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Methodology

The weekly greenhouse gas indicator is believed to be the first of its kind in the world. It uses actual data to determine an accurate figure for the greenhouse gas emissions produced from the three main sources of emissions from energy: coal, natural gas and petroleum. The methodology for calculating weekly emissions from these fuels in NSW, Queensland, Victoria and South Australia is detailed below.

A review of both the Indicator’s methodology and the data released by the Gas Bulletin Board means that the 2010 gas emissions figures have been revised. This increase in coverage has led to an increase in emissions recorded from gas to date this year in Queensland (48.7%), New South Wales (18.5%) and South Australia (18.9%). 2009 gas emissions figures for Queensland have also risen (7.8 percent). Other states remain unaffected for 2009.

Coal


  • Used for electricity generation

Emissions are calculated from the electricity generated by each coal-fired power station in the State using detailed market data from the National Electricity Market Management Company (NEMMCO). Emissions factors are based on the ACIL Tasman Report on NEM Generator Costs, prepared for Inter Regional Planning Committee (IRPC) and NEMMCO, 2009.


Natural Gas


Victoria

  • Used for heating (domestic, commercial and industrial), electricity generation and cooking

Emissions are calculated from the natural gas consumed in the State using detailed gas market data from the Australian Energy Market Operator (AEMO). AEMO data covers some 99% of the natural gas used in Victoria. A small amount (<5%) of the natural gas measured each week is used in non-thermal applications, such as the production of methanol and plastic bags. Emissions factors are based on the Department of Climate Change June 2009 National Greenhouse Accounts (NGA) Factors.

New South Wales, Queensland and South Australia

  • Used for heating (domestic, commercial and industrial), electricity generation and cooking

Emissions are calculated from the natural gas consumed in each State using detailed gas market data from the National Gas Market Bulletin Board. The data on the gas bulletin board represents scheduled injections. This is different to the Daily Gas Consumption data for Victoria, which is withdrawal data (i.e. end-use). This data therefore also includes:

  • unaccounted for gas (gas which may be lost in transportation);
  • compressor gas (gas used to transport the gas through the pipeline); and
  • line-pack gas (gas used to maintain pressure in the pipeline) (gas that remains compressed in the pipeline and may not be used until the next day for instance).

The inclusion of such data, however, only has a marginal impact on the end results.

In addition to gas injections to major pipelines (as recorded by the bulletin board) is added gas consumption from power stations which take their gas directly from gas fields (not via a major pipeline). This includes Condamine Power Station (Qld), Darling Downs Power Station (Qld) and 70 per cent of the gas consumption of Braemar Power Station  (Qld)

Emissions factors are based on the Department of Climate Change June 2009 National Greenhouse Accounts (NGA)

Emissions are calculated from the natural gas consumed in the State using detailed gas market data from the Australian Energy Market Operator (AEMO). AEMO data covers some 99% of the natural gas used in Victoria. A small amount (<5%) of the natural gas measured each week is used in non-thermal applications, such as the production of methanol and plastic bags. Emissions factors are based on the Department of Climate Change June 2009 National Greenhouse Accounts (NGA) Factors.

Petroleum


  • Used for automotive gasoline, diesel (automotive and industrial), LPG (transport and non-transport), aviation (gasoline and turbine) and fuel oil

This is determined on detailed figures provided by the petroleum industry on monthly sales to the Australian Governments Department for Industry and Tourism. Rolling averages of each month's data are used to obtain weekly figures. The averaged monthly figures offer an excellent indication of weekly volumes of petroleum burnt since petroleum sales from week to week are relatively stable. Also, the exact time that emissions occur from the burning of petroleum is uncertain due to the environment's ability to store it. Emissions factors are based on the National Greenhouse Accounts (NGA) Factors, November 2009.

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