Recycling waste as fuel

Waste-derived fuels are an essential source of energy for Tarmac. Using these materials such as meat and bone meal means that we preserve natural resources and reduce emissions that are released during cement manufacture.

New legislation is another incentive for using waste-derived fuels. The UK’s Landfill Tax will increase to £80 per tonne by 2014 and the EU Landfill Directive requires a 50% reduction in biodegradable waste (compared to 1995 levels) sent to landfill by 2013.

Cement production is an energy-intensive process where a mixture of limestone, clay and other raw materials is heated at very high temperatures, traditionally using coal and petroleum coke.

At our Tunstead kiln near Buxton, Derbyshire, replacing coal and petroleum coke with waste-derived materials has reduced fossil fuel use by more than 30%, and cut greenhouse gas emissions by over 15%. This has saved over 140,000 tonnes of fossil fuels at Buxton site since its introduction in 2006.

“We started exploring the environmental benefits of reusing waste-derived materials in the kiln in 2006,” said Hasan Bobat, development manager for Fuels, Raw Materials and Energy at Tarmac Limited. “When tyres were banned from landfill, we decided to trial tyre chips to heat the cement kiln fuel and have used the equivalent of 14 million tyres since then.”

Tunstead built on the success of tyre chips by adding meat and bone meal (MBM) to the fuel mix, a by-product of the meat processing industry. MBM is a non-hazardous, sterilised powder that is usually sent to landfill, but this scheme means that we have used 49,000 tonnes as fuel instead.

Two years ago, we started using Calfuel, a Solid Recovered Fuel (SRF), made from non-hazardous materials including paper, cardboard, plastics, textiles and wood chips. Fuels such as Calfuel make a significant contribution to reducing emissions because 50% of Calfuel is biomass (made from paper, cardboard and wood) – which means it is carbon neutral.

In 2011, more than 37% of Tunstead kiln’s total heat requirement was provided by non -fossil fuels. As well as saving these waste-derived materials from going to landfill, this also reduced our CO₂ emissions by over 36,000 tonnes.