representing land areas and on land-use databases used for the inventory
8.2 Solid waste disposal on land [6A] 1 Source category description
In 2012 there were 22 operating landfill sites, as well as a few thousand old sites that are still reactive. CH4 recovery takes place at 53 sites in the Netherlands. As a result of the anaerobic degradation of the organic material within the landfill body, all of these landfills produce CH4 and CO2. Landfill gas comprises about 50 per cent (vol.) CH4 and 50 per cent (vol.) CO2. Due to a light overpressure, landfill gas migrates into the atmosphere. At several landfill sites, the gas is extracted before it is released into the
atmosphere and subsequently used as an energy source or flared off. In both of these cases, the CH4 in the extracted gas is not released into the atmosphere. The CH4 may be degraded (oxidized) to some extent by bacteria when it passes through the landfill cover; this results in lower CH4 emissions.
Anaerobic degradation of organic matter in landfills is a time-dependent process and may take many decades. Some of the factors influencing this process are known; some are not. Each landfill site has unique characteristics: concentration and type of organic matter, moisture and temperature, among others. The major factors determining the decreased net CH4 emissions are lower quantities of organic carbon deposited into landfills
(organic carbon content × total amount of land-filled waste) and higher methane recovery rates from landfills (see sections 8.2.2 and 8.2.3).
The share of CH4 emissions from landfills in the total national inventory of greenhouse gas emissions was 6 per cent in 1990 and 2 per cent in 2012 – a decrease of 74 per cent. This decrease is partly due to the increase in recovered CH4 – from about 5 per cent in 1990 to
15 per cent in 2012 – but also to the decrease in methane produced at solid waste disposal sites and the decrease of the relative amount of methane in landfill gas from 60 per cent to 50 per cent.
In 2012, solid waste disposal on land accounted for 81 per cent of total emissions from the Waste sector and 2 per cent of total national CO2-equivalent emissions (see Table 8.1).
Figure 8.1 Sector 6 ‘Waste’: trend and emission levels of source categories, 1990-2012.
1990 1995 2000 2005 2010 0 4 8 12 16 Tg CO2-eq. 6D. Other
6B. Waste water handling CH4 6B. Waste water handling N2O 6A1. Managed Waste Disposal on Land
www.prtr.n
l
Table 8.1 Contribution of main categories and key sources in Sector 6 Waste.
Sector/category Gas Key Emissions
base year Emissions 2011 Emissions 2012 Change 2012 - 2011 Contribution to total in 2012 (%) Gg Tg CO2 eq Gg Tg CO2 eq Gg Tg CO2 eq Gg by sector of total gas of total CO2 eq 6 Waste CH4 585.8 12.3 161.3 3.4 152.18 3.2 -0.2 87 21 2 N2O 1.6 0.5 1.6 0.5 1.6 0.5 0.0 13 5 0.3 All 12.8 3.9 3.7 -0.2 100 2 6A Solid Waste disposal on Land CH4 572.0 12.0 150.8 3.2 141.6 3.0 -0.2 81 20 2
6A1 Managed Waste disposal on Land CH4 L.T 572.0 12.0 150.8 3.2 141.6 3.0 -0.2 81 20 2 6B Waste water handling N2O L2 1.6 0.5 1.5 0.5 1.5 0.5 0.0 12 5 0.2 CH4 13.8 0.3 9.5 0.2 9.5 0.2 0.0 5 1.3 0.1 All 0.8 0.7 0.7 0.0 18 0.3 6D Other CH4 0.06 0.00 1.0 0.0 1.1 0.0 0.0 0.6 0.2 0.01 N2O 0.00 0.00 0.11 0.00 0.11 0.00 0.0 0.1 0.0 0.00 All 0.00 0.1 0.1 0.0 1.6 0.03 National Total GHG emissions (excl. CO2 LULUCF) CH4 1.224.4 25.7 727.2 15.3 712.0 14.9 -0.3 N2O 64.5 20.0 30.2 9.4 29.5 9.1 -0.2 All 213.2 195.1 191.7 -3.4
The policy that has been implemented in the Netherlands is one directly aimed at reducing the amount of waste sent to landfill sites. This policy requires enhanced prevention of waste production and the increased recycling of waste, followed by incineration. As early as the 1990s, the government introduced bans on the use of certain categories of waste for landfilling; for example, the organic fraction of household waste. Another method
implemented to reduce landfilling was to raise the landfill tax to comply with the increased costs of incinerating waste. Depending on the capacity of incineration, the government can grant exemption from these ‘obligations’. Due to this policy, the amount of waste sent to landfills has decreased from more than 14 million tons in 1990 to 3 million tons in 2012, thereby reducing emissions from this source category.
Methodological issues
A more detailed description of the method used and EFs can be found in the protocol 14-034 on the website http:// english.rvo.nl/nie, as indicated in section 8.1.
Activity data on the amount of waste disposed of at landfill sites are mainly based on the annual survey performed by the Working Group on Waste Registration at all the landfill sites in the Netherlands. These data can be found on the website http://english.rvo.nl/nie and are documented in Rijkswaterstaat (2013a). This document also contains the amount of CH4 recovered from landfill sites yearly. The IEFs correspond with the IPCC default values.
In order to calculate CH4 emissions from all the landfill sites in the Netherlands, it was assumed that all waste was disposed of at one landfill site; an action that started in 1945. As stated above, however, characteristics of individual sites vary substantially. CH4 emissions from this ‘national landfill’ were then calculated using a first-order decomposition model (first-order decay function) with an annual input of the total amounts deposited and the characteristics of the landfilled waste and the amount of landfill gas extracted. This is equivalent to the IPCC Tier 2 methodology. Since the CH4 emissions from landfills are a key source, the present methodology is in line with the IPCC Good Practice Guidance (IPCC. 2001).
Parameters used in the landfill emissions model are as follows:
• Total amount of landfilled waste;
• Fraction of degradable organic carbon (DOC) (see Table 8.2 for a detailed time series);
• CH4 generation (decomposition) rate constant (k): 0.094 up to and including 1989, decreasing to 0.0693 in 1995; decreasing from 2000 to 2004 to 0.05 (IPCC parameter) and remaining constant thereafter; this corresponds to a half-life of 14.0 years (see Table 8.2 for a detailed time series);
• CH4 oxidation factor: 10 per cent;
• Fraction of DOC actually dissimilated (DOCF): 0.58 until 2000 (see also Oonk et al. 1994); from 2000 to 2004, decreasing to 0.5 (IPCC parameter) and remaining constant thereafter;
• CH4 conversion factor (IPCC parameter): 1.0;
• The fraction of methane in landfill gas recovered has been determined yearly from 2002 onwards based on the composition of landfill gas at all sites with CH4 recovery. For the years up until 2001, the fraction of methane in landfill gas has been set at 60 per cent. Trend information on IPCC Tier 2 method parameters that change over time is provided in Table 8.2. The change in DOC values was due to such factors as the prohibition on depositing combustible waste in landfills, whereas the change in k-values (CH4 generation rate constant) was caused by a sharp increase in the recycling of vegetable, fruit and garden waste in the early 1990s. Moreover, since 2008 there has been a decrease in the amount of combustible waste deposited in landfills, due to overcapacity at incineration plants. The integration time for the emissions calculation is defined as the period starting from 1945 to the year for which the calculation is made.
8.2.2 Uncertainty and time series consistency
Uncertainty
The Tier 1 uncertainty analysis shown in Tables A7.1 and A7.2 of Annex 7 provides estimates of uncertainties by IPCC source category and gas. The uncertainty in CH4 emissions from solid waste disposal sites is estimated to Table 8.2 Parameters used in the IPCC Tier 2 method that change over time (additional information on solid waste handling part).
Parameter 1990 1995 2000 2005 2010 2011 2012
Waste generation rate (kg/cap/day) 1.52 1.50 1.69 1.75 1.66 1.67 1.61
Fraction MSW disposed to SWDS 0.38 0.29 0.09 0.01 0.00 0.01 0.01
Fraction DOC in MSW 0.13 0.13 0.11 0.06 0.03 0.03 0.03
CH4 generation rate constant (k) 0.09 0.07 0.07 0.05 0.05 0.05 0.05
Number of SWDS recovering CH4 45 50 55 50 53 53 53
be approximately 23 per cent in annual emissions. The uncertainty in the activity data and the EF are estimated to be less than 0.5 per cent and 23 per cent, respectively. For a more detailed analysis of these uncertainties (see
Rijkswaterstaat, 2014). Time series consistency
The estimates for all years are calculated from the same model, which means that the methodology is consistent throughout the time series. The time series consistency of the activity data is very good, due to the continuity in the data provided. Since 2002, the fraction of CH4 in landfill gas has been determined yearly based on the composition of the landfill gas (at CH4 recovering sites). It is expected that this will reflect the average fraction of CH4 in the landfill gas better than the default used in previous inventories and it slightly reduces uncertainties in the emissions estimations of the post-2001 period. This ‘new’ CH4 fraction is only used to estimate methane in the recovered biogas and not for the generation of methane within the landfill site.
8.2.3 Source-specific QA/QC and verification
The source categories are covered by the general QA/QC procedures, as discussed in Chapter 1, and the specific QA/ QC, as described in the document for QA/QC of outside agencies 2011 (Wever et al., 2011).8.2.4 Source-specific recalculations
Compared with the previous submission, no recalculations took place for this submission.