Use of Biomass as a Fossil Fuel Replacement in Australian Cement Kilns
Presented at the Bioenergy Australia 2003 Conference
Held 8-10 December in Sydney
by Matthew Warnken and co-authored by Damien Giurco

Cement and cement products are essential materials in the Australian construction and building industry of today. The cement industry in Australia comprises Adelaide Brighton Ltd, Blue Circle Southern Cement Ltd and Cement Australia Pty Ltd. These three companies operate ten cement works, which together account for 100 per cent of integrated clinker and cement supplies in the country.

Environmental issues have taken on an increasing importance in the Australian Cement Industry, as evidenced by plant upgrades to improve energy efficiency and to reduce emissions, the release of a second Cement Industry Environment Report and a growing uptake of alternative raw materials and alternative fuels offering environmental benefits.

Alternative fuels that are being used by cement kilns to replace traditional fossil fuels include tyres, carbon anode dust & spent pot linings from the aluminium industry, a blend of recovered oils, dewatered sludges and grease trap emulsions and solvent based fuel. These alternative fuels currently account for approximately 6 per cent of thermal energy requirements for the Australian Cement Industry.

There are also a range of biomass-based alternative fuels that are able to be used by cement kilns including wood, tallow, dried biosolids, wheat residues, rice hulls, the woody component from composted organics, grape marc (residual skins from winemaking) and some types of process engineered fuel (for example, residual paper from material recovery facilities - MRFs).

The uptake of biomass-based alternative fuels is in its infancy, but is poised to increase in the coming year to similar tonnages as for existing alternative fuels. This would put biomass fuel use at 45,000 tonnes per annum (tpa) out of a total alternative fuel use of approximately 100,000 tpa. (However, biomass-based alternative fuels generally provide less thermal energy per tonne when combusted than the average for existing alternative fuels, meaning that the 'energy delivered' difference will be greater than the 'tonnes delivered'.)

Advantages of using biomass as a replacement fuel include conservation of non-renewable fossil fuels, reduction in greenhouse gas emissions by offsetting fossil fuel use, recovery of a higher resource value from previously wasted materials, conservation of landfill space in some instances, a reduction in Nitrogen Oxide (NOx), ability to utilise complementary alternative materials owing to reduction in ash content (coal replacement), less concerns regarding the composition of the fuel from a technical and community perspective (as compared against other alternative
fuels) and an overall improved environmental performance. Additional benefits of a financial nature in terms of lower cost of fuel are also realised.

Barriers to the use of biomass include the capital cost for new processing and handling equipment (both on and off site), transport and logistics arising from the dispersed nature of the sources of the biomass fuel, process issues such as managing the quality of the fuel, wear on refractory brick linings, kiln ring build-up, lower productions rates and changed material recipe.

As the use of biomass-based alternative fuels is just beginning, there are still challenges to overcome in order to harness all of the advantages that biomass fuels have to offer the cement industry. These include gaining a 'community licence to operate', gaining regulatory approval and gaining access to potential supply that achieves the right balance of economic benefits for the fuel supplier and user.

Overall there is a growing interest within the cement industry regarding the use of alternative fuels (with specific attention given to biomass-based alternative fuels), as a means of achieving economic and environmental goals. Biomass in particular, has many advantages to offer the cement industry in Australia. The use of biomass is set to increase in the short term, provided that the technical barriers can be overcome in an economic manner and that fossil fuel replacement projects can gain the support of both the community and regulators.

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Copyright © 2005 Warnken ISE
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