ABSTRACT
Analysis of exhaust emissions from engines fueled with petrol, diesel and their blends with biodiesel was carried out.The biodiesel was produced from waste cooking oil via transesterification. Physicochemical analysis of the waste cooking oil and biodiesel were carried out using ASTM methods. Analysis of exhaust emissions (CO, CO2, O2 and NOx) from petrol and diesel vehicles as well as big and small generators were also carried out using a Bacharach Portable Combustion Analyzer 2. Ten of each of the petrol vehicles (motorcycles, tricycles, mini-buses and small cars) were analysed and their average CO, CO2 and NOx emissions were calculated. Ten small and ten large capacity generators were also analysed. Petrol and diesel were blended with biodiesel and used to fuel 3 generators and 1 motorcycle at different blend ratios ranging from B5 to B40. The results of the analysis for biodiesel are as follows: moisture content (0.05%), specific gravity (0.90), acid value (0.22 mgKOH/g), sulphur content (0.01%), flash point (155 oC), kinematic viscosity (1.90 m2/s), pour point (-3.00 oC), ash content (0.09%), iodine number (13.45 gI2/100g) and calorific value (34,400 kJ/g). Mini-buses emitted the highest concentration of CO (3511.7 ppm) and CO2 (6.0%) while small cars emitted the highest concentration of NOx (27.1 ppm) and the lowest concentration of CO (2131.9 ppm) and CO2 (3.5%). However, tricycles emitted the lowest concentration of NOx (3.5 ppm). For diesel vehicles (6 tankers and 6 trailers), the Trailers emitted the highest CO (744.8 ppm) while tankers emitted higher CO2 (1.6%) and NOx (114.7 ppm). Although the diesel vehicles are heavy duty vehicles, they emitted significantly (P<0.05) lower concentrations of CO and CO2 but with a significantly (P<0.05) higher NOx than the petrol vehicles. The concentrations of CO from all the petrol and diesel vehicles exceeded the 2nd European emission standard (1996) adopted by Nigeria. Small generators emitted more CO (2876.8 ppm) while the large generators emitted more NOx (30.6 ppm) and CO2 (6.58%). However, there was no significant difference (P>0.05) between the emissions from large and small capacity generators. At every blend ratio, there was a significant percentage reduction in CO, CO2 and NOx emitted in the small and large petrol-biodiesel generators but an increase in NOx in motorcycle with every increase in blend ratio. There was also an increase in the emission of NOx in diesel-biodiesel generator and a decrease in CO and CO2 with every increase in the blend ratio. With the inability of the vehicular emissions to adhere to an already obsolete adopted Nigerian emission standard, it is expected that the Nigerian environment with about 10 million vehicles and numerous generators will not meet the WHO (2016) air quality standard of 9 ppm (CO) and 0.0128 ppm (NOx) which the sixth (2014) European vehicular emission standard was designed to achieve. Therefore these emissions would enhance health and environmental hazards associated with exposures to these pollutants
TABLE OF CONTENTS
TITLE PAGE………………………………………………………………………………..……..i
CERTIFICATION.. ii
DEDICATION.. iii
ACKNOWLEDGEMENTS. iv
ABSTRACT. v
Table of Contents. vi
List of Figures. ix
List of Tables. x
CHAPTER ONE: INTRODUCTION.. 1
1.1 Introduction. 1
1.2 Transport and Climate change. 3
1.3 Impact of different emission types. 6
1.3.1 Carbon monoxide. 7
1.3.2 Nitrogen Oxides (NOX) 7
1.4 The Kyoto Protocol 8
1.5 Justification for the Study. 9
1.6 Research Objectives. 10
CHAPTER TWO: LITERATURE REVIEW… 11
2.1 Air pollution. 11
2.2 Vehicle Emissions. 11
2.3 Factors affecting the emission levels. 12
2.3.1 Engine Design Parameters. 12
2.3.1.1 Air/Fuel Ratio and Mixture Preparation. 13
2.3.1.2 Ignition Timing. 14
2.3.1.3 Compression Ratio and Combustion Chambers. 14
2.3.2 Vehicle Non – Engine Components. 14
2.3.2.1 Tyres. 14
2.3.2.2Cooling technology. 15
2.3.2.3 Lighting. 15
2.3.2.3Traffic characteristics. 15
2.3.2.4 Road Characteristics. 16
2.3.2.5 Fuel Quality. 16
2.4 Health Effects of Exhaust Emissions— Case Studies. 17
2.5 Biodiesel 19
CHAPTER THREE: EXPERIMENTAL.. 21
3.1 Sample Collection. 21
3.2 Characterization of Waste Cooking Oil 21
3.2.1 Specific Gravity. 21
3.2.2 Moisture Content 21
3.2.3 Determination of Viscosity. 21
3.2.4 Acid Value/Free Fatty Acid (FFA) 22
3.2.5 Peroxide Value. 22
3.2.6 Iodine Value. 23
3.2.7 Saponification Value. 23
3.2.8 Refractive Index. 24
3.3 Biodiesel Production. 24
3.4 Separation of biodiesel from by-products. 24
3.5 Purification of biodiesel by washing. 24
3.6 Characterization of Biodiesel 24
3.6.1 Specific Gravity. 24
3.6.2 Kinematic Viscosity. 25
3.6.3 Moisture Content 25
3.6.4 Flash Point: 25
3.6.5 Pour Point 26
3.6.6 Acid Number 26
3.6.7 Sulphur Content 26
3.6.8 Iodine Value. 26
3.6.9 Ash Content 27
3.6.10 Determination of Calorific Value. 27
3.7 Sample Size of Vehicles and Generators. 27
3.8 Equipment Setup and Exhaust Gas Measurement 28
CHAPTER FOUR: RESULTS AND DISCUSSION.. 29
4.1 RESULTS. 29
4.2 DISCUSSION.. 35
CONCLUSION.. 59
REFERENCES. 60
CHAPTER ONE
INTRODUCTION
1.1 INTRODUCTION
In the last century, the level of carbon dioxide in the atmosphere has increased by more than 30% as a result of human activities. The effects of climate change are becoming more pronounced and they include droughts, floods, heat waves and changes in the weather patterns. Global temperatures have increased by almost 0.8°C over the past 150 years. Without any global action, it is expected that temperatures will increase further by 1.8 – 4 °C by 2100 (IPCC, 1996). It is anticipated that this rise will result in sea level increment of 15 to 95 centimeters. While the transportation sector is crucial to a nation’s economy and personal mobility, it is also a significant source of GHGs. Nearly 50% of global CO, HCs, and NOx emissions from fossil fuel combustion come from internal combustion engines (ICE). The contribution of the transport sector to total CO2 emissions in developed nations is forecast to increase from 20% in 1997 to 30% in 2020 (Ken et al., 2004). The transport sector accounts for almost all the oil demand growth around the world (Ming et al., 2009). The world transportation oil demand has continuously risen with increasing GDP. World forecasts show that transport oil demand in developing nations will increase three times more than in developed nations. Increasing income will cause a tremendous increase in car ownership in developing countries, where the vehicle stock is expected to triple (IEA, 2006). Developing countries account for about 10% of the global automobile population and a little over 20% of the global transport energy consumption. In comparison, the United States alone consumes about 35% of the World’s transport energy (Shiva, 2006).
Road vehicles are among the main consumers of world energy and they dominate global oil utilization, consuming up to 80% of transport energy. The transport sector’s share of oil consumption has been increasing steadily at around 0.6% per year. Current policies are not sufficient to control road vehicle energy use. Even if governments implement all the measures that are currently being considered, projections by the International Energy Agency (IEA) show that road vehicle energy use would still rise between now and 2030 at 1.4% per annum respectively(IEA, 2006). In developing nations, it is envisaged that with rising income and the rapidly rising mobility that accompanies it, the increase in automobile emissions will be even greater than the developed nations. Steady growth in vehicular populations has put environmental stress on urban centers in various forms particularly causing poor air quality. There is growing evidence that links vehicle pollutants to human ill health. Motor vehicles are major emission sources for several air pollutants, including nitrogen oxides (NOx) and carbon monoxide (CO) (Suresh et al., 2009). These pollutants have significant adverse effects on human beings and the environment. Vehicle emissions cause both short and long term problems associated with health effects. For example, HCs and NOx are the precursors of ozone gas, which has effects ranging from short term consequences such as chest pain, decreased lung function, and increased susceptibility to respiratory infection, to possible long-term consequences, such as premature lung aging and chronic respiratory illnesses (WHO, 2005).
The most affected group is the urban inhabitants especially the traffic policemen who are exposed to the fumes for a long period of time. Children attending a school located near a busy way in Utrecht, Netherlands were compared with children attending a school located in the middle of a green area in a suburban area. It was discovered that respiratory diseases were more pronounced in the urban than suburban children (Suresh et al., 2009). The severity of the problem increases when traffic flow is interrupted and the delays and start-stops occur frequently. These phenomena are regularly observed at traffic intersections, junctions and at signalized roadways. Emission rates depend on the characteristics of traffic, vehicles and type of road intersections. The age of a vehicle and maintenance levels also contribute to the emissions of all classes of vehicles. Further, the fuel quality has a direct effect on the vehicular exhaust emissions (Perry and Gee, 1995).
In most developing countries of the world vehicular growth has not been checked properly by environmental regulating authorities leading to increased levels of pollution (Han et al, 2006). Traffic emissions contribute about 50-80% of NO2 and CO concentration in developing countries (Fu, 2001; Goyal, 2006). This situation is alarming and is predicated on the poor economic disposition of developing countries. Poor vehicle maintenance culture and importation of old vehicles, which culminates in an automobile fleet dominated by a class of vehicles known as ‘’super emitters’’ with high emission of harmful pollutants, has raised this figure of emission concentration(Ibrahim, 2009). The increase in this traffic-related pollution is not based on the aforementioned factor only, but also on low quality fuel, poor traffic regulation and lack of air quality implementation force. These are clear indices to high levels of traffic-related pollution in developing countries.
In Nigeria as well as in other developing countries, which are not yet fully industrialized, majority of the air pollution problems result from automobile exhaust. In the major towns of some developing countries, because of tropical nature of the climatic conditions, many activities are performed outdoors. People stay along the busy roads every day either to do their work or to sell their wares. Therefore, the ill effects on health due to air pollution resulting from automobile exhaust emission must be very serious indeed (Ayodeleand Bayero, 2009).
Enugu State in the absence of a reliable public transport system, has had air pollution worsened because of an increased number of old second-hand cars, taximotorbikes (popularly called okada), substandard petrol and other products imported into the country. There is presently no available data on emission and impact of air pollution in Enugu state, but it is anticipated that air pollution will become a major health problem if adequate mitigation measures are not taken (Nwadiogbu et al., 2013). In Nigeria much attention is given to general industrial pollution and pollution in oil industries, with little reference to damage or pollution caused by mobile transportation sources of air pollution (Faboya, 1997; Iyoha, 2002; Magbagbeola, 2001). Pollution from mobile transportation is on the rise due to increase in per capital vehicle ownership, thus resulting in high congestion on Nigeria city roads and increase in the concentration of pollutants in the air, consequently, increasing health risks for human population. In addition compared with the large volume and varieties of studies carried out in the developed world, exposure studies carried in Nigeria are relatively scarce. So as a vital step in focusing attention on these problems, it is necessary to know the types of air pollutants present along with the level of each pollutant.
1.2 TRANSPORT AND CLIMATE CHANGE
According to the IPCC guidelines, the direct greenhouse gases are carbon dioxide, methane, hydro-fluorocarbons, per-fluoro-carbons (PFCs), sulphurhexafluoride (SF6) and nitrous oxides. The indirect greenhouse gases include nitrogen oxides (NOX), carbon monoxides (CO), non-methane volatile organic compound (NMVOC), hydro fluorocarbons (HFCs) and sulphurdioxide (SO2). Some GHGs such as CO2 occur naturally and are emitted to the atmosphere through natural processes and human activities. Other GHGs (e.g., fluorinated gases) are created by human activities. Current vehicle fleets emit significant amounts of carbon monoxide (CO), nitrogen oxides (NOx), total organic gases (TOGs) or reactive organic gases (ROGs) more commonly known as volatile organic compounds, VOCs), particulate matter (PM) and carbon dioxide (CO2). The VOC and NOx are precursors to secondary ozone formation and aerosols and more importantly, particulate matter and ozone are the two critical pollutants of greatest concern causing human health deterioration and leading to a social cost (Guihaet al., 2009). The direct greenhouse gases have different effectiveness in radiative forcing. This can be determined by comparing their Global Warming Potential (GWP). GWP is a means of providing a simple measure of the relative radiative effects of the emissions of the various gases. The index is defined as the cumulative radiative forcing between the present and a future time horizon expressed relative to that of CO2. It is necessary to define a time horizon because the gases have different lifetimes in the atmosphere. Methane and Nitrous oxide have a greater GWP than carbon dioxide as shown Table 1.1.
Table 1.1: Global Warming Potential defined on a 100-year horizon.
| Green House Gases | Global Warming Potential |
| Carbon Dioxide | 1 |
| Methane | 21 |
| Nitrous Oxide | 310 |
| HFCs | 140 -11,700 |
| PFCs | 6,500 – 9,200 |
| SF6 | 23,900 |
Source: IPCC, 1996
The main sectors contributing to emission levels include energy, Industrial processes, solvents, agriculture, land use change and forestry and waste. The power generation sector currently accounts for 24% of the CO2 emission. Many forms of transportation create GHG (including CO2) emissions, both direct and indirect. Transport is one of the major contributors to air pollution problems at the local, region and global levels contributing 14% of the global carbon dioxide emissions. It relies on fossil fuel burning, primarily oil, and is now the fastest-growing source of greenhouse gas emissions, particularly in developing countries. Transportation accounts for 27% of total global energy consumption. Greenhouse-gas emissions (CO2 and CFCs) from motor vehicles in developing countries contribute less than 3% to the global greenhouse effect, compared to a 9 to 12°% contribution from motor vehicles inOrganisation for Economic Co-operation and Development(OECD) countries and Eastern Europe (Asif, 1993).
There is growing number of motorcycles being used for fast transportation in cities and towns across Nigeria. This has contributed to a large percentage of the automobiles in Nsukka town. An analysis of motor cycle emissions is of great importance given their growing numbers. Motor cycles are preferred to mini buses for public transport because of their mobility and convenience. According to the Taiwan Environmental Protection Administration (TEPA), motorcycles contribute 38% of the total CO, 64% of HC and 3% of NO emitted from automobiles (Lin et al., 2008). This implies that motor cycles have a potential of producing high amounts of emissions if not checked.
Figure 1.1: Global Share of CO2 emission by Sector.
Source: Stern, 2006
According to the IPCC (1996), the world’s temperature is expected to increase over the next hundred years by up to 5.8°C. This is much faster than anything experienced so far in human history. The goal of climate change policy should be to keep the global mean temperature rise to less than 2°C above pre-industrial levels. At 2°C and above, damage to ecosystems and disruption to the climate system increases dramatically. This means that global emissions will have to peak and start to decline by the end of the next decade at the latest. Given that personal mobility is a pre-requisite of economic and modern life, the question arises on how to meet the mobility needs of a contemporary lifestyle and yet reduce direct and indirect emissions of GHGs. This is shown in Figure 1.2. Figure 1.2: Projected growth in CO2 emission levels in the world
Source:Stern,2006.
From Figure1.2, assuming a business as usual scenario, the largest source of transport emissions is the OECD North America producing 37% of the total emissions. This is confirmed by the world highest car ownership of 0.6 vehicles per person in North America (Stern, 2006).Africa has the lowest projected CO2 emission growths followed closely by Asia. This is as a result of the low industrialization levels in these regions. However, the need to develop will see a twist in the future as the developing countries push for more industrialization to match the OECD.
1.3 IMPACT OF DIFFERENT EMISSION TYPES
Although automobiles contribute to the degradation of air quality, there is no simple means of measuring the precise impact. The impact will vary from city to city, depending upon such factors as vehicle density, the split between petrol and diesel vehicles, the type of vehicles on the road and their average age, the traffic management systems in place and atmospheric conditions. The pollutants from motor vehicles have significant adverse effects on human beings and the environment.
1.3.1 CARBON MONOXIDE
Carbon monoxide (CO) is a tasteless, odourless, and colourless gas produced by the incomplete combustion of carbon-based fuels. Exposure to carbon monoxide interferes with absorption of oxygen from haemoglobin in the red blood cells. After a prolonged exposure, this impairs perception and thinking, slows reflexes, causes drowsiness and can cause unconsciousness and death. A combined exposure to CO and other pollutants, promotes morbidity in people with circulatory problems. It is associated with less worker productivity and general discomfort.
1.3.2 NITROGEN OXIDES (NOX)
NOx is a generic term for mono-nitrogen oxides namely NO and NO2 which are produced during combustion at high temperatures. At ambient temperatures, oxygen and nitrogen do not react with each other. However, in an internal combustion engine, high temperatures lead to reaction between N2 and O2 to yield nitrogen oxides. NOx is categorized into three types that include; thermal NOX, fuel NOx and Prompt NOx (Bosch and Jansenn, 1988).
Thermal NOX is formed by the oxidation of N2 at high temperatures of about 1300K according to the following;
N2 + O2 2NO H298 = 180.6 KJ/mol
The thermal NOx emission from an engine can be controlled by lowering the combustion temperature such as operating the engine under excess air (fuel – lean) conditions. However, these approaches are not very effective though recent approaches based on High Temperature Air Combustion (HiTAC) are effective. The second category called fuel NOX is formed from the oxidation of nitrogen present in fuels. This is relatively independent of temperature at normal combustion temperatures. The third category, prompt NOx, is formed by the reaction of hydrocarbon fragments with atmospheric nitrogen to yield products such as HCN and H2CN2. The products are subsequently oxidized to NO in the lean zone. NO can further react with oxygen to form NO2 or N2O.
NO2, along with volatile organic compounds, (VOCs), is a precursor of ground-level ozone and other photochemical pollutants. Exposure to NOX increases susceptibility to viral infections such as influenza and irritation in the lungs causing bronchitis and pneumonia. This results in sensitivity to dust and pollen in asthmatics. Most of these health effects are in combination with other pollutants.
1.4 THE KYOTO PROTOCOL
Recognising the threats on the climate worldwide, the signatories to the 1992 UN Framework Convention on Climate Change agreed on the Kyoto Protocol in 1997. The Protocol finally entered into force in early 2005 and its 165 member countries meet twice annually to negotiate further refinement and development of the agreement. Only one major industrialised nation, the United States, has not ratified Kyoto Protocol. The Protocol commits its signatories to reduce their greenhouse gas emissions by 5.2% from their 1990 level by the target period of 2008-2012. This has in turn resulted in the adoption of a series of regional and national emission reduction targets. In the European Union, for instance, the commitment is to achieve an overall reduction of 8%. In order to help reach this target, the EU agreed to increase its proportion of renewable energy from 6% to 12% by 2010.The Kyoto treaty does not require specific reductions in each sector (Difiglioand Lewis, 2000).
Greenpeace is calling for industrialised countries’ emissions to be reduced by 18% from 1990 levels for this second commitment period, and by 30% for the third period covering 2018-2022. Only with these cuts do we stand a reasonable chance of meeting the 2°C target. The Kyoto Protocol’s architecture relies fundamentally on legally binding emissions reduction obligations. To achieve these targets, carbon is turned into a commodity which can be traded. The aim is to encourage the most economically efficient emissions reductions, in turn leveraging the necessary investment in clean technology from the private sector to drive a revolution in energy supply. Signatory countries agreed a negotiating ‘mandate’, known as the Bali Action Plan, in December 2007. The action plan commits all developed countries to take on quantified greenhouse gas emission reduction targets. The developing counties commit to nationally appropriate mitigation actions, implying that they are not required to meet any specific targets. However, under the Bali Action Plan, no specific emission targets were set. It was expected that negotiations would be concluded in 2009 with a final agreement on the second Kyoto commitment period; however, this was not achieved at the UNFCC conference that was held in Denmark, Copenhagen in 2009.
1.5 JUSTIFICATION FOR THE STUDY
Transportation comes with significant undesirable side effects, particularly in terms of air pollution in urban areas and emissions of greenhouse gases, which can impact global climate change. Evidence is also growing of transport’s negative impact on local populations, particularly on the poor in developing world cities. The health consequences of urban air pollution are high. Transport related air pollution increases the risk of death particularly from cardiopulmonary causes, allergic illness such as asthma, cancer, etc. The long term air pollution from cars in Austria, France and Switzerland triggered an extra 21,000 premature deaths per year from respiratory or heart diseases, more than the total number of annual traffic deaths in the three countries (Chow et al., 2006). The need to move away from oil as a major source of energy is growing every year. Biofuel will reduce the dependence on oil and also reduce the trade deficit of nations, especially the developing nations. However, for biofuel to compete with the fossil fuel and have the possibility of replacing it as the primary energy source, it needs to be easy, cheap and fast to produce; waste oil is a good example of a primary energy source.
Most households (60%) live on less than a dollar a day, not enough to cater for a minimum standard of living. These have affected the quality of life style and health of most Nigerians. Most households in Nigerian cities operate small capacity fossil fuel electric power generators for electricity supply. This was due to the fact that the Power Holding Company of Nigeria (PHCN) solely responsible for generation and supply of electricity to the public have not fared well in the discharge of its mandate. Small household generators in Nigeria operate an average of 6 hours daily, while average distance of generator away from building was 5.6m.These alongside poor ventilation have influenced the quality of indoor air in the household.
With the public ban placed on motorcycles in major cities in Nigeria, towns like Nsukka have too many motorcycle operators and no proper investigation has been made into the estimation of the level of emissions from motorcycle in comparison with that from cars and tricycles. Nigeria also is at the brink of economic meltdown cum the persistent power shortage experienced, purchasing and operating of small capacity petrol generator (SCGG) seem the most viable option for most Nigerians but the ban placed on the importation of this set of generators makes it a very difficult option. It is very needful to analyse the gaseous emissions from these generators and see the difference between them and the large capacity petrol generators (LCGG). It is also very needful to investigate ways of reducing the emissions from vehicles and generators especially the publicly banned ones— motorcycles and small capacity petrol generators by blending their fuels with biodiesel fuel.
1.6 RESEARCH OBJECTIVES
The overall objective of this research is to evaluate the level of pollution from automobile and generator exhaust gases in Nsukka town through monitoring of gaseous emissions from petrol, diesel and biodiesel blends engines.
The specific objectives of the research include;
- To determine and compare the concentrations ofgaseous emissions (CO, CO2 and NOx) from different automobile types.
- To determine and compare the concentrations of gaseousemissions(CO, CO2 and NOx) from small and large capacity generators.
- To produce biodiesel from waste cooking oil.
- To analysethe impact of biodiesel blends on exhaust emissions.
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