Page 77 - AGL Sustainability Report 2011

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Environment
Sustainability Performance Report 2011 75
Environmental risk
Air
AGL has a portfolio of power generation plants which
are fuelled by the combustion of a range of traditional
and non-traditional fuels which result in the emission
of combustion products to the atmosphere.
Approach
AGL has gas fired power plants at Torrens Island in South Australia
and Somerton in Victoria, and an increasing range of smaller plants
powered by non-traditional fuels at the sites of some of AGL’s major
customers. All of AGL’s thermal power plants produce emissions to
air, as do AGL’s Rosalind Park Gas Plant at Camden and Hydrocarbon
Extractions plant in New South Wales, and gas and oil operations
acquired from Mosaic in Queensland. For many of these sites, air
emissions are regulated by State government agencies via site-
specific licences.
The emissions generated by the power generation units at AGL’s
major customer sites are a consequence of harnessing the energy
contained within what would otherwise be considered ‘waste’
streams. These ‘wastes’ are put to good use as fuel, rather than
disposed of with no reclamation of their calorific value. For
example, power is produced from burning biogas at the Melbourne
Water Werribee Sewage Treatment Plant in Victoria, and from
burning macadamia nut shells at the Suncoast Macadamia plant
in Queensland.
AGL recognises that emissions to air from its plants can potentially
contribute to regional airshed environmental issues, such as
photochemical smog, so it is important that plants run efficiently
and within the parameters set by regulatory licences. Undertaking
regular maintenance helps keep equipment running efficiently,
and AGL regularly monitors emissions to verify compliance with
regulatory requirements. Emissions are reported to regulators as
required and also to the Federal Government’s National Pollutant
Inventory (NPI) each year. The NPI is a database of emissions from
Australian industrial facilities that use certain amounts of the 93
substances listed on the inventory.
Air emissions of nitrogen oxides (NO
x
), sulphur dioxide (SO
2
),
particulates (measured as PM
10
), carbon monoxide (CO) and
volatile organic compounds (VOC) from AGL’s portfolio of
operated electricity generation facilities represented less than
2% of emissions for each pollutant type reported to the NPI for
the electricity generation sector for FY2010. While not material,
AGL will continue to monitor and, where possible, minimise
these emissions.
Performance
During FY2011, AGL’s NO
x
and PM
10
emissions rose slightly. The
Torrens Island Power Station is AGL’s largest electricity generation
plant, and largest source of NO
x
and PM
10
emissions. In FY2011,
greater generation activity at Torrens Island has resulted in higher
emissions from the power station as shown on
page 76.
Torrens Island Power Station has the capacity to run on either
natural gas or fuel oil. Natural gas is a cleaner fuel and is the primary
fuel used. Fuel oil, which has relatively high sulphur content, provides
a back-up option to run if natural gas becomes unavailable. In
FY2011, greater amounts of natural gas and fuel oil were used due
to the increased generation activity at the Torrens Island Power
Station, resulting in higher SO
2
emissions from this facility.
AGL’s overall SO
2
emissions were significantly lower in FY2011, as
were emissions of CO. These reductions largely reflect a change
in emission estimation technique which provides more accurate
calculations for some major customer sites. Previously, emissions
from AGL’s seven landfill gas generation facilities and the Melbourne
Water biogas unit at Werribee were estimated based on the total
volume of biogas entering the generation facilities (including inert
components, such as carbon dioxide and nitrogen). In FY2011,
emission estimates for these sites are based on the volume of the
actual fuel component (methane) from the biogas combusted at
each of the sites.
Although AGL’s VOC emissions rose in FY2011, largely due to the
acquisition of the Mosaic gas and oil assets in Queensland in October
2010, they were still well below FY2009 figures. The lower VOC
emissions in FY2010 and FY2011 are largely the result of the
introduction of a ‘Leak Detection and Repair’ (LDAR) program at the
Hydrocarbon Extractions plant in 2009. The LDAR program includes
the regular measurement and abatement of fugitive emissions
of VOCs.