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Chapter 10: Recalculations and improvements

This chapter summarises the recalculations and improvements made to the New Zealand greenhouse gas inventory following submission of the 1990–2006 inventory. The chapter summarises material that has already been described in Chapters 3–8.

Each year, the inventory is updated (existing activity data and/or emissions’ factors may be improved) and extended (each inventory submission includes a new inventory year). The inventory may also be expanded to include emissions from additional sources if a new source has been identified within the context of the revised 1996 IPCC guidelines (IPCC, 1996) and good practice guidance (IPCC, 2000 and 2003). Recalculations may also occur if activity data and emission factors have become available for sources that were previously reported as “NE” (not estimated) due to a lack of data.

The use of revised methodologies and activity data in any sector will result in recalculation of the whole time series from 1990 to the current inventory. This means estimates of emissions in a given year may differ from emissions reported in the previous inventory submission.

10.1 Explanations and justifications for recalculations

10.1.1 Energy sector

Recalculations for the entire energy sector have resulted in a decrease of 46.3 Gg CO2-e in 1990 and a decrease of 58.7 Gg CO2-e in 2006 due to applying year-specific calorific values for all fuel types (section 3.2.2).

10.1.2 Industrial processes sector

In this submission, New Zealand has recalculated the following within the industrial processes sector:

  • carbon dioxide estimates for steel and limestone, coke and electrodes (section 4.2.5 and 4.4.5) were calculated from total steel emissions including the emissions from energy. This would correct any underestimates from previous submissions where these estimates were calculated from total steel emissions excluding energy

  • emissions from ammonia production due to updated emission factors. These factors are now gas-field specific (section 4.3.5)

  • perfluorocarbon emissions from aluminium productions due to applying the current supplied data (section 4.4.5)

  • the 1991 and 1992 estimates for aluminium production, CO2 and PFC emissions due to revised interpolation of values (section 4.4.5) that exclude any influence of assumptions used in previous submissions

  • hydrofluorocarbon and PFC emissions from refrigeration and mobile air-conditioning due to corrections, updated assumptions and the inclusion of new activity data (section 4.7.5)

  • sulphur hexafluoride emissions from electrical equipment due to an increase in activity data availability (section 4.7.5).

10.1.3 Solvents and other products

As described in section 5.1.5, New Zealand has changed the notation keys applied in the common reporting format tables for CO2, SO2, CO and NOx are now “NE” as no detailed IPCC methodologies are available to estimate these emissions.

10.1.4 Agriculture

All activity data reported in the agriculture sector has been updated with the latest available data (Statistics NZ table builder and Infoshare database, 2008).

10.1.5 LULUCF

The net uptake of forest land was recalculated in this submission due to planted forest data into first or subsequent rotations now available (section 7.2.5). Emissions from deforestation were also updated due to revised modelling (section 7.2.5).

Emissions from cropland were recalculated due to an updated emission factor. The apportioning of emissions from liming of soils between the cropland and grassland categories led to recalculations (section 7.3.5).

10.1.6 Waste

Emissions from municipal solid waste were recalculated due to updated composition values for all years prior to 2004, and due to the application of the IPCC (2006) spreadsheet (section 8.2.5).

Emissions from wastewater were recalculated due to adjustments made to activity data (section 8.3.5).

The corrections made to modelling errors led to recalculations of emissions from waste incineration in this submission (section 8.4.5).

10.2 Implications for emission levels

The overall effect of all recalculations in the 2009 inventory submission is shown in Figure 10.3.1. There is a 0.2 per cent (95.0 Gg CO2-e) decrease in emissions for the base year, 1990 and a 0.3 per cent (269.0 Gg CO2-e) decrease in emissions for the 2006 year.

10.3 Implications for emission trends

In New Zealand’s 2008 inventory submission (1990–2006), emissions were 25.7 per cent above the level reported in 1990. As a result of the recalculations in the 2009 inventory submission, total emissions for 2006 were 25.5 per cent above 1990. Changes in trends for individual sectors (excluding solvents) are discussed in the following sections. Solvents are not included because emissions are negligible throughout the time series.

Figure 10.3.1 Effect of recalculations on total greenhouse gas emissions

Figure 10.3.1 Effect of recalculations on total greenhouse gas emissions

Year 2006 inventory (submitted in 2008)
(Gg CO2-equivalent)
2007 inventory (submitted in 2009)
 (Gg CO2-equivalent)
1990 61,947.9 61,852.8
1991 62,433.1 62,036.4
1992 63,591.0 63,219.6
1993 62,984.6 62,953.0
1994 64,179.8 64,117.1
1995 64,461.1 64,466.5
1996 66,016.0 66,030.3
1997 68,789.0 68,885.5
1998 66,915.9 66,970.2
1999 68,782.3 68,616.3
2000 70,711.7 70,597.7
2001 73,082.3 73,115.8
2002 73,435.2 73,452.4
2003 75,983.8 76,005.1
2004 74,941.5 75,054.0
2005 77,353.7 77,174.7
2006 77,868.1 77,599.1

Energy sector

The recalculations made within the energy sector (Figure 10.3.2) are explained in section 10.1.1. Emissions in 1990 have decreased 46.3 Gg CO2-e and decreased by 58.7 Gg CO2-e in 2006 (Figure 10.3.2). These recalculations were responsible for a 0.1 per cent decrease of the 1990 recalculation in total emissions and a 0.1 per cent decrease of the recalculation for the 2006 year.

Figure 10.3.2 Effect of recalculation on the energy sector

Figure 10.3.2 Effect of recalculation on the energy sector

Year 2006 inventory (submitted in 2008)
Gg CO2-equivalent)
2007 inventory (submitted in 2009)
(Gg CO2-equivalent)
1990 23,499.1 23,452.8
1991 23,775.2 23,750.8
1992 25,502.5 25,465.1
1993 24,805.5 24,809.3
1994 25,064.6 25,066.9
1995 24,998.5 25,042.7
1996 26,044.9 26,075.3
1997 28,399.5 28,477.4
1998 27,012.3 27,027.4
1999 28,251.1 28,160.8
2000 28,934.8 28,987.3
2001 30,806.5 30,855.9
2002 30,887.9 30,951.4
2003 32,491.8 32,550.1
2004 31,704.9 31,845.2
2005 33,582.0 33,479.0
2006 34,069.3 34,010.6

Industrial processes

The recalculations made within the industrial processes sector (Figure 10.3.3) are explained in section 10.1.2. Emissions in 1990 have increased 6.5 Gg CO2-e and increased 0.7 Gg CO2-e in 2006. These recalculations were responsible for a 0.011 per cent increase of the 1990 recalculation in total emissions and a 0.001 per cent increase of the recalculation for the 2006 year.

Figure 10.3.3 Effect of recalculation on the industrial processes sector

Figure 10.3.3 Effect of recalculation on the industrial processes sector

Year 2006 inventory (submitted in 2008)
 (Gg CO2-equivalent)
2007 inventory (submitted in 2009)
(Gg CO2-equivalent)
1990 3,402.7 3,409.2
1991 3,553.9 3,235.7
1992 3,622.1 3,328.4
1993 3,297.6 3,304.9
1994 3,242.7 3,246.2
1995 3,386.7 3,390.2
1996 3,554.0 3,556.9
1997 3,298.8 3,308.1
1998 3,512.8 3,517.1
1999 3,666.1 3,678.7
2000 3,643.3 3,648.0
2001 3,767.5 3,777.3
2002 3,975.5 3,951.1
2003 4,280.1 4,287.6
2004 4,042.4 4,052.8
2005 4,245.7 4,266.9
2006 4,233.1 4,233.8

Agriculture

Emissions in 1990 have increased 12.2 Gg CO2-e and 176.4 Gg CO2-e in 2006. These changes were responsible for a 0.02 per cent increase of the 1990 recalculation in total emissions and a 0.2 per cent decrease of the recalculation for the 2006 year.

Figure 10.3.4 Effect of recalculation on the agriculture sector

Figure 10.3.4 Effect of recalculation on the agriculture sector

Year 2006 inventory (submitted in 2008)
 (Gg CO2-equivalent)
2007 inventory (submitted in 2009)
(Gg CO2-equivalent)
1990 32,498.9 32,511.1
1991 32,529.2 32,534.1
1992 31,931.0 31,943.2
1993 32,331.1 32,331.5
1994 33,346.3 33,310.4
1995 33,745.3 33,728.9
1996 34,074.5 34,070.0
1997 34,760.0 34,780.5
1998 34,116.0 34,171.1
1999 34,714.3 34,660.8
2000 35,959.1 35,836.0
2001 36,380.4 36,403.9
2002 36,477.8 36,509.4
2003 37,136.2 37,136.2
2004 37,186.1 37,188.7
2005 37,579.1 37,519.1
2006 37,667.6 37,491.2

LULUCF

The recalculations made within the LULUCF sector (Figure 10.3.5) are explained in section 10.1.5. The recalculations have resulted in a decrease to total net LULUCF emissions and removals of 1,128.1 Gg CO2-e in 2006 and an increase of 2,369.2 Gg CO2-e in 1990.

Figure 10.3.5 Effect of recalculation on LULUCF net removals

Figure 10.3.5 Effect of recalculation on LULUCF net removals

Year 2006 inventory (submitted in 2008)
 (Gg CO2 -equivalent)
2007 inventory (submitted in 2009)
(Gg CO2 -equivalent)
1990 -20,507.7 -18,138.5
1991 -18,648.5 -17,271.4
1992 -16,646.9 -15,145.9
1993 -16,957.1 -14,907.0
1994 -16,479.6 -15,895.5
1995 -15,924.9 -15,892.6
1996 -16,647.5 -16,652.0
1997 -17,719.5 -18,620.4
1998 -19,675.9 -18,859.3
1999 -19,557.8 -19,143.3
2000 -19,974.3 -19,971.5
2001 -20,092.1 -20,358.2
2002 -20,673.3 -20,033.3
2003 -20,619.6 -21,230.0
2004 -24,230.3 -24,853.6
2005 -23,681.9 -25,273.7
2006 -22,749.3 -23,877.3

Waste

The recalculations made within the waste sector (Figure 10.3.6) are explained in section 10.1.6. Emissions in 1990 have decreased 67.5Gg CO2-e and 34.6 Gg CO2-e in 2006. The recalculations were responsible for a 0.1 per cent decrease of the 1990 recalculation in total emissions and a 0.1 per cent decrease of the recalculation for the 2006 year.

Figure 10.3.6 Effect of recalculation on the waste sector

Figure 10.3.6 Effect of recalculation on the waste sector

Year 2006 inventory (submitted in 2008)
 (Gg CO2-equivalent)
2007 inventory (submitted in 2009)
(Gg CO2-equivalent)
1990 2,505.7 2,438.2
1991 2,532.0 2,472.9
1992 2,492.4 2,439.8
1993 2,506.7 2,463.5
1994 2,481.9 2,449.3
1995 2,285.7 2,259.6
1996 2,296.7 2,282.3
1997 2,284.6 2,273.3
1998 2,228.4 2,208.1
1999 2,104.0 2,069.2
2000 2,127.3 2,079.3
2001 2,080.5 2,031.3
2002 2,037.8 1,984.4
2003 2,023.4 1,978.8
2004 1,959.8 1,918.9
2005 1,902.5 1,865.4
2006 1,857.8 1,823.2

10.4 Recalculations in response to the review process and planned improvements

10.4.1 Response to the review process

In response to past review reports, New Zealand has improved transparency and QA/QC. Following the 2008 inventory submission, members of the national inventory team visited many of New Zealand’s industrial companies. These meetings enhanced the national inventory team’s knowledge of the processes and the quality assurance procedures applied at the plants. The meetings also increased the companies’ knowledge of national inventory reporting requirements and emission calculation methods. An example of an improvement from these visits is the increased explanation provided in this submission for the variation in the time series for emissions from aluminium production.

The capacity of the national system has increased since the 2008 inventory submission. The Ministry of Agriculture and Forestry has employed inventory staff for the agriculture and LULUCF sectors. The Ministry for the Environment has employed a back-up for the national inventory compiler. Further, documentation of the national submission, compiler role has increased. In compiling this inventory, another person was employed from December to February to assist with quality checking.

The cross-government inventory team was provided with more formal guidelines for compiling this submission. A memo detailing deadlines, processes and areas of improvement to focus on was distributed to all sector experts. The deadline for all chapters and final estimates of numbers was moved back to late November. This allowed more time for quality checking. Regular one-on-one meetings were established between the national inventory compiler and the sector experts. Regular meetings were established between managers involved in the cross-government inventory team.

During 2008, CRL Energy was contracted to provide activity data and emission calculations for the consumption of HFCs, PFCs and SF6 for the 2007–2012 calendar years.

10.4.2 Planned improvements

Priorities for inventory development are guided by the analysis of key categories (level and trend), uncertainty surrounding existing emission and removal estimates, and recommendations received from previous international reviews of New Zealand’s inventory. The inventory improvement plan and the quality control and quality assurance plan are updated annually to reflect current and future inventory development. The risk register also helps New Zealand prioritise improvements to the inventory.

Planned improvements to methodologies and emission factors are discussed under each sector as appropriate.

10.5 Summary of recent improvements to the inventory

New Zealand’s QA/QC and improvement plans ensure continuous improvement of the inventory. Tables 10.5.1 to 10.5.4 show the improvements made to the inventory from the 2001 to the 2009 inventory submissions.

Table 10.5.1 Improvements made to New Zealand’s 2001 to 2004 inventory submissions

Area of improvement Inventory submission year
2001 2002 2003 2004
National System       Complete common reporting format tables Explanatory text increased
Sector Energy       Explanatory text increased
Industrial Processes HFCs, PFCs and SF6 upgraded to Tier 2 method Lime and Dolomite included   Upgraded Tier 3 methodology for SF6 electrical equipment CH4 from methanol production reported back to 1997 Explanatory text increased
Solvents       Anaesthesia use of N2O included
Agriculture     CH4 ruminant emissions upgraded to Tier 2 N2O EF and excretion rates revised  
LULUCF        
Waste   Solid Waste upgraded to Tier 2    
QA/QC       Plan developed Trial of Tier 1 quality check sheets

 

Table 10.5.2 Improvements made to New Zealand’s 2005 to 2007 inventory submissions

Area of improvement Inventory submission year
2005 2006 2007
National system Explanatory text increased UNFCCC CRF reporter tool applied    
Sector Energy Coal emission factors revised Explanatory text increased Vehicle fleet model used to verify CO2 emissions Included national energy balance  
Industrial Processes CH4 from methanol production reported for entire time series Explanatory text increased Improving halocarbon data collection, especially HFC from air-conditioning units Included soda ash CO2 emissions  
Solvents      
Agriculture Included horse excreta N2O emissions Explanatory text increased Reallocated dairy excreta between lagoons and pasture CH4 manure management upgraded to Tier 2 N2O emission factor (EF1) changed to be New Zealand-specific Calculation spreadsheets improved by reducing the number of externally linked sheets
LULUCF Added emissions & removals for all categories where AD available    
Waste      
QA/QC Extension of Tier 1 QC checks to include number of non-key sources Extension of Tier 1 QC checks to include a number of non-key sources  

 

Table 10.5.3 Improvements made to New Zealand’s inventory submission for 2008

Area of improvement Improvements made
National system Explanatory text increased.
Sector Energy Updated constant calorific values to year-specific values for petrol and diesel
Industrial Processes Cement activity data updated Separated limestone, coke and electrode emissions from iron and steel Updated activity data for aluminium time series Updated activity data on HFC and PFC consumption
Solvents 2002–2005 time series updated based upon updated activity data
Agriculture All data recalculated to single-year values
LULUCF

All data recalculated to single-year values

Forest-land removals updated based upon updated carbon yields; harvesting and new planting data; new assumptions for the clearance of grassland with above-ground woody biomass and biomass burning

Waste Solid waste emissions updated 2003–2005 to correct sampling errors Domestic and commercial wastewater emissions were updated 2002–2005 based on new organic product data Industrial waste water time series updated Incinerated waste data included
QA/QC

Inventory compilation deadline moved to allow more time for CRF and NIR quality checking

KPMG quality checked key category data for consistency between data spreadsheets, the CRF Reporter and the NIR

Risk register established

 

Table 10.5.4 Improvements made to New Zealand’s inventory submission for 2009

Area of improvement Improvements made
National system

An additional person has been recruited and trained in the national inventory compiler role at the Ministry for the Environment

Additional people were recruited for the agriculture and LULUCF sectors in the Ministry of Agriculture and Forestry

Increased documentation for the national inventory compiler role.

Sector experts provided with formal inventory compilation guidelines

Regular meetings established between the managers involved in the inventory cross-government team and between the sector experts and the national inventory compiler

All calculations used in Article 3.3 LUCAS project have been included in a calculation and reporting application (under development)

Sector Energy Year-specific calorific values for all fuel types updated and the inclusion of the weighted annual average CO2 emission factor for natural gas
Industrial Processes Emissions from limestone, coke and electrodes use were separated from total iron and steel emissions (including emissions from fuel combustion) The emission factors for ammonia were updated based on the weighted average of all gas fields Increased explanation provided for variations in the time series for emissions from aluminium production Interpolation of 1991 and 1992 data for aluminium production
Industrial Processes (cont) Collection of data for F-gases for industrial processes contracted for a 5-year period with the one provider Increased information provided and revision of some of the assumptions for consumption of HFCs, PFCs and SF6    
Solvents Changes made to some of the notations keys
Agriculture Inclusion of nitrification inhibitor mitigation technology under the agriculture soils category
LULUCF Forest-land data apportioned over converted and remaining categories Emissions from liming of soils were apportioned over grassland and cropland Cropland New Zealand-specific N2O emission factor updated
Waste Nappies were removed from the solid waste composition values prior to 2004 The IPCC (2006) spreadsheet model has been applied for solid waste Estimated total organic waste prior to 1997 was adjusted for population growth Improved accuracy of estimated CH4 estimates
QA/QC

Inventory compilation deadline moved to allow more time for quality checking of the common reporting format database and the national inventory report

Quality checked key category data for consistency between data spreadsheets, the common reporting format tables and the national inventory report

An extra person recruited December–February to assist with quality checking

Risk register established and used to help prioritise inventory improvements

The quality assurance of the waste sector was completed before submission