Air emissions - mercury (Hg)
AGL Loy Yang mercury emissions increased 18%. Total coal combustion increased 15%, and electricity production increased 18%, aligning with the increase in mercury emissions.
Bayswater Power Station mercury emissions increased 81%. Mercury emissions are calculated using 6 monthly stack test measurements and total gas flow through units in the reporting period. Stack test measurements were consistently higher in FY21 than FY20, due to a combination of operating conditions at the time of testing, resulting in a consistent increase in emissions across units.
Liddell Power Station mercury emissions increased less than 1%. Stack test measurements were occasionally higher in FY21 than FY20, resulting in a minor increase in mercury emissions.
AGL Torrens mercury emissions decreased 25%. Emissions are calculated using emission factors and total gas combustion. Total gas throughput declined compared to FY20 (down 17%). The removal of heavy fuel oil from AGL Torrens operations, and transition to light fuel oil combustion, also contributed to mercury emissions reduction, as the emissions factor of light fuel oil for mercury is lower.
FY21 data was updated in November 2021. A subset of the FY21 data (comprising emissions associated with the combustion of black coal and diesel at the Bayswater and Liddell power stations, black and brown coal as well as natural gas at AGL Loy Yang, and natural gas and fuel oil at AGL Torrens, and estimates of fugitive emissions at these sites) was reported with the initial release of the FY21 Annual Report and ESG Data Centre on 12 August 2021.
For the purposes of this data set, AGL Torrens comprises the Torrens Island Power Station and the Barker Inlet Power Station which commenced operation in December 2019.
The National Assets were sold in FY19.
Emissions from Kwinana Power Station were included from FY20.
Air emissions data for AGL sites is publicly reported NPI data (see www.npi.gov.au/).
The emission factors used in AGL's NPI reports are sourced from relevant industry emission estimation technique manuals available on the NPI website.