Fossil fuels continue to deplete with use as they are irreplaceable. In addition, the environmental impact with the continuous use of these conventional fuels has generated global concern due to the production of harmful emission gases. An alternative source of energy has become inevitable. Technological advancements in the area of biomass use for both aviation and power generation are at different levels of development. There is however the need for an integrated approach to assess gas turbine engine behaviour in terms of performance, emission and economics when they are running on biofuels. The current research work is concerned with finding alternative fuel resources for use on stationary gas turbine engines for power generation with the necessary identification of suitable biofuels using a multidisciplinary approach. A techno-economic, environmental and risk assessment (TERA) model comprising the performance, emissions, economics and risk modules has been developed. There had been several simulations of two gas turbine engines (GTEs) to ascertain the effects of both ambient and operating conditions and the effect of fuel types on the engines. These simulations were done with the use of an in-house code-the Turbomatch and a code developed for the steam cycle which is employed for the combined cycle simulation. Cont/d.

Concentrating solar power plants can integrate cost-effective thermal energy storage systems and thereby supply controllable power on demand, an advantage against other renewable technologies. Storage integration allows a solar thermal power plant to increase its load factor and to shift production to periods of peak demand. It also enables output firmness, providing stability to the power block and to the grid. Thus, despite the additional investment, storage can enhance the performance and economic viability of the plants. However, the levelized cost of electricity of these plants yet remains higher than for other technologies, so projects today are only viable through the provision of incentives or technology-specific competitive bid tenders. It is the variability of the solar resource, the myriad roles that storage can assume, and the complexity of enhancing the synergies between the solar field, the storage and the power block, what makes the development of adequate policy instruments, design and operation of these plants a challenging process. In this thesis a comprehensive methodology for the pre-design and analysis of concentrating solar power plants is presented. The methodology is based on a techno-economic modeling approach that allows identifying optimum trade-off curves between technical, environmental, and financial performance indicators. A number of contemporary plant layouts and novel storage and hybridization concepts are assessed to identify optimum plant configurations, in terms of component size and storage dispatch strategies. Conclusions highlight the relevance between the sizing of key plant components, the operation strategy and the boundaries set by the location. The interrelation between critical performance indicators, and their use as decisive parameters, is also discussed. Results are used as a basis to provide recommendations aimed to support the decision making process of key actors along the project development value chain of the plants. This research work and conclusions are primarily meant to set a stepping stone in the research of concentrating solar power plant design and optimization, but also to support the research towards understanding the value of storage in concentrating solar power plants and in the grid. / Koncentrerad solkraft erbjuder möjligheten att integrera kostnadseffektiv termisk energilagring och därmed behovsstyrd kraftkontroll. Detta är en viktig fördel jämfört med andra förnybara energiteknologier. Lagringsintegration tillåter solkraftsanläggningar att öka sin lastfaktor och skifta produktion till tider med största efterfrågan. Vidare möjliggör lagring fast elproduktion vilket leder till förbättrad nät- och kraftturbinstabilitet. Därför kan termisk lagring öka anläggningsprestanda och ekonomiskt värde trots ökande initiala kapitalkostnader. I termer av specifik elproduktionskostnad (LCOE) ligger koncentrerade solkraftsanläggningar med lagring fortfarande högre än andra kraftteknologier och anläggningsprojekt blir endast lönsamma genom subventionsmodeller eller teknologispecifika konkurrensutsatta anbudsförfaranden. Att hitta adekvata policylösningar och optimala design och operationsstrategier är en utmanande process eftersom det gäller att hitta rätt balans mellan variabel solinstrålning, lagring av energi och tid för produktion genom optimal design och operation av solmottagarfält, kraftblock och lagringskapacitet. I denna avhandling presenteras en omfattande metodik för pre-design och analys av koncentrerande solkraftverk. Metodiken baseras på en tekno-ekonomisk modelleringsansats som möjliggör identifiering av optimala avvägningssamband för tekniska, ekonomiska och miljöprestanda indikatorer. Metodiken tillämpas på ett antal moderna anläggningslayouter  och lagrings- och hybridiseringskoncept för att identifiera optimal kraftanläggningsdesign i termer av komponentprestanda och lagringsanvändningsstrategier. I slutsatsen poängteras relevansen av att hitta rätt storlek på nyckelkomponenter i relation till lagringsstrategi och randvillkoren som ges av konstruktionsläget för optimal ekonomisk och miljömässig prestanda. Resultaten används för att formulera rekommendationer till nyckelaktörer i beslutsprocessen genom hela kraftanläggningens värdekedja från politisk beslutsfattare till anläggningsingenjör. Forskningen och slutsatserna i detta arbete skall i första hand ta ett steg framåt för optimering och design av solkraftsanläggningar men även tillhandahålla en metodik för utvärdering av lagringslösningar och dess specifika värde för solkraftsanläggningar och elnätet. / <p>QC 20160829</p>

The increased demand for broadband communications has led to the rapid development of the conventional terrestrial and satellite wireless communications systems. One of the main challenges to next generation wireless systems is to deliver high-capacity and cost-efficient solutions to cope with an increasing usage of broadband services and applications. In the recent years, an emerging competitive system has attracted the attention for providing wireless broadband communications and other services based on quasi-stationary aerial platforms operating in the stratosphere known by high altitude platforms (HAPs), and located 17-22 km above the earth surface. This solution has been described by the International Telecommunication Union (ITU) as "a new and long anticipated technology that can revolutionize the telecommunication industry''. The HAP systems provide important advantages such as low cost, high elevation angles, low propagation delay, easy and incremental deployment, flexibility in operation, broad coverage, broadcast and broadband capability, ability to move around in emergency situations, etc. Therefore, they have been proposed by ITU for the provision of fixed, mobile services and applications, e.g. the third generation (3G) services licensed by ITU and backbone link for terrestrial networks in remote areas. This thesis explores and investigates the wireless communication and techno-economic performance of terrestrial systems and HAPs. An overview of research and development on aerial platforms worldwide is given. Coexistence performance and techniques of heterogeneous systems to provide broadband wireless communications based on Worldwide Interoperability Microwave Access (WiMAX) are investigated. A heterogeneous scenario is developed to examine the coexistence performance of heterogeneous systems. The capacity and deployment aspects of HAPs are analyzed, and further compared with terrestrial Universal Mobile Telecommunications Systems (UMTS) through techno-economic studies including a proposed partnership based business model for HAPs. Performance of wireless sensor network applications via HAPs is also investigated, and shows the high potential of HAPs for large-area and long-endurance surveillance and emergency applications. The thesis shows that communications from the aerial platforms provide the best features of both terrestrial and satellite systems. HAPs can effectively coexist in a heterogeneous radio environment, and are competitive solutions in urban and suburban scenarios in terms of capacity, coverage and business perspective. This makes HAP a viable competitor and complement to conventional terrestrial infrastructures and satellite systems.

Most of the world’s electricity is being generated through conventional sources of energy like coal and nuclear. People are realizing the dire effect of using these fuels, and the amount of CO2 being released into the environment. Therefore, in recent year there has been a shift in emphasis towards cleaner ways of generating electricity. One such recent trend is solar photovoltaics (PV), which has seen rapid growth over the years. This ever-increasing trend of adopting PV system allows consumers to be producers or “Prosumers”. Due to the irregular production capability of solar PV, the need for an energy storage system like a battery bank is on the rise as well. This report evaluates how solar PV can be used in combination with a battery bank to supply the annual electricity demand for a household with little to no support from the grid. The building is assumed to be located in Bangalore, India. The energy demand for the household is estimated based on the requirements of a basic Indian house standard. The size and configuration of each component have been done with regards to the total load demand. Furthermore, the cost of the whole system is estimated in order to evaluate the feasibility of the grid-tied system from an economic perspective. The results show that a PV system consisting of four 270W solar panels, a battery bank of eight150Ah lead-acid batteries and a 48V 4kW inverter is required to meet the annual energy demand of the house. The results show that from a technical standpoint, the above-mentioned technology is feasible. The results from the economic evaluation show that the localized cost of energy(LCOE) for the system is ₹6.01/kWh or € 0.078/kWh or 0.84SEK/kWh and the payback time for the given system is 16.19 years. On the bright side, there are new technological advancements in the PV field every day, which could mean that an energy system of this type can be an achievable and practical alternative. Most of the world’s electricity is being generated through conventional sources of energy like coal and nuclear. People are realizing the dire effect of using these fuels, and the amount of CO2 being released into the environment. Therefore, in recent year there has been a shift in emphasis towards cleaner ways of generating electricity. One such recent trend is solar photovoltaics (PV), which has seen rapid growth over the years. This ever-increasing trend of adopting PV system allows consumers to be producers or “Prosumers”. Due to the irregular production capability of solar PV, the need for an energy storage system like a battery bank is on the rise as well. This report evaluates how solar PV can be used in combination with a battery bank to supply the annual electricity demand for a household with little to no support from the grid. The building is assumed to be located in Bangalore, India. The energy demand for the household is estimated based on the requirements of a basic Indian house standard. The size and configuration of each component have been done with regards to the total load demand. Furthermore, the cost of the whole system is estimated in order to evaluate the feasibility of the grid-tied system from an economic perspective. The results show that a PV system consisting of four 270W solar panels, a battery bank of eight 150Ah lead-acid batteries and a 48V 4kW inverter is required to meet the annual energy demand of the house. The results show that from a technical standpoint, the above-mentioned technology is feasible. The results from the economic evaluation show that the localized cost of energy (LCOE) for the system is ₹6.01/kWh or € 0.078/kWh or 0.84SEK/kWh and the payback time for the given system is 16.19 years. On the bright side, there are new technological advancements in the PV field every day, which could mean that an energy system of this type can be an achievable and practical alternative.

Concerns over both environmental issues and about the depletion of fossil fuels have acted as twin driving forces to the development of renewable energy and its integration into existing electricity grids. The variable nature of RE generators assessment affects the ability to balance supply and demand across electricity networks; however, the use of energy storage and demand-side response techniques is expected to help relieve this situation. One possibility in this regard might be the use of water electrolysis to produce hydrogen while producing industrial-scale DSR services. This would be facilitated by the use of tariff structures that incentive the operation of electrolysers as dispatchable loads. This research has been carried out to answer the following question: What is the feasibility of using electrolysers to provide industrial-scale of Demand-side Response for grid balancing while producing hydrogen at a competitive price? The hydrogen thus produced can then be used, and indeed sold, as a clean automotive fuel. To these ends, two common types of electrolyser, alkaline and PEM, are examined in considerable detail. In particular, two cost scenarios for system components are considered, namely those for 2015 and 2030. The coastal city of Darnah in Libya was chosen as the basis for this case study, where renewable energy can be produced via wind turbines and photovoltaics (PVs), and where there are currently six petrol stations serving the city that can be converted to hydrogen refuelling stations (HRSs). In 2015 all scenarios for both PEM and alkaline electrolysers were considered and were found to be able to partly meet the project aims but with high cost of hydrogen due to the high cost of system capital costs, low price of social carbon cost and less government support. However, by 2030 the price of hydrogen price will make it a good option as energy storage and clean fuel for many reasons such as the expected drop in capital cost, improvement in the efficiency of the equipment, and the expectation of high price of social carbon cost. Penetration of hydrogen into the energy sector requires strong governmental support by either establishing or modifying policies and energy laws to increasingly support renewable energy usage. Government support could effectively bring forward the date at which hydrogen becomes techno-economically viable (i.e. sooner than 2030).

Expanding access to electricity is central to development in East Africa but massive increases in investment are required to achieve universal access. Private sector participation in electrification is essential to meeting electricity access targets. Policy makers have acknowledged that grid extension in many remote rural areas is not as cost effective as decentralized alternatives such as microgrids. Microgrid companies have been unable to scale beyond pilot projects due in part to challenges in raising capital for a business model that is perceived to be risky. This thesis aims to identify and quantify the primary sources of investment risk in microgrid utilities and study ways to mitigate these risks to make these businesses more viable. Two modeling tools have been developed to this end. The Stochastic Techno-Economic Microgrid Model (STEMM) models the technical and financial performance of microgrid utilities using uncertain and dynamic inputs to permit explicit modeling of financial risk. This model is applied in an investment risk assessment and case study in Rwanda. Key findings suggest that the most important drivers of risk are fuel prices, foreign exchange rates, demand for electricity, and price elasticity of demand for electricity. The relative importance of these factors is technology dependent with demand uncertainty figuring stronger for solar and high solar penetration hybrid systems and fuel prices driving risk in diesel power and low solar penetration hybrid systems. Considering uncertainty in system sizing presents a tradeoff whereby a decrease in expected equity return decreases downside risk. High solar penetration systems are also found to be more attractive to lenders. The second modeling tool leverages electricity consumption and demographic data from four microgrids in Tanzania to forecast demand for electricity in newly electrified communities. Using statistical learning techniques, improvements in prediction performance was achieved over the historical mean baseline. I have also identified important predictors in estimating electricity consumption of newly connected customers. These include tariff structures and prices, preconnection sources of electricity and lighting, levels of spending on electricity services and airtime, and pre-connection appliance ownership. Prior exposure to electricity, disposable income, and price are dominant factors in estimating demand.

Uncertainty in the global energy market and negative environmental impacts associated with fossil fuels has led to renewed interest in alternative fuels. The scalability of new technologies and production pathways are critically being evaluated through economic feasibility studies and environmental impact assessments. This work investigated the conversion of agricultural wast, delactosed whey permeate (delac), with yeast fermentation for the generation of biofuel via hydrothermal liquefaction (HTL). The feasibility of the process was demonstrated at laboratory scale with data leveraged to validate systems models used to perform industrial-scale economic and environmental impact analyses. Results showed a minimum fuel selling point of $4.56 per gasoline gallon equivalent (CGE), a net energy ratio (NER), defined as energy required to process biofuel divided by energy in the biofuel produced, of 0.81 and greenhouse gas (GHG) emissions of 30.03 g CO2-eq MJ-1. High Production costs can be attributed to operational temperatures of HTL while the high lipid yields of the yeast counter these heating demands, resulting in a favorable NER. The operating conditions of both fermentation and HTL contributed to the majority of GHG emissions. Further discussion focuses on optimization of the process, on the metrics of TEA and LCA and the evaluation of the process, on the metrics of TEA and LCA, and the evaluation of the process through a sensitivity analysis that highlights areas for directed research to improve commercial feasibility.

Australia is recognising that carbon capture and storage (CCS) may be a feasible pathway for addressing increasing levels of CO2 emissions. This thesis presents a preliminary economic assessment and comparison of the capture costs for different Australian CO2 emission sources. The capture technologies evaluated include solvent absorption, pressure swing adsorption (PSA), gas separation membranes and low temperature separation. The capture cost estimated for hydrogen production, IGCC power plants and natural gas processing is less than A$30/tonne CO2 avoided. CO2 capture cost for iron production ranges from A$30 to A$40 per tonne CO2 avoided. Higher costs of A$40 to over A$80 per tonne CO2 avoided were estimated for flue gas streams from pulverised coal and NGCC power plants, oil refineries and cement facilities, and IDGCC synthesis gas. Based on 2004 and 2005 EU ETS carbon prices (A$30 to A$45 per tonne CO2 avoided), the cost of capture using current commercially available absorption technology may deter wide-scale implementation of CCS, in particular for combustion processes. A sensitivity analysis was undertaken to explore the opportunities for reducing costs. The high cost for capture using solvent absorption is dependent on the energy needed for solvent regeneration and the high capital costs. Cost reductions can be achieved by using new low regeneration energy solvents coupled with recycling the waste heat from the absorption process back to the steam cycle, and using low cost ???fit-for-purpose??? equipment. For membrane and PSA technologies, the capture costs are dominated by the flue gas and post-capture compressors. Operating the permeate or desorption stream under vacuum conditions provides significant cost reductions. Improvements in membrane and adsorbent characteristics such as the adsorbent loading or membrane permeability, CO2 selectivity, and lower prices for the membrane or adsorbent material provide further cost benefits. For low partial pressure CO2 streams, capture using low temperature ???anti-sublimation??? separation can be an alternative option. Low costs could be achieved by operating under low pressures and integrating with external sources of waste heat. Applying the cost reductions achievable with technology and process improvements reduces the capture and CCS costs to a level less than current carbon prices, making CCS an attractive mitigation option.

The objective of this research was to develop novel and applicable methodologies to solve systematically problems along a roadmap of constructing a globally optimum biorefinery design. The roadmap consists of the following problems: (1) synthesis of conceptual biorefinery pathways from given feedstocks and products, (2) screening of the synthesized pathways to identify the most economic pathways, (3) development of a flexible biorefinery configuration, and (4) techno-economic analysis of a detailed biorefinery design. In the synthesis problem, a systems-based "forward-backward" approach was developed. It involves forward synthesis of biomass to possible intermediates and reverse synthesis starting with desired products and identifying necessary species and pathways leading to them. Then, two activities are performed to generate complete biorefinery pathways: matching (if one of the species synthesized in the forward step is also generated by the reverse step) or interception (a task is determined to take a forward-generated species with a reverse-generated species by identifying a known process or by using reaction pathway synthesis to link to two species.) In the screening problem, the Bellman's Principle of Optimality was applied to decompose the optimization problem into sub-problems in which an optimal policy of available technologies was determined for every conversion step. Subsequently, either a linear programming formulation or dynamic programming algorithm was used to determine the optimal pathways. In the configuration design problem, a new class of design problems with flexibility was proposed to build the most profitable plants that operate only when economic efficiency is favored. A new formulation approach with proposed constraints called disjunctive operation mode was also developed to solve the design problems. In the techno-economic analysis for a detailed design of biorefinery, the process producing hydrocarbon fuels from lignocellulose via the carboxylate platform was studied. This analysis employed many state-of-the-art chemical engineering fundamentals and used extensive sources of published data and advanced computing resources to yield reliable conclusions to the analysis. Case studies of alcohol-producing pathways from lignocellulosic biomass were discussed to demonstrate the merits of the proposed approaches in the former three problems. The process was extended to produce hydrocarbon fuels in the last problem.

Η παρούσα διπλωματική εργασία πραγματεύεται την τεχνοοικονομική μελέτη ενός υβριδικού συστήματος στη νήσο Γαύδο, νότια του νομού Χανίων Κρήτης. Το συγκεκριμένο αντικείμενο της διπλωματικής επιλέχθηκε σε συνδυασμό με πρακτική άσκηση πάνω στο ίδιο θέμα στην εταιρεία ΔΕΗ Ανανεώσιμες. Στόχος της μελέτης είναι η διερεύνηση των εναλλακτικών λύσεων παραγωγής ηλεκτρικής ενέργειας στα μη διασυνδεδεμένα νησιά. Η ανάγκη αυτή προκύπτει από το εξαιρετικά υψηλό κόστος της παραγόμενης μεγαβατώρας σε νησιά όπως η Γαύδος. Με σκοπό την πλήρη ανάλυση του θέματος, αρχικά μελετώνται τα ιδιαίτερα τοπολογικά χαρακτηριστικά της Γαύδου και οι πιθανές θέσεις εγκατάστασεις του υβριδικού συστήματος βάσει μετρήσεων. Σημαντική παράμετρος της ανάλυσης αυτής είναι η κατά το δυνατόν μικρότερη επέμβαση στο οικοσύστημα του νησιού και ο σεβασμός της χλωρίδας και της πανίδας του. Στη συνέχεια, έχοντας καταλήξει στην δομή του προτεινόμενου συστήματος εξετάζονται συγκεκριμένες εμπορικές λύσεις με εκτενή έρευνα αγοράς. Η τελική επιλογή των προτεινόμενων προιόντων έγινε με βάση το χαμηλότερο κόστος και την υψηλότερη αξιοπιστία, διότι η συνεχής πρόσβαση στο νησί για συντήρηση του συστήματος δεν ενδείκνυται. Τo επόμενο βήμα της παρούσας μελέτης είναι διαστασιολόγηση του συστήματος, ώστε η λειτουργία του συστήματος να καλύπτει στο έπακρον το φορτίο σε μόνιμη και σε μεταβατική κατάσταση λειτουργίας. Οι βασικές μετρήσεις που απαιτούνται για αυτήν την μελέτη είναι χρονοσειρές αιολικού δυναμικού, ηλιακού δυναμικού και φορτίου. Το κομμάτι αυτό της διπλωματικής υλοποιήθηκε στο λογισμικό Homer. Το Homer προτείνει κάποια συστήματα που τεχνικά ικανοποιούν τις αρχικές προδιαγραφές του δικτύου και παράλληλα τα κατατάσσει με οικονομικούς κριτήρια. Για αυτό το λόγο, στην διπλωματική εργασία ακολουθεί οικονομική μελέτη των προτεινόμενων συστημάτων βάσει των όρων επένδυσης της αγοράς και του χρόνου απόσβεσης του επενδυμένου κεφαλαίου. Η οικονομική, λοιπόν, μελέτη οδηγεί στην πρόταση ενός τελικού υβριδικού συστήματος που καλύπτει τις ανάγκες του νησιού, σέβεται τα ιδιαίτερα χαρακτηριστικά του και είναι οικονομικά βιώσιμο ή μα συνάμα και κεδροφόρο. Στη συνέχεια το τελικό σύστημα εξετάζεται καθαρά από τεχνικής πλευράς σε μόνιμη και μεταβατική κατάσταση λειτουργίας. Πραγματοποιείται μελέτη ροής φορτίου και σφαλμάτων με τα λογισμικά του Power World και του Matlab συγκρίνοντας παράλληλα τα αποτελέσματά τους. Ιδίως το μοντέλο που κατασκευάστηκε στο Matlab, μπορεί να αποτελέσει ισχυρή βάση για την περαιτέρω μέλετη του συστήματος. Αξίζει να σημειωθεί, τέλος, ότι έχει καταβληθεί μεγάλη προσπάθεια ώστε η μελέτη και η προσομοίωση του συστήματος να ανταποκρίνονται με κάθε λεπτομέρεια στις ρεαλιστικές συνθήκες και τα χαρακτηριστικά του νησιού της Γαύδου και του υπάρχοντος συμβατικού σταθμού παραγωγής ενέργειας. / This thesis deals with the techno-economic study of a hybrid system on the island of Gavdos, south of Chania Crete. The object of this thesis was chosen in conjunction with practice on the same theme in the PPCR. The aim of the study is to explore the alternatives of electricity produced in the non-interconnected islands. This need arises from the extremely high costs of producing megawatts on islands like Gavdos. In order to fully analyze the issue, initially studied the particular topological features of Gavdos and possible installation locations of the hybrid system under measurement. An important aspect of this analysis is at least possible interference in the ecosystem of the island and the respect of flora and fauna. Then, having come to the structure of the proposed system are discussed specific trade solutions with extensive market research. The final selection of featured products was based on the lowest cost and highest reliability, because the continuous access to the island for maintenance of the system is not appropriate. To the next step of this study is sizing system, that operation of the system to cover the most of the load in permanent and transient operation. The basic measurements required for this study is time series wind power, solar and load capacity. This part of the thesis was implemented in software Homer. The Homer suggests some systems that meet the technical specifications of the original network while the ranks with economic criteria. For this reason, the thesis follows economic study of the proposed schemes under the terms of the investment market and the payback on invested capital. Economic therefore study leads to proposing a final hybrid system that meets the needs of the island, the particular features and is economically viable but also transcendent kedroforo. Then the final system considered purely from a technical standpoint in steady state and transient operation. Carry out a study load flow and fault with the Power World software and Matlab while comparing their results. Particular model was built in Matlab, can be a strong basis for further study of the system. It should be noted, finally, that has made ​​great efforts to study and simulation of the system to respond in detail to realistic conditions and characteristics of the island of Gavdos and the existing conventional power plant.