Page 68 - AGL Sustainability Report 2011

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Climate
change
AGL Energy Limited 66
Carbon risk
Energy Supply Footprint
The Energy Supply Footprint is an estimate of the
greenhouse gas emissions associated with the
consumption of electricity and gas by AGL’s customers.
The Energy Supply Footprint covers greenhouse gas
emissions resulting from the production, transportation,
distribution and consumption of electricity and gas
throughout the energy supply chain.
Electricity Supply Footprint
Greenhouse gas emissions are produced during the generation of
electricity (primarily carbon dioxide) from the combustion of fossil
fuels such as coal and natural gas. Energy losses occur across the
energy supply system (transmission and distribution systems, and
power stations’ auxiliary loads).
Power stations therefore have to generate more electricity than is
used by end-use consumers, to cover the losses associated with the
transmission and distribution networks used to deliver electricity to
the customers. The direct (physical) emissions occur at the point of
generation (power stations), where the fuel is combusted. There are
few direct emissions from transmission and distribution, and there
are no direct greenhouse gas emissions at the consumer end of the
supply chain.
The Energy Supply Footprint emissions associated with the provision
of electricity to AGL’s customers in FY2011 has slightly decreased
since FY2010 to 36.5 MtCO
2
e, in line with a minor decrease in total
sales. The emissions intensity of electricity supplied in FY2011 has
also remained relatively constant compared to FY2010.
Gas Supply Footprint
In the case of gas supply, greenhouse gas emissions arise from
production and processing at gas fields, transmission, distribution,
and when gas is combusted by AGL’s customers in their homes and
businesses.
During gas production, there is some venting of carbon dioxide and
methane at the gas field, minor fugitive emissions during processing,
and the combustion of some natural gas to operate processing
equipment. Further emissions occur during transmission and
distribution, comprising fugitive emissions and emission arising from
the use of additional natural gas in compressors along the pipelines.
At the consumer end of the supply chain, the combustion of natural
gas produces the bulk of the supply chain greenhouse gas emissions.
The Energy Supply Footprint emissions associated with the provision
of gas to AGL’s customers has remained constant at 11.5 MtCO
2
e
compared to FY2010, with gas sales also remaining relatively
constant. The intensity supplied to AGL customers in FY2011 has
remained relatively constant compared with FY2010.
Note
1 AGL has revised the methodology used to calculate the AGL Energy Supply
Footprint. Values for previous years have been recalculated using the new
methodology, and will therefore be slightly different to values previously reported.
The Gas Supply Footprint includes all supply chain and combustion emissions
associated with selling gas to AGL’s customers, including mass market, commercial
and industrial, and wholesale. However, emissions from the natural gas that
AGL supplies to power stations are not included, to avoid double counting (the
Electricity Supply Footprint includes upstream and generation emissions from
supplying electricity).
Gas Supply Footprint
1,2
Source
Emissions (MtCO
2
e)
FY08
FY09
FY10
FY11
Production
1.6
1.7
1.5
1.4
Transmission and distribution
0.4
0.4
0.4
0.4
Consumption
9.6
9.4
9.6
9.7
Total
11.7
11.5 11.5
11.5
Note
1 AGL has revised the methodology used to calculate the AGL Energy Supply
Footprint. Values for previous years have been recalculated using the new
methodology, and will therefore be slightly different compared to values
previously reported. The Gas Supply Footprint includes all supply chain and
combustion emissions associated with selling gas to AGL’s customers, including
mass market, commercial and industrial, and wholesale. However, emissions
from the natural gas that AGL supplies to power stations are not included, to
avoid double counting (the Electricity Supply Footprint includes upstream and
generation emissions from supplying electricity).
2 Values may not sum to total due to rounding.
Electricity Supply Footprint
1
Source
Emissions (MtCO
2
e)
FY08
FY09
FY10
FY11
Generation
37.7
35.1
34.7
33.2
Transmission and distribution
3.0
2.8
3.5
3.3
Consumption
0.0
0.0
0.0
0.0
Total
40.7 37.9
38.2
36.5
Note
1 AGL has revised the methodology used to calculate the AGL Energy Supply
Footprint. Values for previous years have been recalculated using the new
methodology, and will therefore be slightly different compared to values
previously reported.
The new methodology simplifes the Footprint by using factors published by the
Commonwealth Government, rather than AGL-specifc data.