CHAPTER ONE

1.0 INTRODUCTION

During the last decade worldwide concern with global climate has highlighted the challenge faced by both industrialized and developing countries in maintaining a sustained process of development. Nigeria, like other developing countries, shares the need for fast economic growth given the current low standard of living and rising population. It also shares the global concern of protecting the environment.

Increase in the concentration of greenhouse gases has become one of the most hazardous impacts on our environment. It has resulted into an increase in the temperature of the earth (Akpojotor and Akporhonor, 2005). It is predicted that the global average temperature will rise by about 1.6 oC - 6 oC by the year 2100 if current trends of greenhouse gases emission continue (IPCC, 1995). This increase in the average temperature of the earth is termed global warming. It occurs when greenhouse gases trap the sun’s heat.  When sunlight reaches the surface of the earth, some of it is absorbed by the earth’s surface and this warms the earth. It is a case of heat transfer since the earth’s surface is much cooler than the sun and radiates energy at much longer wavelengths than the sun. Some of these longer wavelengths are absorbed by greenhouse gases in the atmosphere before it can be lost to space. The absorption of this long wave radiant energy warms the atmosphere. Greenhouse gases also emit long wave radiation both upward to space and downward to the surface. The downward part of this long wave radiation emitted by the atmosphere is the greenhouse effect (Pearce, 1998)

The major greenhouse gas responsible for global warming is CO2. Atmospheric CO2 derived from multiple natural sources including volcanic out gassing, the combination of organic matter and the respiration processes of living anaerobic organisms. Apart from these natural phenomena, man-made sources include the burning of various fossil fuels for power generation in the industry, Agriculture, transportation, domestic uses etc (Albert, 1987).  The growing belief is that increase in man-made sources of CO2 emissions are responsible for global warming, hence it is also known as anthropogenic climate change. These man-made sources depend on the economies of the various countries. This corroborates the report that the concentration of CO2 has increased substantially since the industrial revolution and is expected to continue to be so (Walter, 2004).

The adverse effects of the increasing temperature of the earth’s surface include  increases in global average air and ocean temperatures, widespread melting of snow and ice, and rising global average sea level leading to flooding etc(Wikipedia 1). This flooding is expected to affect African countries on the coastline such as the southern part of Nigeria (Raufu, 2002). There is also the fear of health related problems and uncertain effects on Agriculture (Parker, 2007). Thus in general, the geographical location of a country will determine the level of the consequences of global warming on it. This supports the report by scientists at the Lawrence Livermore National Laboratory in the U.S that the effects of global warming are for the first time visible on a local scale (Walter, 2004).

It is surprising to note that in Nigeria, there is still no clear leadership in tackling the issue of climate change and the predicted consequences. While it has been a national agenda in many countries even with relatively high CO2 emission, it is only in June 2009 that a desk office under the auspices of the Nigeria Climate Action Network (Nigeria CAN) was inaugurated in the Federal Ministry of Science and Technology Abuja.

As pointed out in 2005 (Akpojotor and Akporhonor), though Nigeria is not considered by global indices of classification an industrialized nation, the amount of CO2 emitted into the atmosphere in the country can be alarming when compared to those released in some other developing countries. The reason being that the over 140 million populations based on the 2006 census which makes her the most populated African country and the 8th most populated country in the world, means a large transport potential which may translate into a remarkable emission of CO2. This has been aggravated by the epileptic power supply from the national grid and deforestation in the tropical parts of the country (Small and Kazimi, 1995).

It is worthy of note that from the International Energy Agency (Wikipedia 2), Nigeria is ranked 40th among 216 countries in CO2 emission with 95,756 thousand metric tonnes, as against the United States with a CO2 emission of 5461,014 thousand metric tonnes which makes her 2nd, behind China with an emission of 7,031,916 thousand metric tonnes. This total emission does not indicate the variation in emission level from place to place in the county. Therefore it cannot be used for proper environmental planning and policy making. The purpose of this research project is to have a database of CO2 emission in Nigeria. In this work, how to obtain the total amount of CO2 emission in any given place is demonstrated. Note that only CO2 emissions from some major petroleum products (petrol, diesel and kerosene) were used in this research project. The implication is that there are other major CO2 emitters in the country such as coal/peat, natural gas, deforestation and cement which are not included in this work.

1.1 HISTORY OF CARBON DIOXIDE

Carbon dioxide (CO2) was one of the first gases to be described as a substance distinct from air. In the 17th century, the Flemish chemist Jan Baptist Van Helmont observed that when he burned charcoal in a closed vessel, the mass of the resulting ash was much less than that of the original charcoal. His interpretation was that the rest of the charcoal had been transmuted into an invisible substance he termed a "gas" or "wild spirit".

The properties of carbon dioxide were studied more thoroughly in the 1750s by the Scottish physician Joseph Black. He found that limestone (calcium carbonate) could be heated or treated with acids to yield a gas he called "fixed air." He observed that the fixed air was denser than air and supported neither flame nor animal life. Black also found that when bubbled through an aqueous solution of lime (calcium hydroxide), it would precipitate calcium carbonate. He used this phenomenon to illustrate that carbon dioxide is produced by animal respiration and microbial fermentation.

In 1772, English chemist Joseph Priestley published a paper entitled Impregnating Water with Fixed Air in which he described a process of dripping sulphuric acid on chalk in order to produce CO2, and forcing the gas to dissolve by agitating a bowl of water in contact with the gas. This was the invention of Soda water.

Carbon dioxide was first liquefied in 1823 by Humphry Davy and Michael Faraday. The earliest description of solid carbon dioxide was given by Charles Thilorier, who in 1834 opened a pressurized container of liquid CO2, only to find that the cooling produced by the rapid evaporation of the liquid yielded a "snow" of solid CO2.

1.2 CO2 AS A CHEMICAL COMPOUND

CO2 is a colourless, tasteless gas that is about one half times as dense as air under ordinary conditions of temperature and pressure. It does not burn, and under normal condition it is stable inert and non-toxic. It will however support combustion of magnesium oxide and carbon. It is fairly soluble in water; a standard test for the presence of CO2 is its reaction with limestone to form a milky white precipitation of calcium hydroxide. CO2 occur in nature both free and in combination (e.g. in carbonates). It is a part of the atmosphere, making up about 1% of the volume of dry air. Because it is a product of combustion of carbonaceous fuels (coal, coke, oil gasoline, cooking gas etc), there is therefore usually more of it in city air than country air. There are three principle commercial sources of CO2. High purity CO2 is produced from some wells. The gas is obtained as a by product of chemical manufacture, as in the fermentation of grain to make alcohol and the burning of limestone to make lime. It is also manufactured directly by burning carbonaceous fuels for commercial use; it is available as liquid at lower pressure and as the solid dry ice. But we are mainly concerned with CO2 burnt from fuel ice (petrol, diesel and kerosene) which is of great impact to the global environment and its emissions into the atmosphere thereby increasing the effect of global warming on the environment.

1.3 CHEMICAL AND PHYSICAL PROPERTIES OF CO2

Carbon dioxide is colourless. At low concentrations, the gas is odourless. At higher concentrations it has a sharp, acidic odour. It can cause asphyxiation and irritation. When inhaled at concentrations much higher than usual atmospheric levels, it can produce a sour taste in the mouth and a stinging sensation in the nose and throat. These effects result from the gas dissolving in the mucous membranes and saliva, forming a weak solution of carbonic acid. This sensation can also occur during an attempt to stifle a burp after drinking a carbonated beverage. Amounts above 5,000ppm are considered very unhealthy, and those above about 50,000ppm are considered dangerous to animal life.

At standard temperature and pressure, the density of carbon dioxide is around 1.98 kg/m3, about 1.5 times that of air. The carbon dioxide molecule (O=C=O) contains two double bonds and has a linear shape. It has no electrical dipole, and as it is fully oxidized, it is moderately reactive and is non-flammable, but will support the combustion of metals such as magnesium.

At atmospheric pressure and a temperature of −78.51°C (−109.32 °F), carbon dioxide changes directly from a solid phase to a gaseous phase through sublimation, or from gaseous to solid through deposition. Solid carbon dioxide is commonly called "dry ice", a generic trademark. It was first observed in 1825 by the French chemist Charles Thilorier. Dry ice is commonly used as a cooling agent, and it is relatively inexpensive. A convenient property for this purpose is that solid carbon dioxide sublimes directly into the gas phase, leaving no liquid. It can often be found in grocery stores and laboratories and is also used in the shipping industry. The largest non-cooling use for dry ice is blast cleaning.

CARBON DIOXIDE (CO2)

Properties of CO2

Structure of CO2

Crystal Structure of CO2                                             Molecular shape of CO2

1.4 THE PRESENT STATE OF ATMOSPHERIC CO2 CONCENTRATION

The world's most current data for atmospheric CO2 is measured at the Mauna Loa Observatory in Hawaii. Measurements are made and reported independently by two scientific institutions: Scripps Institution of Oceanography and the National Oceanic and Atmospheric Administration (NOAA).

The average annual concentration of CO2 in the atmosphere were measured for 2008 - 2010 and observed to be 385.57 ppm, 387.36 ppm and 389.78 ppm for 2008, 2009 and 2010 (Mauna Loa Observatory). For the past decade (2001 - 2010) the average annual increase is 2.04 ppm per year. Since the 1958 start of precision CO2 measurements in the atmosphere, the annual mean concentration of CO2 has only increased from one year to the next.   The CO2 data below give a simple overview of the annual trend.

Annual Data | Atmosphere  CO2  

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