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

New Zealand emission factors are based on 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 gross calorific value to net calorific value follows the Organisation for Economic Co-operation and Development and International Energy Agency assumptions:

  • net calorific value = 0.95 × gross calorific value for coal and liquid fuels
  • net calorific value = 0.90 × gross calorific value for gas.

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

Table A2.1 Gross CO2 emission factors used for New Zealand’s energy sector in 2008 (before oxidation)
  Emission factor
(t CO2/TJ)
Emission factor
(t C/TJ)
Source
Gas      
Maui 52.37 14.28 1
Kapuni Treated 53.02 14.46 1
Kapuni low temperature separator 84.10 22.94 1
Weighted average for distributed gas 53.59 14.61  
Methanol – mixed feed (1990–1994) 62.44 17.00 3
Methanol – low temperature separator (1990–1994) 83.97 22.94 3
Kaimiro 55.09 15.02 2
Ngatoro 53.07 14.47 3
Rimu/Kauri 51.85 14.14 3
Waihapa/Ngaere + Tariki/Ahuroa 54.85 14.96 3
McKee 54.30 14.81 3
Mangahewa 57.40 15.65 3
Turangi 54.67 14.91 3
Pohokura 54.23 14.79 1
Liquid fuels      
Regular petrol 66.48 18.13 4
Petrol – premium 66.91 18.25 4
Diesel (50 ppm) 69.53 18.96 4
Jet Kerosene 68.53 18.69 4
Av gas 65.89 17.97 4
Fugitive – flared 65.10 17.75 4
Liquefied petroleum gas 60.43 16.48 2
Heavy fuel oil 73.90 20.16 4
Light fuel oil 72.86 19.87 4
Bitumen (asphalt) 72.40 19.75 4
Biomass      
Biogas 100.98 27.54 5
Wood (industrial) 104.15 28.41 5
Wood (residential) 104.15 28.41 5
Coal      
All sectors (sub-bituminous) 91.20 24.87 2
All sectors (bituminous) 88.80 24.22 2
All sectors (lignite) 95.20 25.96 2

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

2. New Zealand Energy Information Handbook (Eng et al, 2008)

3. Specific gas field operator

4. New Zealand Refinery Company

5. IPCC guidelines (1996)

Table A2.2 IPCC (1996) CH4 emission factors used for New Zealand’s energy sector for 1990 to 2008
  Emission factor
t CH4/PJ
Source
Natural gas    
Electricity – boilers 0.09 IPCC Tier 2 (Table 1–15) natural gas boilers
Electricity – large turbines 5.40 IPCC Tier 2 (Table 1–15) large gas-fired turbines >3MW
Commercial 1.08 IPCC Tier 2 (Table 1–19) natural gas boilers
Residential 0.90 IPCC Tier 2 (Table 1–18) gas heaters
Domestic transport (compressed natural gas) 567.00 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 0.86 IPCC Tier 2 (Table 1–15) residual oil boilers – normal firing
Electricity – distillate oil 0.86 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 – liquid petroleum gas 1.05 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 0.67 IPCC Tier 2 (Table 1–19) distillate oil boilers
Commercial – liquid petroleum gas 1.05 IPCC Tier 2 (Table 1–18) propane/butane furnaces
Residential – distillate oil 0.67 IPCC Tier 2 (Table 1–18) distillate oil furnaces
Residential – liquid petroleum gas 1.05 IPCC Tier 2 (Table 1–18) propane/butane furnaces
Agriculture – stationary 0.19 IPCC Tier 2 (Table 1–49) diesel engines (agriculture)
Mobile sources    
Liquid petroleum gas 28.50 IPCC Tier 2 (Table 1–44) passenger cars (uncontrolled)
Petrol 18.53 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 1.90 IPCC Tier 2 (Table 1–48) jet and turboprop aircraft
Coal    
Combustion     
Electricity generation 0.67 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 0.67 IPCC Tier 2 (Table 1–16) dry bottom, wall fired coal boilers
Commercial 9.50 IPCC Tier 2 (Table 1–19) coal boilers
Residential 285.00 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 285.00 IPCC Tier 1 (Table 1–7) wood – residential
Biogas 1.08 IPCC Tier 2 (Table 1–19) gas boilers
Table A2.3 IPCC (1996) N2O emission factors used for New Zealand’s energy sector for 1990 to 2008
  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 (compressed natural gas) 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 0.29 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 0.29 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 0.29 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
Liquid petroleum gas (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    
Liquid petroleum gas 0.57 IPCC Tier 1 (Table 1–8) oil – all sources except aviation
Petrol 1.43 IPCC Tier 2 (Table 2.7 in GPG (IPCC, 2000))

US gasoline vehicles (uncontrolled)

Diesel 3.71 IPCC Tier 2 (Table 2.7 in GPG (IPCC, 2000)) all US diesel vehicles
Fuel oil (ships) 1.90 IPCC Tier 2 (Table 1–48) ocean going ships
Aviation fuel/kerosene 1.90 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) 3.80 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 the Ministry of Economic Development 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 two main sources of non-sample error are the respondent and the processing error explained below.

  • Respondent error: The Ministry of Economic Development 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: The Ministry of Economic Development 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 Eng et al (2008). 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 Quarterly Statistical Return of Coal Production and Sales conducted by the Ministry of Economic Development on behalf of 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 incorrect Australian New Zealand Standard Industrial Classification), respondent error (eg, incorrect values supplied) and errors made during processing survey results or non-response imputation. The Ministry of Economic Development 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 because of 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. In 2009, the Ministry of Economic Development took over the New Zealand Coal Sales and Production Quarterly Survey. Prior to 2009, when Statistics New Zealand ran the survey, seven sectors were used. The survey now splits coal sold into over 20 sectors using the Australian and New Zealand Standard Industry Classification 2006 classification (Australian Bureau of Statistics and Statistics New Zealand, 2006).

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 IPCC (1996) default values.

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 3.3, New Zealand now uses the gas production of all fields 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.

This is calculated based on all the gas production fields (Ministry of Economic Development, 2009b).

Table A2.4 Variation in New Zealand’s CO2 emission factors for distributed natural gas (before oxidation)
Year National average
(kt CO2/PJ)
1990 52.96
1991 52.98
1992 52.93
1993 52.69
1994 52.52
1995 52.34
1996 52.49
1997 52.50
1998 52.46
1999 52.10
2000 52.28
2001 52.50
2002 52.66
2003 52.61
2004 52.72
2005 52.71
2006 52.76
2007 53.49
2008 53.59

A2.4 Energy balance for year ended December 2008



























Table A2.5 New Zealand energy balance for year ended December 2008 (Ministry of Economic Development, 2009b)
Converted into Petajolues using Gross Calorific Values Coal Oil Natural Gas Renewables Electricity Waste Heat TOTAL
   Bituminous Sub-bitum. Bituminous & Sub-bitum. Lignite Total Crudes/
Feedstocks
LPG/
NGL
Petrol Diesel Fuel Oil Av. Fuel/
Kero
Others Total Hydro Geothermal Solar Wind Biogas Wood Total
Indigenous Production 75.78 47.89 123.67 3.80 127.47 127.62 4.24           131.85 159.93 80.32 113.21 0.32 3.81 2.87 40.42 240.95   1.21 661.41
+Imports 2.86 11.19 14.06 0.00 14.06 223.72 5.00 40.21 38.00 1.75 11.78 7.28 327.74                     341.80
-Exports 78.51   78.51 0.00 78.51 119.83 0.00 1.31 0.01 7.78 0.00 0.00 128.94                     207.45
-Stock Change     -17.38   -17.38 -2.41 0.04 -0.23 -1.39 3.16 1.72 -0.37 0.52 -0.01                   -16.87
-International Transport               0.00 1.47 13.46 37.33 0.01 52.27                     52.27
TOTAL PRIMARY ENERGY 0.13 59.08 76.60 3.80 80.40 233.92 9.19 39.12 37.91 -22.65 -27.27 7.64 277.86 159.94 80.32 113.21 0.32 3.81 2.87 40.42 240.95   1.21 760.36
ENERGY TRANSFORMATION     -59.07   -59.07 -234.13 -0.55 69.64 75.54 29.66 41.00 5.17 -13.67 -89.76 -80.32 -103.45   -3.81 -2.59 -4.42 -194.59 137.29 -1.21 -220.99
Electricity Generation     -43.09   -43.09                 -60.76 -80.32 -96.20   -3.81 -1.83   -182.16 146.08   -139.94
Cogeneration     -9.29   -9.29                 -23.12   -1.25     -0.76 -4.42 -6.43 11.51 -1.21 -28.54
Oil Production           -234.13   70.62 74.31 29.65 41.40 13.22 -4.93                     -4.93
Other Transformation     -6.66   -6.66                                 0.00   -6.66
Losses and Own Use     -0.03   -0.03   -0.55 -0.98 1.23 0.01 -0.39 -8.05 -8.74 -5.87   -6.00         -6.00 -20.30   -40.93
Non-energy Use                       -12.81 -12.81 -17.98                   -30.79
CONSUMER ENERGY (calculated)     17.53 3.80 21.33   8.64 108.77 113.45 7.01 13.73 0.00 251.38 52.20   9.76 0.32 0.00 0.28 36.00 46.36 137.29 0.00 508.57
Agriculture     1.73 0.01 1.74     0.81 7.60 1.85 0.15   10.41 1.62               6.78   20.54
Agriculture and Hunting     1.73 0.01 1.74     0.80 5.68 0.00 0.15   6.63 1.62               6.31   16.30
Fishing               0.01 1.92 1.85 0.00   3.78                 0.46   4.25
Industrial     14.67 4.08 18.75   2.61 3.55 14.97 2.05 0.11   23.28 37.06   5.81       28.25 34.06 53.31   166.46
Other Primary Industry               0.01 3.44 0.31 0.00   3.76 0.11               1.39   5.26
Food Processing               0.00 0.06 0.10 0.00   0.16 9.76               7.84   17.77
Textiles                           0.63               0.55   1.18
Wood, Pulp, Paper and Printing                           5.40               12.38   17.78
Chemicals                           13.44               2.81   16.26
Non-metallic Minerals                           1.56               0.94   2.50
Basic Metals                 0.00         3.11               22.96   26.07
Mechanical/Electrical Equipment                           0.54               0.90   1.44
Building and Construction                0.01 2.06 0.01 0.05   2.13 0.11               0.78   3.02
Unallocated     14.67 4.08 18.75   2.61 3.54 9.41 1.62 0.06   17.23 2.40   5.81       28.25 34.06 2.75   75.19
Commercial     4.06 0.55 4.61   3.46 1.15 29.42 4.34 14.46   52.84 4.40   3.86     0.28 0.00 4.14 33.35   99.34
Transport Industry     0.08   0.08   1.70 0.68 25.27 4.07 13.86   45.58 0.15               1.92   47.73
Other Commercial     3.98 0.55 4.53   1.76 0.47 4.15 0.27 0.60   7.26 4.25   3.86     0.28   4.14 31.43   51.61
Residential     0.15 0.22 0.36   2.56 0.00 0.01 0.00 0.00   2.57 5.38   0.10 0.32     7.75 8.17 44.76   61.24
Unallocated               105.44 57.83 0.00 0.06   163.34                     163.34
CONSUMER ENERGY (observed)     20.62 4.85 25.46 0.00 8.64 110.96 109.82 8.25 14.78 0.00 252.44 48.46 0.00 9.76 0.32 0.00 0.28 36.00 46.36 138.20 0.00 510.93
Statistical Differences     -3.08 -1.04 -4.13   0.00 -2.19 3.63 -1.24 -1.05 0.00 -1.06 3.74   0.00 0.00   0.00 0.00 0.00 -0.91 0.00 -2.36

A2.5 Fuel Flow Diagrams for year ended December 2008

Figure A2.1 New Zealand coal energy flow summary for 2008

Figure A2.1 New Zealand coal energy flow summary for 2008

This figure provides a schematic diagram of New Zealand’s coal production, delivery and use.

Figure A2.2 New Zealand oil energy flow summary for 2008

Figure A2.2 New Zealand oil energy flow summary for 2008

1. This difference is the own use of fuels at the Refinery. These fuels (asphalt, fuel oil, refinery gas and natural gas) are accounted for under the category 'Energy Industries' for liquids fuels and natural gas. This will consequently lead to the statistical difference for liquid fuels and natural gas being larger than they actually are.

This figure provides a schematic diagram of New Zealand’s crude oil and feedstocks, refinery, finished products and use

Figure A2.3 New Zealand gas energy flow summary for 2008

Figure A2.3 New Zealand gas energy flow summary for 2008

1. Gas Venting and Flaring consists of venting and flaring at gas and oil fields, flaring at the New Zealand Refining Company (NZRC), and venting at the Kapuni Gas Treatment Plant (KGTP). These numbers are combined to protect the confidentiality of the companies involved . The data from the two later of these three, does not originate from the "Gross Production" number. This will therefore lead to the statistical difference between calculated and observed gas neing larger than it actually is.

2. This category also consists of the combustion of 'refinery gas'. This is a synthetic gas produced gas produced by the NZRC through cracking, reforming and other processes. This 'refinery gas' is not a natural gas but is placed within the 'natural gas category'. It does not originate from the gross production figure and will therefore lead to the statistical difference between calculated and observed gas being larger than it actually is.

This figure provides a schematic diagram of New Zealand’s gas production, delivery and use.