Cement production is an inherently carbon intensive process, primarily driven by the base chemical reaction resulting from the decarbonisation of limestone. This contributes around 70% of the carbon emissions created from cement production.
Like other cement manufacturers globally, we continue to investigate and monitor technologies to reduce these emissions that are created through this base limestone chemical reaction – however this is a longer-term approach and relies on advancements in technology to be achievable.
The combustion of thermal fuels to heat the raw materials contributes the other 30% of our emissions footprint and is where our short term opportunities to reduce process emissions.
For over 15 years we have used up to 30% Biofuel from demolition timber waste, treated timber waste, sawmill waste and landfill timber diversion. This is the most significant factor in having the lowest carbon emissions per tonne of cement of the available sources in NZ. When comparing carbon emissions against other cement plants worldwide once again our performance is best practice.
Golden Bay Cement leads the industry in Australasia by publishing the first Environmental Product Declarations for cement and holding third party Environmental certification with Environmental Choice and Declare.
Our NZ made cement has been independently assessed to demonstrate a 20% lower carbon emissions per tonne of cement than our import competitors*
*Golden Bay Cement EPD 2019 vs Holcim NZ Cement EPD 2019
Understanding the environmental impacts of a building is increasingly important to designers and architects, and to their customers. Golden Bay Cement are making it easier for these professionals to choose the right product through voluntarily publishing Environmental Product Declarations (EPDs) for what we make. EPD's are leading practice in environmental transparency – they detail the environmental impact of a product over its full life cycle and are independently verified.
Our next step along our alternative fuels strategy is to introduce Tyre Derived Fuel. This will further replace coal by up to another 30% and allow Golden Bay Cement to be part of a sustainable solution to reduce tyres that are illegally dumped or sent to landfills within New Zealand.
We continue to assess the use of further alternative fuel sources as part of our overall strategy to reduce our reliance on fossil fuels.
Currently the most attractive means to reduce the amount of emissions for Golden Bay Cement and the industry is to use an increased amount of Supplementary Cementing Materials (SCM) in cement and/or concrete.
Current availability of ‘man made’ SCMs such as Fly Ash or Blast Furnace Slag is ever decreasing as demand increases which also drive up the cost of these materials. To put it into perspective there are 5 billion tonnes cement produced annually and only 500 million tonnes fly-ash produced annually and 250 million tonnes of water-quenched GBFS produced annually.
These synthetic SCMs may help us in the short term to address demand for lower carbon cement and concrete but we believe the most sustainable solution to this lies within NZs abundance of volcanic ash resources available in NZ. Golden Bay Cement are currently investigating these resources to form part of our longer term strategy.