Present and prospective energy use potentials of selected agricultural wastes in Nigeria

The present study reviews the potential energy applications of wastes derived from rice, cocoa, and oil palm to augment energy needs while helping to abate environmental pollution. It also highlights the potentials of animal dungs for energy production in Nigeria. The country currently produces about 2.7 × 106 tons of rice annually, containing 0.540 × 106 tons of rice husk and a similar quantity of straw, which can be used for energy production. About 6.22 × 109 MJ of energy can be derived from the 266 000 tons (which could rise to 490 000 tons by 2015) of cocoa pods, which are currently produced and discarded annually. This could be utilized to generate process heat, either through thermal cycle or biochemical conversion. With respect to oil palm wastes, Nigeria generated about 0.344 × 106 tonnes of empty fruit bunches, 0.246 × 106 tonnes of palm shells, 0.633 × 106 tonnes of palm oil mill effluent, and 0.382 × 106 tonnes of mesocarp fibre in 2012, which are capable of producing substantial amounts of energy. Nigeria's livestock population is increasing at an annual rate of 3.2%, with current dung production of 407 × 103 tons/day (cow), 28 × 103 tons/day (pigs), 6.6 × 103 tons/day (chicken broilers), etc., which is estimated to produce 6.8 × 106 m3 of biogas daily. Electricity derivable from this quantity of biogas can provide lighting for 2.4 × 106 rural households in Nigeria.