There is enough scientific evidence to support the contention that gradual changes in global climate are being caused by excessive accumulation of certain gases in the Earth’s atmosphere, due mainly to anthropogenic activities. One major consequence of the excessive accumulation of these gases in the atmosphere is the greenhouse effect. Climate change is a global issue, and hence the need for intergovernmental action to combat it. The recognition of the threat posed by the continued emission of greenhouse gases into the atmosphere led to the Rio Summit on Climate Change and the United Nations’ Framework Convention on Climate Change (UNFCCC) in 1992. Nigeria ratified the UNFCCC in August 1994. Carbon dioxide (CO₂) is by far the most important greenhouse gas (GHG). Most of the anthropogenic CO₂ emissions are due to the combustion of fossil fuels in various sectors of the economy—i.e. the energy supply system and the end-use sector. Hence, it is always possible to link GHG emissions to energy production and utilisation.

On the basis of official results of the 1991 national census, which gave the population of Nigeria as 88.5 million people, and the assumption of an average growth rate of 2.85% per annum, it is estimated that there were 108 million inhabitants in Nigeria in 1998. Nigeria has an abundant supply of natural energy-reserves, amongst which are oil, natural gas, coal, bitumen, and renewable energy resources. Over the years, however, the energy sector of Nigeria has been primarily dominated by petroleum, and this has been the prime mover of economic and social development. As a result of increasing earnings from oil exports, domestic energy consumption has been rising roughly in unison with developments in the economic and social frontiers within the last two decades.

As at the end of 1998, Nigeria’s proven oil-reserves were 21,000 million barrels and efforts are underway to increase this to 25,000 million barrels. Despite the proven reserves and a large quantity of probable reserves, oil production has been below 650 million barrels per annum, on average, between 1980 and 1995. Crude-oil production, export and consumption trends for this period are shown in Fig. 2. From this, we observe that domestic requirements for crude oil have been steadly increasing for most of the period, at an average of 7% per annum. There are four petroleum refineries in Nigeria, with a total design capacity for 450 thousand barrels of oil per day. However, for the last 2 years, the refineries have been faced with various production problems. This has led to an acute shortage of petroleum products all over the country and consequently massive importations of fuel in a bid to support domestic demand, especially in the transport sector.

Nigerian gas reserves were estimated at about 3.36×10⁶ million m³ in 1998. The gas-to-oil ratio of the Nigerian crude is quite high, with the resultant effect that about one half of the estimated gas reserves appears as associated gas, i.e. gas produced along with crude oil; the other half exists as non-associated gas in isolated gas-deposits.

Natural gas consumption in Nigeria is low compared with the available resource base. In 1995, for example, of the 32,000 million m³ of gas produced, only 15% was consumed domestically; the remaining 85%, i.e. mainly associated gas, was flared. A good proportion of the associated gas lifted with crude oil is flared because there are no adequate infrastructures to supply the gas to possible end-users, if collected, and also because of the fact that the recovery cost of associated gas is much higher than for non-associated gas. Consequently, since the available non-associated gas can meet domestic demand for many years to come, there is no motivation to recover the associated gas that is currently being flared, and this has been the trend for some time. As at 1990, Nigeria contributed 27% of the total gas flared globally, i.e. the largest percentage in the world. However, in recent years, there has been some increase in the demand for natural gas. For example, about 3.4% of the total commercial energy consumption was consumed as gas in 1970, reaching about 38.6% in 1990. This is due to the increase in demand for gas in the fertiliser and petrochemical industries, as well as an increase in the number of gas-fired power plants.

Although measures are being taken to recover some of the associated gases currently being flared, gas-flaring in the oil industry will continue to be a major source of environmental pollution and an important component of Nigeria’s total CO₂ emissions, for some time to come. Some of the efforts being made to find economic uses for the flared gas include the West African Gas Pipeline Project, under which Nigeria is to supply gas to some West African countries (notably Ghana, Togo and Benin), the Oso Natural-Gas Liquids project, and the Escravos Gas-Flare Reduction Plant.

As with oil and gas, Nigeria has abundant coal resources. Data from the Nigerian Coal Corporation revealed that there is an estimated reserve of 2700 million tonnes. This consists of proven reserves of about 640 million tonnes and probable reserves of 2060 million tonnes. Of the total amount of coal resources, less than about 50 million tonnes are coking coal. Table 1 shows the trend and quantity of coal extracted between 1980 and 1992.

Because of the out-dated mining practices and ageing equipment, coal production at the mines is low, with a correspondingly high production cost. Before 1990, the Nigerian Railway Corporation and the National Electric Power Authority were the major consumers of coal in the country. However, following the replacement of coal locomotives with diesel engines and the retirement of the last coal-fired power plant, there has been a decline in the demand for coal consumption in Nigeria. Presently the major consumer of coal is the cement factory at Nkalagu, which accounts for over 90% of total domestic demand from 1985 until the present. Small quantities are also used for cooking in households close to the mines and by small-scale industries.

Electricity generation in Nigeria is primarily by three hydro-power plants and six gas-/oil-fired thermal plants. Nigeria’s hydro-potential is estimated to be of the order of 8000 MW, of which only 1900 MW had been exploited by 1990. Hydro-power generation has been an important part of the electricity-generation mix of the national grid, with its share ranging between 22% in 1983 to 46% in 1995. Electricity consumption rose from 4.6 TWh in 1980 to about twice this value in 1995. Despite this steady rise, at an average of 4.6% per annum, electricity consumption per capita in Nigeria as of 1994 was a mere 0.136 MWh annually, one of the lowest in Africa. These estimates do not include autogeneration, however.

As a result of incessant power outages, autogeneration is an important feature of power generation in Nigeria, especially in the industrial and residential sectors. Although data on private power generators are scarce, it is believed that the installed capacity of these generators was about 1760 MW in 1990, amounting to about 30% of grid capacity of the nation’s only electricity utility, the National Electric Power Authority (NEPA). Major factories in the industrial city of Lagos now run on diesel generating-sets for their production process, and only use the NEPA supply when off-production. If autogeneration is taken into consideration therefore, Fig. 4 does not present the whole picture of electricity production and consumption in the country.

Wood is probably the most important non-commercial fuel in Nigeria. It is used mainly for cooking in rural and some urban households. It is also the last resort during periods of acute scarcity of kerosene and gas, which are not unusual in urban centres. Wood in some cases is converted into charcoal and used either as a supplement to fuelwood or mainly by itself for cooking.

Fuelwood and charcoal are also used in small industries, such as food-processing factories, bakeries, brick manufacturing and beer brewing. The consumption data for fuelwood and charcoal are subject to controversy because data sources are limited: it is, however, estimated that consumption of the products would account for about two-thirds of the total final energy-consumption in the country. Annual fuelwood consumption has been estimated to be 80 million m³, or 43.4 million tonnes.