Teses / dissertações sobre o tema "Utilisation of energy"

This report is a thesis for BTH in collaboration with the company Saab Kockums AB. In order to meet future environmental and economical demands, a vessel must reduce its fuel consumption to have a smaller climate impact and save money. Waste heat recovery systems (WHRS) captures the thermal energy generated from a process that is not used but dumped into the environment and transfers it back to the system. Thermal energy storage (TES) is the method of storing thermal energy which allows heat to be used whenever necessary. Some applications of TES are seasonal storage, where summer heat is stored for use in the winter or when ice is produced during off-peak periods and used for cooling later. The purpose of this study is to investigate the possibilities of utilising a vessel’s waste heat by converting thermal energy into electrical energy. This thesis also aims to investigate conditions for SaltX Technology’s nano-coated salt as a potential solution for thermal energy storage. Initially, the expectations and requirements a future WHRS were investigated in a function analysis. Continuously, the method consisted of a combination of a literature review and dialogue with stakeholders. The literature review was used as a tool to identify, select and study concepts of interest built on scientifically proven facts. Dialogues with stake holders were held as a complement to the literature study to find information. The study showed that an organic Rankine cycle has the highest efficiency for low-medium temperature heat and is therefore most suitable to recover thermal energy from the cooling water. The concept of a steam Rankine cycle is most suitable for recovering thermal energy from the exhaust gases for direct use.The study obtained conditions and important properties for storing thermal energy in salt for later use. Finally, the result showed that a Stirling engine is the most efficient concept for conversion of stored energy into electrical energy. The conclusions are that there are great possibilities for waste heat recovery on marine defence platforms. A Stirling engine for energy conversion in combinations with thermal energy storage shows most promise as a future waste heat recovery system on this type of marine platform.<br>Denna rapport är ett examensarbete för BTH i samarbete med företaget Saab Kockums AB. Arbetet utforskar möjligheterna att möta framtida miljömässiga och ekonomiska krav genom att låta fartyg minska sin bränsleförbrukning. System för återvinning av spillvärme (WHRS) fångar upp värmeenergi som vanligtvis kyls ner eller släpps ut i naturen och för den tillbaka till systemet. Termisk energilagring (TES) är metoder för lagring av värme som gör det möjligt att använda termisk energi när det behövs. Vissa applikationer av TES är säsongslagring, där sommarvärme lagras för användning på vintern eller när is produceras under vintern och används för kylning senare. Syftet med denna studie är att undersöka möjligheterna att utnyttja ett fartygs spillvärme genom att omvandla termisk energi till elektrisk energi. Detta examensarbete syftar också till att undersöka förhållandena för hur SaltX Technology’s nanobelagda salt kan användas som en potentiell lösning för lagring av termisk energi. Inledningsvis undersöktes WHRS:s förväntningar och krav i en funktionsanalys. Fortsättningsvis bestod metoden av en kombination av en litteraturstudie och dialoger med intressenter. Litteraturstudien användes som ett verktyg för att identifiera, välja och studera intressanta koncept baserade på vetenskapligt beprövade fakta. Dialoger hölls som ett komplement till litteraturstudien för att hitta information. Studien visade att en organisk Rankine-cykel har den högsta verkningsgraden för låg-medelhög temperatur och därför är bäst lämpad för att återvinna energi buren i kylvattnet samt att en ång-Rankine-cykel är bäst lämpad för att utnyttja energin från avgaserna för direkt användning. Studien erhöll förhållanden för termisk energilagring i salt samt viktiga parametrar för systemet. Slutligen visade resultatet att en Stirlingmotor är det mest effektiva konceptet för omvandling av lagrad energi till elektrisk energi. Slutsatserna är att det finns stora möjligheter för återvinning av restvärme på marina försvarsplattformar. En Stirlingmotor för energiomvandling i kombination med termisk energilagring visar störst potential som ett framtida system för återvinning av spillvärme på denna typen av plattformar.

This thesis presents tha findings of an investigation into the use of energy, between the years 1975 and 1984, in five of the major energy-intensive industries in South Africa. Energy use in all economic sectors, from 1964 to 1974, was surveyed in the report "Energy Utilisation in South Africa", published by the Department of Planning and the Environment in 1978. As this report showed the major primary industries to be the largest single users of energy in South Africa, it was decided to isolate a number of major energy-intensive industries for investigation in this study. The 1979 Census of Manufacturing showed five industrial sectors to have consumed 41% by value of the total industrial energy consumption in that year, and it is those with which this thesis is concerned. The five industries are: The Structural Clay Products Industry, The Portland Cement Industry, The Glass Making Industry, The Iron and Steel Industry, The Pulp and Paper Industry.

Thesis (PhD (Electrical Engineering))--Potchefstroom University, 1993.<br>The domestic sector is one of the largest users of nett energy in the RSA (24%, excluding energy used for transport), but it accounts for only 14% of the electrical energy used in the RSA. There is a very strong correlation between the time of the peak of the load for the domestic sector and the time of the peak of the national load. The domestic load is the largest contributor to the peak of the national load. This makes the domestic load more important than is generally realised. Only limited research has been done about the ways in which domestic energy is used in South Africa. Developed countries, such as the United States of America, are continuously engaged in end-use load research, so they have vast data banks available on domestic end-uses of electricity. Data on domestic end-use of electricity are urgently needed especially for South Africa with its very fast growing newly urbanised sector. Since most energy sources are not replenishable, ways and means must be found to promote the wise and effective use of all forms of energy. Effective use of energy can only be promoted if the ways in which electricity is used are known. In this dissertation the electrical energy requirements of the South African domestic sector are analyzed for the present situation and for the next few decades. A model is developed to represent the electrical load. The model has subsections representing the components of the national domestic electrical load, concentrating on electrical energy for domestic water heating, with responses to factors such as: * population growth, * urbanisation, * electrification, * energy efficiency of appliances, * consumer awareness of energy conservation. The model is to be used for scenario planning of the electrical grid. The results of this study will assist to ensure effective planning of the electrical grid of South Africa into the next century.

Tato práce o energetickém využití čistírenských kalů obsahuje popis vlastností kalu (hustota, měrná tepelná kapacita a dynamická viskozita). Stěžejní kapitoly jsou věnovány desintegraci kalu pro zvýšení obsahu sušiny po odvodnění a experimentálnímu zkoumání tvorby emisí při spalování kalu, kde byl posuzován vliv přídavku alkálie. Spalování vysušeného kalu proběhlo ve fluidní vrstvě, byla zkoumána produkce škodlivin a distribuce těžkých kovů. Druhá ucelená část práce je věnována termochemické desintegraci stabilizovaného kalu, přičemž byl experimentálně vyhodnocován vliv na obsah vody v odvodněném kalu. Provedené experimenty sloužily k detekci vhodné teploty a dávky chemikálie. Výsledky experimentů byly rovněž podkladem pro ekonomickou bilanci, která je založena na úsporách za likvidaci menšího množství kalu.

Since blasting is a comminution process, the feasibility of establishing a correlation between the Bond rod mill work index (kWh/t) and some easily measurable physico-mechanical properties relevant to blasting was investigated. Further, the concept of operating blast work index and its potential applications were explored. Four different rock types and a well documented case study of two blasts were selected for this study.<br>The work index is found to be uncorrelated with the density and unconfined compressive strength, slightly related with tensile strength, and well correlated with dynamic rock properties, especially the P-wave velocity and the bulk modulus. The standard deviation in measured compressive and tensile strength values is found to be very high, compared to their seismic and dynamic elastic properties.<br>The case study encompassed two blasts with identical blast-patterns and rock type consuming almost the same amount of explosive (kg/t) but with very different specific blast energies (MJ/t). The agreement between operating work index of the two blasts (13.4 kWh/t vs. 13.1 kWh/t) and laboratory work index (17.0 kWh/t) was modest (within 30%). The operating work index corresponding to either blast has been used to predict the product size (P$ sb{80}$) of the other. The choice of feed size (F$ sb{80}$) was discussed; whereas the previous researchers had used the theoretical value of infinity, the use of much smaller value, the average of effective burden and spacing, was proposed. This concept is used in a proposed method to estimate blasting energy requirements as a function of blast geometry, rock type and desired product size. Future test work that would provide a data base and validation for this concept is described.

<p>The increased concentration of greenhouse gases in theatmosphere, in particular CO₂, is changing the Earth’s climate. Accordingto the Kyoto protocol, where the international community agreedon binding emission targets, developed countries are committedto reduce their greenhouse gas emissions. The increased use ofbiomass in energy systems is an important strategy to reduce CO₂emissions. The purpose of this thesis has been toanalyse the opportunities for Sweden to further reduce CO₂emissions in the energy system, by rationallyutilising woody biomass energy. The characteristics of currentcommercially operating biofuel-based CHP plants in Sweden aresurveyed and systematically presented. A consistent andtransparent comprehensive reference base for system comparisonsis given. Furthermore, the fuel effectiveness and contributionto CO₂reduction is calculated. The governmentalsubsidies of the CHP plants’investment, expressed as costof specific CO₂reduction, appears to be low.</p><p>The competitiveness of biomass-fuelled energy production inrelation to fossil-based production with carbon capture isanalysed, showing that the biomass-fuelled systems provide acompetitive option, in terms of cost of electricity andefficiencies. The remaining Swedish woody biofuel potential ofat least 100 PJ/yr is principally available in regions with abiomass surplus. Transportation is therefore required to enableits utilisation in a further national and international market.Refining the biofuel feedstock to pellets, or even furtherrefining to motor fuels (DME, methanol or ethanol) or power,could facilitate this transport. Different options for fuelrefining are studied and compared. The entire fuel chain, fromfuel feedstock to end users, is considered and CO₂emissions are quantified. Substituting fuelpellets for coal appears to be the most costeffectivealternative and shows the largest CO₂reduction per energy unit biofuel. Motor fuelsappear more costly and give about half the CO₂reduction. Transportation of the upgraded biofuelpellets is highly feasible from CO₂emissions point of view and does not constitute ahindrance for further utilisation, i.e. the pellets can betransported over long distances efficiently with only limitedemissions of CO₂.</p><p>Bioenergy utilisation has additional features forenvironmental improvement, apart from the CO₂aspect. Waste heat from biofuel-based CHP can becost-effectively used in conjunction with sewage treatment. Theincoming sewage water to the nitrification process can bepreheated with the waste heat, and thereby substantiallyenhance the nitrification and the reduction of ammoniumnitrogen during the winter season.</p><p><b>Keywords:</b>CO₂reduction, energy system, biofuel, CHP, refining,fuel pellets, ethanol, methanol, DME, fuel substitution, sewagewater, nitrification.</p>

Energy plays a pivotal role in human development. Not only is it sine qua non for national economic development, but it also provides services that enhance social development including, health and sanitation, education, potable water, cooking. In spite of this, at present, there are about two billion people without access to modern sources of energy, most of them in the rural areas of the developing world. Consequentially, the social and economic development of these two billion people hangs in the balance. In recent times, however, considerable advocacy has taken place in the academic and policy studies, environmental fora, and national agenda about solar PV energy technology serving as a panacea to the energy problems of rural populations in developing countries, especially Sub-Sahara Africa, whilst also helping to reduce greenhouse gas emissions. Notwithstanding this great advocacy, the literature on the dissemination of this technology has been incomplete in fostering understanding on the discourses surrounding its low dissemination rates in rural Ghana compared to countries such as Kenya and Zimbabwe; the sustainability of installed solar PV systems; and the usefulness of solar PV in serving the needs of the rural poor. In resorting to an interdisciplinary approach (methodology and theoretical foundation), this study has explored the energy perspectives of Ghana, the dynamics of rural electrification and energy needs, and the interplay of processes and forces underpinning the adoption and non-adoption of solar PV in rural Ghana. Results of this study show that, Ghana has abundant renewable energy resources, especially solar radiation. However, the study further reveals that the resource base alone of solar PV technology is not the panacea to its successful dissemination and the energy needs of all in rural Ghana. Significantly, this study has shown that the adoption and non-adoption perspectives of solar PV in rural Ghana and the sustainability of installed solar PV systems, as well as the disparate levels of solar PV dissemination in Ghana, Kenya and Zimbabwe, are contingent on multi-dimensional circumstances. This stands in contrast to the majority of literature that often emphasise cost as the sole determining factor of the non-adoption of solar PV in most developing countries. Results of this study therefore have implications for rural energy supply policy approaches and other institutional arrangements on solar PV issues in Ghana.

The persistent increase in the price of energy, the clamour to preserve our environment from the harmful effects of the anthropogenic release of greenhouse gases from the combustion of fossil fuels and the need to conserve these rapidly depleting fuels has resulted in the need for the deployment of industry best practices in energy conservation through energy efficiency improvement processes like the waste heat recovery technique. In 2006, it was estimated that approximately 20.66% of energy in the UK is consumed by industry as end-user, with the process industries (chemical industries, metal and steel industries, food and drink industries) consuming about 407 TWh, 2010 value stands at 320.28 TWh (approximately 18.35%). Due to the high number of food and drink industries in the UK, these are estimated to consume about 36% of this energy with a waste heat recovery potential of 2.8 TWh. This work presents the importance of waste heat recovery in the process industries in general, and in the UK food industry in particular, with emphasis on the fryer section of the crisps manufacturing process, which has been identified as one of the energy-intensive food industries with high waste heat recovery potential. The work proposes the use of a dual heat source ORC system for the recovery and conversion of the waste heat from the fryer section of a crisps manufacturing plant to electricity. The result, obtained through modelling and simulation, shows that the proposed technology can produce about 92% of the daily peak electricity need of the plant which is currently 216 kW. Also, the economic analysis shows that the proposed technology is viable (even at an inflation rate of 5.03% and discounted rate of 6%), with a payback period of approximately three years and net present value of over £2.2 million if the prices of electricity and carbon is at an average value of £0.16 and £13.77 respectively throughout the 30 years service life of the plant. The life cycle assessment study shows that the proposed technology can reduce the CO2 emission by 139,580 kg/year if the electricity produced is used to displace that which would have been produced from a conventional coal-fired power plant.

This thesis reports the investigation of Bismuth oxybromide (BiOBr) semiconductor material as an efficient photocatalyst for the sunlight harvesting as well as environmental cleanup. I have utilised different synthetic methodologies to obtain BiOBr and its derivatives, such as co-precipitation, ultrasonification, and photo-deposition; and have studied their structural and optical properties by X-ray diffraction and surface analysis techniques. I report the synthesis and characterisation of two new p-n heterojunction systems, AgBr-BiOBr and BiOBr-ZnFe₂O₄, and have performed initial studies on photocatalytic reaction and their catalytic decomposition mechanisms. I have also reported the surface modification method including the deposition of noble metal on BiOBr to investigate the role played by the noble metal and the interactions between semiconductor and metal using various characterisation measurements. Furthermore, a continuous series of BiOBr-BiOI solid solutions were synthesised, characterised and the photocatalytic degradation was performed on the as-obtained semiconductors, to study the band structure properties of the solid solutions.

Food and drink processing industries are extremely large consumers of thermal energy as well as bio waste producer. There are huge opportunities to utilise the bio wastes for energy generation. In this project two cases were studied. Fermented grains and hops are used for the beer production and at the end the used materials are disposed with the yeast as organic wastes, in a similar way rice spirit is produced from a mixture of grains which are discarded at the end as spent grains. The feasibility of using the waste individually or in a mixture as feed for Anaerobic Digestion (AD) was evaluated. This project has considered the concepts of generating a more environmentally friendly thermal energy using solely the bio wastes from the industry and if applicable the low grade waste heat available to integrate a waste to energy system. In order to assess the viability of the use of the bio wastes, experimental work in the laboratory for the characterisation of the waste streams as well as an energy audit was performed. Continuous Stirred Tank Reactors (CSTR) were run for a period of time at mesophilic and thermophilic conditions, using the waste grains individually and in a mix. Once the bio methane potential was determined, simulations of the process were executed using engineering software and compared with the data gathered from the site visit. It is found that the figures of final composition of the product as well as the mass and energy balance were similar to the data obtained. The results showed the potential to use the spent grains as feed for the AD plant to produce biogas is positive, covering up to 70% of the total fuel required for production in the case of the brewery and 100 % in a spirit plant. It was also noticed that running the system at thermophilic temperature had a better performance in terms of methane content. The biogas could be used instead of the fossil fuel being used at the moment. Replacing the current use of fossil fuel will be a positive impact in CO2 emissions reduction as well as economic performance for the brewery, since these bio wastes are often given away to farmers free of charge or more expenses would be incurred in discarding them from the site. This will lead to self-sustained production process and improve the waste management.

CMOS technology scaling improves the speed and functionality of microprocessors by reducing the size of transistors. Static power dissipation also increases as a result of scaling however, and has been identified as a limiting factor in technology scaling. As current technology approaches that limit, techniques are required both at the technology-level and in the architecture design to reduce sub-threshold leakage, which accounts for the majority of static power dissipation. This thesis presents an approach to predict the idle periods of execution units at runtime and power-gate them during these periods to eliminate their static power leakage. We exploit similar execution characteristics across loop iterations to build a prediction of the units required to execute an entire loop from the units used over the first few iterations. The utilisation of each execution unit is monitored for each iteration, and thresholds are used to determine which units should be power-gated for the remainder of the loop. Three techniques are presented: Loop-Directed Mothballing (LDM), Extended Loop-Directed Mothballing (ELDM) and schedule balancing. LDM power-gates execution units only during innermost loops, which are simple to detect at runtime. ELDM extends this method to all loops using loop entry and exit information gathered offline. The balancing scheduler is developed to balance the types of instruction issued each cycle, to encourage reuse of execution units and make unnecessary units easier to detect. Extensive simulation using traces of 16 benchmarks from the SPEC CPU2006 suite demonstrates that LDM reduces the energy-delay product of our simulated superscalar processor by 10.3%. For traces with a low proportion of executed instructions inside innermost loops, ELDM improves the energy-delay product by up to 13% by allowing the technique to be applied to other loops in the trace. Employing schedule balancing with ELDM achieves similar savings, and simplifies the hardware required to make predictions.

In order to significantly lower the environmental impact from human activities, numerous efforts and approaches related to the transformation of human activities have developed during the last decades. Examples of such efforts are policies and strategies at different levels, some with a top-down approach focusing on extensive institutional changes, and some with a bottom-up approach focusing on industrial actors and industry-led activities. One essential aspect of these efforts concerns the energy used producing the products and services provided within our society. This includes, for example, improved efficiency of processes in order to minimise the amount of energy used, or optimisation of efficiency by using energy with the lowest possible exergy value. It can also be about re-use of energy, which is the focus of this thesis. Heat, which is the main by-product of all energy systems, can be utilised for heating purposes to lower the primary energy demand for heating. Increased utilisation of excess heat, however, requires collaboration between normally unrelated actors, those with a supply of and those demanding excess heat. In Sweden, which is a Northern European country with high demand for heat, the tradition of large energy-intensive manufacturing industries generating large amounts of excess heat, in combination with well-established district heating distribution systems, constitute good conditions for excess heat utilisation. Despite the fact that Sweden is among the world leaders in utilising excess heat, there is however, still a large unutilised potential. From this background, the objective of this thesis is to identify challenges behind excess heat utilisation for heating purposes, and to propose practical suggestions to facilitate expanded excess heat utilisation. The overall objective is analysed with a focus on drivers and barriers behind interorganisational collaborations on excess heat utilisation, important components of interorganisational business models and how the technical conditions regarding supply and demand could be facilitated by strategic municipal spatial planning processes. The research is largely based on interviews conducted with societal actors with different perspectives on excess heat utilisation; energy companies, industries generating high-grade excess heat, facilities generating low-grade excess heat, facilities demanding low-grade excess heat, experts of utilisation of low-grade excess heat, branch organisations, municipal spatial planners, energy- and climate advisors, and developers. Document studies have been conducted in order to collect case specific knowledge. The research questions are explored based on literature studies on the principles of industrial symbiosis, business model perspective and strategic planning. Further, they are examined in a Swedish context. It is concluded that the three perspectives complement each other by providing a system perspective on increased utilisation of excess heat as they seek to contribute both environmental and financial benefits at both a company and societal level. In order to facilitate further utilisation of excess heat it is important to focus on the organisational factors of humility, honesty, transparency, trust, fine-grained information transfer, joint problem solving, and shared visions of common goals, which are important conditions behind development of functional and long-term durable collaborations. Business models for collaboration could contribute to the creation of these organisationally important conditions. Such business models could also provide knowledge on how to create and capture joint values. For some collaborations involving actors lacking the technical knowledge related to the capturing and distribution of excess heat, a third-party providing services related to the technical knowledge required could be beneficial. Collaborations in which one of the actors consists of an energy company often entail the technical knowledge required. This implies that different collaborations involving different types of actors and under different prevailing financial, technical and organisational conditions require customised and flexible business solutions. Local authorities could, through their overall function, initiate interorganisational collaborations on excess heat within the framework of municipal spatial planning. The results do however show that the investigated planning processes could develop more extensive stakeholder participation to include further societal actors related to excess heat. More extensive stakeholder participation, have the potential to initiate new development of collaborations on excess heat between normally unrelated actors, both with and without involvements of third-party knowledge brokers. A broader participation is also expected to result in increased knowledge on how to plan to further facilitate the condition of excess heat utilisation.

In the present study a thorough characterisation of biomass residue obtained from bio diesel production is done. The experiments are performed in the State University of Campinas in Sao Paulo, Brazil. It also investigates the feasibility to carry out thermo chemical energy conversion processes like pyrolysis and gasification on the biomass residues. The residue obtained after oil extraction from the seeds of Jatropha curcas and glycerol – a by product of bio diesel production process are the samples characterised. The samples are subjected to proximate analysis, calorimetry and TGA- thermo gravimetric analysis to characterise. Moreover a literature survey of thermo chemical process likes pyrolysis and gasification is carried out. It was found that in the test sample of Jatropha curcas residue the volatiles are in a range of 67-70 wt%, fixed carbon content 18-21 wt% and ash 6-13 wt%. The average calorific power of the three Jatropha curcas residue samples was 20.5 MJ/Kg, 20.63 MJ/Kg and 21.24 MJ/Kg respectively. While in case of glycerol it was 25.60 MJ/m3. The maximum weight loss for Jatropha curcas residue occurs in the temperature range of 330-350 0C and for glycerol it is in range of 285-3000C. It was concluded that it is technically and economically feasible to gasify the residue of Jatropha curcas owing to it high calorific power and volatile matter content. Jatropha curcas residue also has a high ash content so special design consideration should be made to handle ash while designing its gasification system. In case of glycerol, technically, it can be gasified to convert it into high value products but it is necessary further study in order to determine if it is economically feasible.

Following an ongoing change towards an increasingly renewable power generation system Swedish grid operators are facing several challenges in coming years. As authorities plan for the decommissioning of nuclear power an increased reliance on de-centralised energy sources such as photo-voltaic distributed generation (PVDG) is expected. A technology observed in some cases to accompany local power quality issues severe enough to impose grid expansion measures from distribution system operators (DSOs). Considering a combination of an indicative utilisation inefficiency of classical grid expansion measures and a recent year maturing of various energy storage technologies, this report sets out to evaluate the possibility of utilising centralised energy storage systems (ESSs) for deferment of classical grid expansion measures. For the purpose of identifying the most prominent problem scenarios of modern production- and consumption behaviours as well as the possible solutions offered by centralised ESSs, a literature review of journal articles and technical reports was conducted in combination with a case-study of an existing urban grid operated by Umeå Energi Elnät AB (UEEN). The work regarding ESSs is directed with specific focus towards evaluating which ESS services can potentially facilitate grid expansion deferment and what ESS placement is advisable for efficient utilisation. Assessing possible grid safety implications, potential for peak load shaving and the presently most suitable energy storage technology was also within the scope of the study. The literature review reveals PVDG induced feeder line over-voltage and transformer overload the most likely and previously observed implications imposing grid expansion measures. The former more prominent in elongated, typically rural, grids and the latter in more densely populated urban grids. For deferment of over-voltage related grid expansion measures a centralised ESS can be utilised for voltage support provided placement is made close to the affected grid section, presumably far out the affected feeder line. This result is coherent throughout the reviewed literature and is supported by the results of the case-study. Distribution transformer overload and its imposed grid expansion measures can be deferred through load re-allocation and peak load shaving, two services proven achievable by centralised ESSs and the capacity for which increases if ESS placement is made closer the distribution transformer. Provided present regulatory and standards are adhered to upon installation, significant negative impact of centralised ESSs on distribution grid safety can be avoided. Most energy storage technologies, including battery based energy storage technologies indicated from the literature review providing the most suitable characteristics for use in centralised distribution grid ESSs, utilise well established systems for grid connection hence no presently unsolvable grid safety implications are identified. Technical reports of real applications of centralised ESSs reinforce this argument as successful implementation without ESS caused grid safety implications have been achieved in the Swedish distribution grid in the past.

Renewable energy in Libya, in particular solar and wind energy, can partly cover current local energy demands. It can also, through connections to the Middle East, Africa and Europe, provide neighbouring countries with electricity. Additionally, with the increase in energy demand around the world, and the international effort to reduce carbon emissions from fossil fuels, there has been a drive in many oil-rich countries to diversify their energy portfolios and resources. Libya is currently interested in utilising its renewable energy resources in order to reduce the financial and energy dependency on oil reserves. This research investigates the current utilisation and the future of renewable energy in Libya, and the challenges and opportunities for investment in renewable energy in Libya. This study has explored the possibility of utilising the available renewable energy resources in Libya to offer the Libyan government a strategy for providing sustainable energy resources. This is expected to reduce carbon emissions, and help achieve an economically, socially and environmentally sustainable energy future. Interviews have been conducted with managers, consultants and decision makers from different government organisations, and have included energy policy makers, energy generation companies and major energy consumers. A comprehensive survey has been conducted to evaluate several characteristics of domestic energy demand and energy consumption in Libya. The findings have indicated that, despite the recent political changes and the challenges that face the implementation of renewable energy technologies in Libya, renewable energy opportunities are still strategically of high importance. Solar and wind energy are considered the main sources of renewable energy for Libya. It has been found that energy demand is increasing in Libya and that renewable energy could be a solution to cover some of this demand. In addition, the results have indicated that there are no clear policies that support the implementation of renewable energy projects within Libya, and no clear legislation aimed at the types of technical, commercial and environmental issues which must be addressed for the implementation of renewable energy projects in Libya. Legislations governing the legal support for facilitating the spread of renewable energy in Libya are also limited. Moreover, there is a need to attract investors in renewable technologies by enhancing the country's infrastructure and improving the existing investment regulations.

The main objective of this study is to survey the market prospects of non-conventional power-generating and transforming equipment in the Pacific Rim, a region where most of the newly industrialised and oil producing countries are found. The Asia and Pacific region is pioneering the application of, and trade in, non-conventional energy equipment. Partly because they have been at the forefront of developing both the technology and the markets for the products under review, and partly because of their potential as producers, users, traders, the following countries have been selected for study: Indonesia, the Philipines, Thailand, and Malaysia. The technologies covered are: solar photovoltaic systems, small hydropower, wind energy, solar thermal, and biomass (fuelwood/charcoal, biogas, digesters, and biomass gasifiers). In implementing an analysis of this nature, a multi-disciplinary approach must be undertaken. Therefore, this thesis not only examines the technical aspects but the social, political, economic, and environmental consequences of the utilisation and dissemination of renewable energy systems. In order to discover the role that renewable energy systems play in each country, the overall energy context must be understood. Too often energy systems analysis and planning is done in an insular fashion, with conventional energy usage and planning accomplished separately from non-conventional energy systems. In many of the countries studied non-conventional/renewable energy has been handled by an alternative agency, generally one in charge of rural development, and as such, renewable energy systems in the Pacific Rim have not fared as well as they could have.

In the context of energy transition, geothermics play an important role for the heating and cooling supply of both residential and commercial buildings. Thereby, the increasingly and intensive utilisation of shallow geothermal resources bears the risk of over-exploitation and thus poses a future challenge to ensure the sustainability and safety of such systems. Particularly, the well-established technology of borehole heat exchanger-coupled ground source heat pumps is applied for the thermal exploitation of the shallow subsurface. Due to the complexity of the involved physical processes, numerical modelling proves to be a powerful tool to enhance process understanding as well as to aid the planning and design processes. Simulations can also support the management of thermal subsurface resources, planning and decision-making on city and regional scales. In this work, the so-called dual-continuum approach was adopted and enhanced to develop a coupled numerical model considering flow and heat transport processes in both the subsurface and borehole heat exchangers as well as the heat pumps’ performance characteristics, and including the relevant phenomena influencing the underlying processes. Beside the temperature fields, the efficiency and thus the consumption of electrical energy by the heat pump is computed, allowing for the quantification of operational costs and equivalent carbon-dioxide emissions. The model is validated and applied to a number of numerical studies. First, a comprehensive sensitivity analysis on the efficiency and sustainability of such systems is performed. Second, a method for the quantification of technically extractable shallow geothermal energy is proposed. This procedure is demonstrated by means of a case study for the city of Cologne, Germany and its implications are discussed<br>Im Rahmen der Energiewende nimmt die Geothermie eine besondere Rolle in der thermische Gebäudeversorgung ein. Die zunehmende, intensive Nutzung oberflächennaher geothermischer Ressourcen erhöht die Gefahr der übermäßigen thermischen Ausbeutung des Untergrundes und stellt damit eine wachsende Herausforderung für die Nachhaltigkeit und Sicherheit solcher Systeme dar. Zur Erschließung oberflächennaher geothermischer Energie wird insbesondere die etablierte Technologie Erdwärmesonden-gekoppelter Wärmepumpen eingesetzt. Aufgrund der daran beteiligten komplexen physikalischen Prozesse erweisen sich numerische Modelle als leistungsfähiges Werkzeug zur Erweiterung des Prozessverständnisses und Unterstützung des Planungs- und Auslegungsprozesses. Zudem können Simulationen zum Management thermischer Ressourcen im Untergrund sowie zur Planung und politischen Entscheidungsfindung auf städtischen und regionalen Maßstäben beitragen. Im Rahmen dieser Arbeit wurde, basierend auf dem sogenannten ”dual-continuum approach” und unter Berücksichtigung des Einflusses der Wärmepumpe, ein erweitertes gekoppeltes numerisches Modell zur Abbildung der in Erdwärmesonden und dem Untergrund stattfindenden Strömungs- und Wärmetransportprozesse entwickelt. Das Modell ist in der Lage, alle relevanten Einflussfaktoren zu berücksichtigen. Neben den Temperaturfeldern im Untergrund und der Erdwärmesonde werden die Effizienz und damit der Stromverbrauch der Wärmepumpe simuliert. Damit können sowohl die Betriebskosten als auch der äquivalente CO 2 -Ausstoß abgeschätzt werden. Das Modell wurde validiert und in einer Reihe numerischer Studien eingesetzt. Zuerst wurde eine umfassende Sensitivitätsanalyse zur Effizienz und Nachhaltigkeit entsprechender Anlagen durchgeführt. Weiterhin wird ein Verfahren zur Quantifizierung des technisch nutzbaren, oberflächennahen geothermischen Potentials vorgestellt und anhand einer Fallstudie für die Stadt Köln demonstriert, gefolgt von einer Diskussion der Ergebnisse

Les travaux de cette thèse portent sur l'optimisation des flux énergétiques et informatiques dans un réseau intelligent ayant pour but d'alimenter un centre de calcul via des énergies renouvelables. Dans cette thèse sont traités les problèmes liés à la mise en commun des informations de types énergétique et informatique dans une contrainte de réactivité forte à travers la création d'une architecture pour un réseau intelligent. La modélisation d'un tel réseau doit permettre la prise de décision de manière dynamique et autonome. L'objectif de cette modélisation, via un réseau intelligent, est l'optimisation des ressources renouvelables afin de diminuer l'empreinte écologique<br>The work of this thesis deals with the optimization of energy and computer flows in an intelligent network aiming to supply a data center via renewable energies. In this thesis are treated the problems related to the pooling of energy and computer information in a strong reactivity constraint through the creation of an architecture for an intelligent network. The modeling of such a network must allow the decision making in a dynamic and autonomous way. The objective of this modeling, via an intelligent network, is the optimization of renewable resources in order to reduce the ecological footprint

1. High temperature decreased food intake, growth rate, energy retention as protein and water retention but had no effect on energy retention as fat and little effect on total energy retention. 2. High temperature did not affect the proportion of apparent metabolisable energy retained as protein or the efficiency of energy retention from apparent metabolisable energy. However, it increased the proportion of apparent metabolisable energy retained as fat. The latter effect was attributable to the reduced energy requirement for thermoregulation. 3. Offering the birds a choice between a "high-protein" and a "high-energy" diet did not improve growth when the animals were exposed to high temperature (30°C). Moreover, choice-feeding led to decreased food intake and, in turn, growth rate in birds kept at moderate temperature (20°C) when compared with those given a complete compound diet. 4. Compared with birds kept at 20°C and fed <I>ad libitum, </I>there was a lower concentration of plasma triiodothyronine in birds kept at 20°C but pair-fed the same amount of food as birds eating <I>ad libitum </I>at 30°C. Triiodothyronine concentration was shown to be affected directly by food intake as well as by ambient temperature. 5. High temperature reduced the quantity of digesta in the gut. It was suggested that this may be due to a reduced ability of the gut to process food. 6. Dietary modifications such as finely grinding and wetting the food led to increased food consumption and growth rate at high temperature. 7. Increasing the sodium chloride content of a finely ground and wetted diet improved metabolisability. 8. Increasing the protein content of a finely ground and wetted diet increased body weight gain but caused decreases in total energy retention, protein retention efficiency and metabolisability. 9. It is usually assumed that reduced food intake at high temperature results firstly from a decrease in energy requirements for thermoregulation and secondly from the need to minimise heat stress by reducing the heat increment of feeding. However, the results of this project suggest that the domestic fowl reduces its food intake at high temperature not to reduce or limit heat production, but because the gut is limited in the amount of food it can process. If the gut is "assisted" by providing wetted or finely ground food, food intake, growth rate and heat production all increase.

This thesis carries out an analysis of PV panel installations in the region of Östergarnslandet, situated in the Swedish island of Gotland. A low-voltage grid of 0.4 kV in the region is examined with the help of software Open DSS. This is done with the data provided by the distribution grid owner, Gotlands Elnät AB (GEAB). The potential impacts created by the PV installations in terms of exceeding currents, voltages and harmonics are assessed and thereby the hosting capacity of Solar PV in the houses and on the whole grid is studied.   Moreover, a theoretical review of the Smart Energy Management System (SEMS) is investigated about the performance and the devices involved in the system. Also, a battery which is a part of SEMS is modelled, taking into account the production and consumption of a single household connected in the grid. The battery sizes for various PV installations at the home is suggested via NPV analysis with the intention to increase the self-consumption and to reduce the cost of the electricity bill. In addition, a survey is conducted in the region with support from the Department of Earth Sciences, Uppsala University Campus Gotland. The survey is made to determine the attitude of the people in Östergarnslandet towards an energy transition. The results show that the maximum amount that can be installed or the hosting capacity of solar in the studied grid is 120 kW. From the simulations, it shows that the impacts created by these PV installations do not violate the specified Grid norms. From the theoretical analysis, SEMS is found to be a better solution for energy management at homes. The performance study done shows that 33 % of the solar energy produced in the home is directly used at the time of production. The remaining energy is used for battery charging for the future supply of power and feeding to the grid. The battery modelled for 10- kW PV installation in the home is found to be 9-kWh and the same for a 15-kW installation. Meanwhile, for a 20- kW installation, a 15-kWh battery is found to be ideal from the study. The survey conducted in the region has turned out to be positive as people are supportive of the energy transition. The responders have marked photovoltaics as the prime option for investment in energy production which assures that it has a good future in the area.

Thesis (MScEng)--University of Stellenbosch, 2002.<br>ENGLISH ABSTRACT: The cost of powering Antarctic research stations by conventional diesel electric generator systems is high (Steel, 1993). In order to reduce these costs and airborne pollution due to the combustion of fossil fuels, an investigation into renewable energy sources has been conducted, with the focus on wind turbine energy generation. The aim was to see whether a wind turbine is feasible, both technically and economically, for partial energy production at the SANAE IV base. The existing diesel electrical generators will still be used for the base demand, when there is not enough wind or when the energy demand is more than can be produced by the wind turbine. The work accomplished for this study explains and motivates a MSc. (Eng.) thesis on the feasibility of installing wind electricity generators at Antarctica. This evaluation was done for the South African research station SANAE IV in Antarctica. It provides information on the literature consulted to date, the theoretical and practical work covered, the theoretical investigations, the results obtained and future implementations. Also included in this work was a trip to Antarctica, so that all the relevant data, like wind speeds and wind direction could be measured. Another reason for having done the trip was to do an energy audit for SANAE IV, so that the energy demand for the base could be established. The energy demand of the base varies among other factors, for summer and winter conditions, for day and night conditions, and for population variations. With the information obtained during the trip, the theoretical evaluation of a possible wind turbine system was performed. With the aid of the data from the 6 m wind mast, wind profiles have been established, from which Wei bull distributions were obtained, and the energy output from 5 different wind turbines, in the range between 10 kW and 100 kW, were calculated. The annual energy production of the 100 kW wind turbine is 430 MWh with a capacity factor of 49 %. The annual energy demand of the base amounts to 1153 MWh, thus the wind turbine could contribute up to 30 % of the power needed at the base taking losses, such as availability and maintenance losses, into account. From the automatic weather station of the South African Weather Services, positioned at SANAE IV, wind speed and direction data for the year 2001 was obtained and this data was analyzed. The results show that the winds at SANAE IV are highly directional, coming mostly from an eastern and southeastern direction. This highly directional wind pattern is well suited for wind turbine application. The average wind speed, being measured at 10m height, is 10.8 m/s and the hourly averaged maximum wind speed for the year 2001 is 38.9 mls. From the wind analysis, site survey, cold weather issues and connection to the electricity grid of the base, it becomes evident that the North Wind NWIOO/19 100 kW wind turbine is the best-suited wind turbine for installation at SANAE IV. One of the major advantages of the NW100/19 is that it features a tilt-up tower erecting system that enables the wind turbine to be installed without the use of a crane. The NW100/19 is the only turbine rated at 100 kW, with this feature. From the economic analysis it is evident that a wind turbine, with the complete installation, operation and maintenance costs, features a break even period of 10 years, when installed at SANAE IV. This relatively short breakeven period, considering that the life of the turbine is 30 years, originates from the fact that the average wind speed at the base is about 11 mis, which is relatively high and yields enormous power productions. This wind turbine operates for approximately 80 % during a year, which is very high, making this renewable energy source very attractive as a power-generating source for SANAE IV. The cost per kWh produced by the wind-diesel system is R1.63/kWh, while the cost per kWh produced by the current diesel generators, satisfying the power demand of the base, is R1.94/kWh. Thus the hybrid system can reduce the cost of power produced by almost 20 %, which again demonstrates the attractiveness of using wind power at SANAE IV. From an environmental point of view, the use of wind power at SANAE IV is favorable, since a wind turbine has minimal effects on the environment at Antarctica. The cost of emissions and fuel spills were calculated for SANAE IV. The fuel saving, resulting from the operation of a wind turbine at SANAE IV, converts to a saving in externalities of about R500 000.00 per year, using an evaluation method that was applied to remote Alaskan villages. It can therefore be concluded that the aims of the project have been fully accomplished and that the use of wind power at SANAE IV is indeed a very attractive option, regarding all the criteria mentioned above. When it is being decided that a budget will be provided for a wind turbine installation, the economic analysis has to be refined, due to the uncertainty of the market value of the South African currency.<br>AFRIKAANSE OPSOMMING: Die koste verbonde aan krag voorsiening vir Antarktiese navorsingstasies deur middel van konvensionele diesel elektriese kragopwekkers is baie hoog (Steel, 1993). Om hierdie kostes en lugbesoedeling weens die verbranding van fossielbrandstowwe te verminder, is 'n ondersoek na hemubare energiebronne gedoen, met die fokus op windturbiene energie opwekking. Die doelwit van die studie was om te sien of 'n windturbiene aanwending vir kragopwekking vir die SANAE IV stasie lewensvatbaar is, gebaseer op tegniese en ekonomiese uitgangspunte. Die bestaande diesel elektriese kragopwekkers sal nog altyd gebruik word vir kragopwekking, as daar nie genoeg wind is nie, of as die energievraag hoer is as wat kan verskafword deur die wind turbine. Die werk wat vir hierdie studie voltooi is belig en motiveer 'n MSc(Ing) tesis oor die lewensvatbaarheid vir installering van 'n windelektriese kragopwekker op Antarktika. Hierdie evaluasie is gedoen vir die Suid Afrikanse navorsingstasie, SANAE IV, op Antarktika. Dit behels informasie oor die literatuur verwerk tot dusver, die teoretiese en praktiese werk gedoen, die teoretiese ondersoeke, die resultate verkry en toekomstige verwesenlikings. Werk ook ingesluit was 'n expedisie na Antarktika toe, sodat al die relevante data, soos wind spoed en rigtings gemeet kon word. Nog 'n rede om die expedisie te doen was om energie data van SANAE IV te meet, sodat die energieverbruik van die basis bevestig kon word. Die energieverbruik van die basis varieer ten opsigte van somer en winter kondisies, van dag en nag variasies en inwonergetalle. Met die informasie verkry gedurende die expedisie kon 'n evaluasie gedoen word vir 'n moontlike windturbiene stelsel op Antarktika. Met die hulp van 'n 6tn wind toring kon wind profiele gekry word, waarvandaan Weibull verdelings bereken is en die kragopwekking van 5 verskillende windturbienes bereken is, wat wissel van 10 kW tot 100 kW. Die jaarlikse energieopwekking vir die 100 kW wind turbine is 430 MWh met 'n kapasiteitsfaktoor van 49 %. Die jaarlikse energieaanvraag van die stasie is 1153 MWh. Dus kan die wind turbine ongeveer 30 % van die jaarlikse energieaanvraag dek, as verliese soos beskikbaarheids- en instandhoudingsverliese III berekening gebring word. Wind spoed en rigting data vir die jaar 2001 is verkry van die outomatiese weerstasie van die Suid Afrikaanse Weer Diens, wat geposisioneer is by die SANAE IV stasie, en hierdie data is geanaliseer. Die resultate verkry bewys die direksionele stabiliteit van die winde by SANAE IV, waarvandaan die meeste winde uit die oostlike en suidoostlike rigting kom. Hierdie hoogs gekosentreede winde is baie goed geskik vir windturbiene aanwending. Die gemiddelde wind spoed, wat gemeet is op 'n hoogte van 10 m is 10.8 m/s en die uurlike gemiddelde maksimum wind spoed vir die jaar 2001 is 38.9 m/s. Van die wind analise, terrein analise, koue weer informasie en koppeling van die wind turbine by die bestaande elektrisiteits netwerk word bevestig dat die North Wind NW100119 100 kW windturbiene die geskikste windturbiene vir installasie en werking by SANAE IV is. Een van die grootste voordele van die NW100/19 windturbiene is dat dit 'n selfoprigdende meganisme het, wat sonder die hulp van 'n kraan werk. Die NW100/19 is die enigste windturbiene in sy klas, wat so 'n funksie het. Van die ekonomiese analise kan afgelei-word, dat 'n wind turbine met volledige installasie, werking en diens kostes, 'n kapitale terugbetalings periode van 10 jaar het, as dit by SANAE IV geinstalleer word. Hierdie tydperk is relatief kort, as gekyk word na die ontwerp leeftyd van 30 jaar van die NW100/19 wind turbine. Die rede vir die kort terugbetalings periode is afkomstig van die hoe gemiddelde wind spoed by SANAE IV, wat enorme kragopwekking tot gevolgtrekking het. Dit kan ook gesien word aan die hoe werkingsure van die turbine wat 6942 uur per jaar is. Dus wek die turbine vir omtrent 80 % van die jaar krag op, wat beinvloed dat 'n wind turbine opsie vir SANAE IV baie aantreklik is. Die koste per kWh krag opgewek vir die wind-diesel sisteem is R1.63/kWh, terwyl die koste per kWh krag opgewek vir die huidige diesel generator opstelling R1.941kWh is. Dus kan 'n kostebesparing van tot 20% van die energie onkostes verkry word, wat weer eens beklemtoon, dat die wind-diesel sisteem baie aantreklik vir kragopwekking by SANAE IV is. Vanaf 'n omgewingsoogpunt gesien het die gebruik van 'n wind turbine stelsel by die SANAE IV stasie net weglaatbaar klein invloede op die omgewing in vergelyking met die lugbesoedeling van die diesel kragopwekkers. As die koste verbonde aan lugbesoedeling en brandstof lekkasie besoedeling bereken word kan die wind turbine stelsel omtrent R500000.00 per jaar aan besoedeling onkostes spaar. Die getalle vir besoedelings onkostes is gebaseer op die evaluasie van besoedeling vir afgelee Amerikanse dorpies (Isherwood et al., 1999). Dit kan dus afgelei word vanaf die bogenoemde bevindings, dat die doelwitte van die tesis bereik is en dat wind krag opwekking by SANAE IV inderdaad 'n baie aantreklike moontlikheid is. Wanneer 'n begroting beskikbaar gestel word vir 'n windturbiene stelsel vir SANAE IV, moet die ekonomiese analise geoptimeer word weens die onsekerheid van die markwaaarde van die Suid Afrikaanse Rand.

Thesis (MScEng (Mechanical and Mechatronic Engineering))--University of Stellenbosch, 2005.<br>There are numerous challenges that have to be overcome in order to generate the electrical and thermal energy required to power Antarctic research stations in a technically, economically and environmentally suitable manner. Consequently the costs associated with generating energy at these latitudes are high, and ways are constantly being sought to improve energy generation methods and protect the pristine environment. These endeavours are strongly encouraged by the Antarctic Treaty. This thesis aims to investigate the technical and economic feasibility of using solar energy at South Africa’s SANAE IV (South African National Antarctic Expedition IV) station in Antarctica. The idea of using solar energy in Antarctica is not novel, and as is shown a number of stations have already capitalised on opportunities to generate savings in this manner. Similarly, at SANAE IV, there exists the opportunity to alleviate an increased summer energy load on the station and reduce diesel consumption through the proper implementation of such a system. There is also ample scope to use wind energy, which would have a marked positive impact on the base’s operation. The data used in this thesis was obtained mainly during the 2004/2005 takeover expedition to South Africa’s SANAE IV station in Antarctica. Included are measurements of total and diffuse radiation that were measured during the months of January and February 2005, and which form an important part of the investigation. Since there are currently no radiation sensors, or any historical record of measured radiation at the station, the only measured data available from SANAE IV was the data recorded during the 2004/2005 takeover expedition. By further collecting archived values of fuel consumption, electricity generation and load profiles, an energy audit of the station was also completed during the 2004/2005 takeover expedition. The expected savings that could be generated by solar systems were calculated by considering the use of both photovoltaic and solar thermal devices at the South African station. The 40 kW photovoltaic system that was investigated was able to significantly reduce the load on the dieselelectric generators, however it was only possible to fully recover the initial costs sunk into commissioning the system after 21 years. The installation of such a system would equate to a Net Present Value of 302 915 Rand at the end of the 25 year system lifetime (assuming a real hurdle rate of 8 % and fuel price escalation rate of 5 %), saving 9 958 litres of diesel annually generating energy at a cost of 3.20 Rand/kWh. It should be noted, however, that under more ideal conditions (i.e. less attractive alternative investment opportunities, higher fuel price escalation rates and a stronger emphasis on environmental concerns) investment into a photovoltaic system could potentially breakeven after approximately 10-15 years, while simultaneously significantly improving base operation. Furthermore, it was found that a flat-plate solar thermal collector utilised with the snow smelter at SANAE IV is better suited to generating savings than photovoltaic devices. The average cost of generating electricity after commissioning such a system with a 143 m2 collector field would be approximately 3.13 Rand/kWh, as opposed to the 3.21 Rand/kWh of the current diesel-only system, and would realise an annual fuel saving of approximately 12 245 litres. The system would arrive at a breakeven point after approximately 6 years, and represent a Net Present Value of 2 148 811 Rand after 25 years. By further considering environmental factors such as the cost of removing soiled snow from Antarctica and diesel fuel emissions the magnitude of the net present savings would increase by approximately 500 000 Rand over the expected 25 year project lifetime. The opportunity to install a solar energy system at SANAE IV therefore warrants action. There is potential not only to generate savings over the operational lifetime but also to preserve the environment in accordance with the desires of the Antarctic Treaty. It is firmly believed that with careful planning and implementation such a project can and should be successfully undertaken.<br>Centre for Renewable and Sustainable Energy Studies

The desire to develop national greenhouse gas (OHO) emission inventories and mitigation strategies to reduce carbon footprint of cattle production systems, has prompted interest to fill the knowledge gap of OHO emission from young cattle in the UK. The current UK government funded study was undertaken over a two-year period to evaluate the effects of gender (steers vs. heifers) of growing Holstein cattle (6 to 22 months of age) on enteric methane emissions and energy and nitrogen utilisation and then to use these data to develop prediction models for quantification of carbon footprint of the dairy production sector. Twenty 5-month old Holstein cattle (10 steers and 10 heifers) were used in successive 28 d feeding period, with measurements undertaken at age of 6, 12, 18 and 22 months, to investigate the effects on feed intake, live weight gain, energy and nitrogen (N) utilisation and enteric methane (CH4) emission. Throughout the study, cattle were offered a diet for ad libitum intake containing a single perennial ryegrass silage mixed with concentrates. In the first period, the concentrate supplement was offered at a ratio of 550 g/kg of dry matter (DM), while it was given at a fixed rate of 2 kg DM daily in other 3 periods. During each measurement period, the cattle were housed as a single group in cubicle accommodation for the first 20 d, then individually in metabolism units for the next 3 d, and then in indirect open-circuit respiration calorimeter chambers for the final 5 d with feed intake, faeces and urine outputs and gaseous exchange measured during the last 4 d.

The present thesis studies the potential for introducing the technology of co-electrolysis of carbondioxide (CO2) and water (H2O) through a Solid Oxide Electrolyser Cell (SOEC) in a top gas recyclingblast furnace (TGR-BF) in a steel plant. TGR-BF, commonly presented in literature as a promisingcarbon capture and storage (CCS) pathway for the steel industry, can drastically decrease theseemissions by successively recycling up to 90 % of the top gas from a blast furnace (EU, 2014) andsequestering the CO2 from the highly carbon concentrated remaining top gas. Blast furnaces (BF)represent about 20 % of the total carbon dioxide emissions of a steel plant (Carpenter, 2012). Based onthe current research status of SOEC, this report aims at exploring the utilisation of carbon dioxidecaptured from TGR-BF through a simultaneous electrolysis of CO2 and H2O, a novel and highly efficientpathway of producing valuable synthetic gas (syngas), used in chemical and industrial applications.It is important to note that neither of the technologies is yet in commercialisation phase, and that thesuggested installation would presently not be possible, but nevertheless provides an interesting pathwaytowards closing the carbon cycle of steelmaking. To give an idea of the magnitude of the SOECinstallation and its syngas production if combined with TGR-BF, an analysis of existing case studies ofeach technology was made. The SOEC system modelled by Fu et al. (2010) was scaled to fit the CO2emissions of Ruukki Metals steel plant in Raahe, Finland, for which data is abundant and reliable. Tohighlight the integration potential of the two separate technologies, a conceptual process flow chart wasdesigned and a literature review of the respective technologies performed, allowing the identification ofintegration challenges, presented in the analysis. The literature study reveals that challenges for thesystem include: gas purity requirements, gas composition requirements, scalability, life-timecompatibility, plant complexity and high variation of plant infrastructure. In the discussion, difficultiesrelated to a technology shift in a traditional industry are considered. For further research, mathematicalmodelling of thermodynamics of the system as well as an economic assessment are recommended.<br>Följande studie utforskar potentialen att implementera co-elektrolys av koldioxid (CO2) och vatten(H2O) genom en fastoxid elektrolyscell (SOEC) i en masugn där återvinning av masugnsgasen tillämpasgenom s.k. Top-Gas Recycling Blast Furnace (TGR-BF). Masugnen representerar omkring 20 % av detotala koldioxidutsläppen från ett stålverk (Carpenter, 2012) varför TGR-BF i flera studier beskrivs somen lovande teknik för avskiljning och lagring av koldioxid (CCS) i stålindustrin. TGR-BF har potentialenatt drastiskt minska utsläppen genom att återvinna upp till 90 % av masugnsgasen (BFG) och avskiljningav koldioxid från den CO2-rika gasen som återstår. Genom att kartlägga den senaste forskningen inomSOEC och analysera resultat från försöksanläggningar som tillämpar TGR-BF syftar denna studie attutforska möjligheten för ett kombinerat system där koldioxiden från masugnsgasen, genom en simultanco-elektrolys av CO2 och H2O, används för syntesgasproduktion; en viktig gas i många kemiska ochindustriella tillämpningar.Det är viktigt att poängtera att ingen av de två teknikerna idag är kommersialiserade och att enintegration av dessa för tillfället därför inte är genomförbar, men att studien tillhandahåller en intressantmöjlighet för minskade koldioxidutsläpp för stålindustrin. För att undersöka skalbarheten mellan de tvåteknikerna genomfördes en fallstudie på Ruukki Metal’s stålverk i Raahe, Finland kombinerat med ettSOEC-system som tillämpats av Fu m.fl. (2010) i deras modellering av syntesgas genom co-elektrolys.Fallstudien uppskattar att 2838 ton syntesgas per dag skulle kunna produceras från den infångadekoldioxiden i stålverket Raahe, Finland. Ett konceptuellt flödesschema utformades för att åskådliggöraintegrationspunkterna för de två teknikerna. En litteraturstudie gjordes i syfte att förstå vilka utmaningaren sådan integration skulle innebära. Dessa utmaningar, tillsammans med utmaningar för de två enskildateknikerna, presenteras i analysen. Litteraturstudien påvisade att utmaningar för det integrerade systemetinkluderar: krav på gasernas renhet samt sammansättning, systemens skalbarhet, livstid samtkomplexiteten och variationen mellan olika stålverk. Analysen och diskussionen behandlarsvårigheterna med stora teknikskiften i en traditionell industri. För vidare studier rekommenderas enmatematisk modellering av systemet där termodynamiska och ekonomiska aspekter behandlas.

Tidal currents and rivers are promising sources of renewable energy given that suitable turbines for kinetic energy conversion are developed. To be economically and technically feasible, a velocity distribution that can give a high degree of utilization (or capacity factor), while the ratio of maximum to rated velocity is low would be preferable. The rated velocity is defined as the velocity at which rated power is achieved. Despite many attempts to estimate the resource, however, reports on the possible degree of utilisation from tidal currents and rivers are scarce. In this paper the velocity distribution from a number of regulated rivers, unregulated rivers and tidal currents have been analysed regarding the degree of utilisation, the fraction of converted energy and the ratio of maximum to rated velocity. Two methods have been used for choosing the rated velocity; one aiming at a high fraction of converted energy and one aiming at a high degree of utilisation. Using the first method, with a rated velocity close to the maximum velocity, it is unlikely that the turbine will reach the cut-out velocity. This results in, on average, a degree of utilisation of 23% for regulated rivers, 19% for unregulated rivers and 17% for tidal currents while converting roughly 30-40% of the kinetic energy. Choosing a rated velocity closer to the mean velocity resulted in, on average, a degree of utilisation of 57% for regulated rivers, 52% for unregulated rivers and 45% for tidal currents. The ratio of maximum to rated velocity would still be no higher than 2.0 for regulated rivers, 1.2 for unregulated rivers and 1.6 for tidal currents. This implies that the velocity distribution of both rivers and tidal currents is promising for kinetic energy conversion. These results, however, do not include weather related effects or extreme velocities such as the 50-year velocity. A velocity factor is introduced to describe what degree of utilisation can be expected at a site. The velocity factor is defined as the ratio U-max/U-rate at the desired degree of utilisation, and serves as an early indicator of the suitability of a site.

The thesis aims to introduce and accelerate the construction of building integrated photovoltaic (BIPV) or building integrated wind turbines (BIWT); considered as part of sustainable buildings. These types of buildings are important in reducing CO2 emission in Bahrain as building and construction sector is responsible for nearly 40 to 50 % of total energy use in Bahrain. Major commercial and residential building construction in Bahrain has been surveyed, making it a rich database for future make-over to BIPV or BIWT. Among these projects, there are only two sustainable building projects in Bahrain, i. e. Bahrain World Trade Centre and Euro-University - yet, not started. The Strengths, Weaknesses, Opportunities, and Threats (SWOT) of having sustainable building projects in Bahrain have also been thoroughly and carefully discussed. Many policies, mechanisms and options set by different entities {OECD, UNEP's Sustainable Building and Construction Initiative (SBCI), ISES, LEED and BREEAM} has been discussed which can be used by the government or the parliament to accelerate the execution of sustainable building projects in the kingdom of Bahrain to meet the objectives of Bahrain Economic Vision 2030. Two large existing buildings in Bahrain that can be considered BIPV and BIWT or sustainable building were investigated. These are: Almoayyed Tower (the first skyscraper in Bahrain) - published in Building and Energy Journal in 2008 - and Bahrain International Circuit (classified as the world's best Formula I circuit) - published in Building and Environment Journal and Applied Energy Journal in 2006 and in The Open Construction and Building Technology Journal in 2008 . The cost of make-over, its advantages, drawbacks, concerns, and the annual reduction in CO2 emissions of these two building have been investigated. The incident of solar radiation on horizontal, vertical and tilted surfaces and the solar electricity acquired from installing photovoltaic modules integrated to the building (BIPV) has been made in additional to the calculation of the available wind speeds at different locations in Bahrain and at different heights from the ground. These data are important in making a thorough economic and environmental assessment for make-over to sustainable buildings in Bahrain. A novel model is established that allows the calculation of the Sustainable Building Index (SBI) - published in Building and Energy Journal in 2008. This index will reveal the potential in Bahrain (and probably neighbouring countries) in engaging in BIPV or BIWT (partial sustainable buildings). The index varies from 0.1 to 1.0; the higher the index the more willingness of the community to involve with sustainable buildings. For Bahrain, the calculated SBI is 0.48 which indicates that more efforts must be made on increasing the Drivers and minimizing the Barriers. This requires suitable mechanisms which the thesis has already made available. These mechanisms are used to achieve a compromise between the investors in Bahrain, the government and contractors (or builders) which will encourage and boost the development and dissemination of sustainable buildings in the kingdom of Bahrain. A novel comprehensive model to accelerate the sustainable buildings project in Bahrain has also been made (published in The Open Construction & Building Technology Journal in 2008). Also, two novel empirical relations were established to estimate the cost of solar and wind electricity to be used for BIPV and BIWT. The thesis aims to solve the vicious circle of blame: Bahrain investors like to fund sustainable buildings but there is no demand for them; the constructors can build sustainable buildings but the developers do not ask them; and the developers would ask for sustainable buildings but the investors won't pay for them.

The problems of lack of potable water, food and electrical power in and around the desert environment are analysed and their solutions based on the utilisation of indigenous renewable energy resources are evaluated in the current research. Self-contained, decentralised solar energy powered processes are devised in the research results as means to attain the objectives of supplying electrical power, potable water and food to the communities living in the deserts in environmentally sustainable manner. Needs analysis of desert community, a questionnaire survey, desert energy model utilisation scenarios, solar potential assessment and environmental emissions reduction strategy are used as means of analysis in the current research. A potential assessment of a desert site Islamkot, at Thar is carried out to demonstrate the capability of available solar potential to meet the energy needs of underground pumping, desalination of aquifer water potable water, cultivation of wheat, rice and pulses and domestic power consumption. The needs analysis estimates the amounts of electrical power needs of potable water desalination, agricultural commodities cultivation and electrical power needs per person per day, which can be scale up for any number of communities living in and around the deserts. The results reveals that indigenous solar potential capability can be used to produce the required amounts of electrical power to meet the water, wheat, rice, pulses, electrical power, drinking, non-drinking and cultivation water needs of the desert communities in environmentally sustainable manner. The research results are practicable and can be implemented to meet the energy needs of isolated communities living in and around the deserts in the long run. However, sustainable efforts would be required to encourage stakeholders to initiate a process of small, medium and large scale solar power utilization in and around the deserts.

Les data centers sont des infrastructures qui hébergent un grand nombre d’équipements informatiques. Plus de 99% de la puissance électrique consommée par les composants électroniques est transformée en chaleur. Pour assurer leur bon fonctionnement il est donc nécessaire de les refroidir. Cette opération est majoritairement réalisée par l’emploi de systèmes de climatisation à air très énergivores. De plus, la densité de puissance dissipée au sein des baies informatiques est en augmentation permanente. Nous arrivons alors aux limites de l’utilisation de l’air comme fluide caloporteur pour le refroidissement. Les études réalisées durant cette thèse concernent l’amélioration de l’efficacité énergétique des systèmes de refroidissement des baies électroniques par l’exploitation de liquides comme fluides caloporteurs. Cette approche permet de bénéficier de coefficients d’échanges thermiques et de capacités de refroidissement plus importants, avec des perspectives plus viables pour la revalorisation de la chaleur issue des data centers.Durant la thèse, quatre solutions de refroidissement ont été évaluées. Des expérimentations ont été menées à l’échelle de serveurs et d’une baie informatique. Une instrumentation conséquente permet de mettre en évidence le bon refroidissement des composants et de déterminer des indicateurs d’efficacité énergétique des systèmes étudiés. A partir des résultats expérimentaux, deux modèles numériques sont développés par une approche nodale et une identification des paramètres par méthode inverse. Ces modèles pourront être dupliqués à l’échelle d’une salle informatique afin de quantifier les gains potentiels de deux solutions de refroidissement liquide<br>Data centers are facilities that house a large numbers of computer equipment. More than 99% of the electrical power consumed by the electronic components is converted into heat. To ensure their good working, it is necessary to keep them under their recommended temperatures. This is mainly achieved by the use of air conditioning systems which consume a lot of electrical power. In addition, the power density of computer racks is constantly increasing. So the limits of air as a coolant for electronic equipment cooling are reached.Studies conducted during this thesis concern the improvement of energy efficiency of cooling systems for electronic rack by using liquids as heat transfer fluids. This approach gives higher heat exchange coefficients and larger cooling capacity with more viable aspects for the recovering of heat from data centers.Four cooling solutions are evaluated. Experiments are conducted on several servers and on a computer rack. A consistent instrumentation helps to highlight the efficiency of components cooling and allows us to identify energy efficiency indicators of the studied systems. From the experimental results, two numerical models are developed by a nodal approach and a parameter identification by inverse method is carried out. These models can be duplicated at the scale of a data center room in order to quantify the potential gains of two liquid cooling solutions

The European Union(EU) has set an ambitious goal of reducing the Green House Gas(GHG) emissions with at least 80-95% in 2050 compared to 1990 levels. Due to the difficulties of avoiding all emissions in other sectors such as transport and agriculture the power sector should be close to 100% renewable. For the European energy system this means that the fossil fuel power has to be strongly reduced and that a vast amount of wind and solar power would have to be installed towards 2050. Due to the long life times of fossil fuel powered plants, 2050 is only one investment cycle away. It is therefore important that the possibilities and challenges of the 2050 energy system are investigated today. A scenario giving the installed capacities in each country for the energy system in 2030 is given in the Scenario Outlook and adequacy forecast(SO&amp;AF) published by the European Network of Transmission System Operators for Electricity(ENTSO-E). The energy system in 2030 is also analysed in the Twenties project by SINTEF Energy Research. In the &#147;Energy Roadmap 2050&#148; produced by the European Commission(EC) a scenario with a high share of renewable energy towards 2050 is presented. The main aim of this thesis is to analyse how the further development of wind and solar power after 2030 will influence some key parameters in the power system. One of the focus areas is on how the utilisation of wind and solar power will change when increasing the capacities. Another important issue is how the increased amount of wind and solar influence the thermal production, and how the production mix might change from 2030 to 2050. The flow in High Voltage Direct Current(HVDC) corridors and how the increased amounts of wind and solar towards 2050 influence this flow is another important topic. The last issue that is treated in this thesis is how the costs and bottleneck costs changes as the production mix is changed from 2030 to 2050 levels, especially how the wind and solar influence the congestion costs separately or combined.This study were performed by doing simulations with the Power System Simulation Tool(PSST) model. First a base scenario was simulated, using 2030 data from the SO&amp;AF. Then simulations were done with wind and solar capacities set to 2050 level, separately and combined. This was to reveal the effect the wind and solar power has on the parameters in the power system. In the last scenario, &#147;2050 Whole&#148;, the dataset was adapted as best as possible to the 2050 scenario found in the Energy Roadmap 2050.The utilisation of the wind and solar plants decrease when the Renewable Energy Source(RES) capacities are increased to 2050 level compared to the 2030 base scenario. The main explanation to this is that the increased amount of RES gives more grid congestions, which limits the production. The other explanation is that the wind and solar potential actually exceeds the load for some hours. When the wind and solar power is increased to 2050 level the amount of fossil production strongly decrease, due to the higher marginal costs of fossil plants. This causes the share of renewable production to increase from 47% in the 2030 base scenario to 83% in the 2050 whole scenario. The highest concentration of renewable power is on the continent, especially in Germany. The flow on the HVDC cables goes from being mainly export from the Nordic countries and Great Britain to the continental countries in the 2030 base scenario to an increased amount of export from the continent in the &#147;2050 Whole&#148;. When the RES capacity is increased to 2050 level the total operating costs in the system goes down, due to the wind and solar power having zero marginal cost. The bottleneck cost become higher as the amount of RES is increased, implying that the grid becomes more congested. However it turns out that increasing the wind capacity alone, gives higher bottleneck cost than increasing both the wind and solar. This is because the solar power has a beneficial diurnal pattern, while the wind power has a beneficial seasonal pattern. This means that the combination of wind and solar power follow the load pattern better than just the wind power and therefore causes less strain on the grid.The fact that the utilisation of wind and solar strongly decrease and that the congestion costs become much higher in the 2050 scenario compared to the 2030 scenario implies that further grid reinforcements might be necessary if such high amounts of renewable power becomes a reality. The high variation in prices and exchange for some areas, that give a high strain on the grid, suggests that new storage possibilities should be investigated for the 2050 energy system.

Avec l’augmentation de la part des énergies renouvelables intermittentes (solaire et éolien) dans les mix énergétiques, des problèmes dans la stabilité de la fourniture d’électricité peuvent se présenter. La solution pour compenser ces fluctuations réside dans la production flexible de biogaz. Le biogaz peut en effet être stocké puis utilisé en période de demande; sa production doit donc être assurée de manière flexible, contrairement à ce qui est fait actuellement sur la majorité des digesteurs. L’objectif de la thèse était d’étudier et de déterminer les limites de digesteurs biogaz en fonctionnement flexible. Trois réacteurs de 15L, alimentés avec trois mélanges différents de deux substrats solides, ont été alimentés pendant 550 jours en fonctionnement flexible. Il a été démontré au cours de cette thèse que le fonctionnement flexible avec des surcharges organiques ponctuelles n’avait aucune incidence négative à long terme sur la production de méthane. La flexibilité instantanée a été définie comme la marge entre le maximum de production sur un réacteur et sa production de base. Elle a été fortement influencée par la charge de base du réacteur et par les cinétiques de dégradation des substrats utilisés en surcharge, mais très peu par l’intensité des surcharges appliquées. L’utilisation de substrats rapidement dégradables en surcharge a permis d’atteindre un maximum de production de 1 à 1,2 LCH4/Lréacteur.j dans les premières 24 heures, même sur des réacteurs alimentés de base avec du fumier, conduisant à des flexibilités allant de +92 à +150%. Ce plafond dépend de la vitesse d’hydrolyse des substrats et il peut être relevé en utilisant des composés plus simples à dégrader en surcharge (type glycérol). Un mode opératoire prêt à être validé sur des installations pilote a été défini ; il précise la démarche à suivre pour la détermination du maximum de production et le niveau de la charge de base à adopter, pour une flexibilisation optimale de la production de méthane sur les CSTR. Un modèle simple, basé sur deux vitesses de dégradation, a également été développé et proposé pour simuler un fonctionnement flexible sur un réacteur<br>With the increasing share of intermittent renewable energies in the electricity mix, some stability problems are expected in the grid. The solution consists in using biogas as buffer energy. Biogas can be stored, then used on-demand. As the storage is limited, biogas production should be flexible. The aim of this thesis was to study and determine the limits of anaerobic reactors in a flexible operation. Three 15L reactors, fed with three different mixtures of two solid substrates, were fed for 550 days in flexible operation. It was demonstrated in this thesis that flexible operation with one-off overloads had no negative impact on methane production on long-term. The flexibility was defined as the margin between the maximum production on a reactor and its baseload production. It was strongly influenced by the baseload of the reactor and the substrates used in overloads, but not by the intensity of the overloads applied. The use of readily degradable substrates in overloads allowed a maximum production of 1 to 1.2 LCH4/Lreactor.d to be achieved in the first 24 hours, even in reactors fed mainly with manure, leading to flexibility ranging from +92 to + 150%. This ceiling depends on the rate of hydrolysis of the substrates. It can be increased by using compounds that are of a simpler structure (glycerol for example). An operational strategy ready to be validated on pilot plants has been defined; it specifies the approach for the determination of the maximum production and the level of the baseload to be adopted, for an optimal flexibilization of the methane production on CSTRs. A simple model, based on two degradation rates, has also been developed to simulate flexible operation of anaerobic reactors

The Member States of EU27 need to accelerate the integration of energy efficient technology solutions to reach the 20% energy efficiency target set for 2020. At current pace, projections indicate that only half of expected primary energy reductions will be reached. To meet the energy demands of growing populations and a vibrant economy, while simultaneously reducing primary energy supplies, the European continent faces a new kind of challenge never previously encountered. The identification and application of feasible, competitive, and comprehensive solutions to this problem are of highest priority if the remaining gap is to be closed in time. How is this multi-dimensional and complex dilemma to be dissolved? In this work, expanded use of district heating technology is conceived as a possible solution to substantially reduce future primary energy demands in Europe. By extended recovery and utilisation of vast volumes of currently disregarded excess heat from energy and industry sector fuel transformation processes, district heating systems and combined generation of heat and power can improve the general efficiency of the European energy balance. To investigate the possible range of this solution, this thesis introduces a set of methodologies, theoretical concepts, and model tools, by which a plausible future excess heat utilisation potential, by means of district heat deliveries to residential and service sectors, is estimated. At current conditions and compared to current levels, this potential correspond to a threefold expansion possibility for directly feasible district heating systems in European urban areas and a fourfold increase of European excess heat utilisation.

This thesis details a series of studies to evaluate the effects of different dietary treatments on production performance and N utilisation in lactating dairy cows, with a particular emphasis on urinary N excretion. Firstly a digestibility trial was performed to investigate the effect of concentrate crude protein (CP) content (14.1, 16.1 and 18.1% CP) and cow genotype (Holstein vs Holstein x Swedish Red) on N and energy utilisation, nutrient digestibility, methane emissions and milk production. Reducing concentrate CP content decreased urinary and milk urea N outputs, without negatively effecting productivity, methane or energy utilisation parameters. However, crossbreeding of Holstein cows resulted in reduced gross energy, digestible energy and metabolisable energy intake and milk energy output. Regression equations were produced for estimating milk urea and urinary N output. The same concentrate feeds were then evaluated over a grazing season on pasture to examine effect on milk production and milk urea N parameters. Findings indicate concentrate CP content was negatively related to milk N/N intake and milk urea N content showed a strong tendency to increase with concentrate CP content. The effect of protein source was evaluated in a second digestibility trial. Specifically the rate of fresh white clover (WC) inclusion (0, 20 or 40% dry matter (DM) basis) in fresh perennial ryegrass based iso-nitrogenous diets on milk production, nutrient digestibility and N metabolism was investigated. White clover had no effect on production parameters despite a quadratic effect on DM and organic matter intake. However, WC inclusion linearly decreased digestible organic matter in total DM and digestibility of fiber, while increased digestibilities of N and gross energy were associated with the low WC (20%) diet. Relative to N intake, the low WC diet decreased fecal and manure N output rates while the high WC (40%) diet linearly decreased milk N output.

L'intégration d'un accumulateur de chaleur dans les systèmes de refroidissement d'un véhicule permet d'optimiser la gestion thermique du groupe motopropulseur et ainsi de réduire la consommation et les émissions polluantes du véhicule. L'intérêt d'un tel accumulateur réside dans sa capacité à stocker / déstocker de l'énergie dans des matériaux à changement de phase (PCM) avec des puissances échangées en adéquation avec les besoins de l'automobile. La problématique scientifique concerne l'intensification, dans un volume restreint, des transferts thermiques dans le matériau de stockage. Le recours à des échangeurs compacts et l'optimisation de la géométrie des ailettes du côté du PCM permettent d'une part de maximiser la puissance échangée grâce à l'augmentation de la surface d'échange avec le PCM et d'autre part d'optimiser la capacité énergétique en améliorant le taux de remplissage en PCM. Le problème est abordé ici de deux façons : théorique, par le développement d'un modèle numérique d'optimisation, puis expérimentale, par la mise au point d'un banc d'essai et de prototypes. Le modèle numérique, validé à partir d'essais, a servi à optimiser la conception de l'accumulateur de chaleur. Enfin, l'intégration de ce composant dans un module de refroidissement pour améliorer la montée en température du groupe motopropulseur a montré des gains significatifs sur le temps de fonctionnement à froid du moteur, réduisant ainsi les émissions polluantes<br>Integration of heat accumulator within engine cooling systems allows to optimize powertrain thermal management and to reduce vehicles consumption and pollutant emissions. Interest of such accumulators lies in their capacity to store and release energy within phase change materials (PCM) with powers in accordance with the automotive needs. Scientific problem concerns heat transfer enhancement, for a limited volume, in a phase change material. The use of compact heat exchangers filled with PCM and the optimization of fin design allow to maximize heat transfer thanks to extended heat transfer area with PCM. On the other hand, energy storage capacity is optimized by increasing PCM volume ratio. The problem is approached by two ways: theoretically, by the development of a numerical model of optimization, and experimentally, by the development of a test bench and several prototypes. The numerical model of heat accumulator, validated with test results, was used to run a parametric study to optimize the conception of the heat accumulator, in particular the fin design. Finally, integration of this new component within the cooling system in order to improve the warm-up of the powertrain has shown significant gains on the functioning time of engine during cold start, leading to reduced pollutant emissions

Innovation programmes require organisations to transfer both technology and knowledge to the diverse actors who operate within innovation eco-systems. The changing relationship between science and society has witnessed the growth of public private partnerships (PPP) to create new knowledge, while also triggering the emergence of a new role for universities as catalysts for innovation. This brings many challenges, stemming from the inherent nature of knowledge and the complex interactions involved with inter-disciplinary knowledge transfer. Concurrently, these public-funded programmes come under increasing scrutiny to demonstrate greater societal and economic impact as a return on research investment. Knowledge generated within the UK low carbon energy innovation system has the potential to facilitate the achievement of national emission targets. However, while knowledge may be successfully created, there is no guarantee that it will be disseminated and utilised in a way that contributes to the achievement of knowledge-related objectives. Current literature concentrates on the micro level inhibitors and enablers of knowledge transfer; however, a gap in empirical work which investigates system level knowledge interactions is evident. Research and practical application in this field has historically centred on technology transfer whilst under-emphasising the crucial role of knowledge within this complex, socio-technical innovation system. The overall aim of this qualitative study is to achieve a better understanding of the influences of knowledge transfer across a defined innovation system. This is achieved through the perceptions of participants via two case studies; one in a PPP and one in a University. Semi-structured interviews were conducted with twenty-eight participants, along with document analysis and participant observation at workshops, to investigate the participant perceptions. A three tier (macro-, meso- and micro-level) data analysis approach was adopted to reflect the systems level interactions. The study found that knowledge transfer is often perceived as the dissemination of information via explicit forms of knowledge, which may or may not be used by stakeholders to achieve innovation objectives. The main barriers to stakeholders utilising knowledge included: accessibility to knowledge; fit-for-purpose knowledge; stakeholder motivation/ability to use the knowledge; and viewing knowledge as an object. While there is an emerging impact agenda in academia, cultural and normative influences direct researchers towards traditional academic outputs (e.g. publications). Knowledge utilisation by stakeholders was found to be maximised through relational, stakeholder driven models, which view knowledge as a process. Knowledge utilisation was context specific, and, due to complex system influences, was never guaranteed to occur. Although planning for knowledge utilisation was undertaken at both the PPP and the University, implementing and measuring results was found to be difficult due to dynamic system influences such as understanding stakeholder motivations, resourcing constraints and complexity in the desired project outcomes. This makes adaptability and responsiveness important qualities for knowledge producers, while also necessitating specific skill sets. Based on this work, a set of principles were developed which should guide more effective utilisation of knowledge and promote more impactful research outcomes.

Thesis (MBA)--Stellenbosch University, 2012.<br>Tyre waste from end-of-life tyres (ELTs), sometimes erroneously defined as a type of waste, in fact represents a renewable energy resource that is highly competitive as replacement fuel to coal in the form of tyre-derived fuel (TDF) or useable as rubber crumb in other products. In this research study, the main utilisation options considered were based on rubber crumbing through ambient and cryogenic processing. Pyrolysis, the so-called ‘holy grail’ of tyre technologies, rubberised asphalt products, TDF options and various other product options from tyre crumb as basis were considered. Although pyrolysis technology is highly commendable and environmentally friendly, it is still a process with too many variants and presents an unstable economic model that is not attractive to entrepreneurs. Rubberised asphalt depends on policy decisions from local and national authorities supporting initial higher spending and allowances on budgets to acquire future savings from the longevity in the product. The policy requirements and the instability that politically-inspired decisions carry with them are contributing to the unattractiveness of this solution to the entrepreneurial fraternity. Through government requiring a certain percentage of asphalt pavements to contain rubber (like in the United States of America (USA)), rubberised asphalt could be a very useful and viable option to produce. In the USA, the Environmental Protection Agency (EPA) recently avoided the return to coal in industrial kilns currently using TDF based on its beneficial carbon dioxide (CO2) emission and cost structures by defining TDF as Reasonably Available Control Technology (RACT) to existing coal-burning industrial kilns. In South Africa, the usage of TDF should be of interest to Eskom and the cement industry. TDF (produced from end-of-life tyres), defined as a renewable energy resource due to its proven biomass component and with its high calorific value, presents higher energy output values in comparison to coal and furthermore presents the industry with lower input costs per ton and reduces the CO2 emission factor. Entrepreneurial intervention involving Eskom and/or the cement industry in South Africa with the utilisation of end-of-life tyres as renewable energy resource is an overdue business opportunity. With more than ten million tyres per year available in South Africa and a stockpile of more than fifty million waste tyres, sustainability of TDF supplies is a reality. TDF is much cheaper per ton than coal and emits approximately 20 percent less CO2 and/or CO2e than low-grade coal to produce the same electricity output. From all the information gathered, it is clear that in countries where coal energy is extensively used, TDF utilisation not only reduces the tyre waste issues, but it also serves as an environmentally-friendly renewable energy resource in electricity production and cement kilns; the industry with some of the highest CO2 emission risks. The final chapter of this report presents a schedule representing the choice of tyre processing and disposal methods ranked by environmental preference and defining the priorities linked to process and product choice.

The primary objective of this PhD program was to investigate the impact of training at a constant-load moderate-intensity (FATmax) compared to work-matched high-intensity intervals (HIIT) on the metabolic, physiological and psychosocial health profiles of sedentary overweight and obese men. This study was unique in that it was the first time the effect of exercise intensity had been investigated to examine concurrently the components of whole-body energy metabolism and body composition as measured using gold standard techniques. Based upon the positive alterations in blood lipids, body composition, cardiorespiratory fitness and substrate oxidation, it appears that training at FATmax can positively impact health parameters as well as, or if not better than, high-intensity training. Furthermore, there are ramifications for public health messages and obesity management strategies arising from these findings, primarily attributable to the increased exercise adherence and the reduction in health risks stemming from the significant loss of abdominal visceral adipose tissue after FATmax training.

Využití vody, spotřeba energie a emise skleníkových plynů (GHG) jsou rozhodujícími ukazateli a do značné míry souvisí s udržováním nebo dosahováním environmentální a sociální udržitelnosti. Tato práce prezentuje vyvinuté metodiky. Představuje také provedené případové studie, které prozkoumaly a identifikovaly Water-Energy-GHG Nexus (WEGN) z pohledu dodavatelského řetězce. Pro analýzu a návrh sítě WEGN jsou navrženy tři metodiky, které jsou založeny na nové aplikaci a integraci modelu vstup-výstup (IO), geografického informačního systému (GIS) a sítě dodavatelského řetězce (SCN), a zároveň řeší výzvy, které dříve neumožňovali praktické implementace. Použitelnost těchto metod je prokázána třemi komplexními případovými studiemi zaměřenými na odvětvovou environmentální účinnost, regionální environmentální účinnost a kritické přenosy WEGN. Mezi mé příspěvky v této oblasti patří: i. Nový nástroj pro hodnocení založený na IO pro identifikaci regionální environmentální účinnosti z hlediska WEGN, zejména pro regiony, které jsou úzce propojenyobchodem. ii. Pokročilá integrace metodik GIS a IO (GIS-IO) za účelem odhalení a mapování sítě WEGN, sledování kritických meziregionálních a sektorových toků WEGN, vyjasnění regionálních, odvětvových a celosvětových vzorců sítě WEGN a určení souvisejících výhod pro různé regiony. iii. Efektivní metoda hodnocení založená na IO a SCN pro kvantifikaci sektorových koeficientů WEGN. Navrhované metodiky, s podporou sady komplexních základních rovnic, transformují komplikované výzvy identifikace a analýzy sítě WEGN do snadno srozumitelného formátu, z čehož vznikají robustní řešení pro zlepšení posuzování environmentální udržitelnosti a zmírnění environmentálních tlaků. Například v jedné z případových studií ukazují výsledky nového přístupu GIS-IO zjevné rozdíly mezi různými zeměmi v rámci EU27, mezi různými sektory a také pokud srovnáme EU27 jako blok zemí, s ostatními státy světa. Analýza ukázala, že země EU27 přispěly o 1.4 Gt nižšími emisemi CO2, o 64.5 Gm3 menší spotřebou vody a 4.9 × 104 PJ nižší spotřebou energie ve srovnání se zbytkem světa, přičemž generovaly ekvivalentní ekonomickou produkci. To má dramatický dopad na globální prostředí. Největší úspěch v CWE mezi zeměmi EU27 měly Německo, Francie a Itálie. Práce doporučuje, aby EU27 poskytovala více technické podpory zemím, které těchto výsledků nedosahují, aby se zvýšila účinnost využívání zdrojů.

This thesis describes a series of three experiments designed to estimate the nutritional cost of the immune response to the gastrointestinal nematodes Trichostrongylus colubriformis and Teladorsagia circumcincta in sheep. For each experiment, animals were allocated hierarchically by liveweight into one of four groups that were either infected (group IF), similarly infected and concurrently immuno-suppressed with weekly intramuscular injections of 1.3mg kg liveweight (LW)-1 of methylprednisolone acetate (group ISIF), immuno-suppressed only (group IS) or remained as controls (group C). Body composition of all animals was estimated using x-ray computer tomography prior to infection and at the conclusion of each study with bodyweight and faecal nematode egg counts (FEC; eggs gram-1 of fresh faeces (epg)) measured along with blood samples taken for the determination of levels of serum proteins, phosphate and antibodies. In the first trial (Chapter 3), the nutritional cost of both the acquisition and maintenance of immunity to gastro-intestinal nematodes was investigated using immunologically naive 5-month-old lambs and immunologically competent 17-month-old ewes during infection with 2,000 and 4,000 L3 infective T. colubriformis larvae d-1, respectively (80 L3 T. colubriformis larvae kgLW-1 d-1). Profiles of FEC and comparative worm burdens at slaughter indicated an effective immune response was maintained in IF ewes and developed in IF lambs while successfully suppressed in both ISIF lambs and ISIF ewes and was confirmed by serum antibody titres. The typical reduction in voluntary feed intake as a consequence of infection was observed in IF lambs (0.30, p&lt0.001) but not in IF ewes, ISIF lambs or ISIF ewes, and appeared to be associated with L3 IgA. Gross efficiency of use of metabolizable energy (ME) for net energy (NE) deposition was reduced by 0.20 in lambs during acquisition of immunity and by 0.16 in ewes maintaining an established immunity. Infection in immuno-suppressed animals reduced efficiency by 0.05 and 0.15 for lambs and ewes. These findings allowed the hypothesis that the reduction in feed intake and nutrient utilization in young parasitized sheep is caused by physiological signalling associated with the acquisition phase of the host immune response to infection, rather than simply the damage caused by the parasite per se. The second trial (Chapter 4) investigated the influence of metabolizable protein (MP) supply on the metabolic disturbances associated with the acquisition phase of the immune response during infection with 2,000 L3 T. colubriformis d-1. Groups of lambs were offered either a low protein (L; 62g MP kgDM-1) or high protein diet (H; 95g MP kgDM-1). Patterns of total daily egg excretion indicated that an effective immune response was developed in HIF, but not LIF, HISIF nor LISF and was confirmed by comparative worm burdens. The proportionate reduction in feed intake in immunologically normal animals was reduced through the provision of additional protein, being 0.12 in HIF and 0.23 in LIF. Regardless of diet, infection did not cause a reduction in feed intake in immuno-suppressed animals (p&gt0.05). Infection proportionately reduced the gross efficiency of ME utilization in immunologically normal animals by 0.23 in HIF (p=0.09) and by 0.51 in LIF (p=0.01), but not in immuno-suppressed animals. Immuno-suppression did not suppress serum L3 IgA levels in seven of the eight HISIF and four of the eight LISIF animals. Furthermore, only four out of the eight immunologically normal animals from both the HIF and LIF groups displayed an L3 IgA response. Consequently, regardless of immuno-suppression treatment, animals were termed as IgA responders (HR or LR) or non-responders (HN or LN). Feed intake was proportionately reduced from day 22 by 0.15 in HR (p=0.03) and by 0.32 in LR (p=0.01), but was not significantly reduced in HN or LN. Gross efficiency of ME utilization was significantly reduced for LN animals only, being proportionately 0.59 (p&lt0.01). These findings allowed the conclusion that additional MP reduced the consequence of immunological signalling that was displayed in reduced feed intake and in nutrient utilization, both of which appeared to be associated with an IgA response. It is hypothesized that the lessening of nutritional disturbance observed in high protein and immuno-suppressed animals could be a consequence of altered physiological signalling during the immunological cascade. The third trial (Chapter 5) utilized lambs infected with the abomasal parasite T. circumcincta to explore the possibility that the reduction in feed intake and nutrient utilization is a universal phenomenon of the acquisition phase of the immune response to nematode parasites inhabiting different organs along the gastrointestinal tract. In addition, immunological changes at the site of parasite infestation in the abomasal mucosa were measured from serial biopsy tissue samples taken from a further twelve animals that were surgically fitted with an abomasal cannula and either infected (CIF) or concurrently infected and immuno-suppressed as described previously (CISIF). The development of immunity in IF animals was accompanied by a 0.17 proportional decrease in feed intake between days 15 to 28 of infection (p&lt0.05) and a 0.20 proportional reduction in nutrient utilization (p=0.07), none of which were observed in ISIF animals. While FEC and worm burdens indicated successful immuno-suppression in ISIF animals, both serum IgA and total antibody production were not reduced. The development of immunity in CIF was reflected in an increase in both mast cells and globule leukocytes in serial abomasal tissue biopsies, both of which were reduced in CISIF (p&lt0.01 for both). In serial biopsy tissue, immuno-suppression did prevent a rise in tissue IgA that was apparent in CIF animals (p&lt0.01) although these changes were not reflected in serum IgA levels. It appears that the alleviation of the reduction in feed intake and nutrient utilization in young lambs through the use of corticosteroid induced immuno-suppression may be a universal phenomenon for both intestinal and abomasal parasites, but the association with and/or role of IgA during infection with T. circumcincta is unclear. In summary, the reduction in feed intake and nutrient utilization in sheep during infection with both the abomasal nematode T. circumcincta and the small intestine nematode T. colubriformis appears to be associated with a component(s) of the acquisition phase of the host immune response, rather than, as conventionally assumed, the direct mechanical damage of the parasite per se. It is hypothesised that the nutritional disturbance as a consequence of infection in young lambs may be the result of pro-inflammatory cytokines involved in immunological signalling that may also be associated with the production of IgA, the effects of which can be reduced through the provision of adequate MP. These studies provide evidence that the immune response to gastrointestinal parasites is nutritionally costly to the animal and have implications for application of manipulations that are intended to promote the development of a strong immune reaction in high producing animals.

Drying is an important unit operation in process industry. Results have suggested that the energy used for drying has increased from 12% in 1978 to 18% of the total energy used in 1990. A literature survey of previous studies regarding overall drying energy consumption has demonstrated that there is little continuity of methods and energy trends could not be established. In the ceramics, timber and paper industrial sectors specific energy consumption and energy trends have been investigated by auditing drying equipment. Ceramic products examined have included tableware, tiles, sanitaryware, electrical ceramics, plasterboard, refractories, bricks and abrasives. Data from industry has shown that drying energy has not varied significantly in the ceramics sector over the last decade, representing about 31% of the total energy consumed. Information from the timber industry has established that radical changes have occurred over the last 20 years, both in terms of equipment and energy utilisation. The energy efficiency of hardwood drying has improved by 15% since the 1970s, although no significant savings have been realised for softwood. A survey estimating the energy efficiency and operating characteristics of 192 paper dryer sections has been conducted. Drying energy was found to increase to nearly 60% of the total energy used in the early 1980s, but has fallen over the last decade, representing 23% of the total in 1993. These results have demonstrated that effective energy saving measures, such as improved pressing and heat recovery, have been successfully implemented since the 1970s. Artificial neural networks have successfully been applied to model process characteristics of microwave and convective drying of paper coated gypsum cove. Parameters modelled have included product moisture loss, core gypsum temperature and quality factors relating to paper burning and bubbling defects. Evaluation of thermal and dielectric properties have highlighted gypsum's heat sensitive characteristics in convective and electromagnetic regimes. Modelling experimental data has shown that the networks were capable of simulating drying process characteristics to a high degree of accuracy. Product weight and temperature were predicted to within 0.5% and 5C of the target data respectively. Furthermore, it was demonstrated that the underlying properties of the data could be predicted through a high level of input noise.