Are waste-based briquettes alternative fuels in developing countries? A critical review

Solid waste management and the increasing energy demand are a global concern. Waste can play the role of alternative fuel, partly reducing the environmental footprint in the waste management sector. Waste briquetting is used as a treatment option for improving waste combustion efficiency, as well as its management and handling. This critical review aims at evaluating the potentialities of this method as a possible solution to introduce alternative fuels in developing countries. Totally, 85 scientific articles available from 1999 to 2021 from international databases were reviewed, and a SWOT analysis has been conducted following the indications underlined in the scientific literature. The outcomes of the review highlight that agricultural waste-based and wood-based briquettes are the most investigated, followed by plastics-based briquettes and paper & cardboard-based briquettes. Waste-based briquettes can be divided into three categories, function of the calorific value: biomass-based (16.22 ± 1.65 MJ kg⁻¹), wood-based (19.03 ± 2.46 MJ kg⁻¹), and plastics and charcoal-based briquettes (24.64 ± 5.29 MJ kg⁻¹). Review findings underline that in-door emissions analysis is lacking, as well as research related to the water boiling test for the valorisation of waste briquetting for cooking and heating systems in developing countries. The current review contributes to highlighting the importance in implementing appropriate technologies for energy production and waste management in developing countries.