Cranfield University has developed a new approach for calculating the potential amount of energy that could be extracted from various waste streams, prior to incineration.

In order to work out the renewable (or biogenic) content of waste, two approaches are currently taken.

The first, manual sorting of waste into its individual components, is not only time consuming but costly and carries certain health and safety concerns. The second, which analyses the flue gas using specialist equipment for carbon dating, is also costly and can only be calculated retrospectively.

This new method from Cranfield uses an image analysis tool alongside microwave analysis. When placed above a conveyor belt in a waste treatment facility, it determines the composition of mixed waste streams and subsequently calculates how much renewable energy is derived from each individual component.

According to scientists at the university, the tool will enable EfW suppliers to accurately prove the amount of biogenic material in each load of mixed waste materials that will produce renewable energy through combustion.

This will have benefits for operators hoping to benefit from renewable obligation certificates (ROCs) subsides.

Cranfield’s lecturer in renewable energy from waste Dr Stuart Wagland said: “The system enables greater operator control over the fuels, allowing for blending to optimise the biogenic content and the overall calorific value, or energy released on combustion.”

It is thought that some 200m tonnes of waste produced each year in England alone could be converted to energy with the potential to supply up to 4% of the UK’s electricity and water heating needs.

The research has attracted interest in the private sector, and work is now being planned, in collaboration with the National Physical Laboratory, to further develop the tools and test them with a number of feedstocks in a range of waste handling facilities.

Maxine Perella

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