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Environment
Sustainability Performance Report 2012 81
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. Some of AGL’s
upstream gas assets also produce emissions to air.
Approach
During FY2012, AGL operated gas fired power plants at Torrens
Island in South Australia and Somerton in Victoria, and a 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 gas operations in New South Wales, and
gas and oil operations in Queensland. For many of these sites, air
emissions are regulated by State Government agencies via site-
specific licences.
The emissions generated by many of 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.
Air emissions are reported to State government regulators as
required, and also to the Federal Government’s National Pollutant
Inventory (NPI) each year. The NPI is a publicly available database
of emissions from Australian industrial facilities.
In recent years, the NPI has indicated that emissions of nitrogen
oxide (NOx), sulphur dioxide (SO
2
), carbon monoxide (CO) and
particulates (measured as PM10) from AGL’s portfolio of operated
electricity generation facilities have accounted for less than 2%
of emissions for each pollutant type for the electricity generation
sector. However, following AGL’s acquisition of the Loy Yang power
station in late June 2012, air emissions will be a material issue for
AGL going forward. Ensuring compliance with air emission limits
from the AGL Loy Yang power station will continue to be a key
priority at the station.
Performance
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 a relatively high sulphur content,
provides a back-up option to run if natural gas becomes unavailable
and is typically used for short periods of time each year. Due to the
fact that the station did not need to run on fuel oil during FY2012,
SO
2
emissions from the power station dropped significantly in
FY2012 compared to previous years. Particulate and VOC emissions
were also lower. NOx and CO emissions at Torrens Island Power
Station were slightly higher in FY2012 compared to FY2011 due
to the fact that power generation output from the station was
slightly higher in FY2012.
During FY2012, power output at Somerton gas-fired power
station was approximately half of the FY2011 power output,
and this is reflected in the Somerton air emissions data.
Emissions from the Hydrocarbon Extractions plant are roughly
proportionate to the amount of LPG produced, which was slightly
higher in FY2011 compared to FY2012. As noted in previous
Sustainability Reports, since FY2010 AGL’s reported emissions of
VOCs have been significantly lower compared to previous years.
This is mostly due to the introduction of a ‘Leak Detection and
Repair’ (LDAR) program at the Hydrocarbon Extractions plant in
2009. The LDAR program comprises the regular measurement of
fugitive emissions of VOCs, and the use of a different EPA-approved
estimation methodology than was used previously. This new and
more accurate estimation methodology results in fugitive emissions
being calculated as approximately 90 percent lower than when
estimated using the former EPA-approved estimation methodology
(which was theoretical and did not incorporate any measured data).
Since FY2010, air emission data from AGL operated power
generation plants at major customer sites has been included in AGL’s
Sustainability Report. The sites include: Suncoast Macadamias,
Melbourne Water Werribee biogas plant, Moranbah power
station, Coopers co-generation plant, Symex co-generation plant
and seven landfill gas generation facilities in New South Wales,
Western Australia and Tasmania. The increase in reported CO and
SO
2
emissions from major customer sites during FY2012 is mostly
attributable to increased generation output from the Werribee
biogas plant.
At Camden Gas Project, gas sales during FY2012 were consistent with
previous years, however there has been an upward trend in reported
NOx and CO emissions. These emissions are mostly influenced by
the compressor engine load, and the tuning parameters used to
optimise the operating performance of each gas compressor as each
compressor approaches their scheduled major overhaul. Air emissions
from the Camden plant are measured by external air monitoring
specialists quarterly and are well below licence limits.
During FY2012, the Silver Springs Oil and Gas Project changed from
being a conventional gas exploration and production operation, to
being primarily an underground gas storage facility. AGL acquired
the depleted Silver Springs/Renlim gas reservoir in the Bowen Surat
Basin in central Queensland in October 2010, and subsequently
developed it into a gas storage facility. The storage facility, which
included commissioning an additional compressor, began operations
in August 2011. The reported increases in NOx, CO and PM10
emissions at Silver Springs in FY2012 are related to the operation of
this new compressor, and old compressors coming back online.