Appendix D: Projected Waste Sector Emissions for the First Commitment Period of the Kyoto Protocol

Introduction

Greenhouse gas emissions arise from three waste sector sources: emissions from solid waste disposal sites (landfills), from domestic and industrial wastewater treatment plants, and from solid waste incineration.

Emissions from solid waste disposal sites comprised 79 per cent of the emissions from the waste sector in 2007. These emissions are the result of anaerobic decomposition of organic matter – primarily garden, food, paper, textile and timber waste. The net amount of emissions produced depend on many factors including the composition of solid waste to landfill, waste disposal practices, and the efficiency of any landfill gas collection system.

Wastewater treatment processes produced 21 per cent of emissions from waste in 2007. Both methane and nitrous oxide are emitted through treating domestic, commercial and industrial wastewater. Factors influencing the amount of emissions include the type of treatment process, the volume of wastewater and the nitrogen content, and whether any resulting emissions are flared.

Emissions from solid waste incineration produced less than 1 per cent of waste sector emissions in 2007. These emissions include carbon dioxide (from combusting materials with some fossil fuel content, such as plastics), nitrous oxide and methane. The emissions arise from hospital and quarantine waste incineration. There has been a significant decrease in incineration emissions since 1990 due to the implementation of national regulations controlling air quality effects and the availability of alternative treatments such as steam sterilisation.

Recent trends

Waste sector emissions in 2007 were 1.821.8 million tonnes of carbon dioxide equivalent (Mt CO₂-e). This is a reduction of 0.6164 Mt CO₂-e (25.9 per cent) below the 1990 baseline value of 2.438 Mt CO₂-e.

This reduction has occurred across all waste sub-sectors. The largest reduction has occurred in the solid waste disposal on land category as a result of initiatives to improve solid waste management practices and increase landfill gas capture rates in New Zealand. Improvements in wastewater treatment technologies and solid waste incineration practises have resulted in smaller inventory reductions.

Modelling

Description of method

The emissions from solid waste disposal are projected using the methodology and variables used in New Zealand’s Greenhouse Gas Inventory 1990–2007 (hereafter, the National Inventory) (MfE, 2009). The methodology uses data specific to New Zealand on waste generation rates, waste composition, percentage of waste disposed to types of landfills and landfill gas extraction and combustion. Data on waste generation has not been collected routinely in the past; however, all assumptions have been clearly expressed in the National Inventory and reviewed by international experts.

The National Inventory uses a MS-Excel model provided by the Intergovernmental Panel on Climate Change (IPCC, 2006) to estimate gross methane emissions from solid waste disposed to landfills. This methodology assumes that the degradable organic components in waste decay slowly throughout a few decades. Emissions of methane are highest in the first few years after the waste was disposed then gradually decline.

The methodology requires an estimate of solid waste generated per capita. This data has been complied through the landfill surveys in 1995 and 2002. Other limited data sets exist for waste composition and have been used. The only variable input into the projections methodology is that of national population, which determines the total volume of waste to landfills. The projections used are from Statistics New Zealand’s National Population Projections (2006 base, series 1, 5 and 9). Other variables remain constant at the values reported in the latest National Inventory (MfE, 2009). Net emissions are projected to be 1.375 Mt CO₂-e for 2010. This is an increase of 0.192 Mt CO₂-e from the 2008 net position report and has come about mainly through correcting for an overestimation of projected landfill gas recovery.

Emissions from wastewater treatment have been estimated using a combination of country-specific methodologies and IPCC good practice models. Emissions are sourced from anaerobic treatment of domestic, commercial and industrial wastewater in municipal and some industrial treatment plants. Some larger treatment facilities flare the resulting methane. Projected emissions for 2010 were estimated by holding the 2007 emission values constant for all sub-sectors except commercial and domestic wastewater treatment. It was necessary to hold these values constant because there were no published projections of the necessary activity data. Methane emissions from domestic and commercial wastewater treatment are a function of human population, so this methodology uses the same Statistics NZ data as in the projections of solid waste described above. Emissions are projected to be 0.35 Mt CO₂-e for 2010. This is an increase of 0.04 Mt CO₂-e from the 2008 net position report and reflects an improved methodology for estimating emissions from industrial wastewater treatment.

Emissions from solid waste incineration were estimated and reported for the first time in the latest National Inventory (MfE, 2009). IPCC 2006 good practice guidance was followed. Emissions of carbon dioxide, nitrous oxide and methane are sourced primarily from the burning of quarantine and hospital waste. There were 10 such incinerators emitting such gases at the start of 2007. Carbon dioxide is counted in the National Inventory where materials with a fossil fuel origin are burnt. Projected incineration activity was assessed through obtaining expected activity estimates from individual incinerators. Emissions are projected to be 0.002 Mt CO₂-e for 2010.

Policies

Policies in place

There are three existing policies that are, or will, affect the amount of greenhouse gas emissions from landfills over 2008 to 2012. In addition, emissions from solid waste disposed on land are proposed to enter the scope of the New Zealand Emissions Trading Scheme from 1 January 2013.

The Waste Minimisation Act 2008

The Waste Minimisation Act was enacted in 2008. This legislation provides for monitoring and reporting of waste disposed and diverted, for the development of producer responsibility schemes, and for the implementation of a national levy on solid waste to fund waste minimisation programmes and infrastructure. There has been no published modelling on the effects of this legislation on any of the variables used in estimating greenhouse gas emissions from landfills. While it is clear that nearly all of the functions of the Act will reduce emissions from landfills, without published and defensible data, the impacts of the Act cannot be built into this report.

The New Zealand Waste Strategy

The New Zealand Waste Strategy was launched in March 2002 with the objective of moving towards zero waste by 2010. The strategy extends to all waste streams including landfill waste, mine and quarrying waste, and sewage. Targets contained by the Waste Strategy are currently being reviewed in light of the implementation of the Waste Minimisation Act. For that reason, no estimation is included in this report of the possible impact of the Waste Strategy on greenhouse gas emissions from landfills.

In the 2008 net position report, assumptions were made on likely reductions in waste volumes, and changes to waste composition from achieving the targets in the Waste Strategy. These assumptions are not included in this report as they are considered to be lacking foundation.

The National Environmental Standard for Landfill Gas Collection

A National Environmental Standard for Landfill Gas Collection and Destruction was introduced in 2004 under Sections 43 and 44 of the Resource Management Act (RMA) to be applied to landfills that will accept over one million tonnes of refuse throughout their design life.

Landfill gas collection estimates were updated for the 2004 National Inventory by Waste Management in 2005. The consultants projected that 7.4 Mt CO₂-e, or 55 per cent, of gross emissions from solid waste disposal sites would be collected by landfill gas systems over the years 2008 to 2012. The consultants used different activity data to develop estimates of gross emissions than used by the latest National Inventory report. Consequently, the consultants’ estimates of recovered methane are probably overestimated. To reduce this problem, the proportion of recovered methane to gross emissions is used in the methodology for this report, instead of the consultants’ projections of absolute reductions. The most likely scenario now holds that landfill gas collections systems will reduce gross emissions by 7.5 Mt CO₂-e over 2008 to 2012.

Projection

Total emissions

Emissions from the waste sector over the first commitment period are expected to be 8.3 Mt CO₂-e. Projected annual emissions for 2010 are expected to be 1.7 Mt CO₂-e per annum.

Figure 1 illustrates the large decrease in emissions since 1990, which as explained above, is primarily due to decreased waste volumes and less organic matter entering landfills. The possible ranges for projected emissions occur through the use of three population growth scenarios.

Figure 1: Projected annual emissions for 2010 and the inventory time series of emissions from the waste sector (million tonnes carbon dioxide equivalent)

Text description for figure 1

Reconciliation with 2008 projection

For the period 2008 to 2012, projected emissions from the waste sector have increased 1.130 Mt CO₂-e (15 per cent) from the 2008 estimates due to several factors:

the IPCC 2006 MS-Excel spreadsheet model used to develop estimates of gross and net methane emissions from landfills required changes to various methodological inputs
methodological changes in modelling emissions from domestic and commercial wastewater treatment. This factor accounts for nearly 25 per cent of the increase
not including any effects of waste minimisation policies, strategies or legislation in the projections of emissions in this report. This factor accounts for over 75 per cent of the increase.

References

IPCC. 2006. Eggleston HS, Buendia L, Miwa K, Ngara T, Tanabe K (Eds). 2006 IPCC Guidelines for National Greenhouse Gas Inventories. Volume 5. Waste. IPCC National Greenhouse Gas Inventories Programme. Published for the IPCC by the Institute for Global Environmental Strategies: Japan.

MfE (Ministry for the Environment). 2009. New Zealand’s Greenhouse Gas Inventory 1990–2007 (in press). Submitted to the United Nations Framework Convention on Climate Change. 15 April 2009, Ministry for the Environment, Wellington.