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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 2004 inventory. It summarises material that has already been described in greater detail in Chapters 3–8.

Each year the inventory is updated (existing activity data and/or emissions factors may be revised) and extended (the inventory 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 IPCC revised guidelines and Good Practice Guidance. 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.

Updating the New Zealand inventory involves revision of last year’s activity data for the agriculture sector and LULUCF category “forest land”. This is because New Zealand uses three-year averages of activity data in these sectors. The updating process replaces the provisional numbers used in last year’s average with actual numbers. For example, the 2005 inventory uses an average of 2004, 2005 and 2006. The livestock statistics and forestry data for the 2004 and 2005 years are finalised data, but only provisional data are available for the 2006 year. In the 2006 inventory, the provisional 2006 figures will be replaced by finalised data released by Statistics New Zealand and the Ministry for Agriculture and Forestry.

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 of a given year can differ from emissions reported in the previous inventory.

10.1 Explanations and justifications for recalculations

10.1.1 Energy sector

The CO2 emission factors for “stationary gas combustion” have been updated by the Ministry of Economic Development. In previous submissions the proportions of Maui and treated gas from the Kapuni gas field have been assumed to be 50 per cent each. The Energy Data File (MED, 2006b) reports annual production of the local gas fields for the period 1970–2005. For the 1990–2005 inventory annual production of gas fields have been used to calculate weighted average annual CO2 emission factors.

The CH4 emission factors for gasoline and diesel oil from “road transport” has been revised. The country-specific emission factors used in previous inventory reports could not be substantiated during the Kyoto Protocol Initial Review (19–24 February 2007) so on advice from the UNFCCC expert review team New Zealand has adopted the IPCC default emission factors for the 1990–2005 time-series and recalculated the data accordingly.

There were also minor recalculations of CO2, CH4 and N2O emissions in several categories in the energy sector due to increased precision in data entry into the CRF Reporter and data revision by the Ministry of Economic Development.

10.1.2 Industrial processes sector

Mineral products

The cement companies submitted complete time-series of CO2 emissions from 1990–2005 to the Ministry for the Environment in early 2007. As explained in section 4.2.5 this has resulted in CO2 emissions attributed to the “mineral products” category being recalculated for the 1990–2005 time-series.

Chemical industry

The CO2 emission factors for the gases used in “ammonia production” have been updated to weighted emission factors based on annual production of the gas fields. Further explanations can be found in sections 4.3.5 and 10.1.1.

Metal production

There were some minor recalculations of CO2 emissions from the “iron and steel” category due to increased precision in data entry into the CRF Reporter.

Consumption of halocarbons and SF6

Emissions from the mixture HFC–245fa/365mfc has been reallocated to the section called “information on additional greenhouse gases” in the CRF tables.

Potential emissions from HFCs and PFCs have been recalculated for the time-series 1990–2005. As explained in section 4.7.5, potential emissions were recalculated to improve their accuracy in the “refrigeration” subcategory.

10.1.3 Solvents and other products

No recalculations were made for this sector.

10.1.4 Agriculture sector

Each year there is a recalculation in activity data for the previous year due to the use of the three-year averaging technique. The provisional livestock population data are updated with the finalised data from Statistics New Zealand.

10.1.5 LULUCF

Each year there is a recalculation in forest planting activity data for the previous year due to the use of the three-year averaging technique.

10.1.6 Waste

Several small changes have been made to the waste sector with resulting recalculations for the 1990–2005 time-series. As explained in section 8.2.5 methane emissions from solid waste disposal have been recalculated due to changes in Lo, degradable organic carbon and MSWx values. Domestic and commercial wastewater emissions were also recalculated back to 1990 due to correction of the scaling up factor for chemical oxygen demand to biological oxygen demand and the addition of wastewater volume data for 1997 as well as the previously used 2001 data.

10.2 Implications for emission levels

The overall effect of all recalculations is shown in Figure 10.3.1. There is a 0.04 per cent increase in emissions for the 2004 year and a 0.01 per cent increase in emissions for the base year, 1990.

10.3 Implications for emission trends

In New Zealand’s 2004 inventory, emissions were 21.3 per cent above the level reported in 1990. As a result of the recalculations, total emissions for 2004 were recalculated as being 21.4 per cent above 1990 (Figure 10.3.1). Changes in trends for individual sectors (excluding solvents) are discussed in the following sections. Solvents are not included because of the very low level of emissions throughout the time-series.

Figure 10.3.1 Effect of recalculation on total greenhouse gas emissions

 

Year

2004 inventory (submitted in 2006) (Gg CO2 equivalent)

2005 inventory (submitted in 2007)

(Gg CO2 equivalent)

1990

61,996.02

61,900.16

1991

62,295.44

62,297.64

1992

64,144.97

64,015.80

1993

63,774.35

63,569.81

1994

64,256.09

64,025.57

1995

64,681.40

64,456.09

1996

66,411.00

66,157.62

1997

68,585.36

68,365.54

1998

67,614.63

67,421.08

1999

69,260.67

69,098.95

2000

70,421.33

70,326.24

2001

73,168.31

73,086.12

2002

73,716.37

73,640.34

2003

75,700.23

75,727.75

2004

75,170.96

75,118.32

 

Energy sector

The major recalculations for the energy sector were from updated CO2 gas emission factors for stationary combustion and updated CH4 emission factors for gasoline diesel oil in “road transportation”. This increased the amount of CO2 by 12.3 Gg CO2-e but reduced the amount of CH4 by 88.9 Gg CO2-e in 1990. In 2004 the amount of CO2 increased by 16.2 Gg CO2-e.

Figure 10.3.2 Effect of recalculation on the energy sector

 

Year

2004 inventory (submitted in 2006) (Gg CO2 equivalent)

2005 inventory (submitted in 2007)

(Gg CO2 equivalent)

1990

23,655.15

23,577.52

1991

23,932.23

23,843.69

1992

25,694.49

25,604.91

1993

24,965.26

24,875.92

1994

25,213.26

25,132.59

1995

25,118.10

25,027.40

1996

26,169.45

26,090.90

1997

28,501.84

28,445.12

1998

27,098.18

27,050.80

1999

28,446.23

28,393.05

2000

28,946.15

28,914.17

2001

30,891.94

30,859.68

2002

30,887.11

30,867.70

2003

32,306.05

32,428.46

2004

31,647.91

31,703.87

 

Industrial processes

Industrial processes

The major recalculation for industrial processes was from cement production. This increased the 1990 value by 75 Gg CO2-e. In 2004 the difference was 5 Gg CO2-e.

Figure 10.3.3 Effect of recalculation on the industrial processes sector

 

Year

2004 inventory (submitted in 2006) (Gg CO2 equivalent)

2005 inventory (submitted in 2007)

(Gg CO2 equivalent)

1990

3,214.61

3,291.24

1991

3,490.54

3,577.93

1992

3,579.77

3,643.80

1993

3,620.09

3,639.84

1994

3,246.48

3,250.14

1995

3,390.45

3,404.98

1996

3,576.49

3,568.01

1997

3,297.94

3,310.25

1998

3,600.04

3,594.65

1999

3,655.24

3,657.38

2000

3,588.31

3,590.67

2001

3,862.63

3,865.13

2002

4,065.35

4,066.01

2003

4,354.66

4,351.65

2004

4,202.53

4,197.35

 

Agriculture

There were no major recalculations in the agriculture sector. Livestock population data for 2005 has been recalculated as explained in section 10.1.4. Some small corrections were made to some emissions estimates during quality checking of the data.

Figure 10.3.4 Effect of recalculation on the agriculture sector

 

Year

2004 inventory (submitted in 2006) (Gg CO2 equivalent)

2005 inventory (submitted in 2007)

(Gg CO2 equivalent)

1990

32,498.88

32,497.09

1991

32,222.38

32,314.01

1992

32,245.03

32,244.50

1993

32,517.41

32,516.66

1994

33,129.93

33,129.68

1995

33,707.07

33,706.06

1996

34,171.97

34,170.14

1997

34,296.64

34,296.12

1998

34,521.31

34,521.39

1999

34,912.79

34,923.13

2000

35,652.39

35,677.54

2001

36,237.15

36,265.60

2002

36,650.63

36,658.33

2003

36,967.97

36,919.50

2004

37,349.63

37,259.47

 

LULUCF

Recalculations for forestry planting activity data are explained in section 10.1.5. The effect of this recalculation in 2004 was a decrease of 1,780.9 Gg CO2-e.

Figure 10.3.5 Effect of recalculation on LULUCF net removals

Year

2004 inventory (submitted in 2006) (Gg CO2 equivalent)

2005 inventory (submitted in 2007)

(Gg CO2 equivalent)

1990

18,977.92

18,980.59

1991

17,550.39

17,555.74

1992

15,794.59

15,802.61

1993

14,619.42

14,630.11

1994

14,227.23

14,240.60

1995

15,084.32

15,100.36

1996

15,396.87

15,415.59

1997

17,059.49

17,080.88

1998

19,308.82

19,332.89

1999

19,924.54

19,951.28

2000

20,215.70

20,245.11

2001

20,513.36

20,545.44

2002

21,243.87

21,278.62

2003

22,742.19

22,785.99

2004

24,482.63

23,380.87

 

Waste

Methane emissions for 1990–2004 from solid waste were recalculated as a result of a number of small changes in solid waste and wastewater as explained in section 8.2.5. The results of these recalculations are shown in Figure 10.3.6. The recalculation resulted in an increase of 10.0 Gg CO2-e in 1990 and 69.3 Gg CO2-e in 2004.

Figure 10.3.6 Effect of recalculation on the waste sector

 

Year

2004 inventory (submitted in 2006) (Gg CO2 equivalent)

2005 inventory (submitted in 2007)

(Gg CO2 equivalent)

1990

2,482.81

2,492.77

1991

2,512.41

2,519.23

1992

2,475.21

2,479.49

1993

2,492.16

2,493.67

1994

2,470.13

2,468.82

1995

2,274.11

2,272.70

1996

2,282.28

2,282.70

1997

2,263.80

2,267.85

1998

2,201.23

2,207.73

1999

2,068.06

2,078.58

2000

2,080.75

2,096.74

2001

2,025.46

2,048.28

2002

1,966.34

1,999.96

2003

1,929.11

1,979.78

2004

1,839.98

1,909.28

 

10.4 Recalculations in response to the review process and planned improvements

10.4.1 Response to the review process

The UNFCCC secretariat facilitated an in-country review of New Zealand’s 2004 inventory submission as part of the Kyoto Protocol Initial Review process. This review took place in Wellington from 19–24 February 2007.

The review process is not expected to finish before July 2007 when the final review report is presented to the Kyoto Protocol Compliance Committee. New Zealand is implementing, where possible, recommendations the expert review team made on the last day of the in-country review. Allowing more time for final quality checking is one such recommendation New Zealand has started to implement with this inventory submission. Other recommendations of the review team in the finalised report will be incorporated into New Zealand’s improvement plan and addressed as time and resources allow.

10.4.2 Planned improvements

Improvements to methodology/emission factors are discussed under each sector as appropriate.

Priorities for inventory development are guided by 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 regularly to reflect current and future development.

10.5 Summary of recent improvements to the inventory

10.5.1 Improvements to the 2005 inventory

The focus for the 2005 inventory has been on improving the inventory national system. This has included improving quality control and assurance processes and improving the data analysis and reporting tool for the agriculture sector. Additional information was sought from various industries involved in the energy and industrial processes sectors to help improve transparency.

10.5.2 Improvements to the 2004 inventory

The focus for the 2004 inventory was on completeness, ensuring all estimates were calculated in accordance with Good Practice Guidance and increased transparency. The inclusion of data using a Tier 1 analysis for all LULUCF categories from 1990 is a significant improvement from the 2003 inventory (where data from 1997 were provided).

The other major improvements to the 2004 inventory include:

  • Upgrading the methodology for CH4 from manure management to a Tier 2 approach.

  • Changing the EF1 emission factor for nitrous oxide emissions from direct nitrogen application to a country-specific emission factor of 1 per cent.

  • Including estimates of CO2 emissions from soda ash use.

  • Including a national energy balance for 2004.

  • Improving the coverage of data collection for halocarbons, especially HFCs from air conditioning units.

  • Implementing a number of recommendations from the quality management review (see Annex 6). This has led to a more structured QA/QC plan and programme.

10.5.3 Improvements in the 2003 inventory

The overall focus for the 2003 inventory was an improvement in the accuracy of the inventory. This is shown in the number of recalculations that were applied across all sectors.

The major improvements to the 2003 inventory include:

  • Separating sectoral coal consumption into three key ranks of coal and using specific emission factors for each.

  • Reporting emissions from a Tier 2 approach for mobile combustion from road transport. This was developed from a vehicle fleet model at the Ministry of Transport.

  • Continuing development of the QA/QC system and extension of Tier 1 QC checks to include a selection of non-key sources and a Tier 2 QC check on the solid waste disposal key source category (refer to Annex 6).

  • Reporting CH4 emissions from methanol production for the entire time-series due to activity data becoming available before 1997.

  • Increasing explanatory text in the National Inventory Report to help understanding of the methodologies and address questions raised by UNFCCC expert review teams, especially in the energy, industrial processes and agricultural sectors.

  • Revising the allocation of dairy excreta between lagoons and pasture.

  • Including N2O emissions from horse excreta.

  • Adding emissions and removals for all LULUCF categories where activity data was available.

  • Using the UNFCCC CRF reporter tool to improve the quality of data entered into the common reporting format.

10.5.4 Improvements in the 2002 inventory

In the 2004 submission for the 2002 inventory, the focus was to provide a complete series of common reporting format tables for 1990–2002. Other improvements included:

  • The development of a preliminary QA/QC plan and the trial of Tier 1 QC checksheets.

  • The trial of a Tier 3 questionnaire to calculate emissions of SF6 from electrical equipment.

  • Reporting N2O use in anaesthesia for the solvent sector.

  • Reporting CH4 from methanol production back to 1997.

  • Increasing explanatory text in the National Inventory Report to help understanding of the methodologies and address questions raised by the UNFCCC expert review teams, especially in the energy and industrial processes sector.

10.5.5 Improvements in the 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 ongoing 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.

10.5.6 Improvements in the 2000 inventory and prior inventories

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