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Annex 2: Methodology and data collection for estimating emissions from fossil fuel combustion

New Zealand emission factors are based on GCV (gross calorific value). Energy activity data and emission factors in New Zealand are conventionally reported in gross terms, with some minor exceptions. The convention adopted by New Zealand to convert GCV to NCV (net calorific value) follows the Organisation for Economic Co-operation and Development (OECD) and International Energy Agency (IEA) assumptions:

  • NCV = 0.95 × GCV for coal and liquid fuels

  • NCV = 0.90 × GCV for gas.

Emission factors for gas, coal, biomass and liquid fuels used in New Zealand are shown in Tables A2.1–A2.3.

Table A2.1 Gross CO2 emission factors used in the energy sector in 2007 (before oxidation)

  Emission factor
(t CO2/TJ)
Emission factor
(t C/TJ)
Source
Gas      
Maui 52.2 14.2 1
Kapuni Treated 53.2 14.5 1
Kapuni LTS 84.1 22.9 2
Weighted average for distributed gas 53.8 14.7  
Methanol – mixed feed (1990–1994) 62.4 17.0 3
Methanol – LTS (1990–1994) 84.0 22.9 3
Kaimiro 65.2 17.8 2
Ngatoro 53.1 14.5 3
Rimu 53.7 14.6 3
Waihapa/Ngaere + Tariki/Ahuroa (1990)* 56.2 15.3 3
Waihapa/Ngaere + Tariki/Ahuroa (2002) 54.2 14.8 3
McKee 54.3 14.8 3
Mangahewa 52.3 14.3 3
Turangi 55.6 15.2 3
Pohokura 55.1 15.0 3
Liquid fuels      
Regular petrol 66.4 18.1 4
Petrol – premium 66.8 18.2 4
Diesel (50 ppm) 69.4 18.9 4
Aviation fuels 68.4 18.7 4
Av gas 65.9 18.0 4
       
Fugitive – flared 65.1 17.8 4
LPG 60.4 16.5 4
Heavy fuel oil 73.6 20.0 4
Light fuel oil 72.9 19.6 4
       
Bitumen (asphalt) 76.9 20.8 4
Biomass      
Biogas 101.0 27.5 5
Wood (industrial) 104.2 28.4 5
Wood (residential) 104.2 28.4 5
Coal      
All sectors (sub bit) 91.2 24.9 2
All sectors (bit) 88.8 24.2 2
All sectors (lignite) 95.2 26.0 2

* For the years 1991–2001, the emissions’ factors for these gas streams are interpolated between the 1990 and 2002 values.

1. Derived by the transmission operator (Vector Ltd) through averaging daily gas composition data

2. New Zealand Energy Information Handbook (Baines, 1993)

3. Specific gas field operator

4. New Zealand Refinery Company

5. IPCC guidelines (1996).

 

Table A2.2 Methane emission factors used in the energy sector (before oxidation)

  Emission factor
t CH4/PJ
Source
Natural gas    
Electricity – boilers 2.745 IPCC Tier 2 (Table 1–15) average for natural gas boilers and large gas-fired turbines >3 MW
Commercial 1.08 IPCC Tier 2 (Table 1–19) natural gas boilers
Residential 0.9 IPCC Tier 2 (Table 1–18) gas heaters
Domestic transport (CNG) 567 IPCC Tier 2 (Table 1–43) passenger cars (uncontrolled)
Other stationary (mainly industrial) 1.26 IPCC Tier 2 (Table 1–16) small natural gas boilers
Liquid fuels    
Stationary sources    
Electricity – residual oil 0.855 IPCC Tier 2 (Table 1–15) residual oil boilers – normal firing
Electricity – distillate oil 0.855 IPCC Tier 2 (Table 1–15) distillate oil boilers – normal firing
Industrial (including refining) – residual oil 2.85 IPCC Tier 2 (Table 1–16) residual oil boilers
Industrial – distillate oil 0.19 IPCC Tier 2 (Table 1–16) distillate oil boilers
Industrial – LPG 1.045 IPCC Tier 2 (Table 1–18) propane/butane furnaces
Commercial – residual oil 1.33 IPCC Tier 2 (Table 1–19) residual oil boilers
Commercial – distillate oil 0.665 IPCC Tier 2 (Table 1–19) distillate oil boilers
Commercial – LPG 1.045 IPCC Tier 2 (Table 1–18) propane/butane furnaces
Residential – distillate oil 0.665 IPCC Tier 2 (Table 1–18) distillate oil furnaces
Residential – LPG 1.045 IPCC Tier 2 (Table 1–18) propane/butane furnaces
Agriculture – stationary 0.19 IPCC Tier 2 (Table 1–49) diesel engines (agriculture)
Mobile sources    
LPG 28.5 IPCC Tier 2 (Table 1–44) passenger cars (uncontrolled)
Petrol 18.525 IPCC Tier 2 (Table 1–27) passenger cars (uncontrolled – mid-point of average g/MJ)
Diesel 3.8 IPCC Tier 2 (Table 1–32) passenger cars (uncontrolled – g/MJ)
Navigation (fuel oil and diesel) 6.65 IPCC Tier 2 (Table 1–48) ocean-going ships
Aviation fuel/kerosene 1.9 IPCC Tier 2 (Table 1–48) jet and turboprop aircraft
Coal    
Combustion     
Electricity generation 0.665 IPCC Tier 2 (Table 1–15) pulverised bituminous combustion – dry bottom, wall fired
Cement 0.95 IPCC Tier 2 (Table 1–17) cement, lime coal kilns
Lime 0.95 IPCC Tier 2 (Table 1–17) cement, lime coal kilns
Industry 0.665 IPCC Tier 2 (Table 1–16) dry bottom, wall fired coal boilers
Commercial 9.5 IPCC Tier 2 (Table 1–19) coal boilers
Residential 285 IPCC Tier 1 (Table 1–7) coal – residential
Biomass     
Wood stoker boilers 14.25 IPCC Tier 2 (Table 1–16) wood stoker boilers
Wood – fireplaces 285 IPCC Tier 1 (Table 1–7) wood – residential
Biogas 1.08 IPCC Tier 2 (Table 1–19) gas boilers

 

Table A2.3 Nitrous oxide emission factors used in the energy sector (before oxidation)

  Emission factor
t N2O/PJ
Source
Natural gas    
Electricity generation 0.09 IPCC Tier 1 (Table 1–8) natural gas – all uses
Commercial 2.07 IPCC Tier 2 (Table 1–19) natural gas boilers
Residential 0.09 IPCC Tier 1 (Table 1–8) natural gas – all uses
Domestic transport (CNG) 0.09 IPCC Tier 1 (Table 1–8) natural gas – all uses
Other stationary (mainly industrial) 0.09 IPCC Tier 1 (Table 1–8) natural gas – all uses
Liquid fuels    
Stationary sources    
Electricity – residual oil 0.285 IPCC Tier 2 (Table 1–15) residual oil boilers – normal firing
Electricity – distillate oil 0.38 IPCC Tier 2 (Table 1–15) distillate oil boilers – normal firing
Industrial (including refining) – residual oil 0.285 IPCC Tier 2 (Table 1–16) residual oil boilers
Industrial – distillate oil 0.38 IPCC Tier 2 (Table 1–16) distillate oil boilers
Commercial – residual oil 0.285 IPCC Tier 2 (Table 1–19) residual oil boilers
Commercial – distillate oil 0.38 IPCC Tier 2 (Table 1–19) distillate oil boilers
Residential (all oil) 0.19 IPCC Tier 2 (Table 1–18) furnaces
LPG (all uses) 0.57 IPCC Tier 1 (Table 1–8) oil – all sources except aviation
Agriculture – stationary 0.38 IPCC Tier 2 (Table 1–49) diesel engines – agriculture
Mobile sources    
LPG 0.57 IPCC Tier 1 (Table 1–8) oil – all sources except aviation
Petrol 1.425 IPCC Tier 2 (Table 2.7 in GPG (IPCC, 2000))US gasoline vehicles (uncontrolled)
Diesel 3.705 IPCC Tier 2 (Table 2.7 in GPG (IPCC, 2000)) all US diesel vehicles
Fuel oil (ships) 1.9 IPCC Tier 2 (Table 1–48) ocean going ships
Aviation fuel/kerosene 1.9 IPCC Tier 1 (Table 1–8) oil – aviation
Coal    
Electricity generation 1.52 IPCC Tier 2 (Table 1–15) pulverised bituminous combustion – dry bottom, wall fired
Cement 1.33 IPCC Tier 1 (Table 1–8) coal – all uses
Lime 1.33 IPCC Tier 1 (Table 1–8) coal – all uses
Industry 1.52 IPCC Tier 2 (Table 1–16) dry bottom, wall fired coal boilers
Commercial 1.33 IPCC Tier 1 (Table 1–8) coal – all uses
Residential 1.33 IPCC Tier 1 (Table 1–8) coal – all uses
Biomass     
Wood (all uses) 3.8 IPCC Tier 1 (Table 1–8) wood/wood waste – all uses
Biogas 2.07 IPCC Tier 2 (Table 1–19) natural gas boilers

A2.1 Emissions from liquid fuels

A2.1.1 Activity data and uncertainties

The Delivery of Petroleum Fuels by Industry Survey conducted by Statistics New Zealand has a ±5 per cent uncertainty associated with the sectoral energy allocation. However, certainty is likely to be greater for the annual totals (Ministry of Economic Development, 2006).

As the survey is run as a census there is no sampling error. The main sources of non-sample error are:

  • respondent error: Statistics New Zealand makes every effort to confirm values supplied by respondents, and given assurances of accuracy. Statistics New Zealand is bound to accept them. If a discrepancy is discovered at a later date, revised values are supplied at the earliest possible opportunity

  • processing error: Statistics New Zealand has thorough checking procedures to ensure that the risk of processing errors is minimised.

A2.1.2 Emission factors and uncertainties

Carbon dioxide emission factors are described in Table A2.1. The CO2 emission factors for oil products are from the New Zealand Refining Company, import data from industry and from Baines (19937). The New Zealand Refining Company estimates a ±5 per cent uncertainty in emission factors (Ministry of Economic Development, 2006).

A2.2 Emissions from solid fuels

A2.2.1 Activity data and uncertainties

The New Zealand Coal Sales Survey conducted by Statistics New Zealand is an ongoing quarterly survey. The survey began in 1981. The survey is a full coverage of the sector and, therefore, has no sampling errors. Non-sampling errors in the survey data may result from errors in the sample frame (eg, units with the wrong New Zealand Standard Industrial Classification), respondent error (eg, wrong values supplied) and errors made during processing survey results or non-response imputation. Statistics New Zealand adopts procedures to detect and minimise these potential errors.

The process of dividing coal use between different sectors will introduce greater uncertainty than the uncertainty in total coal sales. Uncertainty is also introduced from the assumption that coal used by sector is an average of the different ranks. These assumptions are thought to introduce an uncertainty of ±5 per cent (Ministry of Economic Development, 2006).

The sectoral partitioning used for coal was examined in 2003 by the Ministry for the Environment. There was concern in extrapolating sectoral allocations from 1995 to 2002 given some probable changes in sectoral coal usage. However, New Zealand coal industry experts did not consider a survey could be justified due to the difficulty and expense in collating and verifying data from a number of sectors. In addition, the major categories of coal exports, coal used by the residential sector and coal used for steel production and electricity generation are all known accurately and are not affected by the sectoral partitioning.

A2.2.2 Emission factors and uncertainties

The CO2 emission factors for coal are shown in Table A2.1. The non-CO2 emission factors are shown in Tables A2.2 and A2.3. The estimated uncertainty in coal emission factors is ±3 per cent (Ministry of Economic Development, 2006). An uncertainty of ±2 per cent is used for the sub-bituminous coal used in public electricity generation. All New Zealand emissions’ factors are ±2 per cent of the revised 1996 IPCC default values (IPCC, 1996).

A2.3 Emissions from gaseous fuels

A2.3.1 Activity data

Vector Limited, a gas transmission and distribution company, has contracts with large gas users that allow metering errors of ±2 per cent. Whenever the error between the meter-reading and actual gas supplied exceeds 2 per cent, adjustments are made to the reported quantities of gas supplied. Consequently, uncertainty is assumed to have an upper limit of ±2 per cent (Ministry of Economic Development, 2006).

A2.3.2 Emission factors

As discussed in section 3.2.1.5, New Zealand now uses all of the gas production data reported in the New Zealand Energy Data File (Ministry of Economic Development, 2008b) to support the calculation of a weighted average annual CO2 emission factor for natural gas. This average emission factor is applied to a number of categories in the energy sector, such as the manufacturing industries and construction category.

The emission factors for each gas stream are shown in Table A2.1. The CO2 emission factors for distributed gas are shown in Table A2.4.

Table A2.4 Variation in CO2 emission factors for distributed natural gas (before oxidation)

Year National Average
(kt CO2 / PJ)
1990 53.2
1991 52.7
1992 52.7
1993 52.5
1994 52.3
1995 52.1
1996 52.3
1997 52.3
1998 52.2
1999 51.9
2000 52.0
2001 52.0
2002 52.4
2003 52.3
2004 52.4
2005 52.3
2006 52.7
2007 53.3

A2.4 Energy balance for year ended December 2007

Converted into Petajolues using Gross Calorific Values COAL OIL GAS RENEWABLES ELEC
TRICITY
WASTE HEAT TOTAL
   Bituminous Sub-bitum. Bituminous & Sub-bitum. Lignite Total Crudes/
Feedstocks
LPG/
NGL
Petrol Diesel Fuel Oil Av. Fuel/
Kero
Others Total Natural Gas Hydro Geothermal Solar Wind Biogas Wood Total
 
  Indigenous Production 63.59 57.13 120.72 4.12 124.84 87.69 5.75           93.44 169.81 84.66 93.86 0.30 3.37 2.83 43.57 228.59   1.12 617.80
+ Imports 3.50 13.61 17.12 0.01 17.13 212.08 4.14 50.41 40.43 0.01 11.55 7.83 326.45                     343.58
- Exports 63.67   63.67 0.00 63.67 75.29 0.00 0.68 0.00 4.68 0.00 0.00 80.66                     144.33
- Stock Change     9.29   9.29 4.53 0.43 1.65 0.93 -3.65 0.15 -0.38 3.66 0.03                   12.98
- International Transport               0.00 1.34 12.17 38.57 0.00 52.07                     52.07
TOTAL PRIMARY ENERGY 3.42 70.74 64.87 4.13 69.00 219.94 9.46 48.08 38.16 -13.19 -27.17 8.21 283.50 169.79 84.66 93.86 0.30 3.37 2.83 43.57 228.59   1.12 752.00
ENERGY TRANSFORMATION     -44.63   -44.63 -218.11 -0.72 65.82 73.43 24.66 39.74 6.11 -9.07 -100.98 -84.66 -84.08   -3.37 -2.55 -8.14 -182.80 141.59 -1.12 -197.01
of which                                                
Electricity Generation     -26.07   -26.07                 -75.35 -84.66 -76.35   -3.37 -1.67   -166.05 145.08   -122.39
Cogeneration     -0.85   -0.85                 -18.39   -1.73     -0.87 -8.14 -10.74 10.73 -1.12 -20.37
Oil Production           -218.11   66.84 72.76 24.32 38.94 14.20 -1.04                     -1.04
Other Transformation     -17.69   -17.69                 -2.13               2.07   -17.75
Losses and Own Use     -0.03   -0.03   -0.72 -1.02 0.67 0.34 0.80 -8.09 -8.03 -5.11   -6.00         -6.00 -16.28   -35.45
Non-energy Use                       -14.32 -14.32 -23.70                   -38.02
CONSUMER ENERGY (calculated)     20.24 4.13 24.37   8.74 113.90 111.59 11.47 12.57 0.00 260.10 45.11   9.78 0.30 0.00 0.28 35.43 45.80 141.59 0.00 516.97
 
Agriculture     1.45 0.01 1.46     0.93 8.17 1.64 0.22   10.96 1.81               6.23   20.45
of which                                                
Agriculture and Hunting     1.45 0.01 1.46     0.91 5.87 0.01 0.22   7.00 1.81               5.76   16.03
Fishing               0.02 2.31 1.64 0.00   3.96                 0.46   4.42
Industrial     13.47 3.68 17.15   2.92 1.74 13.25 1.51 0.15   19.58 30.79   5.82       27.63 33.45 54.89   155.85
of which                                                
Other Primary Industry               0.01 3.39 0.71 0.00   4.11 0.22               1.18   5.50
Food Processing               0.00 0.04 0.10 0.00   0.14 11.40               7.83   19.36
Textiles                                           0.60   0.60
Wood, Pulp, Paper and Printing                           6.23               13.25   19.49
Chemicals                           7.39               2.87   10.26
Non-metallic Minerals                           5.42               0.88   6.30
Basic Metals                 0.00                         24.25   24.25
Mechanical/Electrical Equipment                                           0.94   0.94
Building and Construction                0.01 1.65 0.01 0.08   1.75 0.13               0.82   2.69
Unallocated     13.47 3.68 17.15   2.92 1.73 8.17 0.70 0.07   13.58     5.82       27.63 33.45 2.27   66.46
Commercial     3.47 0.53 4.00   3.12 1.15 28.52 4.55 14.24   51.58 4.83   3.86     0.28 0.00 4.14 32.65   97.21
of which                                                
Transport Industry**     0.08   0.08   1.56 0.82 26.60 4.23 13.55   46.76 0.25               2.53   49.62
Other Commercial     3.39 0.53 3.92   1.55 0.33 1.93 0.32 0.69   4.82 4.58   3.86     0.28   4.14 30.12   47.59
Residential     0.25 0.30 0.55   2.70 0.00 0.00 0.00 0.00   2.71 5.61   0.10 0.30     7.80 8.20 46.69   63.76
Unallocated**               110.04 60.89 0.00 0.02   170.94                     170.94
CONSUMER ENERGY (observed)     18.64 4.52 23.16 0.00 8.74 113.86 110.84 7.71 14.63 0.00 255.77 43.03 0.00 9.78 0.30 0.00 0.28 35.43 45.80 140.46 0.00 508.21
 
Statistical Differences     1.59 -0.39 1.20   0.00 0.04 0.75 3.76 -2.06 0.00 4.33 2.08   0.00 0.00   0.00 0.00 0.00 1.14 0.00 8.75

For definitions of terms used and data sources see Glossary and Data Sources.

Electricity end use excludes electricity generated and consumed on site.

Breakdowns of industrial coal figures are unknown or confidential.

Waste heat has been removed from Renewables section according to the International Energy Agency definitions.

7  The LPG CO2 emissions factor was confirmed by checks of 2002 gas data.