The primary objective of this research is to study ways to increase the potential of energy production from food waste by co-production of bioethanol and biomethane. In the first step, the food waste was hydrolysed with an enzyme at different concentrations. By increasing the concentration of enzyme, the amount of reducing sugar produced increased, reaching a maximum amount of 0.49 g/g food waste. After 120 h of fermentation with Saccharomyces cerevisiae, nearly all reducing sugars in the hydrolysate were converted to ethanol, yielding 0.43–0.50 g ethanol/g reducing sugar, or 84.3–99.6% of theoretical yield. The solid residue from fermentation was subsequently subjected to anaerobic digestion, allowing the production of biomethane, which reached a maximum yield of 264.53 ± 2.3 mL/g VS. This results in a gross energy output of 9.57 GJ, which is considered a nearly 58% increase in total energy obtained, compared to ethanol production alone. This study shows that food waste is a raw material with high energy production potential that could be further developed into a promising energy source. Not only does this benefit energy production, but it also lowers the cost of food waste disposal, reduces greenhouse gas emissions, and is a sustainable energy production approach.

When fossil fuel substitution with biomass is viewed as a potential solution to global warming caused by greenhouse gas emissions, the demand for biomass fuel pellets has increased worldwide. Although agricultural waste is an attractive potential feedstock for fuel pellet production due to its relatively high calorific value and low cost, its excessive ash content is a major drawback. This research investigates the properties of sugarcane bagasse fuel pellets treated by dry and wet torrefaction and evaluates the economic value of selling the fuel pellets, which were priced based on their quality. It was found that the wet torrefaction could significantly reduce the ash content in the product (1% ash content at a torrefaction temperature of above 180°C), resulting in higher quality and more marketable fuel pellets. Consequently, the yield and the net present value of the production of wet torrefied fuel pellets were greater than those of dry torrefied pellets. Nevertheless, the production of fuel pellets from sugarcane bagasse treated by either process is shown to be economically viable.

In this study, the thermal degradation behavior and kinetic parameters of durian rind were investigated by using the thermogravimetric analysis technique. The experiments were performed in the temperature range of 313 – 1,073 K with the heating rate of 5, 10, 20 and 40 Kmin−1. Three model-free methods namely Friedman (FR) method, Kissinger-Akahira-Sunose (KAS) method, and Flynn-Wall-Ozawa (FWO) method were used to attain the kinetic parameters. The results show that the thermal degradation of durian rind exhibits 3 stages including dehydration stage (up to 380 K), active pyrolysis stage (380 – 680 K) and passive pyrolysis stage (above 680 K). A maximum rate loss shifts to a higher temperature with an increases in the heating rate. The values of kinetic parameters obtained from FR, KAS and FWO methods are in a good agreement with the experimental results. The average activation energies calculated by FR, KAS and FWO methods are reported at 243.02, 220.38 and 218.33 kJmol−1, respectively. Combining with heating value and chemical structure of durian rind, it can be stated that durian rind can become a useful source of alternative fuels and/or chemical feedstocks.

In this study, the thermal characteristics and kinetic parameters of coal/biomass blended fuels (75:25, 50:50 and 25:75 wt.%/wt.%) were investigated by using the thermogravimetric technique under atmospheric air. Three types of agricultural waste biomass including cassava root, palm kernel shell and rice husk were used as raw materials. The experiments were performed under different temperatures, ranging from 313-973 K with the heating rate of 5, 10, 20 and 40 K/min. The results show that the thermal decomposition of biomass exhibit three-four stages including moisture and some light volatile removal stage (up to 463 K), volatile oxidation stage (423-663 K), char combustion stage (663-823 K) and inorganic oxidation stage (803-953 K). Lignite on the other hand exhibits only two main peaks during the entire combustion process, corresponding to the moisture removal (up to 433 K) and the decomposition/oxidation (433-833 K), respectively. In addition, it was also found that the blending of biomass residues improved the ignition temperature of the blended fuels, indicating an improvement of devolatilization of coal. Kinetic studies show that the average apparent activation energies of the co-combustion of coal/cassava root, coal/palm kernel shell and coal/rice husk calculated from the Kissinger-Akahira-Sunose method are reported at ca. 105.25, 179.66 and 121.84 kJ/mol, respectively.

CO2 capture is a promising approach to aid in the mitigation of the global environmental crisis caused by greenhouse gas emissions. The efficiency of adsorbents is critical to the success of this approach. Sugarcane bagasse fly ash (SBA) was used in this study as a support to increase the CO2 adsorption capacity of CaO. The physical and chemical characteristics of SBA treated with various reagents (HCl, H3PO4, CH3COOH, NaOH, NH3, and H2O2) were investigated. The CaO was then loaded at 10–50 wt% on the support surface, and the modified adsorbent was tested for its potential to adsorb CO2. According to the results of the experiments, the acidic reagent increased the surface area of SBA, whereas the base reagents provided SBA with a higher pore volume and a larger pore size. The different surface characteristics of the modified SBA had a direct impact on its CO2 adsorption capacity. The adsorbent with NaOH-pretreated SBA and 50% CaO loading had the highest CO2 adsorption capacity, which was 27% higher than that of unsupported CaO due to the decent distribution of CaO found on the NaOH-treated SBA surface. For a better understanding, a graphical model was finally proposed to describe the aforementioned changes in surface characteristics and adhesion of CaO on the SBA support. These findings show that SBA, a valueless bagasse-incinerating waste material, can be used as a support to increase the CO2 adsorption capacity of adsorbents, transforming it into a more valuable and environmentally sustainable material. Graphical abstract