Assessment of the availability of agricultural residues on a zonal basis for medium- to large-scale bioenergy production in Nigeria

The major agricultural crops grown in Nigeria are millet, yam, cassava, sorghum, rice, groundnut and maize. In terms of area grown (2001-06) the cereals were dominant with sorghum being the major crop grown followed by millet, maize and rice. Agriculture residue availability was based on the 6 zones in Nigeria and included both field residues and processing residues. A number of different scenarios were evaluated whereby Scenario 1 looked at the total potential availability of field residues, Scenario 2 took account of existing uses while Scenario 3 looked at a collection efficiency of 50% of the residues available from Scenario 2. The total amount of agricultural residue available each year was 55.9 Tg per year which equates to a potential energy value of 657.01 PJ. Field residues were the most abundant feedstock available i.e. 38.4 Tg annually compared with 17.4 Tg from processing residues which equated to 452.33 and 204.68 PJ of potential energy respectively. A large proportion of field residue availability (85%) was in the 3 northern zones which represented in excess of 80% of the land area and cereal crops accounted for 88% of field residues available. When competing uses for field residues were included in the analysis under Scenario 2 then the total amount of field residue available was 21.2 Tg which equates to an energy potential of 248.78 PJ. Under Scenario 3 where a collection efficiency of 50% was used residue availability for medium- to large-scale bioenergy production was 10.6 Tg equating to an energy potential of 124.39 PJ. (C) 2012 Elsevier Ltd. All rights reserved.