As energy systems shift away from fossil-fuel based electricity, the non-dispatchability of renewable energy converters (REC) continue to stress the grid infrastructure and conventional thermal generating units. These hybrid electricity systems require energy storage systems to buffer the variabilities of electricity supply and demand. Regenerative air energy storage (RAES) is an emerging technology that shows promise to overcome the barriers of REC variability. RAES uses a novel compressor/expander that approaches isothermal operation by spraying water into the piston/cylinder to absorb/release heat. RAES can be sized for power and energy independently, and has a high round-trip efficiency that can be boosted using low grade waste heat. Because of its novelty, new numerical models are necessary to investigate the sizing and performance of RAES systems. In this thesis a numerical simulation tool is developed to allow flexible and intuitive analysis of a range of hybrid energy systems involving RAES.

Final Master Thesis report EGI 2010-2013   Thesis Title: The Role of Renewable Energies in Energy supply Planning and   Management for Sustainable    Development “Case of Rwanda”. ABSTRACT   This report provides an overview of the main results from the scenarios analysed in the Rwanda energy policy strategy, planning and prospective energy initiatives and alternatives (Hydropower, Biomass, Solar, Methane, Peat, etc.) as well as other Government Development Frameworks meant for poverty reduction strategies and economic development. Under this context, the report attempts to assess the role of renewable energies particularly micro hydropower in solving Rwanda energy supply and management issues for sustainable development. The main conclusion is that renewable energies (micro hydropower) substantially contribute to reducing greenhouse gas emissions and improving diversification of the energy production and supply into the national grid as well as independent off-grid systems particularly in rural based areas that are far from the grid. This becomes even more significant and relevant when considering that electricity access in the country stands at about 14% leaving about 86% of the population especially in rural areas without power supply. Although other technologies are still used to meet urgent and pressing power demand, Renewable energy sources are well placed in offering medium and long term solution in a sustainable manner. To this effect therefore, the report has tried to outline the impacts, costs and benefits of ambitious renewable energy targets for Rwanda in the medium and long term perspectives.

Darbe analizuojami atsinaujinančios elektros energijos ištekliai, pasirinkti remiantis atsinaujinančių išteklių energetikos įstatyme plačiausiai analizuojamais ir didžiausias perspektyvas turinčiais energijos ištekliais Lietuvoje. Išskirti trys pagrindiniai atsinaujinančios energetikos šaltiniai: vėjo energetika, biomasės deginimo metu gaunama elektros energija, bei hidroenergetika, pastarąją skirstome į didžiąsias hidroelektrines ir mažąsias hidroelektrines. Naujuoju atsinaujinančių išteklių energetikos įstatymu tikimasi elektros energijos dalį bendrajame šalies elektros energijos sunaudojime (pagamintos iš atsinaujinančių energijos išteklių), padidinti iki 20 procentų, kas reikštų sparčias AEI elektrinių statybas. Investicijų į atsinaujinančią energiją, taupų jos naudojimą ir naujas technologijas stiprinimas prisideda prie darnaus vystymosi ir padeda kurti naujas darbo vietas, skatinti ekonomikos augimą, stiprinti konkurencingumą ir plėtrą, kad Lietuva galėtų žengti į saugesnę, švaresnę ir konkurencingesnę ateitį. Todėl aplinkosauginiu požiūriu svarbu palyginti AEI elektrinių efektyvumo rodiklius bei atlikti poveikio aplinkai vertinimą, palyginant jų poveikį aplinkos komponentams. / This work analyzes the use of renewable energy resources (wind, hydro and biomass burning) and the effectiveness of their environmental impact. From the pending renewable energy sources in Lithuania we have the highest prospects for wind energy, especially offshore, and biomass burning. Hydropower development opportunities in Lithuania, the typical plains region, where the energy potential of rivers is small and flooding areas causes’ significant ecological damage, prospects are limited. Renewable energy resources impact to the environment is very different. The biggest environmental impacts of hydropower, the smallest - biomass burning derived electricity.

Darbas susideda iš dviejų dalių teorinės bei praktinės. Darbo tikslas – įvertinti vėjo parametrus ir prognozuojamą vėjo elektrinių galią pajūrio ir Tauragės regionams. Teorinėje dalyje aprašoma vėjo energetikos pasiekimai ir perspektyvos Lietuvoje, aptariami vėjo srautų kitimo atmosferos pasienio sluoksnyje dėsningumai, vėjo prognozavimo metodai, vėjo jėgainių konstrukcija ir veikimo principas. Praktinėje dalyje pateikiama vėjo matavimo duomenų statistinė analizė, bei įvertinamas prognozuojamas metinis vėjo jėgainių pagamintos energijos kiekis. / The work consists of two parts: theoretical and practical. The aim of the work is to evaluate the parameters of the wind and prognosticated the power of wind- power- stations for near- shore zones and regions of Tauragė. In the theoretical part the achievements and perspectives of wind energetics in Lithuania are described, the regularity of wind flow changes in atmosphere terminal are discussed, the methods of wind prognostication, the construction and working principle of wind- power- stations. In the practical part the statistical analysis of wind measures is shown and the prognosticated amount of energy produced by wind- power- stations per year is evaluated.

Introduction: The mass print media are a widely-distributed, and often primary, source of health information for the public. Health information in newspapers can amplify or attenuate readers’ perceptions of risk depending on how it is presented. This thesis examines how health information related to wind energy was communicated in Ontario newspapers and includes separate analyses for the presence of fright factors, readability, emergent themes, and emotional tone and sensationalism. As an emerging technology, public understanding of and response to associated health risks and uncertainties towards wind energy can be influenced by media coverage. Methods: Five geographically discontinuous wind energy installations in Ontario and their surrounding communities were selected based on 2006 Canadian Census data. Newspapers serving each community were identified and searched for articles from May 2007-April 2011 on the topic of health effects from wind energy developments. A total of 421 articles from 13 community and 4 national/provincial newspapers were retrieved. In Study #1, a directed content analysis was used to develop a coding instrument based on fright factors known to affect the public’s perception of risk. In Study #2, each newspaper article was analyzed for text readability using the Simple Measure of Gobbledygook (SMOG) readability formula. In Study #3, and as a qualitative component, a semi-directed content analysis was used to find emerging themes and subthemes. Finally, in Study #4, a list of loaded and positive words, informed from previous studies on sensationalism in media reporting and a random sample of newspaper articles included in this study, and the frequency of their appearance was used as a quantitative measure of sensationalism. Results: Study #1: The most commonly reported fright factors were ‘dread’, ‘poorly understood by science’, ‘involuntary exposure’, and ‘inequitable distribution’, occurring in 94% (n=394), 58% (n=242), 45% (n=188), and 42% (n=177) of articles, respectively. The fright factors of ‘dread’, ‘poorly understood by science’, ‘inequitable distribution’, and ‘inescapable exposure’ occurred more frequently in community newspaper articles than in national/provincial ones (p<0.001). Although the total number of occurrences of each fright factor increased following the Green Energy Act, only ‘dread’ (p<0.05) and ‘poorly understood by science’ (p<0.01) increased significantly. Study #2: The mean reading grade level (RGL) of 421 articles on wind turbines and health was at the post-secondary education level (X±SEM; 13.3±0.1). Articles from community and provincial newspapers were written at almost a full RGL lower (13.2±0.2 and 13.1±0.2) than those from national newspapers (13.9±0.2) (p<0.05). Additionally, opinion pieces such as editorial columns were written at a lower RGL than fact-based news articles (13.0±0.2 and 13.5±0.1, respectively; p<0.01). Study #3: The majority of newspaper articles described health effects of wind turbines in general, rather than specific, terms. The most commonly cited causes of health complaints were inadequate setbacks (27%, n=114), noise (21%, n=90), shadow flicker and vibrations (12%, n=49), and electrical exposure (6%, n=27). Other, non-health concerns such as environmental damage (28%, n=117), property values (20%, n=86), aesthetic concerns (18%, n=77), financial burden (18%, n=74), were prevalent and juxtaposed with health issues in 28% of articles (n=118). Concerns with the quality and availability of scientific evidence were frequent in the newspaper articles (34%, n=143), with many articles promoting a moratorium on wind energy developments until further research is conducted (25%, n=103). Study #4: Newspaper articles emphasized negative rather than positive/neutral tone, with community newspapers publishing a higher proportion of negative articles than provincial or national newspapers (X2=6.11, df=1, p<0.05). Conclusion: These findings suggest that the health information related to wind turbines in Ontario newspapers contains a large quantity of fright factors that may produce fear and anxiety in readers, is written at a reading grade level that is too complex for the majority of the Ontario population to fully understand, contains inconsistent information on health effects that often links health concerns with non-health concerns, and is often negative in tone. The influence of the Ontario newspaper media on reader’s risk perceptions of wind energy in Ontario will be important to determine empirically.

The study’s main purpose is to propose a governance framework that meets the priority of sustainable development for the regulation of offshore renewable resources in the OECS region. The study develops an analytical framework for evaluating the recently adopted “Round 3 model of governance” for the regulation of offshore wind and other marine activities in the United Kingdom. The focus is on the licensing procedures applicable to offshore wind development. Thereafter, the study examines the appropriateness of the application of the Round 3 model to the regulation of marine renewables in the OECS, and makes recommendations in that regard. Additionally, through the study of marine renewable resource development, this thesis looks at general conditions for effective ocean governance. In this regard, the thesis argues that strict hierarchical governance of the marine environment is not a desirable approach to effective ocean governance.

Environmental concerns and energy security are two major forces driving the fossil fuel based energy system towards renewable energy. In this context, hydrogen is gaining more and more attention in this 21st century. Presently, hydrogen is produced from reformation of fossil fuels, a process that could not address above two problems. For this it needs to be produced from a renewable carbon neutral energy source. Biomass has been identified as such a renewable energy source. Conversion of biomass through thermo-chemical gasification process in the presence of steam could provide a viable renewable source of hydrogen. This thesis presents an innovative system based on chemical looping gasification for producing hydrogen-enriched gas from biomass. The other merit of this system is that it produces a pure stream of carbon dioxide by conducting in-process capture and regeneration of sorbent. A laboratory scale chemical looping gasification (CLG) system based on a circulating fluidized bed (CFB) is developed and tested. Experiments conducted to gasify sawdust in CFB-CLG system shows that it could produce a gas with as much as 80% hydrogen and as little as 5% carbon dioxide. A kinetic model is developed to predict the performance of the gasifier of a CFB-CLG system, and is validated against experimental results. To understand the science of biomass gasification in the presence of steam and CaO, a number of additional studies are conducted. It show that for higher hydrogen and lower carbon dioxide concentration in the product gas, the optimum values of steam to biomass ratio, sorbent to biomass ratio, and operating temperature are 0.83, 2.0 and 670oC respectively. In CFB-CLG system the sorbent goes through a series of successive calcination-carbonation cycles. Calcination studies in presence of three alternate media, nitrogen, carbon dioxide and steam show, that steam calcination is best among them. An empirical relation for calcination in presence of three media is developed. Owing to the sintering, irrespective of medium used for calcination, the conversion of CaO reduces progressively as it goes through alternate calcination-carbonation cycles. An additional empirical equation is developed to predict the loss in sorbent’s ability during carbonation.

Recently, electric vehicles (EVs) have been gaining attention in passenger transportation due to their greater fuel economy and reduced greenhouse gas (GHG) emissions compared to conventional vehicles (CVs). The amount of GHG emissions reduction from EVs depends on the energy sources used to generate electricity. Wind is a clean, renewable energy source and EVs charged from wind-generated electricity do not produce any emissions. However, wind is variable in nature. This thesis examines the potential impact of EVs on reducing a jurisdiction’s vehicular GHG emissions using locally available wind-electricity. Four methods of charging EVs using wind-electricity are considered, with grid-electricity as a backup, and the overall well-to-wheels GHG emission reductions are discussed. The thesis includes a case study of Summerside. The results show that up to 68% of the EVs’ demands were met with wind-electricity, and Summerside’s vehicular GHG emissions were reduced by between 56% and 73% when compared to CVs.

This thesis presents a novel Zero Voltage Switching (ZVS) approach in a grid connected single-stage flyback inverter without using any additional auxiliary circuits. The soft-switching of the primary switch is achieved by allowing negative current from the grid-side through bidirectional switches placed on the secondary side of the transformer. Basically, the negative current discharges the MOSFET’s output capacitor thereby allowing turn-on of the primary switch under zero voltage. In order to optimize the amount of reactive current required to achieve ZVS a variable frequency control scheme is implemented over the line cycle. In addition, the bi-directional switches on the secondary side of the transformer have ZVS during the turn-on times. Therefore, the switching losses of the bi-directional switches are negligible. A 250W prototype has been implemented in order to validate the proposed scheme. Experimental results confirm the feasibility and superior performance of the converter compared to the conventional flyback inverter. / Thesis (Master, Electrical & Computer Engineering) -- Queen's University, 2012-07-06 16:24:13.385

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