Biofuels made from rice straw, sugarcane waste, discarded plastic
doi:10.1038/nindia.2020.99 Published online 26 June 2020
Researchers from the Indian Institute of Technology in Madras have devised a microwave-assisted heating method that can help convert agricultural and plastic waste into bio-oils1.
They have produced the bio-oils from broadly two types of waste products: agricultural waste such as rice straw and bagasse, a sugarcane waste; and discarded plastics. The researchers say such bio-oils from renewable biomasses and plastic waste are safer alternative to fossil fuels.
India produces 140 million tonnes of rice straw and 40 million tonnes of bagasse annually, including a burden of urban solid waste that contains plastics. Most of such waste products are burnt or thrown away, generating toxic fumes and solid waste.
To convert such wastes into biofuel, the scientists, led by Vinu Ravikrishnan, heated a mixture of rice straw, bagasse, groundnut shell, wood sawdust and two synthetic plastics, polypropylene and polystyrene, in a microwave oven in the absence of oxygen.
Heating the mixture of biomasses and the plastics produced a higher volume of bio-oils than by heating pure biomasses.
The use of a commercial catalyst during the heating process upgraded the quality of the bio-oils. Such bio-oils were found to be as good as light fuel oil, which is used to heat homes, industrial buildings and run off-road vehicles in mines and farms.
This method, the researchers add, could potentially be used to recover resources from a wide variety of waste products, including single-use plastics and non-reusable face masks.
1. Suriapparao, D. V. et al. Effective deoxygenation for the production of liquid biofuels via microwave assisted co-pyrolysis of agro residues and waste plastics combined with catalytic upgradation. Bioresource. Technology. 302, 122775 (2020)