A paper released by bioeconomy consultant NNFCC has explored different end-of-life energy recovery options for municipal solid waste (MSW), in particular converting it to refuse-derived fuel (RDF) or solid recovered fuel (SRF) before sending it onto an energy-from-waste facility.

It argues that pre-treating waste through mechanical biological treatment (MBT) or mechanical heat treatment (MHT) and upgrading it to either RDF or SRF could add considerable value to waste streams.

This form of pre-treatment is often a prerequisite for more advanced thermal treatment technologies such as gasification or pyrolysis which generally offer higher conversion efficiencies than mass-burn incineration.

Benefits include reduced greenhouse gas emissions, as well as fewer metals and less dust in the fly ash residue. Improved downstream efficiency and increased recycling potential were also cited as key advantages.

The paper states: “We can recover energy from waste by simply incinerating it at high temperatures to produce heat and power. But this can be inefficient, particularly if the feedstock has a high moisture content.”

High moisture levels can result in increased efficiency losses and MSW typically has a moisture content between 30% to 40% compared to just 15% to 18% for SRF. In addition, MSW can contain 20% to 40% ash content by mass while the figures for RDF and SRF are 10% to 20%.

“The most appropriate technology to convert waste to energy will depend on its intended end-use and the market for recyclates, but MBT and MHT can offer significant environmental and economic benefits over incineration,” the research concludes.

Maxine Perella

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