Energy and exergy analyses of the Nigerian transportation sector from 1980 to 2010

This paper analyses energy utilisation in the transportation sector of Nigeria using exergy methods. The sector is dominated by the road subsector, with a share ranging from 70.65% in 1990 to 97.51% in the year 2005 and a mean of 88.44%. The road subsector is still the most efficient, with energy efficiency values that range from 9.93% in 1990 to 19.19% in 1986. The corresponding exergy values are 9.28% and 17.93%, respectively. Following the road subsector is the aviation subsector with its least energy consumption share of 0.10% in 2005 and biggest share of 26.25% in 1990. The subsector energy efficiency values range from 0.03% in 2005 to 7.35% in 1990, with corresponding exergy values of 0.026% and 6.87%, respectively. The overall mean energy efficiency in the Nigerian transportation sector for the three decades is 17.11%, while the overall mean exergy efficiency is 15.97%. The road subsector performance has been adversely affected by the massive importation of used vehicles into the country.