Pyrolysis and Char Burnout Characteristics of Cassava Peelings as Potential Energy Source

The pyrolysis behaviour, kinetics and char burnout of cassava peelings as a potential source of energy has been investigated using TGA. Four heating rates: 5, 10, 15 and 20oC/min were used to evaluate the kinetic parameters of the thermal decomposition process using iso-conversional non-isothermal method. An isothermal method was used to evaluate the burnout behaviour of char produced at 20oC/min by adopting the Arrhenius equation. During the pyrolysis process, it was observed that two distinct peaks were identified during hemicellulose decomposition which could be due to component complexity of agricultural waste products. The activation energy at 20% conversion was found to be 164 KJ/mol which is higher than what was observed between 30-50% conversions (151-154 KJ/mol). However, as the conversion increased from 60-90% the activation energy also increased from 162-290KJ/mol which suggests that the pyrolysis reaction progressed through multi step kinetic process. It was observed that the burnout of the chars was found to decrease with increase in heating rate up to the char produced at 15oC/min. However, further increase in the heating rate to 20oC/min during the pyrolysis process produced char with faster burnout profile. This may be due to higher porosity of the chars formed at that heating rate. It was also observed that as the heating rate increased from 5-15oC/min during pyrolysis, the activation energy of the resultant chars reduced. Again, higher activation energy was observed for the char produced at 20oC/min implying that highly porous char structure can diminish mass transfer limitations during char combustion. The pyrolysis and char combustion kinetics will be useful for modelling and the design of thermo-chemical cassava peelings conversion systems Keywords: Biomass pyrolysis, heating rates, char burnout, kinetic

Development and application of heterogeneous catalysts for direct cracking of triglycerides for biodiesel production

PhD ThesisInterest in biodiesel has been growing due to its potential role in moderating global climate change by lowering net CO2 emissions from fuels used for transportation. Most biodiesel fuels are currently synthesized by transesterification using alkaline catalysts and methanol. Heterogeneous transesterification catalysts have begun to be considered as alternatives, but many drawbacks remain. The costs of production and environmental concerns resulting from the ester washing step: neutralization of residual catalyst, removal of soap, glycerol, methanol and absorbent in some cases have prompted the search for more environmentally friendly processes and solid catalysts. Therefore, it is desirable to replace homogeneous or heterogeneous transesterification with the use of heterogeneous catalysts in direct thermocatalytic cracking. In principle, this could reduce the cost of biodiesel production, as it removes the need for alcohol and numerous downstream processing steps which add to the substantial running costs of transesterification. In addition the problem of glycerol in the product is eliminated. Four sulphated zirconia catalysts were synthesized via conventional wet-precipitation and solvent-free methods with different molar ratios of the sulphating agent. Their activity for direct thermocatalytic cracking of rapeseed oil was evaluated at a temperature of 270oC and atmospheric pressure. The nature and concentration of the active Brønsted and Lewis acid sites on the catalysts were examined. Brønsted acid sites were found to be important in the catalytic reaction. The catalysts at this temperature exhibited different selectivities towards formation of saturated and unsaturated methyl esters. The solvent-free catalysts were more active with a conversion of 78% in 21/2 hours, while the wet-precipitated catalysts had a maximum of 66% conversion after two hours. The catalysts prepared by the solvent-free method had 59% yield for methyl ester, with 75% of these being unsaturated. The wet-precipitated catalysts exhibited a lower yield for methyl esters (maximum: 32%), but within this a greater proportion (68%) were saturated. After regeneration, the solvent-free catalysts regained their catalytic properties, whereas the conventional catalysts did not. Three of the catalysts exhibited substantial leaching, with one of the conventional catalysts losing 100% of the sulphate responsible for its activity. Thus, to improve their properties the catalysts were supported with meta-kaolin which resulted in higher Brønsted acidity and better stability.Nigerian government Petroleum Trust Development Fund (PTDF

OPTIMAL DESIGN AND STRESS/STRAIN ANALYSIS OF WIND TURBINE BLADE FOR OPTIMUM PERFORMANCE IN ENERGY GENERATION VIA SIMULATION APPROACH

The blade is a significant part of a wind turbine, due to its role in the conversion process of the wind energy into mechanical energy. The blade during operation is being acted upon by different forces and pressures on high humidity, which gives rise to a high rate of failure of the blade. There is a great need to study these forces and constraints on the design shape of the material blade via a simulation approach. This research focusses on the optimal design and stress/strain analysis of a wind turbine blade for sustainable power generation. This is to enable the manufacturer and end-users of the wind turbine blade to understand how the blade material withstand the forces and pressures acting on the blade during operation in the form of displacement, stress, and strain in high humidity. The design and simulation software employed in this study is Solid Works Visualize 2018. The wind turbine blade is made of AL6061 alloy material. The blade is simulated under two forces, 1 N and 5 N, with the pressure at zero degree. The result from this analysis shows the maximum stress that causes the blade to experience failure during operation, and this failure occurs at 285.377 N/m^2 and 1426.83 N/m^2, respectively. The result from the simulation analysis shows the specific area were the deformation process, and possible failure will occur on the blades. This paper also gives reasonable suggestion for reinforcement of the wind blade during the maintainer's section, which can be applied to achieve optimum performance of the wind turbine blade

Optimization of Process Parameters Influencing Biogas Production from Rumen and municipal waste: Analytical Approach

 Rumen waste with high carbohydrate, protein, and lipid content is considered as a suitable substrate for fermentation for methane gas. In this study, direct substrate and co-digestion of rumen waste (RW) and municipal waste (MW) were used. Samples (fresh cow rumen and food waste) were dried, grinded, and blended with water into a semi-solid to facilitate digestion. Central composite design (CCD) was applied to optimize parameters of co-digestion of RW and MW at a different temperature (29 – 33oC), initial pH values, agitation time (AGT), and carbon-nitrogen ratio (C/N). A comparative analysis was done using RSM in a predictive model of the experimental data obtained in accordance with the CCD. The combined effects of temperature, pH, AGT, and C/N as methane production by fermentation of RW and MW were investigated. Optimization using RSM showed a good fit between the experimental and the predicted data as elucidated by the coefficient of determination with R2 values of 0.9214. Quadratic RSM predicted the maximum yield to be 7764 mL CH4/g volatile solid (VS) at optimal conditions of 31°C; pH 7.05; 6s and C/N ratio 20.33. The maximum methane yield was 8550 mL CH4/g VS, at the optimal conditions for the experimental response obtained. The verification experiment successfully produced 8550 mL CH4/g VS within 30 days of incubation. This experiment indicated that the developed model was successfully and can be used for methane production from animal and municipal waste

Domestic Wind Energy Planning for Deprived Communities in the Tropics: A Case Study of Nigeria

Despite the notable inventions in solar energy, it is still too high for standalone users from developing countries. For example, it cost $2200 to provide power for a two-bedroom apartment while the average citizen lives below the country’s poverty line of$381.75 per year. The use of fossil fuel generators remains cheaper, except there is an affordable energy option for the average populace. The objective of this study is to investigate the wind energy potential for domestic or standalone use in Nigeria. It is proposed that the domestic wind turbine will be relatively cheap for adoption. Hence, there is the need to wholistic examine the prospects of wind energy generation in Nigeria. Though previous studies had been carried out, none has been wholistic as presented in this research work. Forty years wind speed and wind direction dataset, i.e., 1980-2020, was obtained from the Modern-Era Retrospective analysis for Research and Applications (MERRA). The analysis of the wind energy potential across the research locations was considered using five sampling techniques, i.e., considering the general statistics of the forty years dataset; considering ten years in an evenly distributed pattern and accruable wind energy across the nation. It was observed that the early wet season (MAM) is the most unstable among the seasons. Also, sudden multi-directionality of the wind vectorization within forty years was observed. This event is ascribed to evidence of climate change to wind energy generation. Wind energy generation prospect was seen to be generally sustainable and reliable with SON, MAM, DJF and JJA having energy distribution of 325-950 kWh, 539-1700 kWh, 161-650 kWh and 761-3650 kWh respectively. Despite the variation of energy generation over the years within all seasons over Nigeria, it was found that it is predictable and can be optimized using various technological solutions

Optimization of Process Parameters Influencing Biogas Production from Rumen and municipal waste: Analytical Approach

 Rumen waste with high carbohydrate, protein, and lipid content is considered as a suitable substrate for fermentation for methane gas. In this study, direct substrate and co-digestion of rumen waste (RW) and municipal waste (MW) were used. Samples (fresh cow rumen and food waste) were dried, grinded, and blended with water into a semi-solid to facilitate digestion. Central composite design (CCD) was applied to optimize parameters of co-digestion of RW and MW at a different temperature (29 – 33oC), initial pH values, agitation time (AGT), and carbon-nitrogen ratio (C/N). A comparative analysis was done using RSM in a predictive model of the experimental data obtained in accordance with the CCD. The combined effects of temperature, pH, AGT, and C/N as methane production by fermentation of RW and MW were investigated. Optimization using RSM showed a good fit between the experimental and the predicted data as elucidated by the coefficient of determination with R2 values of 0.9214. Quadratic RSM predicted the maximum yield to be 7764 mL CH4/g volatile solid (VS) at optimal conditions of 31°C; pH 7.05; 6s and C/N ratio 20.33. The maximum methane yield was 8550 mL CH4/g VS, at the optimal conditions for the experimental response obtained. The verification experiment successfully produced 8550 mL CH4/g VS within 30 days of incubation. This experiment indicated that the developed model was successfully and can be used for methane production from animal and municipal waste