Energy contents analysis of rice-husk derived from indigenous rice paddy species as sustainable solid biofuel

The need for sustainable and renewable energy is crucial to meeting the rising global energy demand brought on as a result of rapid population growth and economic expansion. Increased reliance on renewable energy resources guarantees a future with cleaner, more economical, and environmentally conscious energy. However, this study explores the renewable potential of indigenous rice-husk as a sustainable energy source. Different home-grown rice varieties and rice production systems in Nigeria were identified through literature review, and rice-husk samples selected across the different agro-ecological rice production zones of the country were characterized. Ultimate analysis was used to determine the elemental composition of the rice-husk samples according to the standard CHNSO test method, and proximate composition was determined using the America Society for Testing and Materials (ASTM) method. Energy content was analyzed for high heating value (HHV) experimental using Cal 2k-Eco Bomb, and theoretically using different empirical formulas. Results showed FARO rice species as the most commonly planted rice species in Nigeria. As of 19th of January 2023, about 74 different varieties of FARO have been approved, registered and recommended for rice farmers in Nigeria. Also, rice is grown throughout the six geo-political zones and the five agro-ecological zones of the country, and about 1.96 to 2.46 million tons of husks are generated in the country from the year 2023. The proximate, ultimate and energy content analysis of the selected rice-husk samples shows that indigenous rice-husks are suitable as feedstock in combustion chambers. The experimental HHV of all samples varies from 11.927 MJ/Kg (RHEbonyi) to 15.086 MJ/Kg (RHKwara) and the theoretical HHV for all the considered empirical formulas ranges from 13.237 MJ/Kg (RHGombe) to 18.015 MJ/Kg (RHKano). However, by properly harnessing the extremely abundant rice-husk, the nation can achieve about 200 MW per year of cleaner, affordable and environmentally conscious energy, particularly during the current hard-hit fuel subsidy removal period in the country. Also, policy should be made to integrate the implementation and control of rice husk power plant projects into the country's energy framework.