Environmental aspect of pavement, unlike its economic counterpart, is seldom considered in the theoretical study and field practices. As a highly energy and material intensive infrastructure, pavement has great potential to contribute to the environment protection, which, in root, depends on the in-depth understanding of the environmental impacts, holistically and specifically. A life cycle assessment (LCA) model is used to fulfill the goal. This research firstly carried out extensive literature review of LCA studies on pavement to identify the major research gaps, including: incompleteness of the methodology, controversy of the functional unit, and unawareness of feedstock energy of asphalt, etc. Based on that, a comprehensive methodology to apply the LCA model in the context of pavement engineering was developed. The five-module methodology, including material module, maintenance and rehabilitation (M&R) module, construction module, congestion module, and end of life module, covers almost every stage of pavement for a life time. The unique contribution of the proposed methodology lies in the deep-going modeling of the congestion module due to construction and M&R activities and the great efforts on the usage module. Moreover, the proposed methodology is a complex structure, demanding many sub-models to enrich the model bank and therefore another three contributions are made accordingly. Specifically, the environmental damage costs (EDCs) were calculated based on the estimates of the marginal damage cost of involved air pollutants; a function describing the relationship of pavement roughness and average vehicle speed was established; and an improved pavement M&R optimization algorithm was developed with the incorporation of EDCs. To demonstrate how the proposed methodology can be implemented, a case study of three overlay systems, including hot mixture asphalt (HMA), Portland cement concrete (PCC), and crack, seat and overlay (CSOL), was performed. Through the case study, the PCC option and CSOL options are found to have less environmental burdens as opposed to the HMA option while the comparison between the former two is indeterminate due to the great uncertainties associated with usage module, especially pavement structure effect; and the material, congestion, and usage modules are the three major sources of energy consumptions and air pollutant emissions. Traditionally, cost evaluation of pavement does not refer to EDC while the developed M&R optimization algorithm suggests that EDC occupies a significant fraction of the total cost constitution. And the M&R algorithm leads to a reduction from 8.2 to 12.3 percent and from 5.9 to 10.2 percent in terms of total energy consumptions and costs compared to the before optimization results. On the other aspect, pavement communities seem to prefer long life pavement because they believe small increase of pavement thickness prolongs the service life and thus leads to a smaller marginal cost while the study in Chapter 5 suggests that it may not be always true, at least in terms environmental impacts. Specially, frequently used pavement designs in the U.S. of two design lives, 20 years and 40 years, at three levels of traffic, are evaluated for their environmental impacts using the proposed methodology. It is found that only at high traffic volumes, the 40-year designs carry environmental advantages over their 20-year counterparts while the opposite is true at the low or medium traffic volumes. Unfortunately, it is not possible to determine the watershed traffic volumes due to the disturbance of many external factors.

published_or_final_version / Civil Engineering / Master / Master of Philosophy

This study describes the effects of climate change on food security in agricultural dependent country,Pakistan. Based on secondary sources of data, the study found out the evidences of climate change and itssevere implications on already inadequate and depleted natural resources of the country. The major effectsof climate change are in terms of rise in temperature, variations in precipitation pattern, increasing glaciermelt,and increasing evaporation and increased irrigation water requirements. In addition, the report focuseson Pakistan’s irrigation structure and existent capacity, irrigation water crisis, trans-boundary waterconflicts (internal and external), food shortage and high inflation rate in food components. This shortage offood is mainly because of low-cropped productivity due to irrigation water crisis. Although the country hasworld’s largest integrated irrigation system, however, the water scarcity has made minds of farmers to shiftcultivation from water intensive crops like rice, wheat, cotton and sugarcane to low water required cropsand vegetables putting pressure on food market. Moreover, the crops yield is also less due to strongevaporation and the severity of temperature during long summer season. The constantly rising temperaturefor over last forty years coupled with variations in rainfall pattern often results into uneven surface wateravailability throughout cropping seasons. Further, extraordinary rise in temperature in mountainous regionof Pakistan, causes extra melting of glaciers along with uneven annual precipitation which frequentlyresults into flash floods with millions of people dislocated and loss of billions of worth in food, standingcrops and infrastructure. Pakistan’s population is increasing with over two percent growth rate; therefore,the chief staple foods like wheat, rice, maize, sugarcane, and vegetables have become out of reach of poorpeople and have severe contingent social and economic implications in terms of further enhancing thevulnerability of poor marginalized segments of society.

To ensure energy security, the first to know what is energy, and second, what are the factors of non-security, means that the challenge of energy security. Finally, puts forward some policy or in the case of a reasonable method to solve it according to these problems. At present, energy security is facing two challenges of structural crisis and crisis management system. Concretely, main problems in that security are analyzed, which are considered to affect China and mostly embody in such four big areas as the great pressure in energy supply, the scarcity of relative energy resources, foreign oil dependence is too large, crisis management systems of energy security, the shortage of green energy. Furthermore the counter measures concerned are proposed, including saving energy and increasing the energy utilization rate, to establish strategic energy reserves, strengthening environmental protection and adjusting the primary energy structure. China's rapid economic growth lead to sharp increase in oil imports. Due to China relies on a single chokepoint, the Malacca Strait, which has caused a high degree of concern about the safety of its energy. Nearly three-quarters of its oil imports flowing through the Strait. In view of its strategic importance to China and China’s little sway on the waterway, this view is mainly focused on China’s energy demand and supply in two aspects of concern. The paper analysis of whether the current energy structure is appropriate and sustainable. Because the energy security is facing China's energy is more and more dependent on imported fuel and the need to convert energy to meet the demand of modern society and the rapid growth of the requirements of the economic challenges. Concludes that the China's new policy should focus on energy efficiency, energy saving, renewable energy and turned to the main energy source of natural gas.

Cities are considered to be a major cause of climate change, as a result of city functions, which require energy and emit large quantities of Greenhouse Gases (GHGs). Therefore, cities are being targeted globally as key areas for climate change mitigation. In order to mitigate the impacts of climate change, it is important for policy makers to be able to understand the implications of possible future policy decisions and development plans on emissions. One possible way of developing forecasts is through emissions scenarios, which allow for the development of a series of forecasts based on changes in the drivers of emissions. The city of Durban is a developing city, which aims to promote economic development; however, this development would increase the demand for energy and therefore impact on the GHG emissions in the city. The aim of this study is to develop a number of GHG emissions scenarios that illustrate the implications of various development paths for the city. The methodology applied involved first identifying the gaps in existing GHG inventories for Durban and the data required to close these gaps. The data was input into the Long-range Energy Alternatives Planning (LEAP) tool, which is a physical accounting and simulation tool that allows for the creation of scenarios. Five scenarios were created to illustrate different ways in which the city might develop which are the Growth without Constraints (GWC) Scenario, the Business as Usual (BAU) Scenario, the Natural Transition City, the Slow Go City and the Low Carbon City. Lastly, a sixth scenario, the Required by Science (RBS), was not modelled but created to illustrate what would be required if Durban followed the Intergovernmental Panel on Climate Change (IPCC) stabilisation guideline of a reduction of 60% - 80% of 1990 levels by 2100. Thereafter the IPCC scenarios were downscaled from a national level to a local level using a linear downscaling methodology, in order to illustrate the implications of global development paths on the city. The different development paths had a range of impacts on emissions. Rapid economic growth, with no climate change mitigation in the GWC Scenario, results in a 6.3 times increase in emissions from the base year to 2050. If the city continues with its current policies and strategies as in the BAU Scenario, emissions will increase 3.5 times from the base year. If there is a transition to a post-industrial society, with no climate change mitigation, emissions will increase 3 fold from 2005 to 2050. The National Transition Scenario illustrated that if Durban moves towards a service sector economy, which are predominantly low carbon sector, with no climate change mitigation, emissions will still increase 3.15 times the 2005 levels. If the city is slow to respond to climate change as in the Slow Go City, emissions will increase 2.5 times from the base year. A shift in the structure of the economy and an increase in the use of renewable energy and energy efficiency (i.e. a Low Carbon City) results in reduction in emissions of 1% from 2005. These were compared to the IPCC downscaled scenarios, which followed a similar pattern. The scenarios are comparable to developing city scenarios, but illustrate that the city is lagging behind developed cities. In order to make an impact in the reduction of emissions, it is essential for the city to target the commercial and industrial sector, which is the sector that emits the highest GHG emissions. However all these scenarios are still insufficient for achieving the RBS emissions target of a 60-80% reduction from 1990 levels. Achieving this reduction would require more than a 50% improvement in energy efficiency, structural change in the economy to low energy intensive sectors and a 20% contribution of renewable energy to total energy supply. / Thesis (M.Sc.)-University of KwaZulu-Natal, Westville, 2010.

This thesis considers economic factors for reducing greenhouse gas emissions from utility-scale electricity generation in California. The statewide Emission Performance Standard and Renewables Portfolio Standard have led to the announced and projected retirement of many coal power facilities serving California electricity load. This reality requires new baseload power sources to meet growing energy demands over the next several decades. The economic and environmental feasibilities of competitive baseload generation technologies are assessed to determine suitable replacements for decommissioning coal power plants. Geothermal is identified as the optimal replacement due to its economic baseload functionality, low greenhouse gas emissions, small environmental impact, and resource abundance in many regions of California. Developing geothermal capacity from the Salton Sea could provide southern California with a reliable energy source for decades while simultaneously reducing adverse environmental impacts and greenhouse gas emissions from electricity generation in California.

The current capabilities of SASKTRAN – a radiative transfer model at the University of Saskatchewan in Saskatoon, Canada – are to accurately model the scattering of solar radiation within the earth’s atmosphere for the ultraviolet-visible (UV-Vis) and near infra-red (NIR) regions of the electromagnetic spectrum. However, the current model does not account for the radiation emitted by the ground and atmosphere, approximated by the blackbody spectrum. In the UV-Vis, this contribution is unimportant, but when transitioning to wavelengths longer than 2.5 μm, the solar spectrum decreases in intensity while radiation of terrestrial and atmospheric origin increases along the blackbody curve. At wavelengths longer than 5 μm in the far infra-red (FIR), the blackbody radiation is the dominant source in the atmosphere. A modification to the source code of SASKTRAN was made in order to include the additional effect of this “thermal” radiation – with the help of the spectral line database HITRAN – while still maintaining scattering capabilities of solar radiation. This would make SASKTRAN one of the first radiative transfer models with the ability to model radiation in the difficult region between 3 and 5 μm – the mid infra-red (MIR) region – where the solar and thermal radiation sources are equally diminished and are the same order of magnitude. An introduction is given to atmospheric physics with a focus on the science of infra-red active molecules like H2O, CO2, CH4, N2O, O3, and CO – the so-called “greenhouse gases” – and the measurement techniques used to determine their atmospheric distribution. A theoretical basis is then provided for general radiative transfer, and the physics of molecular absorption and emission is examined in detail. A summary of the implementation of thermal radiation within the SASKTRAN framework is given, followed by verification studies where the model’s radiative transfer calculations in the infra-red are compared against measurements, including those made by the ground-based instrument E-AERI, the space-borne instruments IASI and GOSAT, and against model results from the LBLRTM, another well-verified radiative transfer model.

The amount of greenhouse gases (GHG) emitted due to waste management in the cities of developing countries is predicted to rise considerably in the near future; however, these countries have a series of problems in accounting and reporting these gases. This study investigated GHG emissions from the municipal waste sector in South Africa. In particular, the eThekwini Municipality is researched in detail and current emissions as well as further projections have been calculated. This research has to be placed in the wider context where developing countries (including South Africa) do not have binding emission reduction targets, but many of them publish different greenhouse gas emissions data which have been accounted and reported in different ways. Results from the first stages of this research showed that for South Africa, inventories at national and municipal level are the most important tools in the process of accounting and reporting greenhouse gases from waste. However, discrepancies in the methodology used are a concern. This is a challenging issue for developing countries, especially African ones, since higher accuracy methods are more data intensive. Therefore, the development of local emission factors for the different waste management processes is important as it encourages a common, unified approach. In the accounting of GHG from waste at municipal level, emission factors, based on a life cycle approach, are used with increased frequency. However, these factors have been calculated for many developed countries of the Northern Hemisphere and are generally lacking for developing countries. The second part of this research showed how such factors have been developed for waste processes used in this country. For the collection and transport of municipal waste in South Africa, the average diesel consumption is around 5 dm3 (litres) per tonne of wet waste and the associated GHG emissions are about 15 kg CO2 equivalents (CO2 e). Depending on the type of landfill, the GHG emissions from the landfilling of waste have been calculated to range from -145 to 1 016 kg CO2 e per tonne of wet waste, when taking into account carbon storage, and from 441 to 2 532 kg CO2 e per tonne of wet waste, when carbon storage is left out. The highest emission factor per unit of wet waste is for landfill sites without landfill gas collection and these are the dominant waste disposal facilities in South Africa. The emission factors developed for the different recyclables in the country showed savings varying from -290 kg CO2 e (glass) to – 19 111 kg CO2 e (metals - Al) per tonne of recyclable. They also illustrated that there is variability, with energy intensive materials like metals having higher GHG savings in South Africa as compared to other countries. This study also showed that composting of garden waste is a net GHG emitter, releasing 172 and 186 kg CO2 e per tonne of wet garden waste for aerated dome composting and turned windrow composting, respectively. By using the emission factors developed, the GHG emissions from municipal waste in the eThekwini Municipality were calculated and showed that for the year 2012 net savings of -161 780 tonnes CO2 e were achieved. This is mainly due to the landfill gas to electricity clean development mechanism (CDM) projects and due to recycling in the municipality. In the absence of landfill gas (LFG) collection and utilisation systems, which is typical for the majority of South African landfills, important GHG emission from the anaerobic degradation of waste are recorded. In the near future (year 2014) the closure of one of the three local landfill sites and the re-directioning of the majority of waste to another landfill sites which does not have LFG collection and utilisation, will cause an increase of GHG emissions to 294 670 tonnes CO2 e. An increase in recycling and the introduction of anaerobic digestion and composting has the potential to reduce these emissions as shown for the year 2020. However, only the introduction of a LFG to electricity system will result in the highest possible overall GHG savings from waste management in the municipality. In the absence of the Clean Development Mechanism and the associated financial arrangements, these systems have to be financed locally and might present a financial challenge to the municipality. Therefore, the second intervention which will make a difference by lowering GHG emissions from waste management would be to increase recycling in general and in particular the recycling of paper and metals. Since there is no direct competition for carbon, in addition to recycling, anaerobic digestion can be introduced and this combination will achieve increased savings in the future. If anaerobic digestion is not possible, composting in addition to recycling will also lead to savings, albeit not as high as with anaerobic digestion. The results presented in this study show that life cycle based GHG emission factors for waste and their use can support a unified approach to accounting of GHG and better decision-making for municipalities in the local context. They can give valuable input for the planning and development of future waste management strategies and they can help optimise current municipal solid waste management. / Ph.D. University of KwaZulu-Natal, Durban 2013.

Thesis (M. Env. St.)--University of Adelaide, Mawson Graduate Centre for Environmental Studies, 1993. / Includes bibliographical references (leaves 142-161).

Thesis (doctoral)--Universiteit Utrecht, 2008. / Includes bibliographical references (p. 127-140).