Volume 1 Collation of Key Information on Small, Closed & Operational Sites across Scotland

Transcription

1 Volume 1 Collation of Key Information on Small, Closed & Operational Sites across Scotland Project Code: ORI1-1 Review of options for reducing GHG emissions from landfills in Scotland 212

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3 Volume 1 Collation of Key Information on Small Closed & Operational Sites across Scotland ZWS i TABLE OF CONTENTS Page 1 Introduction The Brief Scope of Volume 1 Collation of Key Information on Historical, Closed and Operational Sites across Scotland Methodology Site Assessment Gas Prediction Modelling Model Output Sensitivity Analysis Global Warming Potential Results GHG Emissions Active Landfill PPC GHG Emissions Recently Closed Landfill PPC GHG Emissions Operational Landfills GHG Emissions Historical Landfill GHG Emissions Total Summary... 2 LIST OF TABLES Table 3.1: Revised Baseline and Targets for Scotland (28 figures) Table 3.2: GHG Emissions LIST OF FIGURES Figure 1.1: Illustration of Site Classification Used... 2 Figure 2.1: Christiansen and Kjeldsen Evolution of Landfill Gas... 7 Figure 2.2: Impact of Organic Content and Moisture Content on Landfill Gas Production... 9 Figure 3.1: Landfill Gas Prediction Estimates for Individual sites (Median Inputs, 5 % v/v Methane, descriptions of sites 1-84 are available in Appendix 2) Figure 3.2: Total Landfill Gas Prediction Estimate (Median Inputs, 5 % v/v methane) LIST OF APPENDICES Appendix 1: Appendix 2: Appendix 3: Summary of Sites Evaluated Model Inputs Zero Waste Scotland Targets Q:/212/UW12/769/1/Reports/Rpt3-1.doc

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5 Volume 1 Collation of Key Information on Small Closed & Operational Sites across Scotland ZWS 1 1 Introduction 1.1 The Brief IKM Fehily Timoney was appointed by WRAP under Contract GHG emissions from landfills in Scotland 212 ORI1-1 to: Volume 1 - Collation of Key Information on Small, Closed and Operational Sites Across Scotland Volume 2 - An Examination and Review of UK and International Best Practice For Mitigation of GHG Emissions Volume 3 - Pilot Landfill Gas Trials at Auchinlea Landfill Site to Test Various Mitigation and Capture Measures Volume 4 - Quantify and Assess the Scale of Emission Reductions Volume 5 Recommendations for Future Works This report forms Volume Scope of Volume 1 Collation of Key Information on Historical, Closed and Operational Sites across Scotland The purpose of this report (Volume 1) is to collate the key information on small historical, closed and operational sites across Scotland in order to define the extent of possible fugitive GHG emissions using gas modelling techniques. In particular, this report aims to define the potential emissions from older sites as these sites, due to their age, are most likely to be producing low calorific landfill gas which can be difficult to oxidise using conventional engine and flare technologies. In this report: historical sites are those with no Pollution Prevention and Control (PPC) permit, closed before (or up to) 21; recently closed sites refers to PPC permitted sites closed post 21, where puts have ceased; and active sites refers to PPC permitted sites still receiving waste. Where the term operational sites is used in this report (or subsequent volumes), this is an umbrella term for both recently closed, and active sites, i.e. PPC permitted sites which are either still receiving waste, or have closed post 21. Figure 1.1 overleaf illustrates the site classification approach used. This assessment uses LandGem version 3.2 landfill gas prediction software. The software requires input waste tonnages for each site and defined input parameters for methane generation rate (k) and potential methane generation capacity (L o ). Waste tonnage data was estimated from data provided by SEPA 1 and a range of representative values for k and L o were provided by IKM Fehily Timoney (IKMFT). Data from historical, recently closed and active sites was used in the analysis. A summary of the sites from which fugitive GHG estimates were assessed is presented in Appendix 1. The output from this report is an estimate of the total estimated GHG emissions post 212 from sites presented to IKMFT by SEPA. 1 Landfill Directive Sites Database- Scotland Rev 24.xls Q:/212/UW12/769/1/Reports/Rpt3-1.doc

6 Volume 1 Collation of Key Information on Small Closed & Operational Sites across Scotland ZWS 2 Figure 1.1: Illustration of Site Classification Used Q:/212/UW12/769/1/Reports/Rpt3-1.doc

7 Volume 1 Collation of Key Information on Small Closed & Operational Sites across Scotland ZWS 3 2 Methodology 2.1 Site Assessment Site Selection IKMFT received an inventory of sites 1 in the Scotland region from SEPA in May 212. No monitoring was carried out on any of the sites. Only sites which were expected to be producing landfill gas were included in the assessment (based on put types). Calculations and selections described hereinafter are based solely on assumptions of waste type, volume and ment dates. Appendix 1 shows a total of 47 sites on the SEPA database. These sites were categorised as follows by SEPA: Open Inert WML issued post 2 and deemed to operate under a PPC permit Current applications (for future permits) Sites that had a SCP /closure notice issued against them albeit they closed pre 21 Sites closed pre 21 Other (no description given) IKMFT made no allowance for potential GHG emissions as might occur from current applications (for future permits) of which there were 15 sites Waste Type IKMFT reviewed the sites and selected only those sites in which a waste description suggested presence of biological materials. GHG fugitive emissions were assumed to occur from sites that received one or more of the following: Household waste Commercial and industrial wastes Sewage sludges Clinical waste Animal carcasses Agricultural waste Organic waste from vegetable processing Sites were deemed to have no GHG emissions for the following reasons: Term "inert" used in waste description Term "industrial special" used in waste description As a consequence IKMFT made no GHG emission estimate for 269 sites GHG Emission Sites Following removal of inert sites, industrial special sites and current applications, GHG emission estimates were calculated for 186 sites. Q:/212/UW12/769/1/Reports/Rpt3-1.doc

8 Volume 1 Collation of Key Information on Small Closed & Operational Sites across Scotland ZWS Waste Intake Tonnage The SEPA database defined annual tonnage limits for 82 sites. This tonnage has been taken to represent actual tonnages received. These tonnages have been used in the GHG emissions assessment. Where tonnages were not available for the remaining 14 sites, two arbitrary theoretical landfill sizes were assumed for the GHG emission assessment to assess potential impact of assumptions on total GHG emissions: Landfill size 1 assumed a footprint of 2, m 2 and an average 15m. This results in a volume 3, m 3. Landfill size 2 assumed a footprint of 4, m 2 and an average 15m. This results in a volume 6, m 3. A density of.8 t/m 3 was assumed for these 14 sites resulting in landfill tonnages of 24, tonnes and 48, for Landfill sizes 1 and 2 respectively Life Span Life span data used in the GHG emission assessment was estimated as follows: Where sites had an estimated date of site closure this closure date was used as the date on which disposal of waste ceased. Life span was calculated where sites defined the annual tonnage and the remaining capacity. Where no information was available a closure year of 215 was assumed. Where opening years for sites were unavailable it was assumed that the sites opened 2 years before the closure date. Where the closure date was unknown the opening date was assumed to be 2. In summary the following assumptions were made: Where the lifespan of the landfill is unknown an assumption of 2 years was made for 27 sites. Where the opening year was unknown, 2 was selected for 5 sites. Where the closure year was unknown 215 was selected for 19 sites Distribution of Unknown Landfills It is worth noting that the application of the assumptions above means that the allocation of unknown landfills into the three classification types described in Section 1.2 and Figure 1-1 was as follows: Active Landfills, 25 no. unknown landfills Recently closed landfills, no. unknown landfills, Historical landfills, 79 no. unknown landfills. The assumptions made are significant, caution must therefore be exercised when interpreting results. Q:/212/UW12/769/1/Reports/Rpt3-1.doc

9 Volume 1 Collation of Key Information on Small Closed & Operational Sites across Scotland ZWS Gas Prediction Modelling Overview Gas prediction modelling typically requires a definition of waste type, tonnage and ment date from which estimates of landfill gas generation can be calculated. The number of assumptions made in this report in order to facilitate a standardised assessment from the available information was significant. Results must therefore be used with caution. The purpose of the gas prediction modelling was to illustrate the potential scale of emissions from historical sites (with no permit), closed sites (with a permit) and operational sites. GasSIM is the model most commonly used for gas prediction GHG emission estimates in Scotland. This model uses a first order decomposition rate equation and has extensive data inputs capabilities. GasSim is a standalone program with limited spreadsheet interface capabilities. LandGEM version 3.2 also uses a first order decomposition rate equation for quantifying emissions from the decomposition of landfilled municipal solid waste landfills. LandGEM software however has significantly less data input parameters and relies on empirical data from U.S. landfills over a wide range of climatic zones. Because the available data inputs from historical sites were limited there was no added advantage in using the more complex GasSim model and a decision was made to use LandGEM to assess GHG emission estimates LandGEM Gas Model The following input parameters have significant impacts on LandGEM GHG emission estimates: Methane Generation Rate (k) Potential Methane Generation Capacity (L ) The input parameter for Non-methane Organic Compound Concentration does not have a significant impact on GHG emission estimates. These parameters are discussed below in more detail. As a general rule the area under gas prediction curves for respective k and L o inputs is the same. The inputs change the peak of gas production and the shape / duration over which gas production occurs. The model used in this GHG emission estimate is an IKMFT modified version of LandGEM version 3.2 designed to facilitate inputs from multiple sites in Scotland Methane Generation Rate (k) The Methane Generation Rate, k, determines the rate of methane generation for the mass of the landfill. The units of k values are 1/year, or year -1. The higher the value of k, the faster the methane generation rate increases and then decays over time. Therefore high values of k result in a curve with a pronounced peak. The value of k is primarily a function of four factors: Moisture content of the waste mass. Availability of the nutrients for micro organisms that break down the waste to form methane and carbon dioxide. Q:/212/UW12/769/1/Reports/Rpt3-1.doc

10 Volume 1 Collation of Key Information on Small Closed & Operational Sites across Scotland ZWS 6 ph of the waste mass, and Temperature of the waste mass. The factor with the most significant influence on k is moisture content. The Scotland region has an average annual rainfall ( ) of 1472 mm 2 There are five k value options within LandGEM ranging from.2 for arid conditions to.7 for wet conditions. Calibration studies carried out by FTC in Ireland for a site having an average rainfall ( ) of 785 mm suggested a k value of.3 was appropriate. In the absence of gas data from the sites we have assumed that the k value lies somewhere in the range.3 and.7. Sensitivity analysis of k values was carried out to assess potential GHF emissions using.3,.5 and.7 respectively Potential Methane Generation Capacity (L ) The Potential Methane Generation Capacity, L o, depends solely on the type and composition of waste d in the landfill. The higher the cellulose content of the waste, the higher the value of L o. The default L o values used by LandGem are representative of MSW. The L o value, as it is used in the first-order decomposition rate equation, is measured in metric units of cubic metres per megagram. The default L o values used by LandGEM to represent MSW waste is 17. Calibration data from the FTC site in Ireland suggested a L o value of 75. An L o value of 96 is used to represent a wet bioreactor. An L o value of 75 was used for the Irish site mentioned above. In the absence of calibration data or waste composition records from the sites, sensitivity analyses assumed L o values of 75, 17 and 265 respectively Non-methane Organic Compound Concentration The Non-methane Organic Compound Concentration (NMOC) concentration in landfill gas is a function of the types of the landfill and the extent of the reaction that produce various compounds from the anaerobic decomposition of waste. NMOC concentration is measured in units of parts per million by volume (ppmv) and is used by LandGem only when NMOC emissions are being estimated. No sensitivity analyses were carried out and a default value of 6 ppmv was used for all GHG emission estimates Methane Content The LandGEM model calculates the total volume of landfill gas produced. The model assumes an average methane concentration over the life gas production. The total landfill gas is therefore a function of the assumed average methane concentration and is deemed to be accurate for methane concentrations between 4% and 6% v/v. 5% has been used in this analysis. Regardless of the assumed methane concentration the total amount of methane remains the same for respective k and L o inputs. Operationally however as the landfill gas methane concentration changes as a function of landfill gas evolution (see Figure 2-1) the landfill gas production flow rate may differ from landfill gas prediction estimates (subject to actual methane concentration). 2 Q:/212/UW12/769/1/Reports/Rpt3-1.doc

11 Volume 1 Collation of Key Information on Small Closed & Operational Sites across Scotland ZWS 7 Figure 2-1 shows the eight Phases of landfill gas evolution 3. Descriptions of respective phases below are summarised comments taken from EU Commission 21 4 Whilst some of the newer landfills will lie within Phases IV & V and some of the older landfills will lie in Phase VII, an assumption has been made in this assessment that all the landfills lie within Phase VI - Methane Oxidation. Phase VI involves methane oxidation when the rate of methanogenesis has fallen to low levels and breakdown in surface waste is aerobic. The ratio of carbon dioxide to methane reflects the change from anaerobic to aerobic processes. The methane scale within this stage can range from 6% methane to %. In summary the theoretical volume of methane gas is represented by the area under the Figure 2-1 magenta curve. The shape of the curve is a function of puts and the time over which this methane is produced is a function of waste breakdown rates. Minimisation of methane (GHG) emissions requires early intervention. Whilst the opportunity for early intervention on closed historical sites has been lost, there still remains a significant volume of landfill gas post the arbitrary date of 212 and below the Figure 2-1 magenta curve. The landfill gas prediction modelling is designed to define this remaining volume. If this volume of landfill gas is significant management should seek to reduce uncontrolled emissions. Figure 2.1: Christiansen and Kjeldsen Evolution of Landfill Gas GHG emission estimates assume that the turquoise line represents an arbitrary year 212 and that future mitigation recommendations as may occur only have the potential to manage GHG emissions methane emissions to the right of this line and below the magenta CH 4 curve 3 Christiansen, TH and Kjedsen, P (1989) Basic biochemical processes in landfills. In Sanitary landfilling: Process, Technology and environmental impact. (Eds YH Christiansen, (R Cossu and R Stegmann), Academic Press, London, UK pp Commission 21, Waste Management Options and Climate Change July 21, Q:/212/UW12/769/1/Reports/Rpt3-1.doc

12 Volume 1 Collation of Key Information on Small Closed & Operational Sites across Scotland ZWS Capture Efficiency The purpose of this assessment is to define the potential fugitive emissions, accordingly the capture efficiency of the landfills has been set at %. This assumes that all landfill gas produced at a site escapes to atmosphere. In reality, a significant proportion of landfill gas on operational sites will be captured by gas collection infrastructure and oxidised in a flare or engine. On historical sites with no synthetic barriers methane oxidation may also occur within the cap (see below). The impact of management practices (capture efficiency and oxidation technologies) is presented in Volume 4 of this study, using findings from the Volume 2 literature review and the Volume 3 pilot trials. 2.3 Model Output Figure 2-1 shows the evolution of landfill gas production. LandGEM model outputs will estimate landfill gas prediction flow rates (with curves of a similar shape (see Figure 3-1) to those shown above in Figure 2-1) for respective landfills with the X axis defining actual flow rate. Using criteria defined in Sections 2.1 and, the analyses will develop a site specific landfill gas prediction estimate for individual subject sites and combine the methane estimates thereafter to produce a methane prediction curve estimate for the whole of Scotland. The area under the combined curves (Illustrated in Figure 2-1 (magenta) methane curve to the right of the 212 cutoff line) will define the tonnes of future GHG (methane) emissions post 212. In assessing potential GHG emissions going forward (post 212) the shape of the prediction curves will be influenced significantly by the methane generation rate k and the potential methane generating capacity L o. To illustrate the potential impacts of basic assumptions Figure 2-2 illustrates the impact of organic and moisture contents. In Figure 2-2, Curve 1 shows gas production from a typical 1, tonne per annum municipal solid waste (MSW) landfill. Curve 2 shows that landfill gas production from Mechanical Biological Treatment (MBT) residual waste arisings, where most of the organic material has been removed, is significantly lower. Curves 1 and 2 illustrate that basic assumptions on historical waste deposits, in the absence of detailed records, may have significant impacts on gas prediction modeling estimates. Biological diversion targets will also have the potential to impact future landfill gas emission volumes from operational landfill sites. Curve 3 reflects gas production from an anaerobic bioreactor which is designed to increase the moisture content of waste during and post ment in order to accelerate waste degradation. Comparison between Curves 1 and 3 shows that moisture content can have significant impacts on the timeline and volumes of landfill gas production. The area (i.e. total volume of gas) under curves 1 and 3 will be similar. However the time lines will vary significantly. In relation to historical and closed sites, waste moisture content can be influenced by; rainfall, daily cover and waste intake volumes, waste depth, cap permeability and cap slope all of which may have significant impacts on future gas volumes. Q:/212/UW12/769/1/Reports/Rpt3-1.doc

13 Volume 1 Collation of Key Information on Small Closed & Operational Sites across Scotland ZWS 9 Figure 2.2: Impact of Organic Content and Moisture Content on Landfill Gas Production Methane Oxidation For the purposes of this exercise, biological oxidation on in-situ caps will consider a worst case of % and an average case of 5%. Values higher than this were not considered as it is extremely unlikely that historical landfills have well maintained caps. 2.4 Sensitivity Analysis The results of the sensitivity analysis for a cut-off year of 212 are shown in Table 3.2. For the purposes of discussion later in the report, reference is made to median input criteria which represent the following input values: K =.5 Lo = 17 Unknown landfill size of 24, tonnes. Q:/212/UW12/769/1/Reports/Rpt3-1.doc

14 Volume 1 Collation of Key Information on Small Closed & Operational Sites across Scotland ZWS Global Warming Potential The modelling estimates from the LandGEM analyses estimate the total volume of LFG (based on % methane) produced post 212 for all sites. Calculations defining the mass of methane produced assume: Molecular weight of methane 16.4 g/mol Molecular weight of CO g/mol Standard molar volume of any gas at STP is 22.4l Molar density of methane.72 g/l. Molar density of CO 2 is 1.96 g/l This analysis assumes a methane content of 5% v/v therefore 1 m 3 of LFG is assumed to contain.5 m 3 of methane and.5 m 3 of CO 2. Based on the criteria above, 1 m 3 of LFG consists of.36 kg of methane and.98 kg of carbon dioxide. As methane has a different effect on the atmosphere than CO 2, a global warming potential (GWP) equivalence has been employed to factor the methane value. This GWP compares the ability of each greenhouse gas to trap heat in the atmosphere relative to another gas. The definition of a GWP for methane is the ratio of heat trapped by one unit mass of methane to that of one unit mass of CO 2 over a specified time period. The 1-year GWP in this analysis is assumed to be For example, it means that 1 kg of methane has the same impact on climate change as 25 kg of carbon dioxide and thus 1 kg of methane would count as 25 kg of carbon dioxide equivalent. The CO 2 equivalent of 1 m 3 of LFG (at an assumed 5% methane content) would be equivalent to approximately 9.98 kgco 2 e. To the numbers in context if a small historical landfill was to have a flare able to oxidise 1 m³/hour of landfill gas with a methane concentration of 2 % v/v continuously and with a destruction efficiency f 98% and a GWP of 25, this would equate to a reduction in CO 2 e emissions of 3,134,71 kg (3.1 mtco2e) every year. This is equivalent to a small family car driving around Scotland 36 times a day assuming a round trip of 979 miles from Edinburgh along the east coast top John O Groats and returning via the west coast (assuming an average carbon dioxide 6 consumption rate of 149 g/km), or is equivalent to 525 car journeys around the circumference of the earth per annum. 5 The GWP values in the Intergovernmental Panel on Climate Change (IPCC) Fourth Assessment Report (AR4) in Q:/212/UW12/769/1/Reports/Rpt3-1.doc

15 Volume 1 Collation of Key Information on Small Closed & Operational Sites across Scotland ZWS 11 3 Results 3.1 GHG Emissions Active Landfill PPC GHG Emissions The total remaining emissions from a cut-off year of 212 from active landfills (i.e. those landfills which are still actively receiving waste for landfill, as of 213) based on criteria outlined above is estimated to be between 1,882 x 1 6 m 3 and 1,63 x 1 6 m 3. Based on the median input criteria and assuming a methane content of 5% v/v methane, the expected remaining LFG is estimated to be 5,683 x 1 6 m 3 or 57 MtCO 2 e Sensitivity Increasing the unknown landfill size by 1% increases the total emissions by 14%. Unknown landfills represent 5% of the active landfills (25 out of 5). The remaining parameters of k and Lo do not have a linear relationship with the resultant emissions output. For example, when the input figure of k is increased by 66% from.3 to.5 it results in an emissions decrease of 17%, while an increase in the k value of 4% from.5 to.7 results in an emissions decrease of 8% Limitations The figures presented above are based on a constant biodegradable content of to the future. The active landfills included in this analysis included 5 out of 186. GHG emissions estimates show that active landfills may contribute between 69% & 9% of the total landfill GHG emissions post 212. Landfill diversion targets set out in the EU landfill directive require member states to reduce the biodegradable content of waste. Specifically, by 22, Scotland s Zero Waste Plan aims to reduce the landfilling of biodegradable municipal waste (BMW) to 1.26 million tonnes as shown in Table 3.2 GHG Emissions. This requires the diversion of an additional 53, tonnes of BMW from landfill. The effects of Scotland Zero Waste Plan diversion targets on emissions from landfills in the region were not modelled for individual sites. However, emissions are directly related to the biodegradable content therefore if, for example, 213 is taken as the cut off year, based on the median input criteria and assuming a methane content of 5% v/v, the expected remaining LFG is estimated to be 4,746 x 1 6 m 3 from active sites. A reduction of 29% from 1.8 to 1.26 million tonnes of BMW will reduce the active landfill contribution to 3,37 x 1 6 m 3 post 213. Further targets which will impact GHG emissions from landfills in Scotland in the future are shown in Appendix 3. Q:/212/UW12/769/1/Reports/Rpt3-1.doc

16 Volume 1 Collation of Key Information on Small Closed & Operational Sites across Scotland ZWS 12 Table 3.1: Revised Baseline and Targets for Scotland (28 figures) 8 Landfill Target Reduction Previous BMW Baseline (1995) and Targets BMW landfill performance - previous definition Additional diversion required to meet target Revised 1995 Baseline and Targets BMW landfill performance new definition Additional diversion required to meet target 1995 Baseline % 75% 5% 35% GHG Emissions Recently Closed Landfill PPC GHG Emissions Emissions from recently closed landfill sites (i.e. those closed between 21 and 212) represent between 1 to 31% of the total remaining LFG emissions from the 212 cut-off year. The total remaining emissions from a cut-off year of 212 from recently closed landfills based on criteria outlined above and assuming a methane content of 5% v/v methane, is estimated to be between 34 x 1 6 m 3 and 3,944 x 1 6 m 3. Based on median input criteria, the expected remaining LFG is estimated to be 1,169 x 1 6 m 3 or 12 MtCO 2 e Sensitivity The assumptions outlined in sections and mean that no unknown landfills fall into the recently closed landfill category. The parameters of k and L o do not have a linear relationship with the resultant emissions output, that is to say that % increase in the k value will not result in linear emissions change. For example, when the input figure of k is increased by 66% from.3 to.5 it results in an emissions decrease of 54%, While an increase in the k value of 4% from.5 to.7 results in an emissions decrease of 41% Limitations The gas prediction modelling estimates for recently closed sites were prepared in the absence of accurate data and it was necessary to input arbitrary estimates for the following parameters: Tonnage Start and finish years Organic fraction Waste degradation rates (k and L o ) 8 Figures are in millions of tonnes Q:/212/UW12/769/1/Reports/Rpt3-1.doc

17 Volume 1 Collation of Key Information on Small Closed & Operational Sites across Scotland ZWS GHG Emissions Operational Landfills Future volumes in this study will generally consider historical and operational landfills, rather than historical, recently closed and active landfills. Operational landfills is the umbrella term used for the combined group of recently closed and active landfills GHG Emissions The total remaining emissions from a cut-off year of 212 from operational landfills (which included all landfills with a closure date after 21) based on criteria outlined above is estimated to be between 2,187 x 1 6 m 3 and 16,313 x 1 6 m 3. Based on the median input criteria and assuming a methane content of 5% v/v methane, the expected remaining LFG is estimated to be 6,855 x 1 6 m 3 or 68 MtCO 2 e Sensitivity Increasing the unknown landfill size by 1% increases the total emissions by 14%. Unknown landfills represent 26% of the operational landfills (25 out of 95). The remaining parameters of k and Lo do not have a linear relationship with the resultant emissions output. For example, when the input figure of k is increased by 66% from.3 to.5 it results in an emissions decrease of 27%, while an increase in the k value of 4% from.5 to.7 results in an emissions decrease of 14% Limitations The figures presented above are based on a constant biodegradable content of to the future. The operational landfills included in this analysis included 95 out of 186. GHG emissions estimates show that operational landfills may contribute between 99.2% & 99.6% of the total landfill GHG emissions post 212. As discussed in 3.1.3, landfill diversion targets will impact on emissions from landfills. For operational landfills, if 213 is taken as the cut off year, based on the median input criteria and assuming a methane content of 5% v/v, the expected remaining LFG is estimated to be 5,456 x 1 6 m 3 from operational sites. A reduction of 29% from 1.8 to 1.26 million tonnes of BMW will reduce the operational landfill contribution to 3,874 x 1 6 m 3 post 213. Further targets which will impact GHG emissions from landfills in Scotland in the future are shown in Appendix GHG Emissions Historical Landfill GHG Emissions Historic landfill sites (i.e. those closed pre 21) represent between and.8% of the total remaining LFG emissions from the 212 cut-off year. These sites have effectively been closed for over 1 years with the amount of LFG emitted by the sites reducing dramatically thereafter. The total remaining emissions from a cut-off year of 212 from historic landfills based on criteria outlined above and assuming a methane content of 5% v/v methane, is estimated to be between m 3 and 126 x 1 6 m 3. Based on median input criteria, the expected remaining LFG is estimated to be 3 x 1 6 m 3 or.3 MtCO 2 e. Q:/212/UW12/769/1/Reports/Rpt3-1.doc

18 Volume 1 Collation of Key Information on Small Closed & Operational Sites across Scotland ZWS Sensitivity Increasing the unknown landfill size by 1% increases the total emissions by 6%. The size of the unknown has significant effect on the emissions estimate as the unknown landfills represent 79 of the 91 landfills closed pre 21. The remaining parameters of k and L o do not have a linear relationship with the resultant emissions output, that is to say that % increase in the k value will result in linear emissions change. For example, when the input figure of k is increased by 66% from.3 to.5 it results in an emissions decrease of 95%, While an increase in the k value of 4% from.5 to.7 results in an emissions decrease of 88% Limitations The gas prediction modelling estimates for historical sites were prepared in the absence of accurate data and it was necessary to input arbitrary estimates for the following parameters: Tonnage Start and finish years Organic fraction Waste degradation rates (k and L o ) 3.5 GHG Emissions Total The total remaining emissions from a cut-off year of 212 from all LFG generating landfills is estimated to be between 2,187x 1 6 m 3 and 16,439 x 1 6 m³. Based on the median input criteria and assuming a methane concentration of 5% v/v, the expected remaining LFG is estimated to be 6,855 x 1 6 m 3 or 68 MtCO 2 e equivalent. Table 3.2 over summarises the emission estimates and CO 2 equivalent for respective sites with assumed LandGEM input options. Figure 3-1 presents total landfill gas prediction (flow rate) estimates for individual landfills assuming a methane concentration of 5 % v/v. Figure 3-2 presents a cumulative methane prediction (flow rate) estimate for all landfills assuming a methane concentration of 5 % v/v, and illustrates the relative flow rates from the landfill classes described above Comparison to Other Models/Databases Scottish Environmental Statistics from August 28, indicated that waste management accounted for 1,425, tonnes CO 2 e in The model used, for the calculation of this figure, is an Intergovernmental Panel on Climate Change (IPCC) prediction model. A backwards calculation was carried out on the 25 reported figure to estimate an equivalent methane emission volume. Figure 3-2 also includes this extrapolated methane emission figure for comparison purposes. While the 25 emission estimate from the IPCC model is significantly less than the 25 year estimate from the LandGEM model discussed above, Scottish Government estimates 11 of total future emissions, i.e. post 212, are similar in magnitude to the LandGEM model estimates prepared for this study. 1 Scottish Environmental Statistics, Scottish Government, August 28 cited in A Climate Change Plan for SEPA, communications, IKMFT SEPA/ZWS, and Q:/212/UW12/769/1/Reports/Rpt3-1.doc

19 Volume 1 Collation of Key Information on Small Closed & Operational Sites across Scotland ZWS 15 For further comparative purposes, the data arising from the Scottish Pollutant Release Inventory (SPRI) database has been interrogated and graphed over time. The SPRI is a database of annual mass releases of specified pollutants to air, water and land from SEPA regulated industrial sites, including landfills. The curves presented in Figure 3-2 for the IPCC model have been developed based on downloaded data from the database for years (22-211, excluding 23) 13. The data analysed was the operator returns for methane emissions from two sectors, namely 5c Disposal of non-hazardous waste, and 5d Landfills. The orange curve on Figure 3-2 (labelled Methane Emissions SPRI database) is the downloaded data for each year. The SPRI database is register of operator reported emissions from sites. In the case of landfill, the methane emissions comprise the fugitive (non-captured) emissions, and those emissions from flares/engines which are un-combusted. In order to extrapolate an overall production value from this data, it is assumed that these two elements combined account for 15% of overall production values. The light blue curve on Figure 3-2 shows this extrapolated methane production in m³/year. It is noted that there is a discrepancy between this extrapolated production graph and the results from the LandGEM model developed for this study, which is in the order of magnitude of two. However, there are a number of limitations to the SPRI dataset, as follows: The SPRI dataset is based on returns from landfill operators, and as such the accuracy of individual returns cannot be guaranteed by SEPA or IKM FT. The number of site included in the SPRI datasets is typically around 7 between , and approximately 5 between The LandGEM model tool includes 82 known landfills and a further 14 unknown landfills, giving a total of 186 landfills modelled over the entire time period considered. A quick check of the landfills with the largest contribution to the IKM FT model showed that of the top 9 landfill sites, no results/data were given for 5 in the SPRI database. Finally, where methane emissions from a particular site are below the reporting threshold of 1, kg/annum, a figure of is returned by the SPRI database; this may lead to the under-reporting of methane emissions. Over the past 3 years, between 35-4% of landfill sites have reported methane emissions below the 1, kg/annum threshold. It is also reiterated that the IKM FT model is limited by the number of crude assumptions which are made throughout the modelling process. Nonetheless, the agreement of the IKM FT model and the IPCC model used previously by SEPA in the quantum of remaining total emissions from landfill sites is encouraging Q:/212/UW12/769/1/Reports/Rpt3-1.doc

20 Volume 1 Collation of Key Information on Small Closed & Operational Sites across Scotland ZWS 16 Table 3.2: GHG Emissions Cutoff year Methane content (%v/v) k L o Unknown LF size Operational Sites (Active + Recently Closed) Remaining LFG (m 3 x 1 6 ) Active Sites Recently Closed sites ± Closed Sites* Total Total MtCO 2 e (methane only) Total MtCO 2 e adjusted # (methane only) 3,633 2,516 1, , , 4,125 3,9 1, , , 4,617 3,51 1, , ,234 5,74 2,53 3 8, , 9,35 6,819 2, , , 1,465 7,935 2, , ,836 8,892 3, , , 14,574 1,63 3, , , 16,313 12,369 3, , ,583 2, , , 3,23 2, , , 3,463 2, , ,855 4,686 1, , , 6,852 5,683 1, , , 7,849 6,68 1, , ,127 7,35 1, , , 1,681 8,859 1, , , 12,235 1,412 1, , ,187 1, , , 2,65 2, , , 3,24 2, , ,957 4, , , 5,96 5, , , 6,854 6, , ,728 6,65 1,78 7, Q:/212/UW12/769/1/Reports/Rpt3-1.doc

21 Volume 1 Collation of Key Information on Small Closed & Operational Sites across Scotland ZWS 17 Cutoff year Methane content (%v/v) k L o Unknown LF size Operational Sites (Active + Recently Closed) Remaining LFG (m 3 x 1 6 ) Active Sites Recently Closed sites ± Closed Sites* Total Total MtCO 2 e (methane only) Total MtCO 2 e adjusted # (methane only) 24, 9,26 8,129 1,77 9, , 1,684 9,67 1,77 1 1, ± The predicted generation figures for recently closed landfills does not vary with changes to the unknown landfill size, due to the assumptions made in relation to opening and closure year for the unknown landfills. * The predicted generation figures for closed landfills varies depending on the input parameters. Input parameter k (methane generation rate) has the most significant impact. Using of a smaller k gives a sharper increase and decrease in generation. # The figures shown in this column use 213 as a cut-off year and have been adjusted by -29% to take account of diversion targets. Q:/212/UW12/769/1/Reports/Rpt3-1.doc

22 Volume 1 Collation of Key Information on Small Closed & Operational Sites across Scotland ZWS 18 Figure 3.1: Landfill Gas Prediction Estimates for Individual sites (Median Inputs, 5 % v/v Methane, descriptions of sites 1-84 are available in Appendix 2) Q:/212/UW12/769/1/Reports/Rpt3-1.doc

23 Volume 1 Collation of Key Information on Small Closed & Operational Sites across Scotland ZWS 19 Figure 3.2: Total Landfill Gas Prediction Estimate (Median Inputs, 5 % v/v methane) Q:/212/UW12/769/1/Reports/Rpt3-1.doc

24 Volume 1 Collation of Key Information on Small Closed & Operational Sites across Scotland ZWS 2 4 Summary The results reported in this report are not absolute values, but rather they aim to define a range of possible values in order to demonstrate the proportions of GHG emissions from respective landfill sites in Scotland. In particular, this report highlights that the most significant contributors to future GHG emissions from landfills will be the operational sites. The contribution from historical landfills is by comparison very low. Whilst the relative contribution from historical landfills is low, the volume of GHG emissions from these sites is still significant and there will be a requirement to define more accurately and manage thereafter GHG emissions from small and closed historical landfills. Reductions in GHG emissions by oxidation of methane on historical landfills will be challenging as the calorific value of this (older) landfill gas will be low and unsuited to prevailing engine and flaring technologies. Furthermore the majority of these sites are unmanned with little or no gas collection infrastructure. Whilst operational (active and recently closed) sites have the advantage of being manned with developed gas infrastructure systems, reductions in GHG emissions by oxidation of methane will become more challenging as the calorific value of landfill gas reduces. At active landfills, this change in calorific value will be primarily driven by the implementation of landfill diversion targets. The effects of these diversion targets have not been modelled in detail in this assessment, and it is recommended that detailed analysis of the likely changes should be carried in order to quantify more accurately future GHG emissions. The pilot trials discussed in Volume 3 were designed to estimate the extent to which methane emissions from landfills may be oxidised using respective technology options for landfill gas with different calorific values. Volume 4 reviews the potential impacts of respective utilisation, flaring and other oxidation technologies on future GHG emissions from landfills. Q:/212/UW12/769/1/Reports/Rpt3-1.doc

25 APPENDIX 1 SUMMARY OF SITES EVALUATED Q:/212/UW12/769/1/Reports/Rpt3-1.doc

26 Site Description Open inert WML issued post 2 & deemed to be a PPC permit Current Applications Sites that had a SCP /closure notice issued against them but now established they closed pre 21 Sites closed pre 21 Other (no description given) Total LFG gener ating inert no info Total LFG gener ating inert no info Total LFG gener ating inert no info Total LFG gener ating inert no info Total LFG gener ating inert no info Total LFG gener ating inert no info Total LFG gener ating inert no info Total Argyll (B) Fort William (B) Perth (B) Orkney (B) Thurso (B) Shetland (B) Glasgow (B) Dumbartonshire (B) Dumfries (Pe) Galloway (Pe) Falkirk (Pe) West Lothian (Pe) Dingwall - North (Pe) Dingwall - South (Pe) Edinburgh (P) East Lothian (P) Renfrew & Inverclyde (P) South Lanark shire (P) Elgin (P) Western Isles (P) Ayrshire (P) Stirling (J) Aberdeen - North (J) Aberdeen Q:/212/UW12/769/1/Reports/Rpt3-1.doc

27 Volume 1 Collation of Key Information on Small Closed & Operational Sites across Scotland ZWS 23 Site Description Open inert WML issued post 2 & deemed to be a PPC permit Current Applications Sites that had a SCP /closure notice issued against them but now established they closed pre 21 Sites closed pre 21 Other (no description given) Total LFG gener ating inert no info Total LFG gener ating inert no info Total LFG gener ating inert no info Total LFG gener ating inert no info Total LFG gener ating inert no info Total LFG gener ating inert no info Total LFG gener ating inert no info Total South (J) Fife (J) Borders (J) Angus (J) Fraserburgh (J) Dundee (J) North Lanarkshire (A) Total Q:/212/UW12/769/1/Reports/Rpt3-1.doc

28 APPENDIX 2 Model Inputs Q:/212/UW12/769/1/Reports/Rpt3-1.doc

29 Landfill 1 Landfill 2 Landfill 3 Landfill 4 Landfill 5 Landfill 6 Landfill 7 Westland Road Transfer Glengorm Landfill and Civic Lingerton Landfill & Moleigh Landfill and Civic Name: Gartbreck Landfill Site Name: Name: Dalinlongart Landfill Site Name: Name: Station + Larkhall Landfill Name: Name: Amenity Site Recycling/Civic Amenity Site Amenity Site, Site, Cordinate NR Cordinate NM Cordinate NS Cordinate NR Cordinate NS Cordinate NM Cordinate Region Argyll Region Argyll Region Argyll Region Argyll Region Argyll Region Argyll Region Cliad Landfill Site, NM Argyll Comments: Comments: Comments: Comments: Comments: Comments: Open(1,tpa, 28 yrs Comments: Open (1, tpa, opening Open (12, tpa, opening based on 28, estimated year chosen as 2) year chosen as 2) Open (24,95 tpa, 28yrs) Open (24,95 tpa, 28yrs) Open(7,tpa, 28 yrs) remaining capacity) Opening year 2 Opening year 2 Opening year 22 Opening year 22 Opening year 22 Opening year 22 Opening year Closure year 23 Closure year 23 Closure year 23 Closure year 23 Closure year 23 Closure year 23 Closure year Open (opening year chosen as 2, 85t remaining capacity, closure year 23 ) 2 23 A (m) A (m) A (m) A (m) A (m) A (m) A (m) B (m) B (m) B (m) B (m) B (m) B (m) B (m) A X B (m 2 ) Density.8 t/m3 Density.8 t/m3 Density.8 t/m3 Density.8 t/m3 Density.8 t/m3 Density.8 t/m3 Density.8 t/m3 3, 36, 698,6 698,6 196, 28, 8, Enter CH 4 (%v/v) 5% Enter CH 4 (%v/v) 5% Enter CH 4 (%v/v) 5% Enter CH 4 (%v/v) 5% Enter CH 4 (%v/v) 5% Enter CH 4 (%v/v) 5% Enter CH 4 (%v/v) 5% Capture Eff. % Capture Eff. % Capture Eff. % Capture Eff. % Capture Eff. % Capture Eff. % Capture Eff. % t t t t t t t

30 Landfill 8 Landfill 9 Landfill 1 Landfill 11 Landfill 12 Landfill 13 Landfill 14 Portree Landfill, Dunvegan Flatfield Landfill, Errol, Name: Gott Bay Landfill Site, Name: Bonaveh Landfill Site, Name: Name: Gallowflats Clay Pit Name: North Forr Landfill Name: Name: Road, Portree. Pethshire Cordinate NM Cordinate NR Cordinate NG Cordinate? Cordinate NN87122 Cordinate? Cordinate Region Argyll Region Argyll Region Fort William Region Perth Region Perth Region Perth Region Open (opening year chosen Open (opening year chosen Comments: as 22, 27972t remaining Comments: as 2, 16983t remaining Comments: Comments: Comments: Comments: Comments: capacity, closure year 23 capacity after 212, closure Open (opening year chosen Closure year 21 (assumed Closure year 21 (assumed Closure year 21 (assumed ) year 23 ) as 2 2 yr lifespan) 2 yr lifespan) 2 yr lifespan) Opening year 22 Opening year 2 Opening year 2 Opening year 199 Opening year 199 Opening year 199 Opening year Closure year 23 Closure year 23 Closure year 22 Closure year 21 Closure year 21 Closure year 21 Closure year Summerston Landfill Site, Balmore Road, Glasgow G23. NS Glasgow Closure year 212 (assume 2 yr lifespan) A (m) A (m) A (m) A (m) A (m) A (m) A (m) B (m) B (m) B (m) B (m) B (m) B (m) B (m) A X B (m 2 ) Density.8 t/m3 Density.8 t/m3 Density.8 t/m3 Density.8 t/m3 Density.8 t/m3 Density.8 t/m3 Density.8 t/m3 27,972 37,783 5, 49, 99, 7,3 1,8, Enter CH 4 (%v/v) 5% Enter CH 4 (%v/v) 5% Enter CH 4 (%v/v) 5% Enter CH 4 (%v/v) 5% Enter CH 4 (%v/v) 5% Enter CH 4 (%v/v) 5% Enter CH 4 (%v/v) 5% Capture Eff. % Capture Eff. % Capture Eff. % Capture Eff. % Capture Eff. % Capture Eff. % Capture Eff. % t t t t t t t