Water use impact of ethanol at a gasoline substitution ratio of 5% from cassava in Nigeria

The process of fuel ethanol production from cassava root is connected to a chain of impacts on the water resource of the country where the cassava plant is grown and the root processed into fuel ethanol. The paper assesses the impact of the domestic production of 5 per cent ethanol (E5) needed under the Nigerian biofuel programme from cassava root on the water resource of Nigeria. Using the 2007 Premium Motor Spirit (PMS) consumption as the baseline, Nigeria will require about 0.49 hm³ of ethanol to blend 9.32 hm³ of PMS to arrive at the 2007 consumption estimates. The impact of the domestic production of this ethanol requirement translates to about 6.0 km³ of water; out of which about 48 per cent is green and about 52 per cent is blue. Addressing future impact typical of a developing economy like Nigeria, a three-scenario analysis was adopted to examine the impact of future growth in cassava-fuel ethanol requirement on the water resource of Nigeria, and also, the impact of improved water use on the future water footprint of E5. The projected water impact of cassava-ethanol production into the future ranges from 6.02 to 7.28 km³, while improved water use could lower these values by about 0.04–2.35 km³ for the same period, 2010 to 2020, under the projection assumptions made.