Concentrated Photovoltaics

70 σ.Στόχος της παρούσας διπλωματικής είναι η βιβλιογραφική ανασκόπηση της τεχνολογίας των συγκεντρωτικών φωτοβολταϊκών (CPV) και στη συνέχεια η μελέτη του ρόλου που μπορούν να παίξουν στην παραγωγή πράσινης, φθηνής ηλεκτρικής ενέργειας σε μεγάλη κλίμακα. Αρχικά, γίνεται μία σύντομη ιστορική αναδρομή στην ιστορία της φωτοβολταϊκής τεχνολογίας, και στη συνέχεια παρουσιάζεται αναλυτικά η τεχνολογία των συγκεντρωτικών φωτοβολταϊκών δίνοντας έμφαση στις διαφορές τους με τα συμβατικά κύτταρα πυριτίου. Έπειτα, παρουσιάζονται οι πιο σημαντικές κατασκευαστικές διαδικασίες (LPE και MOCVD) καθώς και επίκαιρα ζητήματα που αφορούν τις διαδικασίες αυτές. Ειδικό βάρος δίνεται στις τρέχουσες και μελλοντικές δυνατότητες εμπορικής ανάπτυξης των CPV: Παρουσιάζονται σενάρια μελλοντικής υλοποίησης της τεχνολογίας των CPV, καθώς και το τι έχει γίνει μέχρι σήμερα. Αναδεικνύεται ειδικά ο ρόλος των πολυσυνδετικών ηλιακών κελιών(multi-junction solar cells) σαν καταλύτης στη παραγωγή ηλεκτρικής ενέργειας που μπορεί να ανταγωνιστεί ευθέως τις συμβατικές πηγές (άνθρακας, υγραέριο, πυρηνικά καύσιμα). Στο τέλος, αναφέρονται συνοπτικά εφαρμογές μεγάλης κλίμακας. ΘεόδωροςThis diploma thesis is a bibliographical review about Concentrated Photovoltaics (CPV) and the major role they could play in generating solar power on an industrial-size scale. So far, there hasn't been any greek bibliography concerning concentrated photovoltaics and this thesis aims to close that gap. Initially, a small introduction about photovoltaics in general is made, and consenquently CPV technology is explained in detail. Special emphasis is given on its differences with conventional silicon cells. Afterwards, the most important and promising manufactoring processes and techniques are presented(such as LPE and MOCVD) and current challenges and difficulties concerning those techniques are pointed out. Its current and future economic prospects are laid down, especially in comparison to conventional solar cells. Also, we explain in detail why multijunction solar cell technology is an enabler for low cost power generation using concentrated photovoltaic systems. Finally, several current, large scale applications are presented.Θεόδωρος Μ. Μπέλλο

Life-cycle carbon emissions and energy return on investment for 80% domestic renewable electricity with battery storage in California (U.S.A.)

This paper presents a detailed life-cycle assessment of the greenhouse gas emissions, cumulative demand for total and non-renewable primary energy, and energy return on investment (EROI) for the domestic electricity grid mix in the U.S. state of California, using hourly historical data for 2018, and future projections of increased solar photovoltaic (PV) installed capacity with lithium-ion battery energy storage, so as to achieve 80% net renewable electricity generation in 2030, while ensuring the hourly matching of the supply and demand profiles at all times. Specifically—in line with California’s plans that aim to increase the renewable energy share into the electric grid—in this study, PV installed capacity is assumed to reach 43.7 GW in 2030, resulting of 52% of the 2030 domestic electricity generation. In the modelled 2030 scenario, single-cycle gas turbines and nuclear plants are completely phased out, while combined-cycle gas turbine output is reduced by 30% compared to 2018. Results indicate that 25% of renewable electricity ends up being routed into storage, while 2.8% is curtailed. Results also show that such energy transition strategy would be effective at curbing California’s domestic electricity grid mix carbon emissions by 50%, and reducing demand for non-renewable primary energy by 66%, while also achieving a 10% increase in overall EROI (in terms of electricity output per unit of investment)

Cu(InGa)Se 2 THIN-FILM SOLAR CELLS: COMPARATIVE LIFE-CYCLE ANALYSIS OF BUFFER LAYERS

ABSTRACT: A motivation for replacing the current CdS buffer layer in CIGS PV is to avoid potential environmental-and human-health risks related to cadmium compounds. However, to gain a full perspective, such risks should be evaluated throughout the entire life cycle of the CdS, and also of alternative buffer layers. Based on data from the National Renewable Energy Laboratory and Global Solar Energy, we examined the life-cycle Cd emissions during materials production and the deposition processes for CdS and ZnS buffers. We found that the Cd emissions from the buffer layers are minimal compared to the upstream emissions from fossil-fuel-based electricity that the electricity generated from CIGS PV will replace. Accordingly, assuring a higher efficiency of CIGS PV is the best strategy to minimize Cd emissions to the environment In addition, the production of ZnS (and InS) entails some Cd emissions as Cd is present in Zn ores. Based on the current efficiencies of alternative cell designs, CIGS/CdS will create a smaller amount of net Cd emissions than the CIGS/ZnS or CIGS/InS-based alternatives

Assessing the Benefits of Compressed Air Energy Storage on the 2020 Irish Power System

Power systems have evolved as countries implement energy policies focusing on energy efficiency and increased share of renewable energy sources (RES). At the forefront is non-dispatchable generation such as wind and solar. Traditionally power systems were designed for fully dispatchable generating plant. However, these powers systems are under additional pressure due to the variable operational characteristics of RES. Consequently, capital investments in grid reinforcement, interconnection, additional gas generators and smart grid initiatives have been proposed and implemented. Moreover, an increased interest in energy storage technologies has evolved due to their various economic and operational benefits to power systems. Current compressed air energy storage (CAES) plants have shown economic feasibility and reliability. Thus, the main focus of this paper is to investigate and compare two scenarios; one without CAES and a second with CAES as an additional generator in the 2020 Irish power system using power systems simulation software PLEXOS

What are the energy and environmental impacts of adding battery storage to photovoltaics? A generalized life cycle assessment

Renewable electricity generation is intermittent and its large‐scale deployment will require some degree of energy storage. Although best assessed at grid level, the incremental energy and environmental impacts of adding the required energy storage capacity may also be calculated specifically for each individual technology. This paper deals with the latter issue for the case of photovoltaics (PV) complemented by lithium‐ion battery (LIB) storage. A life cycle assessment (LCA) of a 100MW ground‐mounted PV system with 60MW of (lithium‐manganese oxide) LIB, under a range of irradiation and storage scenarios, show that energy pay‐back time and life‐cycle global warming potential increase by 7% to 30% (depending on storage duration scenarios), with respect to those of PV without storage. Thus the benefits of PV when displacing conventional thermal electricity (in terms of carbon emissions and energy renewability) are only marginally affected by the addition of energy storage

A Comprehensive Guide to Solar Energy Systems With Special Focus on Photovoltaic Systems

This book, the most advanced and research focused text on all aspects of solar energy engineering, is a must have edition on the present state of solar technology, integration and worldwide distribution. In addition, the book provides a high-level assessment of the growth trends in photovoltaics and how investment, planning and economic infrastructure can support those innovations. Each chapter includes a research overview with a detailed analysis and new case studies that look at how recent research developments can be applied. Written by some of the most forward-thinking professionals, this book is an invaluable reference for engineers. Key Features Contains analysis of the latest high-level research and explores real world application potential in relation to developments Uses system international (SI) units and imperial units throughout to appeal to global engineers Offers measurable data written by a world expert in the field on the latest developments in this fast moving and vital subject Readership Energy engineers, researchers, graduate students, professors and lecturers in Engineering, scientists and engineers working in energy, industrialists and engineers working in future energy development

Life-cycle carbon emissions and energy implications of high penetration of photovoltaics and electric vehicles in California

California has set two ambitious targets aimed at achieving a high level of decarbonization in the coming decades, namely (i) to generate 60% and 100% of its electricity using renewable energy (RE) technologies, respectively, by 2030 and by 2045, and (ii) introducing at least 5 million zero emission vehicles (ZEVs) by 2030, as a first step towards all new vehicles being ZEVs by 2035. In addition, in California, photovoltaics (PVs) coupled with lithium-ion battery (LIB) storage and battery electric vehicles (BEVs) are, respectively, the most promising candidates for new RE installations and new ZEVs, respectively. However, concerns have been voiced about how meeting both targets at the same time could potentially negatively affect the electricity grid’s stability, and hence also its overall energy and carbon performance. This paper addresses those concerns by presenting a thorough life-cycle carbon emission and energy analysis based on an original grid balancing model that uses a combination of historical hourly dispatch and demand data and future projections of hourly demand for BEV charging. Five different scenarios are assessed, and the results unequivocally indicate that a future 80% RE grid mix in California is not only able to cope with the increased demand caused by BEVs, but it can do so with low carbon emissions (<110 g CO2-eq/kWh) and satisfactory net energy returns (EROIPE-eq = 12–16)

Pathways for minimal and zero liquid discharge with enhanced reverse osmosis technologies: Module-scale modeling and techno-economic assessment

While mechanical vapor compression is typically applied for the concentration of brine, new approaches that are less costly and less energy intensive are needed to facilitate minimal and zero liquid discharge. Several variations of reverse osmosis for high-salinity desalination and increasing recovery rates beyond the pressure limitation of conventional RO have been proposed in the literature. The promise of these enhanced RO approaches entails a reduction in energy consumption when compared with thermal desalination methods. In this paper, low-salt rejection reverse osmosis (LSRRO), cascading osmotically mediated reverse osmosis (COMRO), and osmotically assisted reverse osmosis (OARO) were comparatively assessed via module-scale, cost optimization models to gain an accurate perspective of the performance differences between each of these configurations. We quantified the optimal levelized cost of water (LCOW) of each technology for the case of desalinating feedwater at 70 g/L at 75% recovery, which would result in a brine concentration near 250 g/L, a level that allows further treatment with crystallizers. For baseline scenarios, LCOW results for LSRRO, COMRO, and OARO were 6.63, 7.90, and 5.14 $/m3 of product water, respectively, while the corresponding specific energy consumption (SEC) values were 28.9, 12.8, and 10.3 kWh/m3. A sensitivity analysis is also presented