Thesis (Ph.D.)--The Pardee RAND Graduate School, 2008. / Includes bibliographical references.

Thesis (Ph.D.)-- University of Wisconsin--Madison, 2008. / Includes bibliographical references (p. 138-144).

Thesis (M. S.)--Mechanical Engineering, Georgia Institute of Technology, 2010. / Committee Co-Chair: Haynes, Comas; Committee Co-Chair: Wepfer, William; Committee Member: Jeter, Sheldon. Part of the SMARTech Electronic Thesis and Dissertation Collection.

Pavements are one of the most important components of modern civil infrastructure systems. Being constantly exposed to weather conditions, pavements may be subject to heating and cooling cycles, which vary as a function of the location and are proven to reduce the lifespan and reliability of our transport infrastructure. The most extreme effects of weather are generally seen in the form of overheating of the paving materials or freezing of the pavement surface. In this Thesis, natural convection of air is considered as a means to harvest heat from pavements during hot periods and to provide heat to them when the weather is cold. In the research presented, a buoyancy-driven air flow is allowed through metal pipes installed under an asphalt wearing course. The analysis of the phenomena at work is performed from an experimental, computational, and theoretical point of view. The main contribution to research provided by this Thesis it that the experiments performed show that a convection-powered air flow can be effectively used for the reduction or increase of pavement temperatures up to about �5°C. Moreover, the effects of variations in the design of energy harvesting pavements are quantified and discussed, proving that the installation of all pipes in a single row under the wearing course of a pavement is the overall best solution for the implementation of this technology. Finally, CFD simulations suggest that the air pores that are naturally present in asphalt mixtures are not suitable to allow the air flow required for convection-powered energy harvesting, due to both fluid-dynamic and practical reasons.

This research investigates the potential for employing solar energy as a sustainable power generation source in the Kingdom of Saudi Arabia (KSA). The work maps the availability of solar energy throughout the country, and investigates the feasibility of implementing the technology at two case study locations. These are the existing power generation grid sites of Wadi Aldawasir (located 20° 23′ 22.00″ N 45° 12′ 32.00″ E), and Shuaibah (located 20° 37′ 22.84″ N 39° 33′ 44.02″ E). The first case study site, Wadi Aldawasir, covers an area of 48,900 m2, where parabolic trough solar thermal technology is proposed for power generation. The second case study site, Shuaibah power plant is one of the largest desalination and fossil fuel plants in the world with a 1,030,000 m3/ day capacity. Both case studies were assessed in terms of site specifications with selection based on Direct Normal Irradiation (DNI). A feasibility study examining Concentrated Solar Power (CSP) potential was conducted for both locations, with analysis of weather data, particularly monthly and annual, global horizontal and beam normal irradiation data. From these data, a reasonable estimate of CSP potential, and viability of the technology was determined. Simulation was then performed using Solar Advisor Model (SAM) and Renewable Energy Technology Screen (RETScreen) software, taking into account the location weather data, (DNI, dry-bulb and dew-point temperatures, relative humidity, barometric pressure, and wind speed), technical specification, (solar field, Solar Multiple (SM) Solar collector Assemblies (SCAs), power cycle and thermal storage) and economic parameters (energy unit cost, maintenance, etc.). Simulation evaluated annual energy performance (solar radiation resource of the solar field, electrical energy delivered by solar thermal plant, system losses, required solar field area), levelised cost of unit of power generated, CO2 emissions savings, and other financial feasibility indicators. The work shows that the energy yield of the new solar power plants using proposed CSP technology in both case studies is feasible.

All across the world, attention is turning to renewable energies to serve at least as a partial substitute to fossil fuels in the global energy mix, braking the latter’s depletion and providing a greener solution for a more sustainable future. However, the intermittent nature of most renewable energy sources, wind and solar in particular, raises major concerns over the integration of these technologies, on a large scale, to grid systems. This thesis focuses on large-scale renewable energy storage systems, primarily compressed air energy storage (CAES) systems, which are particularly well suited for renewable energy applications. CAES can play a major role in shaping the future of renewable energy systems for not only can it bring load levelling to the system, but it can also add substantial value by providing ancillary services to the grid. The main focus of this research is adiabatic CAES which endeavours to minimize the use of natural gas by using recuperators and thermal energy storage systems, where the heat from the air during the compression stages is absorbed by a heat transfer fluid, stored, and then supplied back during the expansion process. This project aimed to explore the potential of CAES systems as an energy storage technology for large-scale grid integrated renewable energy system. A computer model was developed to size the different components in the CAES system and also to predict the operational performance of the CAES system for different conditions using MATLAB programming. The thermal energy storage of an adiabatic CAES system was optimized using CFD analysis and experimental testing of the thermal energy storage system was carried out to validate the models. Also, an economic study was performed to assess the feasibility of the CAES system based on a case study of the Egyptian grid. The dynamic simulation of a novel configuration of an adiabatic CAES system showed that the system can achieve improved performance compared to existing CAES plants, while the economic study showed that CAES can improve the economics of a wind farm, at least by the standards of our chosen case study location.

Made available in DSpace on 2014-06-11T19:29:05Z (GMT). No. of bitstreams: 0 Previous issue date: 2011-02-17Bitstream added on 2014-06-13T20:18:51Z : No. of bitstreams: 1 ballottin_dpm_me_araiq.pdf: 2551243 bytes, checksum: 6bc5b0d91a3b15a3677e5d02307c45c8 (MD5) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / A alta demanda de energia no mundo atual, bem como o grande número de problemas ambientais existentes, resultam em uma crescente necessidade por novas fontes de energia, estimulando assim o interesse por fontes alternativas para os combustíveis de origem fóssil. Surge então o Biodiesel, combustível biodegradável derivado de fontes renováveis. No entanto, este biocombustível apresenta certos contaminantes que podem causar sérios danos ao motor e ao ambiente dependente de seus teores. Dentre estes, estão os acilgliceróis, remanescentes da matéria prima para a produção do biodiesel. Por exemplo, a alta concentração destes compostos aumenta a viscosidade do biocombustível, provocando depósitos nos cilindros e nas válvulas diminuindo assim a vida útil do motor. Assim, foi avaliado neste trabalho o comportamento voltamétrico do mono, di e trilinoleato de glicerina através da técnica de Redissolução Adsortiva com Voltametria AC. As curvas analíticas para o mono e trilinoleato de glicerina apresentaram linearidade de 4,0 x 10-8 a 1,6 x 10-6 mol L-1, com limites de detecção da ordem de 10-8 mol L-1. A curva analítica do dilinoleato de glicerina mostrou-se linear de 4,0 x 10-9 a 4,0 x 10-7 mol L-1, com limite de detecção da ordem de 10-9 mol L-1. Os limites de quantificação foram da ordem de 10-8 mol L-1 para o mono e o dilinoleato de glicerina e 10-7 mol L-1 para o trilinoleato de glicerina. Porém, estes não puderam ser determinados simultaneamente e, por isso, utilizou-se um método cromatográfico com detecção eletroquímica para a separação e posterior detecção destes compostos. Os acilgliceróis foram separados em coluna de fase reversa (C-18) operando em modo isocrático com fase móvel tampão fosfato pH 3,0/MeOH 60:40 (v/v) com adição de ácido ascórbico / Currently, the high energy demand in today's world, as well as the environmental problems result in an increased need for developing renewable energy sources, thereby stimulating interest in alternative sources to fossil fuels. Then, Biodiesel comes as a biodegradable fuel derived from renewable sources. However, this biofuel has certain contaminants that can cause serious damage to the engine and the environment if they are present in inadequate amounts. Among these contaminants are the glycerides, remnants of the raw material for biodiesel production. For example, the high concentration of these compounds increases the viscosity of the biofuel causing deposits in the cylinders and valves reducing the engine lifetime. Thus, it was evaluated in this study the voltammetric behavior of glyceryl mono, di and trilinoleate by Adsorptive Stripping technique with AC voltammetry. The analytical curves for mono and tri showed linearity from 4.0 x 10-8 to 1.6 x 10-6 mol L-1, with detection limits of about 10-8 mol L-1. The analytical curve of glyceryl dilinoleate was linear from 4.0 x 10-9 to 4.0 x 10-7 mol L-1, with a detection limit of about 10-9 mol L-1. The quantification limits were in the order of 10-8 mol L-1 for mono and dilinoleate and 10-7 mol L-1 for trilinoleate. However, these could not be determined simultaneously and therefore it was developed a chromatographic method with electrochemical detection for separation and detection of these compounds. The glycerides were separated on a reversed phase column (C-18) operating in isocratic mode with mobile phase pH 3.0 phosphate buffer / MeOH 60:40 (v/v) with addition of ascorbic acid

The economic and environmental benefits secured through the increased integration of photovoltaic (PV) technology into the built environment are undeniable and provide the principal motivation for this research. Present delays in the technology transfer of building integrated photovoltaics (BIPV) can be attributed to the following; material cost, performance guarantee, increased installation complexity and unfamiliar technology. It is well understood that the temperature of a PV material receiving solar irradiation, will increase with solar intensity, while reducing in electrical efficiency. It therefore makes economic sense to minimise the increase in PV material temperature and maximise electrical energy yield. Through the addition of a convecting fluid, flowing over the surface of heated PV material, heat transfer will be induced. With the added benefit of warm air capture from an integrated photovoltaic/thermal (PVT) collector, the economic benefits are increased. But, to ensure maximum utilisation of both thermal and electrical energy production, a significantly more complex control system has to be employed than that for a PV system on its own. Modelling the energy flows within a multifunctional PVT building facade presents a problem of considerable complexity. Previous work in this area has centred on performing finite element analysis of the system in order to find solutions to complex algorithms. It requires considerable computational power to perform these calculations and often the results produced are much more detailed than required. Within this thesis, a fully operational PVT facade model is presented, giving the potential for improved multifunctional facade design. This new model has been developed into a software program for use within the TRNSYS environment. By using the TRNSYS software, a detailed building model has been created and integrated with the new PVT facade model. Simulations were then undertaken to evaluate the energy transfers between internal and external environments and the electrical and thermal energy capturing capabilities of the facade. Simulated results have been evaluated against experimental data taken from a fully operational PVT facade. The results conclude that the presented model simulates the energy flows around, through and within the facade (radiative, conductive, convective and electrical) very well. Performance enhancing development work is due to take place on the operational facade analysed in this work, very soon. This new facade model will be used as a tool to evaluate the proposed changes to the building prior to this development work being undertaken.

Organic Rankine cycles (ORC) have unique properties that are well suited to power generation from low grade heat sources. It is envisaged that a domestic scale ORC Heat Engine can be developed that will be able to run off heat stored in a solar charged rock thermal battery. The use of a thermal battery as the heat source for the ORC system will provide the user with electricity during the day and for a number of hours into the night. The concept presented consists of four key components: rock thermal battery, 1 kW scroll expander, condenser and working fluid pump.

Economies aim to expand over time, which always implies the need for increased energy availability in support of this growth. Governments can use their procurement of energy generation to further enhance the benefit to their economies via certain policy tools. One such tool is Local Content Requirements (LCR) where procurement of a good dictates that a certain value has to be sourced locally. The argument for this tool is that spend is localised and manufacturing, as well as job creation, can be stimulated due to industry establishing in the host economy. However, this practice is distortionary in effect and it does not create a fair playing field for global trade. Furthermore, if the local content definition is weak, or open to manipulation, the goals of such a policy may not be achieved at all. This study looked into the local content requirements of South Africa’s Renewable Energy Independent Power Producer Procurement Programme (REIPPPP) and measured the impact of this policy on the renewable energy sector in general. It was found that, in order to implement a policy such as local content, the host economy had to have certain pre-existing conditions in order to avoid any negative welfare effects. Due to SA not holding all supportive pre-conditions for supporting local content policy, the impact and effect of LCRs has not been optimal and it has not been found to be a sustainable mechanism to continue using into the future indefinitely. The pricing of renewable energy was also found to be higher due to local content and such pricing is passed on to the energy consumer. Therefore, the net welfare impact created for South Africa is diminished in exchange for the creation of jobs and manufacturing, but due to the unsustainability and potential manipulation of the system the country is not maximising the welfare potential from the REIPPPP as it should. It was found that SA renewable energy resources do exist and the logistics infrastructure is strong, providing good potential for investment into renewable energy projects. The demand created by the REIPPPP provided a good market, but there was uncertainty in the long term planning and stability. So, from a market perspective this could be further enhanced. Government had created a sufficient platform for investment, but areas of development such as clusters, R&D and skills training would create a better support environment for LCR policy and strict monitoring of this would also be required to prevent any manipulation. The use of LCRs increases project costs and risk, which is passed onto the energy consumers, but this could be reduced if local goods were more readily available at the right price and at the right quality and quantity. Focus on clusters would once again assist in this regard as independent power producers (IPPs) and engineering procurement and construction (EPC) entities would be able to source components and goods locally in a more cost-effective manner. As the LCRs currently stand in the REIPPPP, it would seem that South Africa is making renewable energy more expensive and although it is argued that this is done for the benefit of creating a new industry and jobs, these are not sustainable and so the current LCR policy will only create short term benefits.