National greenhouse reporting
Climate protection is recognised as an important challenge for the cement industry as it directly contributes approximately 1 per cent to Australia’s GHG signature.
An early industry initiative came through a voluntary agreement with the Australian Government using the Australian Greenhouse Challenge Program. Greenhouse emission (GHG) reduction plans commenced at the signing of this agreement in 1997. This required annual greenhouse gas emissions reporting to the Government through an industry-developed protocol, the Greenhouse Energy Management System (GEMS).
The CIF’s 2005 survey shows abatement projects have yielded a benefit that is 47 per cent better than the reduction target set in the 1997 agreement. The combined industry inventory in the report shows emissions have been reduced by 21 per cent per tonne of cementitious material. This has been achieved by investment in world class technology including:
- precalciner kilns to make clinker
- high-efficiency classifiers fitted on grinding operations
- power controls on filters
- heat recovery initiatives
- low-energy conveying systems to transport plant materials
- substitution of low GHG emission fuels for coal
- substitution of low GHG emission raw materials for limestone
- use of SCMs as alternatives to cement in concrete.
- Establishment of GHG sinks
International GHG reporting
As a participant in the CSI Agenda for Action, the Australian industry furthers its involvement in global climate protection initiatives. Joint activities nominated by the Agenda for Action include developing a universal framework for measuring and reporting greenhouse gas (GHG) emissions from the cement industry. The CIF has been active in helping develop this framework, to ensure consistent, relevant greenhouse emissions inventory reporting and practicability.
The CIF’s experience in GHG reporting has enabled the cement industry to maintain comprehensive data from 1990. The industry has focused on efficiency indicators that monitor performance within its control, such as reducing GHG emissions from the amount of fuel required to produce one tonne of clinker. Other measures such as the absolute amount of GHG emitted from the process are also reported.
A new commitment to greenhouse gas reduction
The Cement Industry has been a member of the Australian Governments Greenhouse Challenge Plus program since 1997, recommitting in 2005 with new reduction targets out to 2012. A range of activities focused on improving inventory accuracy are undertaken including:
- verification of calcination factors by site for the Australian cement industry
- lodgement of supporting documentation for the industry’s 1990 baseline inventory
- development of a common greenhouse calculator for estimating CO2 savings from site projects.
One of Cement Australia ‘s first greenhouse projects at Railton was to plant a tree farm to help offset the generation of greenhouse gases. More than 300 000 Eucalyptus globulus (Tasmanian Blue Gum) trees were planted over 275 hectares at the plant. Growth rates have been excellent, with the trees currently over 10 metres high. It is estimated that the trees will absorb over 40 000 tonnes of carbon dioxide over 15 years until harvesting. This project forms one of Cement Australia’s abatement projects under the Greenhouse Challenge program.
Use of blast furnace slag as a calcined raw material in kiln feed fuels and raw materials
Diminishing supplies of Birdwood clay prompted Adelaide Brighton’s Angaston operations to seek an alternative raw material to assist in the manufacture of its popular Brightonlite cement.
After implementing an action plan and gaining the appropriate approvals, Angaston began conducting trials using blast furnace slag, a by-product of steel manufacturing. Results found that the slag is an ideal alternative to Birdwood clay in making Brightonlite clinker.
Slag contains calcium, silica, and alumina with very low iron oxide, all of which have been calcined, driving off any CO2 during the steel making process.
As the slag has been heated previously, less fuel is required to be burnt in the kiln, reducing the CO2 emissions from combustion. In addition, the calcined calcium in the slag replaces limestone in the raw mix, which is another source of CO2.
Furthermore, as a raw material the slag doesn’t require crushing, saving indirect emissions of CO2 from power generation. The team at Angaston has demonstrated a total of 9000 tonnes of CO2 reduction per year when using slag.