Mass Flow Analysis and Characterization of Selected Agricultural Wastes for Gasification

Abstract

Recycling of crop wastes is essential to value addition in the chain of the agricultural production sector just like it is considered to lower the greenhouse emissions effect on the environment. However, the sustainability of the supply chain of these wastes based on the contemporary patterns of consumption and the viability of establishing new value-adding applications such as new energy generation techniques that can utilize the wastes, required an assessment of the availability of these resources. Hence, research was conducted to determine the availability and further, calculations were done for the estimated ranges of the total quantity of maize, wheat, macadamia, coffee, sugarcane and pineapples wastes produced in the country. Results were then presented in the subsequent sections in this report where An ANOVA test and trends in production were used to assess the crop waste supply chain sustainability. The projections for the production of the chosen crops were optimistic, and it was established that there would be varied quantities of waste from these crops accessible throughout the year. The examination of wastes’ mass flow and availability determined that sugarcane bagasse, rice husks, coffee husks, and macadamia shells showed the highest potential. In addition, the waste producers showed a readiness to sell their garbage in order to generate more revenue. Furthermore, the performed LCA tests confirmed the high production costs, hence emphasizing the need for value addition in the supply chain. Subsequently, proximate and ultimate analysis of the identified feedstock properties presented mean values as; ash content on dry basis as (0.43wt%, 1.13wt%, 22.32wt%, 5.41wt%, 2.89wt%, 4.78wt% and 9.48wt%), moisture content on dry basis as ( 6.96 wt%, 6.07 wt%, 4.51 wt%, 6.21 wt%, 7.36 wt%, 7.15 wt%, and 7.06 wt%), volatile matter on dry basis as (73.99wt%, 85.28 wt%, 63.49 wt%, 75.07 wt%, 75.79 wt%, 77.24 wt% and 79.53 wt%), Fixed carbon content on dry basis wt% as (18.62 wt%, 7.52 wt%, 3.52 wt%, 13.3 wt%, 13.95 wt%, 10.83 wt%, and 13.65 wt%), Gross calorific values on as received basis wt% as ( 19.55 wt%, 18.50 wt%, 13.10 wt%, 16.95 wt%, 16.28 wt%, 16.07 wt%, 15.74 wt%), Sulphur content on as received basis wt% i.e. ( 0.91 wt %, 0.65 wt %, 0.98 wt %, 0.77 wt %, 0.05 wt %, 0.72 wt % and 0.70 wt %), and finally the bulk densities on as received basis as (1.043 g/cm3, 1.164 g/cm3, 1.007 g/cm3, 2.557 g/cm3, 2.683 g/cm3, 1.749 g/cm3, and 1.352 g/cm3), for macadamia, shells, coffee husks, rice husks, bagasse, maize

cobs, maize stalks and wheat straws respectively. The results obtained were compared with those found in literature and discussed conferring to the international standards for solid biofuels. The comparative analysis indicated that most of the feedstocks presented results within the recommended range for biofuel properties. However, a vital information was discovered regarding the Sulphur content in the feedstock above the recommended range. High sulfur in the feedstock can lead to sulfur dioxide (SO₂) production during combustion or gasification, which is harmful to the environment and is capable of causing corrosion of the gasifier components, resulting into equipment fouling thus reducing the plant efficiency and the reliability of the plant. This important discovery underlines the importance of incorporating a syngas cleaning system to mitigate these issues, ensuring cleaner energy generation and maintaining the efficiency of the gasification process. The advantages that Kenya might gain from this research include effective agricultural waste management, which would mitigate environmental issues such as soil deterioration, water pollution, and greenhouse gas emissions. This is due to the fact that this research study aimed at providing sustainable solutions for managing agricultural waste. Furthermore, investigating the possibility of generating gas and power from agricultural crop byproducts can add to the nation's renewable energy portfolio, lessening its need on fossil fuels and improving its energy security. Furthermore, the effective use of agricultural waste aims to generate economic prospects for farmers and entrepreneurs by fostering the creation of new products and energy resources, thus aiding rural development and alleviating poverty. This research promotes resource efficiency and the circular economy, aligning with global sustainability goals. Furthermore, the findings of this research presented vital information to policymakers in designing effective waste management and renewable energy policies that support sustainable agricultural practices and energy production. Based on the technological innovation, the characterization of crop wastes for gas and electricity production focused on driving technological advancements in bioenergy, fostering innovation in waste-to-energy technologies