Like other parts of the world, coal is the oldest commercial fuel, dating in Nigeria from 1916 when 24,000 tons were produced. Production peaked at near one million tons in 1959, before declining to the present insignificant level. This is due to the reduction in the demand for coal arisina from dieselisation of rail transportation, and switching from coal to gas for thermal power generation.
Nevertheless, Nigeria's coal reserves are large, over 2 billion metric tonnes, of which 650 mil- lion tonnes are proven. If fully revitalised, the coal industry could fetch up to 5 billion Naira in export earnings. Coal production is from the Cretaceous Anambra Basin which extends to Dekina in the northern part of the basin in Benue State and to Okigwe in the south. The coal in this basin is sub- bituminous and occurs principally at two levels, the lower coal measures (Mamu Formation) and the upper coal measures (Nsukka Formation).
From north to south, the reserves from seams over one meter thick, are (in million tonnes); Ogboyoga (100), Okaba (70), Orukpa (60), Ezimo (50), and Enugu (50) (FRN, 1987). Coal seams also occur at Gombe in Gombe State. Mine production capaci- ties after full rehabilitation and privatisation could attain the following levels: Onyeama and Okpara (150,000-400,000 tonnes/year), Owukpa (2,500 tonnes/year) and Okaba (15,000-300,000 tonnes/ year). Nigerian subbituminous coal has a high calorific value (5,000-6,000 cal/g or 5500-6500 airdried), low ash and low sulfur contents, with good storage characteristics (Afonja, 1979).
In the Lafia-Obi area of Nassarawa State, good quality cooking coal has been discovered which is suitable for use in the iron and steel industry. If utilised, the Lafia-Obi coal would save the country the high cost of importing cookable coal. Since the Nigerian Coal Corporation has lost nearly all its tra- ditional customers, notably railways and power authority, a recent drive to market its coal overseas offered some hope of recovery.
European buyers in Italy and the United Kingdom have started import- ing Nigerian coal, because its low sulfur content is environmentally acceptable. As already noted, Nigeria has the largest lignite deposit in Africa, with reserves of about 50 million tonnes. The Nigerian lignite belt, of mid-Tertiary age, extends from Oriu in the south-east, through Urnuezeala, Umuahia, Nnewi, Oba, in a 20 to 40km - wide belt across the Niger, to Ogwashi, Asaba, Mgbiigliba and Adiase-Uti in Delta State. It has not yet been exploited.