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• Greenhouse Gas Emissions 90-02
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• Energy Greenhouse Gas Emissions

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This report gives data for all energy sector emissions of greenhouse gases including carbon dioxide (CO₂), methane (CH₄), nitrous oxide (N₂O), other oxides of nitrogen (NO_x), carbon moNO_xide (CO), and non-methane volatile organic compounds (NMVOC). This report augments the energy sector emissions of CO₂ with CO₂ emissions from the industrial processes sector so as to give total CO₂ emission estimates for New Zealand. The latter consist of non-fuel emissions from the production of steel, aluminium, hydrogen, cement and lime. Table 1 and Figure 1 summarise the key results.

It is important to note that while carbon dioxide is the most important greenhouse gas worldwide, methane (in particular, from the agriculture sector) accounts for over 50% of New Zealand's greenhouse gas emissions when allowing for global warming CO₂-equivalence (see Chapter 9).

Table 1: Greenhouse Gas Emissions

Figure 1: Gross CO₂ Emissions by Sector: 1990- 2002

Table 1 gives actual growth in energy CO₂ emissions between 1990 and 2002 as 34.2%, giving estimated trend growth for the period of 2.1% pa. Similarly gross (all sector) CO₂ emissions rose over the period by 33.1%, giving trend growth of 2.0% pa.

Figure 2: Energy CO₂ Emissions by Sector: 2002

Figure 3: Energy CO2 Emissions by Fuel Type: 2002

Figure 2 illustrates each sector's share of 2002 CO₂ emissions from fuel combustion, production, storage and distribution. The domestic transport sector is the largest single source and has increased by 59% since 1990. It accounted for 45% of energy emissions in 2002, compared with 38% in 1990.

A feature of the New Zealand energy sector, however, is the variability of thermal electricity generation. 2001 was a cold, dry winter with above average thermal electricity generation. 2002 was a more `normal' year and CO₂ emissions from thermal electricity generation were considerably (i.e. 15%) lower, making up 18% of total energy emissions, compared to 22% in 2001.

Figure 3 shows the fuel shares of CO₂ emissions from the energy sector in 2002. Liquid petroleum fuels contributed 53% of CO₂ emissions, with the transport sector accounting for about 84% of this total.

Natural gas and coal jointly made up 45% of energy CO₂ emissions, with electricity generation accounting for about 40% of this, and the manufacturing industries sector for 41%.

Estimates of methane emissions from the energy sector (not agriculture) sector are also included in this report. These have risen by about 42% since 1990, but they still account for less than 5% of total methane emissions.

Energy sector emissions of N₂O, NO_x, CO and NMVOC are also provided. These have followed a similar trend to that of CO₂ emissions form the use of transport fuels, and thermal electricity generation.

The Ministry is initiating a review of emission factors. The results will be taken into account in the next edition of this publication. Preliminary indications are that the overall estimates of CO₂ emissions will not be greatly affected, but the estimation of emissions of other gases may be subject to more significant revision.

¹"Mean" represents average annual percentage growth between 1990 and 2002 actual emissions.

²"Trend" represents the underlying average growth after discounting for the annual volatility arising mainly from thermal electricity generation.