Dissertations / Theses on the topic 'Renewable energy sources – Risk assessment'

The growth of the industry and population of South Africa urges to seek new sources of electric power, hence the need to look at alternative power sources. Power output from some renewable energy sources is highly volatile. For instance power output from wind turbines or photovoltaic solar panels fluctuates between zero and the maximum rated power out. To optimize the overall power output a model was designed to determine the best trade-off between production from two or more renewable energy sources putting emphasis on wind and solar. Different measures of risk, such as coefficient of variation (CV) and value at risk (VAR), were used to determine the best hybrid renewable energy system (HRES) configuration. Depending on the investors’ expected returns (demand) and risk averseness, they will be able to use the model to choose the best configuration that suites their needs. In general it was found that investing in a diversified HRES is better than investing in individual power sources.

Les entreprises du secteur de l’énergie sont confrontées à la nécessité de transformer leur modèle économique pour intégrer les préoccupations écologiques et assurer une transition énergétique (TE). Selon la littérature sur les transitions, la prise en compte des risques de ce processus nécessite des approches novatrices orientées vers le long terme, ainsi qu'une conception adaptative des politiques. Dans ce cadre, l'approche de l'écosystème d’affaire joue un rôle important dans la découverte de nouvelles solutions liées à la TE. L'objectif principal de cette thèse est d'examiner l’apport de l'application de l'approche de l'écosystème dans la réduction des risques sous-jacents de ce processus. Par le biais d'entretiens approfondis et une revue de littérature exhaustive, d'un engagement étendu des parties prenantes et d'une interrogation sur les caractéristiques des acteurs de l'énergie dans une série de contextes, le potentiel du rôle de l'écosystème émergent des énergies renouvelables (EEnR) dans la réduction des risques de la TE est étudié. La recherche menée donne un aperçu de la nature holistique de la relation entre les acteurs de l'énergie et explore les obstacles communs rencontrés tels que l'acceptabilité sociale, les risques du marché et la gestion des parties prenantes. Les résultats suggèrent que les entreprises sont conscientes du potentiel d'un EEnR émergent. De nombreuses caractéristiques de ce EEnR ont été trouvées dans les stratégies de partenariat actuelles des acteurs interrogés. Plus largement, une cartographie de cet écosystème émergent a été présentée
Energy companies are faced with the need to transform their business model to integrate environmental concerns and ensure an energy transition. According to the transitions literature, addressing the risks of this process requires innovative, long-term oriented approaches, as well as thoughtful and adaptive policy design. In this framework, the business ecosystem approach plays an important role in the discovery of new solutions during the energy transition. The main objective of this thesis is to examine the contribution of applying the ecosystem approach in reducing the underlying risks of this process. Through exhaustive in-depth interviews and literature reviews, extensive stakeholder engagement, and interrogation of the characteristics of energy actors in a range of contexts, the potential for the role of the emerging renewable energy ecosystem in reducing the risks of the energy transition is explored. The research conducted provides insight into the holistic nature of the relationship between energy actors and explores common barriers encountered such as social acceptability, market risks and stakeholder management. The results suggest that companies are aware of the potential of an emerging renewable energy ecosystem and that most companies view the ecosystem approach positively. Many characteristics of this potential ecosystem, which is in its nascent stage, were found in the current partnership strategies of the interviewed stakeholders. More broadly, a mapping of the emerging renewable energy ecosystem was presented

Thesis (PhD (School of Public Leadership))--University of Stellenbosch, 2012.
Please download the required VENSIM software from: http://www.vensim.com/freedownload.html
ENGLISH ABSTRACT: Technology assessment has changed in nature over the last four decades. It changed from an analytical tool for technology evaluation, which depends heavily on quantitative and qualitative modelling methodologies, into a strategic planning tool for policy-making concerning acceptable new technologies, which depends on participative policy problem analysis. The goal of technology assessment today is to generate policy options for solutions of organisational and societal problems, which at the operational level, utilise new technologies that are publicly acceptable; that is, viable policy options. Energy technology assessment for sustainability is inherently a complex and dynamic process that requires a holistic and transdisciplinary approach. In the South Africa context, specifically, there is no formal and coherent approach to energy technology assessment from a sustainability perspective. Without a formal comprehensive or well integrated technology assessment approach to evaluate the sustainability of any technology, the policy-makers, technology designers, and decision-makers are faced with difficulty in terms of making reasoned decisions about the appropriate technology options. This study developed a framework that incorporates a technology assessment approach, namely, system dynamics, within the broader scope of technology development for sustainability. The framework, termed the Systems Approach to Technology Sustainability Assessment (SATSA), integrates three key elements: technology development, sustainable development, and a dynamic systems approach. The study then provides a guiding process of applying the framework to energy technology assessment theory and practice within the context of sustainable development. Biodiesel, a cleaner burning replacement fuel, argued to potentially contribute to sustainable development, is used for the demonstration. Biodiesel development entails complex interactions of actors such as the technology developers, government at different levels, communities, as well as the natural environment. Different actions or responses in the greater system might hinder or undermine the positive effects of such a development. Based on the SATSA framework, a Bioenergy Technology Sustainability Assessment (BIOTSA) model was developed. The BIOTSA model was used to test the outcomes of a proposed biodiesel production development in the Eastern Cape Province of South Africa on selected sustainability indicators. In addition, some policy scenarios were tested to compare how they assist in improving the selected indicators. The BIOTSA model results are useful in comparing dynamic consequences resulting from a proposed biodiesel production development and the respective policies and decisions that may arise from such a development. The testing and validation of the BIOTSA model was carried out based on structural validity, behavioural validity, and expert opinion. Potential policy scenario outcomes and their implication, on the selected sustainability indicators, were also tested. The opinions of the selected stakeholders indicated that the BIOTSA model was useful in providing an understanding of the potential impacts of the biodiesel development on selected sustainability indicators in the Eastern Cape Province. Thus, the SATSA framework can be applied for assessing sustainability of other renewable energy technologies. In addition, system dynamics provide a useful and a feasible dynamic systems approach for energy technology sustainability assessment. Finally, the model building process and transdisciplinary nature of this study enabled the identification of the potential problems that could arise during the biodiesel production development. In addition, gaps in data and knowledge were identified and the recommendation for future work in this field is highlighted. Nevertheless, the findings of the BIOTSA model could inform policy- and decision-making in biodiesel production development in South Africa. The development of similar models for other renewable energy development efforts is thus recommended. The current efforts to facilitate the large-scale roll out of concentrated solar thermal technologies in Southern Africa, for example, would require the development of a Solar Thermal Technology Sustainability Assessment (SOTTSA) model.
AFRIKAANSE OPSOMMING: Die aard van tegnologie assessering het in die afgelope vier dekades verander. Dit het verander ten opsigte van ’n analitiese hulpmiddel vir tegnologie evaluering, wat hoofsaaklik staatmaak op kwalitatiewe en kwantitatiewe modelleringsmetodiek, na ’n strategiese beplanningshulpmiddel vir beleidvorming met betrekking tot nuwe aanvaarbare tegnologieë, wat afhanklik is van ’n deelnemende beleidsprobleem analise. Vandag se doel vir tegnologie assessering is om beleidsopsies vir oplossings van organisatoriese en sosiale probleme te genereer, wat op operasionele vlak gebruik maak van nuwe tegnologieë wat deur die publiek aanvaar is; met ander woorde, lewensvatbare beleidsopsies. Energie tegnologie assessering vir volhoubaarheid is sonder twyfel ’n komplekse en dinamiese proses wat ’n holistiese en transdisiplinêre benadering benodig. In die Suid- Afrikaanse konteks is daar geen formele en samehangende benadering tot tegnologie assessering vanaf ’n volhoubaarheidsperspektief nie. Beleidsmakers, tegnologie ontwerpers en besluitnemers mag sukkel om beredenerende besluite te neem oor die toepaslike tegnologie opsies sonder ’n formele omvattende of goed geïntegreerde tegnologie assesseringsbenadering om die volhoubaarheid van enige tegnologie te evalueer. Hierdie studie het ’n raamwerk ontwerp wat die tegnologie assesseringsbenadering inkorporeer binne die breë bestek van tegnologiese ontwikkeling vir volhoubaarheid naamlik, stelsel dinamika. Die raamwerk, genoem die Sisteem Benadering tot Tegnologie Volhoubaarheidsassessering (SBTVA) integreer drie sleutelelemente: tegnologiese ontwikkeling, volhoubaarheidsontwikkeling, en ʼn dinamiese stelsels benadering. Verder verskaf die studie ’n leidende proses te opsigte van die toepassing van die raamwerk tot energie tegnologie assesseringsteorie en praktyk binne die konteks van volhoubaarheidsontwikkeling. Biodiesel word gebruik vir die demonstrasie omdat dit gereken word as ’n skoner plaasvervanger vir brandstof en daar aangevoer word dat dit ’n potensiële bydraer tot volhoubaarheidsontwikkeling is. Die ontwikkeling van biodiesel behels komplekse interaksie tussen verskeie akteurs soos tegnologiese ontwikkelaars, die regering op verskillende vlakke, gemeenskappe asook die natuurlike omgewing. Verskeie aksies of reaksies in die groter sisteem mag dalk die positiewe effek van so ontwikkeling ondermyn of verhinder. ’n Biodiesel Tegnologiese Volhoubaarheidsassessering (BIOTVA) model is ontwerp gebaseer op die SBTVA raamwerk. Die BIOTVA model is gebruik om die uitkomste op geselekteerde volhoubaarheidsaanduiders van ’n voorgestelde biodiesel produksie ontwikkeling in die Oos- Kaap Provinsie van Suid-Afrika te toets. Buiten vir die voorafgaande is sekere beleidtoekomsblikke ook getoets om te vergelyk hoe hulle sal help om die geselekteerde aanwysers te verbeter. Die BIOTVA model resultate is behulpsaam in die vergelyking van dinamiese gevolge wat voortspruit uit die voorgestelde biodiesel produksie ontwikkeling asook die onderskeie beleide en besluite wat mag ontstaan van so ’n ontwikkeling. Die toetsing en bekragtiging van die BIOTVA model was uitgevoer gebaseer op strukturele geldigheid, gedragsgeldigheid, en kundige opinie. Potensiële beleidtoekomsblikke uitkomste en die nagevolge, ten opsigte van die geselekteerde volhoubaarheidsaanduiders, is ook getoets. Die opinies van die geselekteerde aandeelhouers het aangedui dat die BIOTVA model bruikbaar is om ’n beter begrip te verskaf ten opsigte van die potensiële impak wat die biodiesel ontwikkeling op geselekteerde volhoubaarheidsaanduiders in die Oos-Kaap Provinsie sal hê. As gevolg hiervan kan die SBTVA raamwerk toegepas word om die volhoubaarheid van ander herwinbare energie tegnologieë te assesseer. Buiten die voorafgaande kan stelsel dinamika ’n bruikbare en uitvoerbare dinamiese stelselbenadering vir energie tegnologie volhoubaarheidsassessering verskaf. Ten slotte, die model bouproses en transdisiplinêre aarde van die studie het gehelp om potensiële probleme wat kan voorkom tydens die biodiesel produksie ontwikkeling te identifiseer. Daarby is gapings in data en kennis ook geïdentifiseer en die aanbevelings vir verdere studie in die veld is uitgelig. Nieteenstaande kan die bevindings van die BIOTVA model beleidmakers en besluitnemers in die biodiesel produksie ontwikkeling van Suid- Afrika inlig. Die ontwikkeling van soortgelyke modelle vir ander herwinbare energie ontwikkelingspogings word aanbeveel. As voorbeeld sal die huidige pogings om die grootskaalse uitrol van gekonsentreerde son termiese tegnologieë in Suider-Afrika te fasiliteer die ontwikkeling van ’n Son Termiese Tegnologie Volhoubaarheidsassesering (SOTTVA) model benodig.

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.

The huge natural energy resources available in the world’s oceans are attracting increasing commercial and political interest. In order to evaluate the status and the degree of acceptability of future Ocean Energy (OE) schemes, it was considered important to develop an Integrated Assessment Methodology (IAM) for ascertaining the relative merits of the competing OE devices being proposed. Initial studies included the gathering of information on the present status of development of the ocean energy systems on wave, OTEC and tidal schemes with the challenges faced for their commercial application. In order to develop the IAM, studies were undertaken for the development and standardization of the assessment tools focussing on: • Life Cycle Assessment (LCA) on emission characteristics. • Energy Accounting (EA) studies. • Environmental Impact Assessment (EIA) over different environmental issues. • Resource captures aspects. • Defining economy evaluation indices. The IAM developed from such studies comprised of four interrelated well defined tasks and six assessment tools. The tasks included the identification of the modus operandi on data collection to be followed (from industry) for assessing respective OE devices, and also advancing relevant guidelines as to the safety standards to be followed, for their deployment at suitable sites. The IAM as developed and validated from case studies in ascertaining relative merits of competing OE devices included: suitable site selection aspects with scope for resource utilisation capability, safety factors for survivability, scope for addressing global warming & energy accounting, the environmental impact assessment both qualitatively and quantitatively on different environmental issues, and the economic benefits achievable. Some of the new ideas and concepts which were also discovered during the development of the IAM, and considered useful to both industry and researchers are given below: • Relative Product Cost (RPC) ratio concept- introduced in making an economic evaluation. This is considered helpful in sensitivity analysis and making design improvements (hybridising etc) for the cost reduction of OE devices. This index thus helps in making feasibility studies on R&D efforts, where the capital cost requirement data and life span of the device is not well defined in the primary stages of development. • Determination of the threshold limit value of the barrage constant - considered useful in determining the efficacy of the planning process. The concept ascertained the relative efficiency achieved for various barrage proposals globally. It could also be applied to suggest the revisions required for certain barrage proposals and also found useful in predicting the basin area of undefined barrage proposal for achieving economic viability. • Estimations made on the future possibility of revenue earnings from the by-products of various OTEC types, including the scope of chemical hubs from grazing type OTEC plants. • Determination of breakeven point- on cost versus life span of wave and OTEC devices studied, which is useful in designing optimum life of the concerned devices. The above stated multi-criterion assessment methodology, IAM, was extended leading to the development of a single criterion model for ascertaining sustainability percent achievable from an OE device and termed IAMs. The IAMs was developed identifying 7 Sustainability Development Indices (SDI) using some the tools of the IAM. A sustainability scale of 0-100 was also developed, attributing a Sustainability Development Load Score (SDLS) percentage distribution pattern over each SDIs, depending on their relative importance in achieving sustainability. The total sum of sustainability development (SD) gained from each SDI gave the IAMs (for the concerned device), indicating the total sustainable percentage achieved. The above IAMs developed, could be applied in ranking OE devices alongside the unsustainable coal power station. A mathematical model of estimating the IAMs was formulated, in order to ascertain the viability to the sustainable development of any energy device. The instruments of IAM and IAMs which have been developed would be helpful to the OE industry in ascertaining the degree of acceptability of their product. In addition it would also provide guidelines for their safe deployment by assessing the relative merits of competing devices. Furthermore, IAM and IAMs would be helpful to researchers undertaking feasibility studies on R&D efforts for material development research, ‘hybridization studies’ (as also new innovations), cost reduction, the performance improvement of respective devices, and any economic gains. With future advancements in OE systems and the availability of field data from large scale commercial applications, the specific values/data of the IAM & IAMs may be refined, but the logic of the models developed in this research would remain the same.

The modern day power grid is a highly complex system; as such, maintaining stable operations of the grid relies on many factors. Additionally, the increased usage of renewable energy sources significantly complicates matters. Attempts to assess the current stability of the grid make use of several key parameters, however obtaining these parameters to make an assessment has its own challenges. Due to the limited number of measurements and the unavailability of information, it is often difficult to accurately know the current value of these parameters needed for stability assessment. This work attempts to estimate three of these parameters: the Inertia, Topology, and Voltage Phasors. Without these parameters, it is no longer possible to determine the current stability of the grid. Through the use of machine learning, empirical studies, and mathematical optimization it is possible to estimate these three parameters when previously this was not the case. These three methodologies perform estimations through measurement-based approaches. This allows for the obtaining of these parameters without required system knowledge, while improving results when systems information is known.
Ph. D.

Current hydro-turbines aim to capture the immense energy available in tidal movements, however commonly applied technologies rely on principles more applicable in hydroelectric dams. Tidal stream currents, such as in Coastal Georgia, are not strong enough to make such turbines both efficient and economically viable. This research proposes a novel low-energy vortex shedding vertical axis turbine (VOSTURB) to combat the inefficiencies and challenges of hydro-turbines in low velocity free tidal streams. Some of the energy in tidal streams is extracted naturally from vortex shedding; as water streams past a bluff body, such as pier, low pressure vortices form alternatively on each side, inducing a rhythm of pressure differentials on the bluff body and anything in its wake. VOSTURB aims to capture this energy of the vortices by installing a hydrofoil subsequent to the bluff body. This foil, free to oscillate, translates the vortex energy into oscillatory motion, which can be converted into a form of potential energy. The presented research will act as a 'proof of concept.' It aims to assess such foil motion, or the ability of VOSTURB to capture vortex energy, and begin to assess the amount of tidal energy that can be theoretically harnessed. In this study a small scale model of VOSTURB, a cylindrical bluff body with a hammer shaped hydrofoil, was tested in a hydraulic flume for various mean flow speeds. Tangential accelerations of the foil's center of gravity were obtained through the use of an accelerometer. The acceleration data was analyzed utilizing Fourier analysis to determine the fundamental frequency of the wing oscillations. The available power to be harnessed from the oscillatory motion was then estimated utilizing this fundamental frequency. Ultimately it was found that the frequency of the VOSTURB foil oscillations corresponded highly with the theoretical frequency of vortex shedding for all moderate to high flow speeds. Low speeds were found to produce inconsistent and intermittent small oscillations. This signifies at moderate to high flow speeds, VOSTURB was able to transform some vortical energy into kinetic. The maximum average power obtained 8.4 mW corresponded to the highest flow velocity 0.27 m/s. Scaled to Rose Dhu prototype conditions this represented 50 W at a flow velocity of 0.95m/s, the maximum available at Rose Dhu. Although it was ascertained that VOSTURB could consistently capture some of the vortical energy; the percentage of which could not be calculated with certainty. Thus, the average kinetic power assessments of the foil were compared to the available power of the mean flow for each flow speed calculated by two methods: (1) over the foil's swept area; (2) the area of fluid displaced by the bluff body immediately in front of the foil. The maximum efficiency of the foil, found for the fastest flow speed was at 18% and 45% respectively. It was found that both average foil power, available flow power, and efficiency all decreased with a decrease in flow velocity. This study can serve as only a preliminary study for the effectiveness of VOSTURB as a hydro-turbine for tidal power. In the experiments, the foil was allowed to oscillate freely with little resistance. Future testing of VOSTURB needs to observe whether the vortex energy can overcome the resistive torque introduced by a generator to induce oscillatory motion as well as further optimize the foil design. While the testing in this project assesses the kinetic energy or power of the vortex shedding, this future testing will provide insight into the actual work that can actually be converted into potential energy or power. Complementing this research, both a Harmonic Analysis of Least Squares (HAMELS) and a Complex Empirical Orthogonal Function (CEOF) Analysis was conducted on available surface height and current velocity data separately from an available Regional Ocean Modeling System (ROMS) model of Coastal Georgia. Such analysis were conducted to observe spatial and temporal tidal patterns advantageous to a possible prototype installation of a tidal turbine such as VOSTURB. The more conventional HAMELS analysis, which isolates components of a signal with a certain frequency, identified temporal and spatial patterns attributed to tidal constituents. CEOF analysis, where major patterns of variance are identified not according to prescribed frequencies, was employed to identify any patterns possible not attributed to the tidal constituents. This study was also in part to observe whether the CEOF analysis could identify any patterns of tidal propagation that could not be resolved by the HAMELS analysis. The CEOF and HAMELS analysis of the surface height output produced very similar results: major modes of surface height variation due to the diurnal and semidiurnal tidal constituents propagating up the estuary. The CEOF results did not produce any additional information that could not be found through the HAMELS analysis of the constituents and presented such results in an arguably more convoluted manner. In addition, the surface height analysis provided no direct insight into areas more advantageous to tidal power. The CEOF analysis of the vector current velocity data however did provide some insight. The CEOF of the current data was able to isolate patterns of variance corresponding to the tidal constituents. However, the CEOF was also able to identify local 'hotspots' of high current magnitudes not resolved by HAMELS. These local areas of high current magnitudes, most likely due to changes in hydrodynamic conditions such as channel constrictions, are advantageous for tidal power applications. These general areas could serve as a starting point for the location selection process for a possible prototype installation of VOSTURB if the area was refined more. Ultimately for a prototype installation of VOSTURB, further experimentation and analysis is required for both the turbine design and placement, such as a power conversion methodology for the turbine and a more spatially resolute set of data to perform a CEOF analysis on. With these tasks completed, the prototype installation will be part of a larger effort between the Georgia Institute of Technology and the Girl Scouts of America to create completely sustainable "Eco-Village" on Rose Dhu Island, GA. With an extensive community outreach planned to educate the public, Rose Dhu, along with championing hydrokinetic energy, will serve as a paradigm for sustainable design and energy.

Diploma thesis deals with analysis of internal microclima of the building , evaluation of its thermal and technical properties and it also deals with its energy comsumption. With using simuation programm, there was designed solutions which will lead not only to lowering of energy consumption but also to improvemnt of komfort for students and tachers.

The increasing demand for energy and the increased depletion rate of nonrenewable energy resources call for research on renewable alternatives. Mapping the availability of these resources is an important step for development of energy conversion projects. For this purpose, the wave power potential along the Atlantic coast of the southeastern USA, and the tidal stream power along the coast of Georgia are investigated in this study. Wave power potential is studied in an area bounded by latitudes 27 N and 38 N and longitudes 82 W and 72 W (i.e. North Carolina, South Carolina, Georgia, and northern Florida). The available data from National Data Buoy Center wave stations in the given area are examined. Power calculated from hourly significant wave heights and average wave periods is compared to power calculated using spectral wave energy density. The mean power within 50 km of the shore is determined to be low, whereas higher power is available further offshore beyond the 3500 m contour line. The tidal stream power potential along the coast of the state of Georgia is evaluated based on the NOAA tidal predictions for maximum tidal currents and three dimensional numerical modeling of the currents with Regional Ocean Modeling System (ROMS). The modeling results are validated against the available measurements. This region has low to moderate average tidal currents along most of the coast, but with the possibility of very strong local currents within its complex network of tidal rivers and inlets between barrier islands. Tidal stream power extraction is simulated with a momentum sink in the numerical models at the estuary scale to investigate effect of power extraction on the estuarine hydrodynamics. It is found that different power extraction schemes might have counterintuitive effects on the estuarial hydrodynamics and the extraction efficiency. A multi-criteria method that accounts for the physical, environmental and socioeconomic constraints for tidal power conversion schemes is proposed to select favorable locations and to rank them according to their suitability. For this purpose, the model results are incorporated into a Geographical Information System (GIS) database together with other geospatial datasets relevant to the site selection methodology. The methodology is applied to the Georgia coast and the candidate areas with potential are marked.

Thesis (Ph.D)--Architecture, Georgia Institute of Technology, 2010.
Committee Chair: Godfried Augenbroe; Committee Member: Ellis Johnson; Committee Member: Pieter De Wilde; Committee Member: Ruchi Choudhary; Committee Member: Russell Gentry. Part of the SMARTech Electronic Thesis and Dissertation Collection.

The demand for energy is increasing worldwide. All applications contributed to increase the demand of all energy industry, and therefore the effect on the environment and the rise in pollution increased significantly. This is considered a large problem, and researchers focused their research on renewable energy for reducing the cost of energy in the future. Geothermal energy has significant impact as a source of electricity generation since it will not harm the environment. There are more than twenty countries that benefit from geothermal plants, which generate more than 6000 megawatts .Three alternatives of geothermal energy technology (GHP, Direct use of Geothermal Heat, and Geothermal Electricity) can be used for supporting electrical systems in Oregon. At the same time, the success of using the geothermal energy alternatives in Oregon relies on different goals for achieving the best geothermal development. Oregon has been ranked third in the potential use of geothermal energy after Nevada and California. The objective from the research study was to develop an assessment model framework that can be used for supporting cost effective renewable energy in Oregon by the development of geothermal energy sources. This research of study was done by using the Hierarchical Decision Model (HDM) and consisted of four levels: Mission, objectives, goals, and alternative. Criteria used in this research study are based on five objectives to know what are the most important factors in the decision-making process. These objectives are: social, environmental, economical, technical, and political. The decision model connected objectives, goals, and alternative for obtaining the accurate decision. HDM used for this purpose to analyze the result of data collected from experts. Seven experts who had experience in the geothermal field participated in this research study, and they gave their judgment in the questionnaire survey link by using pair-wise comparison method. The outcome analysis of the results showed that in terms of objectives that Minimizing Environmental Impact was rated at the highest value at 0.26 with respect to the mission. Within the category of Minimizing Environmental Impact, Seismic Activity and GHG Emissions had higher values. The results show that "Geothermal Electricity," with a rating of 43%, was ranked as the most important alternative with respect to mission, objectives, and goals. "Direct Use of Geothermal Heat" was ranked as the second most important alternative with 31%. The results of this research study were discussed with the experts to get their feedback, and learn from them what requirements are necessary for improvement in the geotechnical energy sector for future research. The experts agreed that this methodology is a good approach to help reach the right decision since this methodology (HDM) divides the problem into small sets, which will make the decision process easier.

Ocean currents are an attractive source of clean energy due to their inherent reliability, persistence and sustainability. The Gulf Stream system is of particular interest as a potential energy resource to the United States with significant currents and proximity to the large population on the U.S. east coast. To assess the energy potential from ocean currents for the United States, the characterization of ocean currents along the U.S. coastline is performed in this dissertation. A GIS database that maps the ocean current energy resource distribution for the entire U.S. coastline and also provides joint velocity magnitude and direction probability histograms is developed. Having a geographical constraint by Florida and the Bahamas, the Florida Current has the largest ocean current resource which is fairly stable with prevalent seasonal variability in the upper layer of the water column (~200m). The core of the Florida Current features higher stability than the edges as a result of the meandering and seasonal broadening of the current flow. The variability of the Gulf Stream significantly increases as it flows past the Cape Hatteras. The theoretical energy balance in the Gulf Stream system is examined using the two-dimensional ocean circulation equations based on the assumptions of the Stommel model for quasi-geostrophic subtropical gyres. Additional turbine drag is formulated and incorporated in the model to represent power extraction by turbines. Parameters in the model are calibrated against ocean observational data such that the model can reproduce the volume and kinetic energy fluxes in the Gulf Stream. The results show that considering extraction over a region comprised of the entire Florida Current portion of the Gulf Stream system, the theoretical upper bound of averaged power dissipation is around 5.1 GW, or 45 TWh/yr. If the extraction area comprises the entire portion of the Gulf Stream within 200 miles of the U.S. coastline, the theoretical upper bound of averaged power dissipation becomes approximately 18.6 GW or 163 TWh/yr. The impact of the power extraction is primarily constrained in the vicinity of the turbine region, and includes a significant reduction of flow strength and water level drop in the power extraction site. The turbines also significantly reduce residual energy fluxes in the flow, and cause redirection of the Gulf Stream. A full numerical simulation of the ocean circulation in the Atlantic Ocean is performed using Hybrid Coordinate Ocean Model (HYCOM) and power extraction from the Florida Current is modeled as additional momentum sink. Effects of power extraction are shown to include flow rerouting from the Florida Strait channel to the east side of the Bahamas. Flow redirection is stronger during peak summer flow resulting in less seasonal variability in both power extraction and residual fluxes in the Florida Current. A significant water level drop is shown at the power extraction site, and so is a slight water level rise along the coasts of Florida and the Gulf. The sum of extracted power and the residual energy flux in the Florida Current is lower than the original energy flux in the baseline case, indicating a net loss of energy reserve in the Florida Current channel due to flow redirection. The impact from power extraction on the mean flow field is concentrated in the near field of the power extraction site, while shifts in the far flow field in time and space have little impact on the overall flow statistics.

Thesis (Ph. D.)--University of Oregon, 2004.
Typescript. Includes vita and abstract. Includes bibliographical references (leaves 93-96). Also available for download via the World Wide Web; free to University of Oregon users.

With the increased penetration of intermittent renewable energy sources (RESs) in future grids (FGs), balancing between supply and demand will become more dependent on demand response (DR) and energy storage. So far, FG feasibility studies, especially those claiming a long-term view, typically do not model the electrical network and/or the effect of DR. Thus, in this thesis, we first present a simulation platform for performance and stability assessment of FG scenarios. The platform considers market simulation, load flow calculation and stability assessment together. Using the platform, we illustrate how displacing conventional generators with RESs, especially inverter-based and intermittent RESs, could have significant impacts on performance and stability of FGs, confirming the importance of stability assessment for FG feasibility studies. Second, to carry out accurate stability analysis of FG scenarios, we need a representation of the aggregate demand including the effect of emerging demand-side technologies (distributed generation (DG), DR and storage). In this research, we propose generic demand models including the aggregated impact of price-responsive users equipped with emerging demand-side technologies (prosumers). The proposed models capture essential behaviour of the prosumers without giving lots of detail which is costly in repeated use for applications such as scenario comparisons. So, such models demand some simplifications, just as conventional generic load modelling did. The proposed frameworks are based on the unit commitment (UC) problem aiming to minimise the system cost. The conventional demand model in the associated optimisation formulations are augmented by including the aggregated influences of prosumers equipped with rooftop photovoltaics (PV)-battery systems. It is noted that as the frameworks are generic, they are capable of easy integration of other demand-side technologies as well. The developed frameworks are intended specifically for modelling net demand by including the impact of prosumers in FG scenario studies. Nevertheless, they do not assume any particular market structure. As such, they are not suitable for modelling of existing electricity markets, but rather their aim are to capture the behaviour of future electricity markets provided a suitable market structure is adopted. Finally, the impact of prosumers on performance and voltage stability of the Australian National Electricity Market (NEM) is studied with the increased penetration of RESs in the grid. We have considered different penetrations of RESs, and assessed the influence of different penetrations of prosumers on the balancing, loadability and voltage stability of the NEM.

Today, a majority of the world’s energy need is supplied through sources that are finite and, at the current usage rates, will be consumed shortly. The high energy demand and pollution problems caused by the widespread use of fossil fuels make it increasingly necessary to develop renewable energy sources of limitless duration with smaller environmental impact than the traditional energy sources.

Three fuels – rapeseed methyl ester (RME), Fischer-Tropsch (FT) diesel and FT jet fuel – derived from biomass, coal or gas were evaluated in this project. The fuel properties evaluated are in most cases listed in standards, often with recommendations, developed for biodiesel, petroleum diesel and jet fuel.

Biodiesel is monoalkyl esters, e.g. RME, produced by transesterification of triglycerides in vegetable oil and an alcohol to esters and glycerin. This produce a fuel that is suitable as a direct substitution for petroleum diesel. Biodiesel may be used in pure form or in a blend with petrodiesel. Oxidative degradation and weak low temperature performance of biodiesel are properties of concern when substituting petrodiesel with biodiesel, as was shown in this project. The experiments show that oxidative stability can be improved with a synthetic antioxidant, e.g. butylated hydroxytoluene (BHT).

The FT process converts syngas (a mixture of hydrogen and carbon monoxide) to a range of hydrocarbons. Syngas can be generated from a variety of carbon sources, e.g. coal, natural gas and biomass. The high-temperature (300-350 °C) FT process with iron-based catalysts is used for the production of gasoline and linear low molecular mass olefins (alkenes). The lowtemperature (200-240 °C) FT process with either iron or cobalt catalysts is used for the production of high molecular mass linear waxes. By applying various downstream processes, fuels suitable for substitution of petrodiesel and conventional jet fuel can be obtained. The FT fuels have lower densities than the conventional fuels. However, conclusions from this project are that most of the properties of FT fuels are better, or equal, than conventional petroleum fuels.

Interferences to supply chains, regardless of whether they are regular, unplanned or intentional, are progressively distorting supply chain execution. Given that such disruptions are probably not going to diminish, for the time being, supply chain risk mitigating solutions will assume an undeniably critical part of the management of supply chains. This research acknowledges the existence of an extensive variety of approaches to mitigate risks across supply chains, yet argues that most methodologies may not be reasonable if the culture of an organisation does not support them. Supply Chain Risk Management (SCRM) has rapidly become of significance to the world economy. Though the supply of electrical energy in Southern Africa affects the economies of nations around the globe, it has received too little consideration from the literary community. The focus of this thesis is to expand the field of SCRM by analysing how different risk assessment and management concepts and practices are comprehended, construed and employed through the region. The majority of developed supply chain management and risk management models are currently entrenched in the US and Europe. Consequently, this research is of high significance since its essential aim was to investigate these concepts and models, in particular, one focused on Africa. This approach enabled the thesis to examine and test components related to SCRM, such as risk categories, risk assessment and risk strategies, in the electrical energy sector in South Africa. The study in this manner offers knowledge that was not otherwise accessible in earlier research. In pursuit of meeting the requirements of the research questions, the supply chain department in the electrical energy supplier was researched. This study adopted the non-probability sampling approach utilising the purposive sampling technique to choose the sampling components from the target population. Data was collected by way of conducting semi-structured interviews and researcher observation, as well as additional documentation in various forms was collected. Interviews were transcribed and evaluated in conjunction with additional data collected during meetings and triangulated using researcher observation. Data interpretation and codification thereof was done using ATLAS.ti 8 by which, twenty-five themes emerged from this study. Supply chain risks comprise value streams; information and affiliations; supply chain activities; and external situations. Among these, information and relationships risks were found to produce selfupgrading risk loops, thereby generating consequent risk impacts after disturbances. To mitigate these risks, the case firm must engage in local and international supply chain implemented strategies, such as building a stable supply chain network, leveraging supply chain information, leveraging outsourcing contracts and developing supply-chain risk collaboration partnerships, although the level of implementation depends on the business context. Among the ten identified themes, building a stable supply chain and developing supply chain collaboration strategies can be useful in strengthening both robustness and resilience in supply chain risk management. Customer orientation had positive impacts on all themes, but disruption orientation and quality orientation influenced only certain types of strategies. The study makes ten recommendations, which can be implemented by the case firm; the results of the interviews are evidence that all the tools are available. The thesis concludes with a summary of overall findings and areas for further research are also highlighted.

Les objectifs récents en ce qui concerne la durabilité des systèmes électriques et l'atténuation des menaces liées au changement climatique modifient la portée des exigences de planification de ces systèmes. D'une part, les systèmes durables d'énergie à faible émission de carbone qui comportent une part élevée de sources d'énergie renouvelables intermittentes(IRES) se caractérisent par une forte augmentation de la variabilité intertemporelle et nécessitent des systèmes flexibles capables d'assurer la sécurité de l'approvisionnement électrique. D'autre part, la fréquence et la gravité accrues des phénomènes climatiques extrêmes menacent la fiabilité du fonctionnement des réseaux électriques et exigent des systèmes résilients capables de résister à ces impacts potentiels. Tout en s'assurant que les incertitudes inhérentes au système sont bien prises en compte directement au moment de la prise des décisions de planification à long terme. Dans ce contexte, la présente thèse vise à développer une modélisation technicoéconomique et un cadre d'optimisation robuste pour la planification des systèmes électriques multi-périodes en considérant une part élevée d'IRES et la résilience aux phénomènes climatiques extrêmes. Le problème spécifique de planification considéré est celui du choix de la technologie, de la taille et du programme de mise en service des unités de production conventionnelles et renouvelables sous des contraintes techniques, économiques,environnementales et opérationnelles. Dans le cadre de ce problème, les principales questions de recherche à aborder sont : (i) l'intégration et l'évaluation appropriées des besoins de flexibilité opérationnelle en raison de la variabilité accrue des parts élevées de la production d'IRES, (ii) la modélisation et l'intégration appropriées des exigences de résilience contre les phénomènes climatiques extrêmes dans la planification du système électrique et (iii) le traitement des incertitudes inhérentes de l'offre et la demande dans ce cadre de planification. En résumé, les contributions originales de cette thèse sont :- Proposer un modèle de planification du système électrique intégré multi période avec des contraintes dynamiques et en considérant un pourcentage élevé de pénétration des énergies renouvelables.- Introduire la mesure du déficit de flexibilité prévu pour l'évaluation de la flexibilité opérationnelle.- Proposer un ensemble de modèles linéaires pour quantifier l'impact des vagues de chaleur extrêmes et de la disponibilité de l'eau sur le déclassement des unités de production d'énergie thermique et nucléaire, la production d'énergie renouvelable et la consommation électrique du système.- Présenter une méthode permettant d'intégrer explicitement l'impact des phénomènes climatiques extrêmes dans le modèle de planification du système électrique.- Traiter les incertitudes inhérentes aux paramètres de planification du système électrique par la mise en oeuvre d'un nouveau modèle d'optimisation adaptatif robuste à plusieurs phases.- Proposer une nouvelle méthode de solution basée sur l'approximation des règles de décision linéaires du modèle de planification robuste.- Appliquer le cadre proposé à des études de cas de taille pratique basées sur des projections climatiques réalistes et selon plusieurs scénarios de niveaux de pénétration des énergies renouvelables et de limites de carbone pour valider la pertinence de la modélisation globale pour des applications réelles
Recent objectives for power systems sustainability and mitigation of climate change threats are modifying the breadth of power systems planning requirements. On one hand, sustainable low carbon power systems which have a high share of intermittent renewable energy sources (IRES) are characterized by a sharp increase in inter-temporal variability and require flexible systems able to cope and ensure the security of electricity supply. On the other hand, the increased frequency and severity of extreme weather events threatens the reliability of power systems operation and require resilient systems able to withstand those potential impacts. All of which while ensuring that the inherent system uncertainties are adequately accounted for directly at the issuance of the long-term planning decisions. In this context, the present thesis aims at developing a techno-economic modeling and robust optimization framework for multi-period power systems planning considering a high share of IRES and resilience against extreme weather events. The specific planning problem considered is that of selecting the technology choice, size and commissioning schedule of conventional and renewable generation units under technical, economic, environmental and operational constraints. Within this problem, key research questions to be addressed are: (i) the proper integration and assessment of the operational flexibility needs due to the increased variability of the high shares of IRES production, (ii) the appropriate modeling and incorporation of the resilience requirements against extreme weather events within the power system planning problem and (iii) the representation and treatment of the inherent uncertainties in the system supply and demand within this planning context. In summary, the original contributions of this thesis are: - Proposing a computationally efficient multiperiod integrated generation expansion planning and unit commitment model that accounts for key short-term constraints and chronological system representation to derive the planning decisions under a high share of renewable energy penetration. - Introducing the expected flexibility shortfall metric for operational flexibility assessment. - Proposing a set of piece-wise linear models to quantify the impact of extreme heat waves and water availability on the derating of thermal and nuclear power generation units, renewable generation production and system load. - Presenting a method for explicitly incorporating the impact of the extreme weather events in a modified power system planning model. - Treating the inherent uncertainties in the electric power system planning parameters via a novel implementation of a multi-stage adaptive robust optimization model. - Proposing a novel solution method based on ``information basis'' approximation for the linear decision rules of the affinely adjustable robust planning model. - Applying the framework proposed to a practical size case studies based on realistic climate projections and under several scenarios of renewable penetration levels and carbon limits to validate the relevance of the overall modeling for real applications

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Dissertação (Mestrado)
IPEN/D
Instituto de Pesquisas Energeticas e Nucleares - IPEN/CNEN-SP

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Dissertação (Mestrado)
IPEN/D
Instituto de Pesquisas Energeticas e Nucleares - IPEN-CNEN/SP

У дисертації вдосконалені наукові засади оцінювання еколого-економічної ефективності впровадження ВДЕ, що враховують екологічні та економічні наслідки їх використання. Це дозволило визначити оптимальну структуру забезпечення електричною енергією національної економіки. Виявлені причинно-наслідкові зв’язки між екодеструктивним впливом на навколишнє середовище та енергетичною, екологічною і економічною безпекою країни. Розвинуто науково-методичний підхід до формування організаційно-економічного механізму впровадження економічно доцільних та екологічно безпечних ВДЕ. Запропоновано методичний підхід до науково-обгрунтовано розподіл фінансових ресурсів на впровадження окремих видів ВДЕ. Застосування методики оцінювання еколого-економічної ефективності дозволяє приймати економічно обгрунтовані й екологічно виважені управлінські рішення щодо енергозабезпечення національної економіки з урахуванням інтересів майбутніх поколінь.
В диссертации усовершенствованы научные основы оценки эколого-экономической эффективности внедрения ВИЭ, учитывающие экологические и экономические последствия их использования. Это позволило определить оптимальную структуру обеспечения электрической энергией национальной экономики. Обнаружены причинно-следственные связи между экодеструктивным воздействием на окружающую среду и энергетической, экологической и экономической безопасности страны. Развит научно-методический подход к формированию организационно-экономического механизма внедрения экономически целесообразных и экологически безопасных ВИЭ. Предложен методический подход к научному обоснованию распределение финансовых ресурсов на внедрение отдельных видов ВИЭ. Применение методики оценки эколого-экономической эффективности позволяет принимать экономически обоснованные и экологически взвешенные управленческие решения по энергообеспечению национальной экономики с учетом интересов будущих поколений.
The dissertation is devoted to development of a theoretical basis for, scientific and methodological approaches to ecological and economic assessment of efficiency of renewable energy use. According to official statistics, 49 % of the world’s greenhouse gas emissions come from the energy sector. Ukrainian energy sector produces 50 % of all greenhouse gas emissions within the country, which makes environmental deprivation one of the most important and urgent issues to be addressed. Casual Loop Diagram (CLD) analysis was used to find a relationship between renewable energy use and environmental, economic, and energy security of a country, in particular during the life cycle of renewable energy sources (RES). The findings of the analysis showed that use of RES reduces consumption of exhaustible energy sources at the stage of their exploitation and increases diversification of energy sources. An increase of energy production from RES in its turn leads to an increase in price of an energy product. Analysis of previous studies has shown that an increase of energy production from RES leads to a reduction in greenhouse gas emissions per unit of GDP. However, the use of RES itself causes environmental destruction, which is usually omitted, but can be identified through analysis of the life cycle of RES. The author proposed a method of ecological and economical assessment of efficiency of renewable energy use, which takes into account positive as well as negative effects of the use of different types of RES during all stages of their life cycle. Proposed methodology suggests calculating environmental damage from the use of RES as the sum of costs of damages at every stage of the life cycle of an energy product – development, exploitation and utilization. This method allows making informed management decisions for the development and use of RES. The next step of this research was to develop a methodological approach to the scientific justification of the optimal structure of energy production based on the combination of conventional and renewable energy sources. The aim of the calculations was to build an optimal model for an energy sector development of a country, based on economic and environmental indicators. The results of applying the optimal model can be used for strategic planning at country level, in particular in managerial decision-making and law making. Development of RES requires considerable financial resources, which are always limited. Therefore, the question of the efficient allocation of available financial resources arises and needs to be addressed. To solve this problem, the author proposes an approach to the formation of organizational and economic mechanism of implementation of economically viable and environmentally safe RES. This approach includes a system of solidarity between stakeholders, interested in a transparent energy market; a management system of RES performance; indicators of an ecological and economic loss from electricity generation processes; financial support for the development of RES at every stage of the life cycle of an energy product. The author provides scientific justification for financial resources allocation, which is based on the Bellman's principles of recurrence, technical and technological forecast for RES. Bellman's recurrence principal allowed to find the optimal allocation of state funds for the transition to RES under conservative and revolutionary scenarios. This approach can be implemented on the basis of cross-sectoral interrelations within energy production system, which implies well-coordinated interaction of authorities, energy companies, and local communities, as well as providing of state incentives for RES implementation. Practical recommendations and methodological justification for ecological and economic assessment of renewable energy use, offered in the dissertation, allow to determine the priority goals for energy sector development at national and industrial levels, as well as to implement programs of environmental protection.

Les systèmes photovoltaïques organiques sont des technologies émergentes présentant de forts potentiels d’économie de ressources et de réduction des impacts sur l'environnement et la santé humaine par rapport aux dispositifs photovoltaïques conventionnels. La méthode de l’analyse du cycle de vie est appliquée afin d'évaluer la façon dont les différents procédés de fabrication, les caractéristiques des dispositifs, la phase d’utilisation et les scénarios de fin de vie des cellules photovoltaïques organiques influent sur ces avantages potentiels. Les impacts de cette technologie émergente sont comparés aux technologies conventionnelles à base de silicium pour établir un référentiel de performance des technologies photovoltaïques.En outre, les effets potentiels sur la santé humaine de l'utilisation de nanomatériaux dans les cellules photovoltaïques organiques ont été spécifiquement étudiés ; et la pertinence de l’analyse du cycle de vie pour évaluer cette catégorie d’impact a été examinée. Ainsi, un nouveau modèle d'évaluation de l'impact sur le cycle de vie est présenté afin de quantifier les dangers potentiels posés par les nanomatériaux. Enfin,ces impacts potentiels sont comparés aux avantages des cellules photovoltaïques organiques sur les cellules à base de silicium
Organic photovoltaics present an emerging technology with significant potential for increasing the resource efficiencies and reducing the environmental and human health hazards of photovoltaic devices. The discipline of life-cycle assessment is applied to assess how various prospective manufacturing routes, device characteristics, uses and disposal options of organic photovoltaics influences these potential advantages. The results of this assessment are further compared to silicon based photovoltaics as a benchmark for performance. A deeper look is given to the potential human health impacts of the use of engineered nanomaterials in organic photovoltaics and the appropriateness of life-cycle assessment to evaluate this impact criteria. A newly developed life-cycle impact assessment model is presented to demonstrate whether the use of and potential hazards posed by engineered nanomaterials outweighs any of the resource efficiencies and advantages organic photovoltaics possess over silicon photovoltaics

Indiana University-Purdue University Indianapolis (IUPUI)
Due to the drastic increase in the cost of fossil fuels and other environmental issues, the demand for energy and its storage has risen globally. Rather than being dependent on intermittent energy sources like wind and solar energy, focus has been on alternative energy sources. To eliminate the need for fossil fuels, advances are being made to provide energy for hybrid electric vehicles (HEV), plug-in hybrid vehicles (PHEV) and pure electric vehicles (EV) thus providing scope for much greener environment. Hence, focus has been on development in lithium ion batteries to provide with materials that have high energy density and voltage. Ortho olivine lithium transitional metals are known to be abundant and inexpensive; these compounds are less noxious than other cathode materials. Advancement in research is being done in finding iron and manganese compounds as cathode materials for advanced technologies. However, Lithium manganese phosphates are known to suffer with poor electrochemical performances due the manganese dissolution in the organic liquid electrolyte due to Jahn-Teller Lattice distortion. This problem was tried to endorse in this thesis. In the second chapter by synthesizing nano sized cathode particles with good electronic conductivity, good performance was achieved. In the third chapter additive olivine cathode was synthesized my modified sol gel process. A wt. % of TMSP was added as an additive in the organic liquid electrolyte. By comparing the properties between the two kinds of electrolytes it was observed that by the addition of the additive in the organic electrolyte good electrochemical properties could be achieved hindering the Mn dissolution in the electrolyte. In the final chapter, a composite solid electrolyte was fabricated by using NASICON-type glass ceramic of Lithium aluminum titanium phosphate (LATP) with organic binder of Polyethylene oxide. The flexible solid electrolyte exhibited good ionic conductivity. An all solid state cell was fabricated using the composite solid electrolyte using LiMn2O4 as the symmetric electrodes. At different pressures, the performance of the solid state cell was studied.

M.Sc. (Geography)
Over the last three years, a number of environmental impact assessment reports (EIARs) pertaining to renewable energy (RE) projects have been submitted for environmental authorisation in South Africa. However, the quality of EIARs have been criticised internationally as well as in South Africa. Poor quality EIARs has the potential to negatively impact environmental decision-making processes and therefore it is vital to provide baseline data regarding the appraisal of such EIARs in South Africa. The present study has evaluated the quality of basic assessment reports (BARs) dealing with RE projects in South Africa. This is crucial in providing key insights to environmental management practice, especially if we are to determine whether or not RE projects have the potential to achieve sustainable development goals linked to clean development mechanisms (CDMs). Apart from assessing quality aspects, the goal of the study was also to analyse the strengths and weaknesses inherent in the EIARs involved. To address the research problem adequately, the Lee-Colley Review Package was utilised with minor adaptations where feasible. Based on the analyses derived from the review package selected, the overall quality of EIARs was found to be 70% satisfactory whilst 80% of the overall scores were borderline quality grades. The review areas pertaining to the description of the development and environment, together with the identification and evaluation of impacts, were better performed than the review areas concerning alternatives, mitigation measures and communication aspects of the EIARs. The strengths of the EIA processes related to the description of the project (purpose, objectives and nature) and site descriptions. Weaknesses of EIARs pertaining to RE projects were identified as insufficient non-technical summaries and poor summaries of the main issues. The review categories pertaining to waste management, mitigation measures and emphasis were not graded as weaknesses of the EIARs. Nevertheless, low numbers of satisfactory quality scores were documented for these review categories, which are particularly concerning. The fairly marginal quality of EIARs pertaining to RE projects may be attributed to lack of sufficient (human resources) capacity and transparency throughout the EIA process in South Africa. These aspects became evident through vague descriptions of impact prediction methods, insufficient elucidation of mitigation measures, a high degree of subjectivity and generally poor communication of EIA results to stakeholders involved. Apart from these findings, the study also made some recommendations for further studies such as the need to examine the following EIA aspects, namely, (1) the characterisation and reduction of elements of subjectivity within existing reports, (2) an assessment of the effectiveness of screening processes in South Africa and (3) the identification of obstacles and barriers hindering effective communication in the presentation of EIA results.

This thesis focuses on the design and characterization of more efficient components for Dye-Sensitized Solar Cells (DSSCs), an example of innovative latest generation photovoltaic systems. DSSCs are considered as a promising alternative to silicon solar cells due to their low cost, flexibility, and facile fabrication. However, a low photo-electric conversion efficiency and stability of these cells are the main obstacles for their large-scale commercial applications. An emerging challenge is to find an optimum set of materials to improve the performance of DSSCs. One of the key components to optimize is the light absorbing dye (also referred as sensitizer) that is employed to enhance light harvesting of TiO2 nanoparticles. Indeed, sensitizers are responsible for DSSCs photovoltaic performances, transparency and color. Another scope of this thesis is the assessment of the environmental performances connected with the fabrication of DSSCs components, namely the sensitizer, through the application of the Life Cycle Assessment (LCA) methodology. Indeed, to evaluate the sustainability of photovoltaic devices, the investigation of the environmental impacts generated during their fabrication is essential in order to improve and optimize the energy and resource efficiency of manufacturing processes and, ultimately, the environmental footprint of the device.

Indiana University-Purdue University Indianapolis (IUPUI)
Lithium-ion batteries are widely used for portable electronics due to high energy density, mature processing technology and reduced cost. However, their applications are somewhat limited by safety concerns. The lithium-ion battery users will take risks in burn or explosion which results from some internal components failure. So, a practical method is required urgently to find out the failures in early time. In this thesis, a new method based on temperature difference between internal point and surface (TDIS) of the battery is developed to detect the thermal failure especially the thermal runaway in early time. A lumped simple thermal model of a lithium-ion battery is developed based on TDIS. Heat transfer coefficients and heat capacity are determined from simultaneous measurements of the surface temperature and the internal temperature in cyclic constant current charging/discharging test. A look-up table of heating power in lithium ion battery is developed based on the lumped model and cyclic charging/discharging experimental results in normal operating condition. A failure detector is also built based on TDIS and reference heating power curve from the look-up table to detect aberrant heating power and bad parameters in transfer function of the lumped model. The TDIS method and TDIS detector is validated to be effective in thermal runaway detection in a thermal runway experiment. In the validation of thermal runway test, the system can find the abnormal heat generation before thermal runaway happens by detecting both abnormal heating power generation and parameter change in transfer function of thermal model of lithium ion batteries. The result of validation is compatible with the expectation of detector design. A simple and applicable detector is developed for lithium ion battery catastrophic failure detection.

This thesis tries to assess the Indonesia fiscal risk because of government guarantees for renewable energy development, particularly the development of geothermal power plants. These plants in Indonesia can be developed either by the PLN (a state-owned enterprise) or by private investors. When the plants are developed by private investors, they have to sell the electricity to PLN as it is the only electricity retailer in Indonesia. If PLN build power plants, it needs loans from financial institutions, but due to its financial condition, those financial institutions need government guarantees which ensure PLN’s ability to service the debts. Meanwhile, when the power plants are developed by private investors, the investors need to be guaranteed that PLN will be able to pay for the purchased power. These guarantees might create a fiscal risk for the government. The government has been stating fiscal risks in its national budget, but it only focuses on the risk exposures without estimating their probabilities. Therefore, this study tries to complete the current budget statement which provides both exposures and probabilities of fiscal risks from government guarantees for renewable energy projects. Furthermore, the government has been applying a simulation model to assess the fiscal risks but it is in a definite number which does not incorporate uncertainties. Whereas uncertainties can alter the government policy. Moreover, the government model to assess fiscal risk on the power sector incorporates general power plants which may not suitable for the renewable energy power, particularly geothermal power. It is then forecasted that it is likely there will be no government guarantee for geothermal projects for 2018 and 2019. However, with less than 10% probabilities of an exposure of up to IDR 18.8 trillion and IDR 25.2 trillion for 2018 and 2019 respectively. Under 90% certainty, the maximum guarantee exposure will be up to IDR 1.9 trillion and IDR 4.1 trillion. As results, these exposures are categorised as low risk because they are below the threshold value of 0.5% of GDP but the government will have a sufficient cash to pay the maximum possible guarantee amounts. These forecasted figured are based on a Monte Carlo simulation model, a stochastic simulation model, for renewable energy power plants. In practical, this model can act as a tool for analysing guarantee proposals, to estimate fiscal risk and economic impacts of the guarantees, to design fiscal risk control policies. Therefore, this study can be applied for decision making regarding government guarantee in Indonesia. In academic point of view, this study explains the transmission of fiscal risk from government guarantees on geothermal projects in Indonesia to the fiscal risk. It also enrich academic perspective on fiscal risk management which is differ from other literatures as it explains fiscal risk from the Indonesian government guarantees, adds knowledge on the relationship between government expenditure, government guarantees on renewable energy development and fiscal sustainability in Indonesia, and provides knowledge through a practical and applicable fiscal risk assessment approach on government guarantees. It is concluded that there will be no government guarantee exposure for geothermal projects in 2018 and 2019, so the government need not to allocate the guarantee expenditures in the national budget for the years.

In the recent years, governments have encouraged the utilization of renewable energy by providing incentives to investors, and enhancing traditional practices in the sector. For example, in Ontario, Canada, local distribution companies can now legally own and operate up to 10 MW generating plant per location as long as it is from a renewable source. Although this trend results in some operational benefits for the host networks, it also creates specific technical challenges and economic problems. New modeling approaches are needed to account for the main features of power produced by these facilities, namely, the uncertainty and uncontrollability. The uncertainty of power produced by weather-based generating facilities affects the decisions of different activities related to the operation of distribution systems. Examples of these tasks include power procurement decisions, the assessment of voltage magnitude variation, and reactive power management. If not properly included, uncertainty could result in non optimal outcome of operational activities of a distribution system operator. Based on different optimization techniques, the thesis introduces several models that capture the uncertain behavior of renewable resources. Two operational tasks were selected for application using the enhanced models: economical operation of distribution system and impact assessment on voltage magnitude. The power procurement problem is an operational challenge to acquire the correct economic mix of power purchases to supply the demand of a local distribution company. Three models have been presented to formulate the power procurement problem with a consideration of the stochastic nature of renewable generation. These models select the optimal quantities of bilateral contracts under uncertain renewable generation and give the option to decision makers to recalculate the powers from other sources. In one of these proposed models, the mean-variance theory is utilized to evaluate the risk associated with the variation of renewable power output on the financial efficiency of a local distribution company. Unlike previous studies, in which renewable power production is identified as a decision variable, in this work the generation from these units is represented as a parameter to model their feature of uncontrollability. Comparison of results obtained from using the proposed models showed that the degree of uncertainty plays an important role in selecting the proper mix. In general, stochastic based algorithms are superior to deterministic approaches when increasing contributions from renewable resources are considered. A major technical problem that may be caused by the uncertain generation of renewable units is the increase of voltage variation. The second part of the thesis introduces a methodology based on a Monte-Carlo technique to assess new installation depending on its impact on the quality of supply voltage. Two different standard measures for supply voltage quality are applied in this approach to provide the decision maker a tool that can be used to authorize new connections of renewable generation. The consistency of results obtained by the two indices applied in the proposed methodology encourages adopting the proposed approach for evaluating the impact of new connections of renewable resources. The models proposed in the thesis contribute to promote safer integration of renewable resources in distribution systems by modeling two main features: uncertainty and non-controllability.

abstract: Electric power system security assessment is one of the most important requirements for operational and resource planning of the bulk power system ensuring safe operation of the power system for all credible contingencies. This deterministic approach usually provides a conservative criterion and can result in expensive bulk system expansion plans or conservative operating limits. Furthermore, with increased penetration of converter-based renewable generation in the electric grid, the dynamics of the grid are changing. In addition, the variability and intermittency associated with the renewable energy sources introduce uncertainty in the electricity grid. Since security margins have direct economic impact on the utilities; more clarity is required regarding the basis on which security decisions are made. The main objective of this work is to provide an approach for risk-based security assessment (RBSA) to define dynamic reliability standards in future electricity grids. RBSA provides a measure of the security of the power system that combines both the likelihood and the consequence of an event. A novel approach to estimate the impact of transient stability is presented by modeling several important protection systems within the transient stability analysis. A robust operational metric to quantify the impact of transient instability event is proposed that incorporates the effort required to stabilize any transiently unstable event. The effect of converter-interfaced renewable energy injection on system reliability is investigated us-ing RBSA. A robust RBSA diagnostics tool is developed which provides an interactive user interface where the RBSA results and contingency ranking reports can be explored and compared based on specific user inputs without executing time domain simulations or risk calculations, hence providing a fast and robust approach for handling large time domain simulation and risk assessment data. The results show that RBSA can be used effectively in system planning to select security limits. Comparison of RBSA with deterministic methods show that RBSA not only provides less conservative results, it also illustrates the bases on which such security decisions are made. RBSA helps in identifying critical aspects of system reliability that is not possible using the deterministic reliability techniques.
Dissertation/Thesis
Doctoral Dissertation Electrical Engineering 2017

In recent years, the unbundling of the electricity market together with the profound “energy landscape” transformation have made the transmission network development planning a very complex multi-objective problem. The climate and energy objectives defined at the European level aim for a deepening integration of the European power markets and the electricity sector is recognized as one of the main contributors to the energy transition from a thermal-based power system to a renewable-based one. In the deregulated framework, network planners have to satisfy multiple different objectives, including: facilitating competition between market participants, providing non-discriminatory access to all generation resources for all customers, including green resources, mitigating transmission congestions, efficiently allocating the network development actions, minimizing risks associated with investments, enhancing power system security and reliability and minimizing the transmission infrastructure environmental impact. Further complexities are related to the significant uncertainty about future energy scenarios and policy rules. In particular, the increasing distributed renewable energy source integration dictated by the European energy targets, raises several issues in terms of future power flow patterns, power system flexibility and inertia requirements, and cost-effective development strategies identification. The thesis aims to investigate various aspects concerning the transmission network planning, with particular reference to the Italian power system and the experience gained working in the “Grid Planning and Interconnections Department” of Terna, the Italian Transmission System Operator. One of the main topics of this work is the use of the series compensation to exploit operating limits of underused portions of the HV – EHV transmission network in parallel to critically loaded ones, in order to control and provide alternative paths for power flows. The purpose is to extend the allowable transmission capacity across internal market sections. To this aim, a specific application of series compensation (together with reconductoring) to exploit the transfer capacity of a 250 km long, 230 kV-50 Hz transmission backbone spanning the critical section Centre South – Centre North is illustrated. The results are validated by means of static assessment and similar applications could be hypothesized for grid portions in the South of Italy where the primary network is mainly unloaded whereas the sub-transmission network reaches high levels of loading because of the huge renewable generation capacity situated there. A further characteristic of modern power systems is the need to integrate high levels of renewable energies while fulfilling reliability and security requirements. The offshore wind farms perspectives in the Italian transmission system are evaluated, considering policies, environmental and technical aspects. Furthermore, the adoption of the HVDC technology in parallel to the AC traditional system topic is addressed: planning static and dynamic studies involving a real HVDC Italian project are proposed. In particular, the impact of the planned HVDC link on the loadability and the dynamic performance of the system is investigated in medium and in long-term future planning scenarios. The evaluation of the thermal performance of a specific grid portion in the South of Italy affected by significant increase of power generation by variable energy sources is proposed both in the current situation and in the future scenarios in order to highlight the benefits related to the presence of the planned network reinforcements. Finally, some issues of the prospective reduced inertia systems are illustrated and a possible methodology to evaluate the economic impact of inertia constraints in long-term market studies is proposed. In the light of the emerging concept of power system flexibility, traditional planning evolved to assess the ability of the system to employ its resources when dealing with the changes in load demand and variable generation. Flexibility analyses of the Italian power system, carried out in terms of some market studies-based metrics and grid infrastructure-based indexes, are provided. The flexibility requirements assessment in planning scenarios are of interest to evaluate the impact of network development actions and have been included in the yearly National Development Plan. The last research topic involves the cost-effective target capacity assessment methodology developed by Terna in compliance with the Regulator directives presented together with the results yielded by its application to each significant market section of the Italian power system. The methodology has been positively evaluated from academic independent expert reviewers, and its outputs are relevant for the policy makers, regulatory authority and market participant to assess and co-design the energy transition plan of a future European interconnected power system.

The supply of petroleum sources is finite, non-renewable and, at the current rate of consumption, it will become severely depleted by 2050. Furthermore, the use of petroleum fuel increases greenhouse gas (GHG) emissions, leading to global warming which is harmful. Thus, there is an urgent need to find alternative sources of energy that are renewable, cost effective and can be produced in a sustainable manner. Non-edible feedstock biodiesels are a promising alternative fuel for reducing most petroleum fuel related environmental problems. They are attracting increasing attention due to their abundant availability and similar physicochemical properties as petroleum-derived diesel. This study carefully investigated six major non-edible vegetable oils (papaya seed oil, stone fruit kernel oil, jatropha oil, rapeseed oil, beauty leaf tree oil and waste cooking oil), that are locally available, out of 350 oil-bearing crops that could be potentially used to produce biodiesel. Four multiple criteria decision analysis (MCDA) methods with twelve physicochemical properties of biodiesel feedstocks and three different weightage (%) determination methods were used to rank these six feedstocks, with the view to find the best performing biodiesel feedstocks. The overall results show that the stone fruit kernel oil (SFO) was ranked as the best performing feedstock on the basis of engine performance amongst the six locally available feedstocks examined, papaya seed oil (PSO) came out as the second best, and the waste cooking oil was the worst performing biodiesel. Alkali catalysed transesterification reaction is the most widely used method for producing biodiesel from oil/animal fats due to its higher conversion efficiency in a short reaction time (30-60 min). The current study was undertaken to optimise the transesterification process for PSO and SFO with the view to increasing the efficiency of biodiesel conversion. A response surface method (RSM) based Box-Behnken design was employed to optimise biodiesel conversion processes for both PSO and SFO. Biodiesel conversion efficiencies of 96.5% and 95.8% were found for PSO and SFO at their respective optimum operating conditions. These PSO and SFO biodiesels were evaluated using a 4-cylinder, 4-stroke Kubota diesel engine. In general, both PSO and SFO blends decreased engine performance slightly compared to diesel as expected, however, SFO biodiesel blends gave about 3% better performance compared to PSO blends. On the other hand, PSO blends (20%) decreased most of the engine emissions by up to 34% except for an increase of about 5% in nitrogen oxide (NOx) compared to diesel. These emission performances are up to 14% better than the corresponding SFO emissions. Although the SFO biodiesel blends have slightly better engine performance than PSO biodiesel blends, the PSO biodiesel blends proved to be a better overall choice due to their excellent environmentally friendly attributes as they can reduce exhaust emissions to a great extent. Therefore, PSO was chosen subsequently to develop interactive relationships between three operating parameters of PSO, namely biodiesel blends, engine load, and engine speed and four responses of brake power (BP), torque, brake specific fuels consumption (BSFC), and brake thermal efficiency (BTE) for engine testing and emissions behaviour. Analysis of variance (ANOVA) and a statistical regression model show that load and speed were the two most important parameters that affect all four responses. The biodiesel blends parameter had a significant effect on BSFC. The engine load and engine speed were the two most important parameters that affect four of the responses (NOx, hydrocarbon (HC), particulate matter (PM) and carbon monoxide (CO)). In-cylinder peak pressures for PSO biodiesel blends were higher than for diesel irrespective of engine speed. Heat release rates of PSO biodiesel blends were found to be lower than for diesel due to lower ignition delays and lower caloric values of biodiesel. The maximum cylinder temperatures of PSO biodiesel blends were higher (3.73%) than that of diesel. To minimise the exhaust emissions, PSO biodiesel blends were mixed with two oxygenated additives, namely diethylene glycol dimethyl ether (diglyme) and n-butanol, to make ternary blends. These blends were tested for both engine performance and emissions. The addition of oxygenated additives increased the BP, torque and BTE values of PSO biodiesel ternary blends and it lowered the average BSFC by 0.5% and 17.7% compared with diesel and PSO blends (20%), respectively. PSO-diglyme-diesel ternary blend performed better than all other binary blends as well as the PSO-n-butanol-diesel ternary blend. The average reductions of HC, CO, NOx and PM of PSO-diglyme-diesel ternary blends compared with diesel were 32.4%, 61%, 0.64% and 47.4% respectively, whereas a 2.8% increase in carbon dioxide (CO2) emission was observed. The average increase of NOx, and CO2 for PSO blends (20%) compared with diesel were 4.1% and 4.5%, respectively. In conclusion, this study provided a solid base of new knowledge regarding biodiesel feedstock selection and optimisation techniques for PSO and SFO, assessed the suitability of PSO and SFO as alternatives to petroleum diesel and analysed how the emissions from these biodiesels could be reduced. These are very useful information for engine manufacturers, Government, stakeholders and policy makers to eliminate the lack of awareness of using second-generation biodiesel in Australia

Energy conservation, efficiency and renewable energy have become a vital part of everyday life and business. The increase in energy cost and the consequences of greenhouse gas emissions necessitates energy management and in particular energy risk management within organisations. Organisations need to manage the possible negative effect that the increased costs will have within the organisation. The present research investigated the introduction of a structured approach to energy risk management within the financial services sector of South Africa. The research followed a quantitative, non-experimental research design by using a structured questionnaire. The questionnaire was sent to managers within the financial services sector. The research investigated the criteria for the implementation of a structured approach to energy risk management such as organisational requirements (culture, corporate social responsibility, management, and finance), governance, energy strategies (energy conservation, efficiency and renewable energy), risk identification, risk management and lastly communication and review. The research found that the structured approach to energy risk management should include the context within the organisation namely organisational requirements, governance and energy strategies. Thereafter the risks within the energy strategies need to be identified, analysed and evaluated, and control measures need to be implemented. It is important to monitor the various energy strategies continuously in order to identify corrections and implement preventative actions. The strategies need to be reviewed and communicated in terms of the various strategies to all stakeholders within the organisation in order to set continual improvement plans. Risk management should form part of the energy management strategies of organisations. The research showed that energy risk management plays an important role in the overall business strategy and that the vast majority of financial services organisations have already implemented some form of energy management. There are however aspects that are still lacking within management strategies that need attention.
D. Phil. (Management Studies)
Business Management

Dissertação de mestrado em Engenharia Industrial
Planning an electricity system of a country is a hard and complex task that involves planners and decision makers in the process of selecting the best option(s) for future energy system plans considering the dynamics of electricity planning process within the society, the environment and the economy. The electricity system is a large-scale, complex and dynamic system and thus, for the purpose of power planning, it is unbearable to consider all specific relations between the electricity system and its external environment. Thus, the planning process frequently requires a logic and simpler representation of the electricity system to support effective decision making. Electricity power planning relies on future projections, constraints and parameters to be incorporated in the planning model. In line with is, deterministic models based on these most likely forecasts can bring simplicity to the electricity power planning but do not explicitly consider uncertainties and risks which are always present on the electricity systems. On the other hand, stochastic models can account for uncertain parameters that are critical to obtain a robust solution, requiring however, higher modelling and computational effort than deterministic models. In this work, a methodology is proposed to include uncertainty into electricity planning model using scenario analysis, without adding the complexity of traditional stochastic optimization modelling. Ultimately, the aim of this work was to propose a methodology to identify major uncertainties presented in the electricity system and demonstrate their impact in the long-term electricity production mix, through scenario analysis. An electricity system close to the Portuguese one was used to demonstrate how renewables uncertainty can be included in the long term planning process, combining Monte Carlo Simulation with a deterministic optimization model. The results of this work indicate that high growth demand rates combined with climate uncertainties represent major sources of risk for the definition of robust optimal technology mixes for the future. This is particularly important for the case of electricity systems with high share of RES as climate change can have a major role on the expected RES power output.
Planear o sistema elétrico de um país é uma tarefa exigente e complexa que implica o desenvolvimento de decisores na seleção da(s) melhor(es) opção/opções para os planos futuros do sistema, tendo em conta a sua dinâmica com a sociedade, o ambiente e a economia. O sistema elétrico caracteriza-se pela grande escala, sendo também complexo e dinâmico e portanto, tornando-se incomportável incluir todas as relações específicas entre o sistema elétrico e a sua envolvente externa durante o planeamento. Assim, este processo de planeamento requer frequentemente uma representação lógica e simples do sistema elétrico por forma a apoiar a tomada de decisão eficiente. O planeamento da produção de eletricidade assenta em projeções, restrições e parâmetros que serão incorporados no modelo de planeamento. Desta forma, os modelos determinísticos baseados nestas previsões podem trazer simplicidade ao processo de planeamento mas não incluem explicitamente as incertezas e riscos presentes nos sistemas elétricos. Por outro lado, os modelos estocásticos permitem incluir incertezas consideradas críticas para obter uma solução robusta, mas requerem um maior esforço de modelação e ao nível computacional comparativamente aos modelos determinísticos. Neste trabalho, é proposta uma metodologia para incluir a incerteza num modelo de planeamento da eletricidade através da análise de cenários, evitando a complexidade da otimização estocástica. Deste modo, o objetivo deste trabalho é apresentar uma metodologia para identificar as principais incertezas presentes no sistema elétrico e demonstrar o seu impacto no mix tecnológico para geração da eletricidade no longo prazo, através da análise de cenários. Um sistema elétrico próximo do caso Português foi usado para demonstrar de que modo as fontes de energias renováveis podem ser incluídas no processo de planeamento de longo prazo, combinando a simulação de Monte Carlo com um modelo de otimização determinístico. Os resultados deste trabalho indicam que um elevado crescimento na procura de eletricidade combinado com a incerteza sobre as condições climáticas representam importantes fontes de risco para a definição de mixes tecnológicos ótimos e robustos para o futuro. Isto é particularmente relevante para o caso das fontes de energias renováveis terem um contributo elevado para os sistemas elétricos, dado que as alterações climáticas poderão afetar significativamente a geração de eletricidade expectável destas tecnologias renováveis.

Dissertação de mestrado em Gestão de Projetos de Engenharia
O setor energético é intrínseco à sustentabilidade de um país, impresso intimamente na sociedade em que vivemos. No entanto, preocupações relacionadas com o futuro deste setor e o seu papel nas alterações climáticas têm surgido nos últimos anos, resultando numa crescente incorporação das energias renováveis no sistema elétrico nacional. Além da problemática ambiental associada aos combustíveis fósseis, esta inclusão é motivada pelo potencial económico e a segurança de abastecimento claramente relacionada com a escassez de recursos. Estas preocupações globais têm vindo a ser reconhecidas pelo governo e politicas Portuguesas. Contudo, a apresentação de um plano, que permita uma trajetória satisfatória para as várias componentes que se relacionam com o sistema elétrico, constitui um processo complexo, mas crucial para cumprir com as metas de sustentabilidade. E, com a introdução das energias renováveis, o risco no sistema tende a aumentar, pelo que a gestão dos riscos assume uma maior relevância no planeamento energético. Nesse sentido, este trabalho procede à avaliação de cenários do sistema elétrico nacional, simulados pelo modelo EnergyPLAN para 2030. As simulações resultantes são sujeitas a uma análise crítica quanto à sua sustentabilidade, determinando quais os impactos esperados da integração de energias renováveis a longo prazo. Explorou-se o sistema numa ótica de mercado interligado, contemplando fatores de custo, de emissão de CO2 e de risco da oferta de eletricidade. A influência da variabilidade das fontes de energia renováveis foi abordada através da combinação dos resultados obtidos por simulação de Monte Carlo no software @Risk e o modelo determinístico EnergyPLAN. Os resultados evidenciam o impacto da variabilidade de energia injetada na rede, por parte das renováveis quando estas apresentam uma participação elevada no sistema. De acordo com os resultados obtidos, nas circunstâncias mais prováveis será de esperar que a integração das energias renováveis seja bem-sucedida, sendo até possível operar como um sistema próximo de 100% renovável em cenários otimistas. Contudo, num cenário de cuja produção correspondente a 36% da produção total, os resultados implicam um agravamento nos custos de 54% e a redução das emissões de CO2 é apenas de 50% em relação ao cenário mais provável de ocorrer, colocando em causa as metas energéticas do país e da sua viabilidade económica. Destaca-se a importância da interligação com Espanha, que se revela fundamental para a viabilidade técnica das soluções, especialmente em cenários extremos de escassez ou de excesso de eletricidade para o sistema elétrico. Quanto à esfera ambiental, nota-se que as emissões tendem a diminuir significativamente, mesmo em circunstâncias pessimistas de produção renovável as simulações apontam para um decréscimo das emissões comparativamente com a situação atual.
The energy sector is intrinsically related to the sustainability of a country and intimately linked to the society we live in. However, concerns related with the future of this sector and its role in climate change have appeared in the last years, resulting in a crescent incorporation of renewable energy sources on the national electricity system. Besides the environmental concerns related to fossil fuels, the inclusion of renewables is motivated by their economic potential and security of supply related to a shortage of resources. These global concerns have been recognized by the Portuguese government and its policies. However, the creation of a plan, that allows a satisfactory trajectory for the various components related to the electricity system, is a complex but crucial process to meet sustainable goals. The introduction of renewable energy sources resulted in an intensification of risks in the electricity system, and therefore risk management is becoming increasingly relevant for the success of energy planning. In this sense, this work proposes to evaluate scenarios of the national electricity system simulated by the EnergyPLAN model for 2030. The resulting simulations were critically evaluated in what concerns their sustainability, determining the expected impacts of the integration of renewable energies in the long term. This dissertation addressed the influence of risks in the electricity system, highlighting the variability of renewable energy sources. For this, a combination of deterministic results and simulation with @Risk software was proposed. The interconnected market perspective was considered, cost and CO2 emission factors were estimated. The results show the impact of the variability of energy injected into the grid for scenarios with a large share of renewables. Under the most likely circumstances, the expectations were for a successful integration of renewable energies and, in some periods, the system would be operating almost as a 100% renewable system, under the optimistic scenario. However, in the case of a 36% renewable production can lead to a serious deterioration of costs of 54% and reduction emissions of 50% compared to the scenario most likely to happen, undermining the country's energy goals and economic viability. The outputs highlight the importance of interconnection with Spain, which is fundamental for the technical feasibility, especially for extreme scenarios of scarcity or excess electricity for the electrical system. As for the environmental sphere, it is noted that CO2 emissions tend to decrease significantly and even under the pessimistic scenario of renewable production, a reduction of emissions is expected.