Biomass and bioenergy potential of cassava waste in Nigeria: Estimations based partly on rural-level garri processing case studies

Advocating production of bio-energy from agricultural crop wastes has double benefits of minimizing land usage and threat to food security. These benefits are specially needed now that issues of greenhouse emissions, deforestation and human over population of the world dominate international discuss. Cassava being a major food crop in Africa, its waste constitutes the major candidate for bio-energy production thus motivating the aim to review its history, production, food value, economic value and bio-energy value. Cassava waste is noted to be suitable feedstock for bio-fuel production from the 1st Generation, 2nd Generation and integrated processes unlike the other Nigerian crop residues that are mainly suitable for the not-yet-viable 2nd Generation bio-fuel production. A procedure for estimating cassava non-food biomass(CnFB) from harvest data is established. The procedure entails use of statistical sampling and regression analysis to establish scaling factors for transforming the data to CnFB. A real case study reflected very accurate and statistically significant error indices. For example, the factor for converting mass of harvested cassava for food production to waste is Rw=0.5263 (R2 = 0.9875 and t-Test = 0.0896) while the factor for estimating mass of peels alone is R12=0.1735 (R2 = 0.9951 and t-Test = 0.1680). The other factors for converting mass of dewatered cassava pulp to waste were established for the case study community as follows; mw=33.7675 Kg per bag (R2 = 0.9611 and t-Test = 0.0665), m3=32.0599 kg per bag (R2 = 0.9865 and t-Test = 0.1944) and rw=1.0508 (R2 = 0.9464 and t-Test = 0.2539). The factors and literature data were used to make long-term projections of CnFB potential of Nigeria. The implications of the projections to the programs of the Nigeria Energy Policy - which pertain to renewable energy integration in the national energy mix, emission reduction and rural electrification via distributed generation - were discussed.