This communication reports the thermo-kinetic behaviours of three different types of biomass samples and their blends with a sub-bituminous high-sulphur coal. Physicochemical properties were evaluated by various fuel characterization methodologies as well as instrumental methods such as thermal (TG/DTG) analysis, Fourier transforms infrared (FTIR) spectrophotometry, scanning electron microscopic (SEM) technique. Thermo-kinetic parameters of various samples were also evaluated by using Coats and Redfern method. Results indicate that the pyrolytic thermal decomposition behaviours of woody biomass samples are quite different from plant leaf-based biomass sample due to the differences in the chemical compositions. Similarly, thermo-kinetic behaviours of coal-biomass blends are significantly different from the pure coal and pure biomass samples. The lowering of reaction order and activation energy of coal decomposition with increasing biomass contents in the blend can be related with the increasing biomass-based volatile matter content in the blends as well as the catalytic effect of biomass-based alkali and alkaline metal enriched biochar. On the other hand, catalytic effect of coal on the pyrolytic biomass decomposition is only observed at higher biomass replacement level. Analyses of the results obtained from calorific value and apparent activation energy reveal the presence of synergistic effects during the combustion of coal-biomass blend in calorimeter as well as the thermal decomposition of blend under nitrogen atmosphere.

Non-edible bio-oil is now produced to substitute crude oil in the production of clean biodiesel. In this study, the optimization of bio-oil yield from Swietenia macrophylla seeds through ultrasonic-assisted solvent extraction (UASE) was investigated. Central composite design of response surface methodology (RSM) was employed to analyze the effects of sonication time (5–25 min) and the hexane-to-biomass ratio (3:1–7:1 mL g⁻¹) to bio-oil yield. The result showed that hexane-to-biomass ratio of 6:1 mL g⁻¹, and sonication time of 10 min was the optimal conditions to attain optimum bio-oil yield of 46.7 ± 0.1 wt%. The bio-oil yield increased when the sonication times were increased, while the hexane-to-biomass ratio was found to have an erratic effect. UASE, compared to conventional method, produced higher bio-oil yield which utilized much lesser solvent at shorter extraction time of 10 min instead of 8 h. Also, UASE produced S. macrophylla bio-oil with much higher energy content than those derived from other recovery methods. GCMS and FTIR analyses results, at optimum conditions, demonstrated the presence of fatty acids and esters in the bio-oil suggesting a high potential for biodiesel production. These include oleic acid (30.0%), linoleic acid (29.2%), stearic acid (13.4%), palmitic acid (13.2%), linolenic acid (11.9%), ϒ-linolenic acid (1.5%) and small traces of some fatty acids. At optimum conditions, the bio-oil produced was found to have 0.95 g mL⁻¹ density, 45.2 cSt kinematic viscosity at 40 °C, 39.95 MJ kg⁻¹ high heating value and 0.55% ash content. The study verified the aid of ultrasonic cavitation in solvent extraction, and the use of RSM is innovative and advanced in perfecting bio-oil production. Typical transesterification of bio-oil was done where 65.8 ± 0.2 wt% biodiesel (fatty acid methyl ester) was produced. The production of biodiesel from bio-oil has scientifically proven which elevate to the limelight the high potential of S. macrophylla seeds for biodiesel production.

The advocacy of producing biofuels from wastes would answer the call for energy and environmental sustainability. This call is very timely considering the issues of global warming, increasing greenhouse gas emissions, diminishing natural resources, and enlarging human population. For one, the increasing generation of waste pulps from the growing numbers of starch-producing industries using cassava (Manihot esculenta Crantz) has become alarming because the improper disposal of these causes putrefaction odor, leachate contamination on water bodies, illnesses/diseases of community residents, and so on. In this work, the potential of cassava waste pulps (CWP) from starch industry was assessed with regard to the extraction of bioethanol via aerobic fermentation. The effect of yeast loading (0–4 tsp) and mashing duration (3–11 min) was evaluated on their influence on the bioethanol yield in CWP fermentation through central composite design of the response surface methodology. The result showed that 5.93 ± 0.03 mL of bioethanol could be extracted from a kilogram of fresh CWP after 7-day aerobic fermentation at conditions of 7 min mashing duration (42 °C) and 1 tsp yeast loading. Yeast loading and mashing duration are both significant with regard to bioethanol production. The gas chromatography analysis revealed 0.08% v/v bioethanol in the fermentation broth.

Evaluating the environmental performance of production systems is necessary for the assessment of ecosystems from the perspective of sustainability. Life cycle assessment is a suitable method of evaluating the environmental impact of a product, process or activity by identifying, quantifying and assessing the resources expended and the emissions and waste released into the environment. The present study used life cycle assessment (LCA) of one ton of potatoes (Solanum tuberosum L.) from the boundary of a farm in Markazi province in Iran. The data were obtained from 120 questionnaires and include input sources from the cities of Arak and Shazand for semi-mechanized and traditional cultivation systems. Investigation of the environmental impact of potato cultivation was done using the LCA method and Simapro 8.0.4 software. It was estimated for abiotic depletion potential, global warming potential and ozone layer depletion potential. The results show that the semi-mechanized farming system has destructive effects on global warming (1.71 kgSb_eq) and causes abiotic depletion (227.56 kgco_2eq). The traditional cultivation method causes ozone layer depletion (0.00005 kgCFC_-11) from diesel fuel consumption by water pumps. The strategies outlined in the alternative framework include replacement by renewable energy, ecological and agronomic pest control and optimization strategies such as development and improvement of machinery in conformity with international standards, training farmers to make optimal use of inputs and education to reduce damaging effects to the environment.

Banana peel waste was explored as a substrate for single-cell oil production using a promising oleaginous yeast Rhodotorula glutinis NRRL Y-1091 and fungus Ganoderma wiiroense under solid-state versus submerged fermentation for 8 days. Higher productivity and yield of lipids of 0.020 g lipid/g starch was recorded in both types of fermentation, with the fungal isolate G. wiiroense as compared to R. glutinis. Amylase, β glucosidase and inulinase activity were also monitored, which followed a similar trend, with highest values on 6th or 8th day of incubation. Lipase activity was not detected in the crude extract of both strains. Inulinase activity was highest at 8th day incubation in submerged fermentation with the fungal isolate G. wiiroense. FAME analyses revealed that the composition of the lipids had promising potential as good-quality biodiesel. The high levels of inulinase activity in the yeast and fungal strains enhanced the production of monomeric sugars from inulin present in banana peel, which, in turn, facilitated greater conversion to lipids and stimulated bio-oil production.