New Zealand's Greenhouse Gas Inventory 1990 - 2002

• Executive Summary
• Chapter 1: Introduction
• Chapter 2: Trends in Greenhouse Gas Emissions
• Chapter 3: Energy
• Chapter 4: Industrial Processes
• Chapter 5: Solvent and Other Product Use
• Chapter 6: Agriculture
• Chapter 7: Land-Use Change and Forestry (LUCF)
• Chapter 8: Waste
• Chapter 9: Recalculations and Improvements
• References
• Annex 1: Key Sources
• Annex 2: Detailed discussion of methodology and data for estimating CO2 emissions from fossil fuel combustion
• Annex 3: Detailed methodologies for source or sink categories
• Annex 4: CO2 reference approach and comparison with sectoral approach, and relevant information on the national energy balance
• Annex 5: Assessment of completeness and (potential) sources and sinks of greenhouse gas emissions and removals excluded
• Annex 6: Quality Assurance and Quality Control
• Annex 7: Uncertainty analysis (Table 6.1 of the IPCC good practice guidance)
• Annex 8: Trend tables from the 2002 Common Reporting Format

Chapter 9: Recalculations and Improvements

9.1 The 2004 submission (2002 inventory)

In this current submission, the format of the inventory report is restructured to fit the format outlined in the UNFCCC reporting guidelines (UNFCCC/2002/CP/8).

9.1.1 Improvements

Improvements in the 2002 inventory include:

• Including a complete set of the CRF for all years 1990-2002.
• Developing a preliminary QA/QC plan and trial of Tier 1 QC checksheets (Annex 6).
• Trialing a Tier 3 questionnaire to calculate emissions of SF₆ from electrical equipment.
• Reporting N₂O use in anaesthesia for the solvent and other product use sector.
• Reporting CH₄ from methanol production.
• Increased explanatory text in the NIR to help understanding of the methodologies and address questions raised by UNFCCC expert review teams, especially in the energy and industrial processes sectors.
• Including more general inventory background and summary information.

9.1.2 Recalculations

The overall effect of all recalculations is shown in Figure 9.1.1. The recalculations change the level of emissions reported in the 2003 submission for 1990-2000 by an average of 0.56%. There is a 1.7% change in the 2001 inventory largely due to the replacement of provisional animal numbers with actual animal numbers in the agriculture sector. This occurs every year of the inventory. Changes in individual sectors are discussed in the following sections. Solvents are not included because of the very low level of emissions throughout the time-series.

Energy Sector

New Zealand reviewed all emission factors used in the energy sector in 2003 (Hale and Twomey, 2003). The review was commissioned based on recommendations from New Zealand's inventory QA procedures (Clarkson, 2001, 2002). The results of the emission factors review were assessed by an independent review panel of New Zealand energy experts prior to review recommendations being used in the inventory. In accordance with Good Practice (IPCC, 2000), where there was a significant difference between country-specific and IPCC default emission factors, and a defensible explanation could not be obtained, New Zealand reverted to the IPCC default emission factors (refer to Annex 2 for detailed information). The 2002 inventory incorporates the emission factors recommended by the review and agreed by the review panel. The implications on emission levels and the trend in emissions from the energy sector are shown in Figure 9.1.2.

Officials at the MED conducted an investigation into the effect of the new emission factors on the 1990 and 2002 inventory data. The analysis compared the previous emission factors with the new emission factors. The analysis identified that for:

• CO₂ emissions: the emissions factor review had relatively little effect on CO₂ emissions. The effect on total energy sector CO₂ emissions is less than 1% in both 1990 and 2002. The category most affected by the review is transport as a result of splitting the petrol, aviation fuels and fuel oil into more specific groups. The changes in transport factors are small, and the overall effects are less than a 1% decrease in 1990 domestic transport emissions and less than a 1% increase in 2002 domestic transport emissions.
• CH₄ emissions: there are two categories where CH₄ emissions are significantly affected by the new emission factors. One category is fugitive emissions which are approximately 80% of total CH₄ energy emissions. The effect of changing from the New Zealand specific emission factor to the IPCC emission factor is a 12% reduction in fugitive emissions for 2002. The other sector significantly affected by the review is transport, where the CH₄ emissions factor from petrol combustion was changed from a New Zealand specific value (60 tCH₄/PJ ) to the top of the IPCC range (18.5 tCH₄/PJ (Annex 2).
• N₂O emissions: the new N₂O emission factors show a 23% decrease in 1990 emissions and a 14% decrease in 2002 emissions. The changes in emission factors arise from a change from New Zealand specific factors to IPCC factors. The net effect is a 35% decrease in 1990 emissions and a 20% decrease in 2002 emissions in the domestic transport sector.
• NO_x emissions: there is a 17% decrease in NO_x emissions from the 2002 level when the new emission factors are used with almost no change from the 1990 level. This change arises largely from the new emission factors for liquid fuels used in transport.
• CO emissions: CO emissions are approximately 30% lower in 1990 and 2002 when the new emission factors are used. Again this is largely caused by decreases to the emission factors for petrol and diesel used in domestic transport.
• NMVOC emissions: emissions of NMVOC decline by nearly 20% from both the 1990 and 2002 levels when using the new emission factors. This is attributed to a decrease in the emission factors for both petrol and diesel.

Industrial processes

There are changes in the estimates of non-CO₂ emissions in the industrial processes sector in the 2002 inventory. The changes resulted from new sources being identified in the survey and a critical examination of previous emission estimates. All revisions are back-calculated through to 1990 (Figure 9.1.3).

The major changes in the industrial processes sector were:

• CH₄ from methanol production was included for the first time in the 2002 inventory due to an omission in previous CRFs. Emissions are calculated back to 1997 (when methanol production data are available).
• PFC emissions data from aluminium smelting reported in previous inventories (1990-1999) were identified by NZCCO officials as being inconsistent with company-supplied emissions records. The inconsistency was investigated and corrected in all CRFs.
• The emission factors for wine, beer and spirits were found to be in error (per hectolitre) and all CRFs were corrected.
• The major user of SF₆ was able to assess holdings more accurately than in the past surveys for 2000 and 2001. The losses have been re-calculated using a 1% emissions factor for the major firm and 2% for all other companies.
• There are some recalculations for the sub-sources of HFC/PFC emissions due to new sources being identified.

Agriculture

Every year of inventory there is a recalculation for the previous year as the provisional animal population is updated with the actual population. This causes an increase in the level of emissions reported (Figure 9.1.4). The other recalculation for 2004 was the inclusion of emissions from savanna burning.

Land-use change and forestry

New proportions of area by NEFD regime have been used to weight the carbon yield in the 2002 inventory. Area data and carbon yields underlying the models in recent reports are similar to those used in previous inventories. The difference in net managed forest CO₂ removals between this and the previous inventory are generally of the order of less than 2% (Figure 9.1.5)

Waste

The emissions for 1990-2001 from solid waste disposal sites are recalculated based on improved population data from Statistics New Zealand. The effect of the improved population data on the waste sector is shown in Figure 9.1.6.

9.2 Improvements and recalculations in previous submissions

9.2.1 The 2003 submission (2001 inventory)

In the 2003 submission, the methodology used to estimate CH₄ emissions from ruminants was upgraded from Tier 1 to a Tier 2 approach consistent with good practice.

As part of the on-going improvement to estimates of N₂O from agricultural sources, a complete recalculation of the time-series was carried out using revised emission factors from IPCC (2000), some revised country specific emission factors and new annual nitrogen excretion rates for the most significant animal classes.

9.2.2 The 2002 submission (2000 inventory)

In the 2002 submission for the year 2000,emissions from solid waste disposal were upgraded to Tier 2 and emissions from small sources previously unreported (lime and dolomite) were included.

9.2.3 The 2001 submission (1999 inventory)

In the 2001 submission for the year 1999, estimates of emissions of the fluorinated gases (HFCs, PFCs and SF₆) gases were upgraded to IPCC (2000) Tier 2 methodology.

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