A dissertation submitted to the Faculty of Science, University of the Witwatersrand, in fulfilment of the requirements for the degree of Master of Science. Johannesburg, 2015. / Over 60% of the Swazi population resides in rural areas and rely on woodfuel for their daily cooking needs. Cooking with woodfuel on open fires is inefficient and unhealthy, leading to millions of deaths of women and children each year while also contributing to environmental degradation. This has necessitated the implementation of Government’s clean cookstoves programme in Swaziland. This study focused on household stove users in six chiefdoms in the Lower Usuthu Sustainable Land Management (LUSLM) Project area in Siphofaneni Swaziland. A survey conducted through the dissemination of a questionnaire was used to investigate how rural perceptions impact on the adoption of clean cookstove technologies as an alternative household energy technology contributing towards sustainable development in rural Swaziland. Results from this study indicate that although cooking on an open fire was the least desired cooking technology, only 2% of households in the project area own clean cookstoves and less than half of the households had knowledge of cookstoves. The study further revealed that over 80% of the households in the survey area would prefer using a clean cookstoves to reduce the labour intensive task of collecting firewood as well as reducing exposure to smoke. The households found to have some knowledge of the benefits of clean cookstoves indicated the willingness to pay for a clean cookstove; however, a third of the respondents indicated a preference of obtaining a free clean cookstove. The price and availability of the clean cookstove in rural areas were two main barriers to increased uptake of the stoves, coupled with the need to purchase new pots. Despite the general lack of awareness of these technologies, challenges such as danger of the stoves to children and stove durability were also cited. The results indicate the need for the ongoing clean cookstove programme being implemented by the Government of Swaziland to improve on its strategy, to focus on incorporation of perceptions of rural stove users in development of appropriate cookstove designs, distribution models, and the design and implementation of a cookstove quality control programme.

Com a crescente demanda por energia renovável e proteção ambiental, a tecnologia de digestão anaeróbica para a produção de biogás tem atraído atenção considerável em torno do mundo. A digestão anaeróbica é um processo biológico que converte a matéria orgânica em um gás rico, o metano. É uma tecnologia bem estabelecida para o tratamento de resíduos e efluentes com alto conteúdo orgânico, provenientes de processos industriais e atividades domésticas. Neste estudo, a vinhaça, um subproduto da indústria sucroalcooleira e o efluente lácteo, subproduto da indústria de laticínios, foram avaliados para produção de biogás em reator UASB. Os efluentes orgânicos usados neste trabalho foram coletados a partir de indústrias de grande porte, localizadas no Brasil e Alemanha. Para a digestão anaeróbica da vinhaça e do efluente láctico foi utilizado um reator do tipo UASB em escala laboratorial, temperatura mesofílica e com capacidade de 87 L. Para digestão da vinhaça, o reator UASB operou durante 15 dias, com COV de 2 Kg DQO m-3 d-3 e TDH de 11,5 dias. Os resultados obtidos mostraram um bom funcionamento do reator UASB aplicado a vinhaça. Este estudo obteve-se uma eficiência de remoção de DQO de 71% e volume de biogás acumulado de 1160 litros com concentração de metano em torno de 48 a 57 %. Para a biodigestão do efluente lácteo, o reator UASB operou durante 51 dias. A eficiência do reator a partir da taxa de carga orgânica de 6 Kg COD m-3 d-3 e tempo de detenção hidráulica (TDH) de 11,8 foi estudada e seu desempenho foi avaliado pelo monitoramento do pH, DQO, relação de alcalinidade FOS/TAC e produção de biogás. Observou- se a eficiência de remoção de DQO em 71,3 %. O pH do reator foi verificado entre 7.0-7.3 e o valor de FOS/TAC entre 0,129-0,152. A produção média de biogás foi observada em 85,8 litros por dia, e o volume específico de biogás entre 0,46-0,71 L /g DQO por dia. O conteúdo de metano no biogás produzido, apresentou o valor máximo e mínimo em 56,6 % e 40 %, respectivamente / With the rising demand for renewable energy and environmental protection, anaerobic anaerobic digestion technology for biogas production has attracted considerable attention around the world. Anaerobic digestion is a biological process that converts organic matter into a methane rich gas. It is a well established technology for the treatment of waste and effluents with high organic content, from industrial processes and domestic activities. In this study, vinasse, a by-product of the sugar and alcohol industry and dairy effluent, a by-product of the dairy industry, were evaluated for biogas production in a UASB reactor. The organic effluents used in this work were collected from large industries located in Brazil and Germany. For the anaerobic digestion of the vinasse and the lactic effluent, a UASB reactor UASB was used in laboratory scale, with a mesophilic temperature and with a capacity of 87 L. For digestion of the vinasse, the UASB reactor operated for 15 days, with COV of 2 Kg COD m-3 d-3 and TDH of 11.5 days. The results obtained in this study showed a good functioning of the UASB reactor applied to vinasse. This study yielded a COD removal efficiency of 71% and an accumulated biogas volume of 1160 liters with a methane concentration of around 48 to 57%. For the digestion of dairy effluent, the UASB reactor operated for 51 days. The efficiency of the reactor from the organic loading rate of 6 kg COD m-3 d-3 and hydraulic holding time (TDH) of 11.8 was studied and its performance was evaluated by monitoring pH, COD, alkalinity ratio FOS / TAC and biogas production. The efficiency of COD removal was observed in 71.3%. The pH of the reactor was verified between 7.0-7.3 and the FOS / TAC value between 0.129-0.152. The average biogas production was observed at 85.8 liters per day, and the specific biogas volume was between 0.46-0.71 L / g COD per day. The methane content in the produced biogas, the maximum and minimum value was observed in 56.6% and 40%, respectively.

Nowadays about 1.2 billion people in world lack modern access to electricity, with the majority of them living in rural areas in low-income and developing contexts. This research addresses the issue of energy access by investigating the design of sustainable business models, and in particular by exploring the combination of Product-Service Systems (PSS) with Distributed Renewable Energy systems (DRE). The combination of PSS and DRE represents a new design approach to explore promising business models for energy access and to deliver clean and affordable solutions in low-income contexts. The overall aim of this research is to explore the applications of PSS and DRE in low-income and developing contexts, thus defining characteristics of these models, their variables and critical factors. Additionally, this research aims at developing a support for companies, practitioners and other stakeholders for designing sustainable PSS applied to DRE, with a specific focus on the idea generation phase of new solutions. The first part of this PhD resulted in the development of a classification system for PSS applied to DRE, in the identification of 15 Archetypal Models and in the collection of critical factors to successfully implement these models. Then, these findings have been translated into three tools for designing PSSs applied to DRE: the Innovation Map, the Design Framework and Cards, the Energy System Map. These tools have been tested, refined and evaluated through a series of iterative applications in South Africa, Botswana, Kenya and the UK. Through the testing activities, which involved a wide range of companies, NGOs, practitioners and experts, the usefulness, usability and completeness of the tools were demonstrated. This research concludes with reflections on the design process for different scenarios of applications and by highlighting further research activities for the field of PSS applied to DRE in low-income and developing contexts.

Solar panels are used in many different applications for generating sustainable energy. Many countries use solar power as a power generation method. It is also, an excellent option for getting power to difficult areas. There are three main systems used when generating solar power: grid-tied, battery banked, and direct driven systems. Most systems use a combination of grid-tied and battery banked so any unused power can be fed back into the main grid for compensation. The solar power application suggested in this thesis will provide USB power to a picnic table enabling students to charge cellphones and other small devices while at the table. The solar panel will be mounted on the top of the picnic table or on a canopy as shading for the table. These locations along with the power generation systems were researched and tested to find the best option.

Sustainable energy solutions are aimed to reduce the consumption of fossil fuels by using renewable energy sources and energy efficiency techniques. This thesis presents two new sustainable energy applications in the field of electrical machines.Polyphase induction motors dominate the energy usage spectrum for industrial and commercial applications. The conventional winding structure used in both synchronous and induction machines has a basic unit of the winding with a 60 degree phase belt and a three phase connection either in star or delta. A new winding structure using an innovative Star-Delta Series Connection (SDSC) which has a high winding coefficient and low harmonic content is presented in this thesis. The principle of the SDSC winding is described. The Electro-Magnetic Belt and Electro-Magnetic Space diagram are two important means to be used for optimization of the new winding. Experimental results from two prototypes confirm the theoretical analysis. The efficiency of the new machine at rated load increased by about 3.8% as compared to the standard machine with a conventional winding structure.Wind energy is one of the most attractive renewable energy options. Wind turbines are designed to couple either synchronous or asynchronous generators with various forms of direct or indirect connection with grid or diesel generators. Permanent magnet (PM) generators using high energy Neodymium- Iron-Boron magnets offer advantages such as direct coupling without gear box, absence of excitation winding and slip rings, light weight and smaller size. This thesis presents the design and development of an outer-rotor PM generator suitable for wind energy conversion. The initial electromagnetic design followed by a Finite Element Analysis is presented in detail. A 20 kW prototype machine was built and extensively tested. It was found that the machine could maintain an ++ / efficiency of about 85% for a wide operating range. Equivalent circuit models were developed. The results of the Finite Element analysis matches closely with the experimental and the designed values.

There is an urgent need for economical, clean, sustainable energy supplies, not only in densely populated areas where electricity grids are appropriate, but also in rural areas where stand-alone power supply systems are often more suitable. Although electrical power supply is very versatile and convenient, it introduces unnecessary complexity for some off-grid applications where direct mechanical shaft power can conveniently be provided by a wind turbine. Wind energy is one of the more promising renewable energy sources. Most wind turbines are of the horizontal axis type, but vertical axis wind turbines or VAWTs have some advantages for direct mechanical drive applications. They need no tail or yaw mechanism to orient them into the wind and power is easily transmitted via a vertical shaft to a load at ground level. Blades may be of uniform section and untwisted, making them relatively easy to fabricate or extrude, unlike the blades of horizontal axis wind turbines (HAWTs) which should be twisted and tapered for optimum performance. Savonius rotor VAWTs are simple and may have a place where the power requirement is only a few Watts, but they are inefficient and uneconomical for applications with larger power requirements. VAWTs based on the Darrieus rotor principle are potentially more efficient and more economical, but those with fixed pitch blades have hitherto been regarded as unsuitable for stand-alone use due to their lack of starting torque and low speed torque. This starting torque problem can be overcome by using variable pitch blades, but most existing variable pitch VAWTs, variously known as giromills or cycloturbines, need wind direction sensors, microprocessors and servomotors to control the blade pitch, making them impracticable for stand-alone, non-electrical applications. A simpler but less well known concept is passive or self-acting variable pitch in which the blades are free to pitch under the combined action of aerodynamic and inertial forces in such a way that a favourable blade angle of attack is maintained without the complexity of conventional variable pitch systems. Several fonns of self-acting variable pitch VAWTs or SAPVAWTs have been described in the literature, several patents exist for variants on the concept, and at least two companies world-wide have attempted to commercialise their designs. However the aerodynamic behaviour of these devices has been little understood and most designs appear to have been based on nothing more than a qualitative appreciation of the potential advantages of the concept. This thesis assesses the potential of both fixed and passive variable pitch vertical axis wind turbines to provide economical stand-alone power for direct mechanical drive applications. It is shown that the starting torque and low speed torque problems of VAWTs can be overcome either by passive variable pitch or by a combination of suitable blade aerofoil sections, either rigid or flexible, and transmissions which unload the rotor at low speeds so that high starting torque is not necessary. The work done for this thesis is made up of a sequence of stages, each following logically from the previous one: 1. Several tasks have been identified which could be performed effectively by a self-starting vertical axis wind turbine using direct mechanical drive. These include, a. pumping water, b. purifying and/or desalinating water by reverse osmosis, c. heating and cooling using vapour compression heat pumps, d. mixing and aerating water bodies and e. heating water by fluid turbulence. Thus it is apparent that such a system has the potential to make a useful contribution to society. 2. A literature survey of existing VAWT designs has been carried out to assess whether any are suitable for these applications. 3. As no suitable existing design was identified, an improved form of SAPVAWT has been developed and patented. 4. To optimise the performance of the improved SAPVAWT, a mathematical model has been developed in collaboration with Mr Leo Lazauskas of the University of Adelaide (see Kirke and Lazauskas, 1991, Lazauskas and Kirke, 1992). As far as the author of the present thesis is aware, this is the only existing mathematical model able to predict the performance of this particular type of SAPVAWT, and one of only two worldwide which model SAPVAWTs. 5. In order to use the mathematical model to predict the performance of a given SAPVAWT, it is necessary to have lift, drag and moment data for the aerofoil profile to be used, over a wide range of incidence and Reynolds numbers. A literature search has revealed large gaps in the existing data. 6. Wind tunnel testing has been carried out to assess the effect of camber on the performance of one set of NACA sections at low Reynolds number, and performance figures for other sections have been estimated by interpolation from existing data. 7. Using the assembled aerofoil data, both experimental and estimated, the mathematical model has been used to predict the performance of both fixed and variable pitch VAWTs. It has been found to predict correctly the performance of known fixed pitch VAWTs and has then been used to predict the performance of fixed pitch VAWTs with cambered blades using newly developed profiles that exhibit superior characteristics at low Reynolds numbers. Results indicate that fixed pitch VAWTs using these blade sections should self-start reliably. 8. To validate the mathematical model predictions for self-acting variable pitch, a two metre diameter physical model has been built and tested in a wind tunnel, and acceptable agreement has been obtained between predicted and measured performance. 9. To demonstrate the performance of a SAP VA WT under field conditions, a six metre diameter turbine has been designed, fabricated, erected and tested. 10. Because a prime mover such as a wind turbine is of no use unless it drives a toad, particular attention has been paid to the behaviour of complete systems, including the wind turbine, the transmission and the load. It is concluded that VAWTs with the improved self-starting and low speed torque characteristics described in this thesis have considerable potential in stand-alone, direct mechanical drive applications.

<p>This thesis will present the result from one main investigation (step 1) and two follow-up studies (step 2 and 3). The main study consists of an interpreting, iterative analysis of statements made by ‘experts’ on contents of education gathered from a questionnaire, which result in a subject-specific content for physics education on sustainable energy systems (SES) presented as a category system. The categories from Step 1 are used as means for analysis in step 2 and 3, which involve the study of educational material and one classroom analysis.</p><p>The results show that the content of physics for upper secondary, in order for students to reach insight, should comprise certain physical concepts and relations not only in “limited contexts” but also in relation to greater contextual connections, in which problematisation and insight in solutions for the future is necessary. These parts should have a similar weight according to the statements of the experts. This is not to be found in either the typical educational material (textbooks) or in one studied classroom teaching example.</p> / <p>Vad ska fysikämnet på gymnasiet innehålla för att elever ska förstå och bli engagerade i samhällets energifrågor samt inse vad en hållbar energianvändning innebär? Hur presenteras energi för gymnasieelever, i läroböcker och i fysikundervisning? Detta har undersökts genom en studie bestående av en inledande huvudstudie samt två mindre uppföljningsstudier och resultatet presenteras i denna licentiatavhandling.</p><p>Huvudstudien består av en tolkande, iterativ analys av skriftliga uttalanden gjorda av fysiker, fysiklärare och energiexperter när de uppmanats att svara på ett antal frågor rörande undervisningens innehåll. Analysen har resulterat i ett ämnesspecifikt innehåll för fysikundervisning om hållbar energi. Ett innehåll sammanfattat i ett kategorisystem som kan ses som underlag för undervisning. De olika kategorierna som framkommit i huvudstudien har sedan använts i två uppföljande studier, dels en innehållsanalys av sex olika läroböcker dels en undersökning av ett fysikklassrum under åtta veckor med undervisning om energi.</p><p>Resultatet från huvudstudien visar att fysikämnets innehåll i gymnasiet med syfte att eleverna ska nå insikt om hållbar energi bör bestå av grundläggande fysikbegrepp och dess samband som i sin tur exemplifieras inte bara i ”begränsade kontexter” såsom en värmepump eller en bilmotor utan även i större sammanhang, exempelvis den egna energianvändningen och energiflöden genom samhället och genom naturen. Inom dessa större sammanhang är det nödvändigt att en problematisering sker och att diskussioner förs om framtida lösningar. Enligt de tillfrågade experterna så ska en jämn fördelning råda mellan fysikaliska begrepp, dess samband och ”begränsade kontexter” samt de större sammanhangen, problemen och lösningarna.</p><p>En sådan fördelning har dock inte återfunnits i vanliga fysikläroböcker och i den klassrumssituation som studerats. Dessa uppföljningsstudier visar på en tonvikt på grundläggande fysikbegrepp, dess samband samt fokus på beräkningskompetens. Detta trots att kursplaner i fysik framhåller vikten av att elever ska erhålla kunskaper och insikter om energifrågor i samhället och energianvändningens påverkan på miljön.</p>

This thesis will present the result from one main investigation (step 1) and two follow-up studies (step 2 and 3). The main study consists of an interpreting, iterative analysis of statements made by ‘experts’ on contents of education gathered from a questionnaire, which result in a subject-specific content for physics education on sustainable energy systems (SES) presented as a category system. The categories from Step 1 are used as means for analysis in step 2 and 3, which involve the study of educational material and one classroom analysis. The results show that the content of physics for upper secondary, in order for students to reach insight, should comprise certain physical concepts and relations not only in “limited contexts” but also in relation to greater contextual connections, in which problematisation and insight in solutions for the future is necessary. These parts should have a similar weight according to the statements of the experts. This is not to be found in either the typical educational material (textbooks) or in one studied classroom teaching example. / Vad ska fysikämnet på gymnasiet innehålla för att elever ska förstå och bli engagerade i samhällets energifrågor samt inse vad en hållbar energianvändning innebär? Hur presenteras energi för gymnasieelever, i läroböcker och i fysikundervisning? Detta har undersökts genom en studie bestående av en inledande huvudstudie samt två mindre uppföljningsstudier och resultatet presenteras i denna licentiatavhandling. Huvudstudien består av en tolkande, iterativ analys av skriftliga uttalanden gjorda av fysiker, fysiklärare och energiexperter när de uppmanats att svara på ett antal frågor rörande undervisningens innehåll. Analysen har resulterat i ett ämnesspecifikt innehåll för fysikundervisning om hållbar energi. Ett innehåll sammanfattat i ett kategorisystem som kan ses som underlag för undervisning. De olika kategorierna som framkommit i huvudstudien har sedan använts i två uppföljande studier, dels en innehållsanalys av sex olika läroböcker dels en undersökning av ett fysikklassrum under åtta veckor med undervisning om energi. Resultatet från huvudstudien visar att fysikämnets innehåll i gymnasiet med syfte att eleverna ska nå insikt om hållbar energi bör bestå av grundläggande fysikbegrepp och dess samband som i sin tur exemplifieras inte bara i ”begränsade kontexter” såsom en värmepump eller en bilmotor utan även i större sammanhang, exempelvis den egna energianvändningen och energiflöden genom samhället och genom naturen. Inom dessa större sammanhang är det nödvändigt att en problematisering sker och att diskussioner förs om framtida lösningar. Enligt de tillfrågade experterna så ska en jämn fördelning råda mellan fysikaliska begrepp, dess samband och ”begränsade kontexter” samt de större sammanhangen, problemen och lösningarna. En sådan fördelning har dock inte återfunnits i vanliga fysikläroböcker och i den klassrumssituation som studerats. Dessa uppföljningsstudier visar på en tonvikt på grundläggande fysikbegrepp, dess samband samt fokus på beräkningskompetens. Detta trots att kursplaner i fysik framhåller vikten av att elever ska erhålla kunskaper och insikter om energifrågor i samhället och energianvändningens påverkan på miljön.

Thermoelectric (TE) module integration into a notebook computer is experimentally investigated in this thesis for its energy harvesting opportunities. A detailed Finite Element (FE) model was constructed first for thermal simulations. The model outputs were then correlated with the thermal validation results of the selected system. In parallel, a commercial TE micro-module was experimentally characterized to quantify maximum power generation opportunity from the combined system and component data set. Next, suitable &ldquo / warm spots&rdquo / were identified within the mobile computer to extract TE power with minimum or no notable impact to system performance, as measured by thermal changes in the system, in order to avoid unacceptable performance degradation. The prediction was validated by integrating a TE micro-module to the mobile system under test. Measured TE power generation power density in the carefully selected vicinity of the heat pipe was around 1.26 mW/cm3 with high CPU load. The generated power scales down with lower CPU activity and scales up in proportion to the utilized opportunistic space within the system. The technical feasibility of TE energy harvesting in mobile computers was hence experimentally shown for the first time in this thesis.

Lithuania has limited domestic energy resources, and is therefore, heavily dependent on imports of oil products and natural gas. Lithuania imported around 90% of its oil and 100% of natural gas in 2009. Particularly, after the accession to the European Union (EU), and decommissioning of main electricity generation source Ignalina Nuclear Power Plant (NPP), energy security became one of the main concerns. Therefore, it is vital to evaluate different pathways the country could take in order to achieve desirable energy security, and ensure sustainable development of the energy system in Lithuania. The study was conducted using LEAP, the Long range Energy Alternatives Planning System, to develop energy policy analysis. Different scenarios presented in the report show how Lithuanian energy system would react in given different circumstances. Moreover, it demonstrates how implementation of existing energy projects separately or combined together would affect the level of energy security and sustainability in Lithuania. The research shows that current government policies could lead Lithuania to more secure and sustainable energy future. However, in a long run higher investments in renewable energy might be more environmentally and economically competitive alternative.