Environmental Performance

NZAS’ greenhouse gas (GHG) emissions are reported to the New Zealand Environmental Protection Agency and are calculated using an agreed methodology approved by the Intergovernmental Panel on Climate Change.  The methodology calculates the tonnes of carbon dioxide equivalents (CO₂-e) produced by the smelter from the consumption of fuels such as diesel, liquid petroleum gas and fuel oil, carbon anodes, electrical energy use and the generation of perfluorocarbon (PFC) gases.

The total calculated carbon dioxide equivalent discharge from NZAS during the year ending 31 December 2019 was 2.10 t CO₂-e / per tonne of aluminium produced.  NZAS increased the metal production by 10,803 tonnes in 2019 compared to 2018 due to a full year of operating Line 4.

In the year ending 31 December 2019 the average energy use was 72 GJ per tonne of aluminium produced.

There were no significant environmental spills to report in 2019.

NZAS continued its extensive waste recycling programme during 2019 to manage its waste arisings in a manner that avoids, where practicably possible, disposal in landfill. This strategy aims to reduce generation and take advantage of reuse, recycling and energy recovery opportunities.

All waste metal, paper, plastics, and cardboard are sorted separately and sent off-site to approved organisations for recycling.  During 2019 approximately 2,500 tonnes of these materials were sent for reprocessing.

During 2019 general waste, carbon material, and clean fill was deposited in separate storage cells at the NZAS landfill.  Cells at the landfill are managed to minimise exposed open faces and are progressively covered with gravel and/or wood chips to minimise fugitive dust.

This material deposited at the NZAS Landfill in 2019 comprised:

• General Waste - 1,492m³
• Clean Waste - 698m³
• Carbon Material - 3,499m³

Waste timber is stockpiled in the landfill for annual chipping to be used as ground cover material on the carbon pile.   An additional 100 tonnes of non-hazardous waste was deposited at the Invercargill City municipal landfill.  During 2019 independent company Inalco processed all current arisings of dross and some dross material that was containerised and stored on site prior to Inalco commencing operations at NZAS.  The long-term plan is for Inalco to process the Ouvea Premix and the landfilled Metal Reclamation Plant (MRP) stockpile.  During 2019 Spent Cell Lining (SCL) generated and some stored within existing dedicated buildings was shipped overseas for processing.

NZAS is committed to preserving the biodiversity on Tiwai Peninsula.  NZAS continued to work with the New Zealand Department of Conservation for ongoing management of the Tiwai Peninsula.

Species of significance located within the proximity of the smelter are:

• Asaphodes frivola moth
• NZ iris
• Euphorbia glauca (by Tiwai Wharf)
• Black fronted tern
• Southern NZ dotterel
• Australasian bitten.

During 2019 NZAS took no specific actions for biodiversity sustainability programmes apart from general pest control on the Tiwai Peninsula.  The New Zealand Department of Conservation continued monthly checking of traps for stoats, weasels, ferrets and other pests on Tiwai Peninsula.