An integrated biorefinery of Madhuca indica for co-production of biodiesel, bio-oil, and biochar: Towards a sustainable circular bioeconomy

The advancement of non-waste biorefinery technology has proved beneficial in effectively using waste biomass resources. The potential of various biorefinery designs to transform biomass into a range of commercially viable products and bioenergies has piqued attention worldwide among the several scenarios proposed to commercialize biofuels. This paper describes the biorefinery of Madhuca indica (M. indica) seeds to generate biochar, biooil, and biodiesel. Pyrolization was used on the de-oiled cake to produce charcoal and bio-oil. The M. indica seed's biochar was utilized as a useful supporting particle to immobilize the enzyme. Through transesterification, the immobilized enzyme transformed the oil extracted from the seed into biodiesel. Using an optimum methanolto-oil ratio of 7.5:1,3 % (w/w) of catalyst, and 16% (v/v) of water content, the method yielded a maximum fatty acid methyl ester (FAME) conversion of 93.4%. Diesel and 20% biodiesel have been assessed in terms of performance and emissions analysis. Comparing a 20 % blend of biodiesel to commercial diesel at full load, the emissions of carbon monoxide (CO) were reduced by 21.2%, hydrocarbon (HC) emissions by 18.02%, and nitric oxide (NO) emissions by 4.33 %. In addition, the capital flow of the suggested biorefinery was assessed using a techno-economic analysis. The biorefinery process payback period for the biodiesel, bio-oil, and charcoal made from M. indica was determined to be 3.1358 years using the Aspen Plus Economic Analyzer. Techno-economic studies reveal that the biorefinery process is highly lucrative and practical. The current study therefore shows methods to use the Madhuca indica seed biorefinery to produce sustainable energy and byproducts with no net emissions of carbon.