credit (e.g. Japan). These credits are the more evident the higher recycling rates are and the more efficient energy recovery is. The findings of this study were presented in May 2014 at the environmental fair IFAT in Munich.

The study’s most important conclusion is that the potential for GHG mitigation in waste management is significant. However, further incentives are necessary to support developing countries as well as some OECD and/or EU countries to develop an integrated closed-cycle waste management system. With regard to the EU, targets to promote diversion of biodegradable waste from landfill and for further development of recycling are important steps in the right direction. For emerging and developing countries the integration of the informal sector in future MSW concepts should be taken into account.

Summary 

The potential for climate change mitigation in the waste management sector is substantial. It can contribute appreciably to national greenhouse gas (GHG) mitigation goals. This has already been examined and shown in previous studies for Germany, the EU27 and in a first approach for selected developing countries and emerging economies using the life cycle assessment (LCA) method (Öko-Institut/IFEU 2005, 2010). The present study determines the mitigation potential for the OECD countries using the LCA method, with an in-depth analysis of the USA. In addition, the study provides a more detailed analysis of the GHG mitigation potentials of India and Egypt as selected developing countries and emerging economies. 

In the context of national reporting commitments under the Kyoto Protocol, only direct GHG emissions are considered in the waste sector, and only those from treatment options without energy recovery. In the National Inventory Reports (NIR), effects from energy use or recycling activities are reported in the energy or industry sector. In contrast to this, the LCA method makes it possible to assess the full effects of waste management activities. The LCA method considers both the direct emissions (debits) from waste treatment and the avoided emissions (benefits, credits) resulting from secondary products or energy generation. The system boundary starts with the waste generated. It thus considers the fate of non-collected waste, if present to a relevant extent, as is the case e.g. in India and Egypt. For collected waste, collection, treatment and recycling to produce secondary products or recover energy are included. The benefit from secondary products in the form of the potential to substitute primary products and conventional energy in other sectors is taken into account via credits in the GHG balance (offsets). In contrast to National Inventory Reports, the LCA method thus allows analysis and assessment of optimisation potentials in the waste sector, providing orientation for decision-makers. The results represent statements of potentials. 

The methodological approach follows ISO 14040/14044. For waste management there are some specifics. For example, the system boundaries start with the waste generated and end with final disposal or production of secondary products instead of “cradle-to-grave”. In addition, the waste sector is typically a multifunctional system. Apart from the main function of disposal of a particular quantity of waste, there are usually additional benefits from the production of secondary products and energy. The ISO standard offers general guidelines for multifunctional systems without further concretisation. In system comparisons, additional benefits from secondary products or recovered energy are usually considered by taking into account substitution processes, accounted for as credits. If avoided emissions through substitution are higher than the direct emissions from waste treatment the net results are negative values (“savings or mitigation potential”). This is to be understood as GHG mitigation potentially taking place in other sectors, namely the energy or industry sector. 

The offsetting of additional system benefits is required for system comparison, e.g. between status quo and future scenarios, in order to establish equal benefits among the systems. However, no specifications as to how substitution processes should be selected are available. This and further methodological questions were discussed with international experts at a methodology workshop in Berlin on 18 June 2012. The goal of that exchange was to improve the comparability and transparency of LCA studies in order to strengthen their suitability as decision-support tools for politics and for planning. The experts agreed that the choice of substitution processes should be limited as it has a major influence on the final results. It was agreed that harmonised emission factors should be used for studies designed to identify mitigation potentials. For material recycling the technical substitution potential is applicable. 

Taking into account the market-related substitution potential would be contradictory because this would mean “the more you substitute the less credit you get”. 

The methodological remarks underscore the fact that mitigation potentials in waste management should not be misunderstood as exact GHG reductions but rather as potentials revealing important methods, options and actions which can significantly contribute to GHG mitigation. 

As an outcome of the workshop, consistent emission factors for material recycling were established (see Sections 4.2.4 and 11.1) and used in this study. For energy recovery the marginal substitution approach (substitution of fossil fuels) was used in the detailed country balances (USA, India, Egypt). In the OECD balance emission factors for the national electricity grid were used instead, as valid data were available for these. 

Data situation for the OECD countries, EU28 and USA 

The presentation of waste management in the OECD countries and the EU28 is based on statistical data of the OECD and Eurostat. These data, which vary in quality, could not be verified and scrutinised for all of the 34 OECD countries and/or 28 EU countries. Some data important for the balance that are not contained in the statistics were taken instead from national publications. Often, though, these gaps had to be closed by plausible assumptions. 

For the separate USA balance, publications by USEPA were analysed comprehensively. This enabled a relatively high degree of accuracy to be achieved. Nevertheless, uncertainties also exist with the data given by USEPA. These were identified and examined in sensitivity analyses. Data from the USA balance were used in the OECD balance, but for symmetry reasons not in the same degree of detail as in the USA balance. 

OECD balance 

The municipal solid waste (MSW) streams in the 34 OECD member states are captured by statistical data from Eurostat and the OECD for the time period 2008 to 2010. In the OECD region it is assumed that the waste generated is equal to the waste treated; i.e. that there are no noteworthy amounts of non-collected or non-treated MSW in this region. Eurostat and OECD do not provide recycling rates per waste fraction. These had to be determined from national information and other assumptions. Information on the waste composition or the state of technology of waste treatment options was also extracted from national data wherever possible, although these partly refer to more distant time horizons. 

In many cases, plausible assumptions had to be made. Thus the waste characteristics (calorific value, carbon content) and the waste composition for Germany were used for the EU28, as in the previous study (Öko-Institut/IFEU 2010). For waste incineration the efficiency ratios of thermal recovery for the EU from (CEWEP 2012) were used for all OECD countries with the exception of the USA. For collected landfill gas, 50% use in combined heat and power (CHP) plants and 50% flaring was assumed, following the findings for the USA. Continued…

Excerpts:

Page 21-24

USA balance 

Data on waste generation and treatment were taken from statistical information from USEPA for the year 2011, given in US short tons (USEPA 2013a, b). To allow comprehensive traceability of the data, the values have not been converted into metric tons. All waste amounts in this section are given in short tons; for precise differentiation metric tons are given in megagrams (Mg). 

In addition, it should be noted that the results here are not directly comparable with those for the USA in the OECD balance as it was possible to calculate the USA balance to a higher degree of accuracy. For example, waste amounts which are usually not considered as MSW (old tyres, lead from lead-acid batteries) were excluded from the mass balance and/or the inventory. On account of national conditions in the USA, the oxidation rate for landfill gas generated was set to 10% , while it was symmetrically and conservatively set to 0% (IPCC default value) for all countries in the OECD balance because the actual situation could not be determined for all 34 member states. Another important difference is that in the USA balance energy generated from waste treatment is offset using the marginal approach instead of the country-specific electricity mix as in the OECD balance. The marginal electricity for the USA is electricity from coal. 

In total about 250 million short tons of waste were treated in the USA in 2011. This is equivalent to about 225 million Mg (721 kg/(cap*a)). The total waste was treated as follows: 

54% landfilling 

11% incineration with energy recovery 

27% recycling 

8% composting 

The vast majority of the waste was landfilled. US landfills are widely equipped with gas collection systems. The landfill gas collection efficiency for the overall landfilling period (100 year time horizon) was set to 50% in the calculations (general cap, see above), even though US landfill operators quote significantly higher landfill gas collection efficiencies and higher values and measurements are also given in the literature and in USEPA publications. These gas collection efficiency data relate to the gas collection phase and cannot be claimed to be valid for the overall landfill period. According to the National Inventory of GHG Emissions (USEPA 2012b), approximately half of the landfill gas collected is used with energy recovery. In the balance, use in a CHP plant was assumed. 

Most waste-to-energy (WtE) plants in the USA produce electricity only. The average net efficiency of electricity generation was determined to be 19%. Key data for waste incineration (calorific value and fossil carbon content) were derived from measurement data provided by the Covanta Energy Cooperation, a relevant operator and contractor of WtE-plants in the USA. The degradable organic carbon content for landfilling was calculated as the difference between the values for incineration and the values determined from the USEPA data on waste composition. 

Composting in the USA is mainly yard waste composting in simple open facilities. Mixed-waste composting also takes place but involves only about 0.2% of the total waste; this was disregarded in the balance. 

For material recycling the shares of source-segregated collection (pre-sorted by residents), single-stream recyclables collection (treated in materials recovery facilities, MRF) and mixed waste collection (treated in mixed waste processing facilities) were each identified and calculated (electricity demand). Waste paper at 70% has by far the largest share in the separated recyclables. The recycling rate for waste paper is 66%. The recycling rate for the other recyclable fractions is between 8% for plastics and 33%/38% (ferrous/non-ferrous metals)2. 

2 The recycling rate for non-ferrous metals breaks down into 21% for aluminum and 68% for other non-ferrous metals; the latter is lead from lead-acid batteries which is not considered in the GHG balance. 

The GHG balance of waste treatment in the USA in 2011 shows a net debit of about 18 million Mg CO2-eq. This is made up of 

net debit collection: +2.2 million Mg CO2-eq 

net debit landfilling: +64.7 million Mg CO2-eq 

net credit recycling: -44.7 million Mg CO2-eq 

net credit incineration: -3.5 million Mg CO2-eq 

net credit composting: -0.6 million Mg CO2-eq 

The influence of a higher gas collection efficiency and the effect of allowing for a carbon sink (landfilling, compost use) were examined in sensitivity analyses. In both cases the result changes from a net debit to a net credit, but neither aspect can be proved securely. The carbon sink is also excluded from the national inventory according to the IPCC guidelines (IPCC 2006). For incineration the difference that arises when the marginal approach rather than the country-specific electricity mix is used to offset energy generation was analysed, as were the effect of a higher fossil carbon content and the effect of cogeneration of heat and power from WtE. In all three cases the result is still a net debit; this is increased in the first two cases and decreased in the last. 

USEPA collects data using a top-down approach: data on waste generation and management method are gathered by analysing production and trade statistics. In contrast to this, a regular bottom-up evaluation is undertaken by the Earth Engineering Center (ECC) of the University of Columbia and the journal BioCycle (“State of Garbage in America”, SOG survey). The SOG survey is based on data provided by waste management agencies in the fifty states. Nevertheless, uncertainties also exist here because only landfills and WtE facilities are required to report the waste amounts treated. In addition, the reported MSW tonnages sometimes include non-MSW; this was excluded wherever possible. 

The SOG survey results in considerably larger waste amounts than the USEPA data; in particular, it shows larger amounts landfilled. According to the survey, the MSW generated in 2011 was about 389 million short tons, of which 64% was landfilled. On the basis of the volumes in the SOG survey the net debit in the GHG balance for the USA is 3.6 times higher at 64.5 million Mg CO2-eq. The GHG emissions from landfilling are nearly twice as high. 

For the USA a medium and an ideal future scenario were analysed with the following conditions: 

2030 medium: 45% recycling, 25% incineration, 30% landfill 

2030 ideal: 60% recycling, 40% incineration, 0% landfill 

As in the OECD balance, it was assumed that 80% of the waste amount “incinerated” is delivered directly to WtE facilities while 20% goes to an anaerobic MBT plant in the medium scenario and to an MBS plant in the ideal scenario. The increase in recycling was arrived at by adapting the recycling rates per fraction. Additional source-segregated food waste in the ideal scenario is assumed to be treated via anaerobic digestion. The characteristics of incineration and landfilling were recalculated to take account of the revised composition of the remaining waste. In contrast to the status quo, the same calculated characteristics were applied equally for incineration and landfilling. Differentiation of quality cannot be retained with an increasing share of incineration in the future scenarios. In addition to the redirection of waste streams in the future scenarios, some technical optimisations were assumed, such as cogeneration of heat and power from waste incineration in line with the assumption in the OECD balance. 

The net results of the future scenarios compared to the status quo are shown in Table 4. As in the OECD balance, the results show that significant GHG mitigation can be achieved by reducing or halting direct landfilling and instead promoting material recycling and energy recovery from mixed waste. The increased credits from incineration are caused mainly by the shift from electricity generation only to cogeneration of heat and power. The medium scenario achieves a GHG reduction of about 72 million Mg CO2-eq. In the ideal scenario the phasing out of landfilling and the correspondingly increased recycling lead to a net credit that is a further 2.6 times higher than in the medium scenario. 

Page 30, Conclusion:

…Information about waste streams and waste characteristics is indispensable for proper steering of waste streams and for planning. For the USA it is therefore recommended that, instead of using the top-down approach, actual waste streams are evaluated. This requires compulsory reporting of the waste delivered to composting, sorting and recycling facilities. In addition, MSW should be weighed separately from other waste. The waste composition should be analysed, at least on a sample basis. The recommendations also apply to OECD countries in which they are not (yet) being implemented. For India and Egypt random samples are recommended as an initial step, especially in rural areas.

In general, a closed-cycle management system requires creation of the infrastructure needed to facilitate high-quality recycling. A market for secondary raw materials or products is also needed. If the corresponding demand can be created, closed-cycle management can be established.

Countries like Germany can support the process of implementing closed-cycle management – for example through transfer of know-how either at either technology or government agency level. They must also ensure, however, that they consolidate and further refine the standards achieved in their own waste management systems.

Page 31

The year 2030 was selected as the time horizon for the future scenarios. It was agreed that in addition to the realistic or “medium” scenario, an ideal scenario would also be considered. The four country inventories that were drawn up are documented in detail in this report. The inventory for the USA should be regarded as a special aspect of the inventory for the OECD countries. The methodology is identical for all inventories, as are some other aspects of the analysis. For example, in the course of the project it was agreed that harmonised emission factors should be used for substitution processes, irrespective of the country being considered. This decision is in line with the recommendations made by experts following the methodology workshop for this project held in Berlin on 18 June 2012. The workshop protocol and the presentations can be downloaded at http://www.umweltbundesamt.de/themen/abfall-ressourcen/abfallwirtschaft/klimaschutz-in-der-abfallwirtschaft. 

The following key findings of the project: 

the clear confirmation that ending landfilling of untreated waste makes a significant contribution to climate change mitigation, 

the fact that even at landfills with state-of-the-art gas collection there is still significant potential for GHG mitigation through materials recovery and subsequently through the use of waste for energy generation, and 

the fact that the waste sector can make a relevant contribution to climate change mitigation in the national context 

were presented and discussed at the final workshop at IFAT in Munich on 8 May 2014.4 It was very clear from the presentation of results and the subsequent discussion that there are obstacles to the implementation of measures in the waste sector. These obstacles are not necessarily financial in nature. They may arise from national priorities, or from inadequate information. In connection with the latter aspect, participants at the closing meeting urged that the present study be made available in English. 

Page 95-98

Landfill 

For various reasons, landfilling in the USA occupies a special position. Firstly, in recent years the USA has witnessed a trend towards the dumping of waste in “wet landfills” (Thorneloe 2012). These wet landfills, which need no leachate treatment, aim to accelerate biological decomposition in the landfill by adding liquid and recirculating the leachate. Measurements show that methane emissions also rise sharply. However, no reliable data are available. According to the recommendations of an expert (Thorneloe 2012), these landfills should not be considered separately. This recommendation has been followed and all landfilling is balanced as described in Section 4.2.5. 

Secondly, another special feature of landfilling in the USA is the gas collection efficiencies quoted, which are relatively high. The majority of landfills in the USA are operated by two large companies, one of which is Waste Management Inc. An expert (Thorneloe 2012) states that the efficiency of the gas collection systems used in landfills varies. Operators postulate the “CO2-neutral landfill” with 95% gas collection efficiency. According to measurements performed by USEPA (ORD), these gas collection efficiencies are unrealistic. Measurement programmes at three landfills yielded the gas collection efficiencies shown in Figure 21.32 However, these apply only to the landfilling period that was considered or investigated. There are no data on effective gas collection efficiencies over the entire storage period, which should be considered to last 100 years. 

WARM (2013) likewise assumes relatively high gas collection efficiencies for the entire storage period. The tool gives the user the option to distinguish between three cases: the typical case, the worst case and an aggressive case. 

– typical = Years 0-2 0% Year 3 50% Years 4-7 75% Years 8-100 95% 

– worst case = Years 0-5 0% Years 6-7 75% Years 8-100 95% 

– aggressive = Year 1 25% Years 2-3 50% Years 4-7 75% Years 8-100 95% 

The effective gas collection efficiency over the 100-year time span is not given; it depends on the annual methane formation rate that is applied. However, it can be assumed that the effective gas collection efficiency, if calculated, would be over 80% and hence significantly higher than is generally postulated under the current state of scientific knowledge. It is for this reason that (EEA 2011), for example, does not adopt the high gas collection efficiencies reported by some EU countries; instead, a maximum technically feasible effective national gas collection efficiency of 45% is assumed, even if all landfills have gas collection systems. 

In the USA the Clean Air Act (CAA)33 in principle requires all large landfills to install gas collection systems within five years of the depositing of waste. These systems are extended successively to new areas of the landfill as soon as more waste is dumped. The landfill gas that is collected is then either flared off or used for energy recovery. In 2005, according to information in (Kaplan et al. 2009a), 427 out of 1,654 municipal landfills in the USA practised landfill gas collection with subsequent energy recovery with a total capacity of 1,260 MW. 

Detailed up-to-date statistics on landfills in the USA were provided to UBA by USEPA in the form an Excel file.34 Analysis of this data indicated 1,504 landfills classed as “open”. 1,034 of these (69%) have a gas collection system. According to annual waste acceptance rates, 93% of landfill capacity is equipped with a gas collection system and 97% of this also has gas flaring. In the light of this it was assumed for this study that all landfills have gas collection systems installed. 

The gas collection efficiencies specified by landfill operators and in the WARM tool are also viewed critically within USEPA (Thorneloe 2012). While the MSW-DST likewise tends to assume high gas collection efficiencies (see Figure 22, 80% from the 3rd year of gas collection), (Kaplan et al. 2009a) points out conversely that landfilling also results in significant methane leaks on the scale of 60-85%. 

According to the inventory report of USEPA (2012), the amount of methane captured in 2010 was only 57%. However, this figure cannot be used directly for comparison of the status quo, because the methane emissions in national reports include all emissions from old deposits (usually since 1950); these emissions may arise from old landfill cells without gas collection systems. In general, though, the scientific evidence suggests that a national average effective gas collection efficiency of up to 80% over the lifetime of the deposits is not realistic. In this study the maximum effective gas collection efficiency considered to be technically possible was set at 50% (Section 4.2.5); this is the figure used here for the standard case in the USA balance. To demonstrate the influence of a high gas collection efficiency, an effective gas collection efficiency of 75% was analysed as a sensitivity. This figure roughly corresponds to the measurements in Figure 21. 

The calculation for landfill generally uses the procedure for managed landfill described in Section 4.2.5. For the USA balance the default values in (IPCC 2006) are again used. The gas collection efficiency used, though, differs from this (see above) and in a further deviation the DOC is calculated on the basis of the country-specific waste composition. The following figures were used in the calculations: 

– DOC = 15.9% (see Table 44) 

– DOCf = 50% (IPCC default value) 

– Methane content = 50 Vol% (IPCC default value) 

– MCF = 1 (IPCC default value for managed landfills) 

– Effective gas collection rate = set at 50% (sensitivity 75%) 

– OX = 10% (IPCC default value for well-managed landfills) 

The oxidation factor (OX) of 10% according to the IPCC is justified for well-managed landfills (see Section 4.2.5). According to Figure 22, the MSW-DST tool assumes an oxidation rate of 15% for the USA. According to (IPCC 2006), OX values higher than the 10% figure should be very well documented and referenced and supported by national statistics. The available publications do not provide any such evidence for the higher oxidation rate. The analysis therefore uses the figure of 10% recommended for well-managed landfills in (IPCC 2006). In a departure from this, the OECD balance uses a symmetrical and conservative oxidation factor of 0% for all countries, because the situation in the 34 individual OECD countries could not be identified.

Information on the use of landfill gas is contained in the Excel file supplied by USEPA. According to this information, 44% of open landfills with gas collection use the landfill gas in a small-scale CHP unit, 23% provide no information, 13% use the landfill gas directly or for heat generation, 6% use it in gas turbines, 5% practise co-incineration, 4% produce biomethane, 3% use the landfill gas to evaporate the leachate, and the remaining 3% report “other” use. This information is not linked to landfill gas quantities and so cannot be analysed in terms of the quantity of landfill gas collected. According to the inventory report of USEPA (2012), in 2010 around half of the collected landfill gas was flared off and half was used for gas-to-energy. It is assumed that gas-to-energy involves use in small-scale CHP units. As with biogas use, a methane slip of 1% of the methane input is assumed and the efficiencies are set at 37.5% for electricity and 43% for heat (see Section 4.2.6). For heat it is generally assumed that on a national average 20% of the surplus heat can be used externally. If surplus electricity is produced, it is treated for substitution purposes as marginal electricity (see Section 4.1.2). 

The same assumptions on landfill gas use were made as in the OECD balance. However, in that balance surplus electricity was credited via substitution of the average electricity mix, not substitution of marginal electricity. In the OECD balance this applies to all electricity generated. For the USA balance, the influence of marginal electricity versus average electricity is considered in a sensitivity analysis of waste incineration. 

To read the entire peer-reviewed expert study prepared for the the German BMU click here.

Note: Even though this study was completed in 2015 nothing considerable has changed in the US.

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