Cement manufacturers in New Zealand use alternative waste fuels for a substantial part of their operations, and are continually examining the practicalities of increased supplementation as part of their strategic operations.
The environmental benefits of using alternative fuels in cement production are numerous. The need to use non-renewable fossil fuels such as coal is reduced. Using alternative fuels also maximises the recovery of energy from waste, reduces methane emissions, and saves landfill space by using a product that would otherwise not have an outlet.
Golden Bay Cement uses wood waste along with standard coal to fuel its Portland kiln. Wood waste is a cleaner burning fuel than coal, and has the potential for greater production efficiencies while at the same time decreasing carbon emissions. This is also a much more environmentally friendly way to dispose of wood waste, which would otherwise be sent to landfills.
Golden Bay Cement has recently completed a partial re-design and technology upgrade to accommodate the change to mixed fuel use. Initially, wood waste fuel will account for some 10-20% of the company’s production energy needs. With further work planned at the plant, it is likely there will be an even greater replacement of coal as the prime energy source.
Up to 20% of the total thermal energy requirement at Holcim New Zealand’s Westport Works has been routinely replaced by used oil, making possible a very significant reduction in the consumption of non-renewable coal. During 2006, about 13,300 tonnes of used oil, provided through the government-approved Used Oil Recovery Programme, was consumed in the kilns.