A comprehensive methodology for the statistical characterization of solar irradiation: application to the case of Morocco

The prediction and characterization of solar irradiation relies mostly on either the use of complex models or on complicated mathematical techniques, such as artificial neural network (ANN)-based algorithms. This mathematical complexity might hamper their use by businesses and project developers when assessing the solar resource. In this study, a simple but comprehensive methodology for characterizing the solar resource for a project is presented. It is based on the determination of the best probability distribution function (PDF) of the solar irradiation for a specific location, assuming that the knowledge of statistical techniques may be more widely extended than other more complex mathematical methods. The presented methodology was tested on 23 cities across Morocco, given the high interest in solar investments in the country. As a result, a new database for solar irradiation values depending on historical data is provided for Morocco. The results show the great existing variety of PDFs for the solar irradiation data at the different months and cities, which demonstrates the need for undertaking a proper characterization of the irradiation when the assessment of solar energy projects is involved. When it is simply needed to embed the radiation uncertainty in the analysis, as is the case of the techno-economic valuation of solar energy assets, the presented methodology can reach this objective with much less complexity and less demanding input data. Moreover, its application is not limited to solar resource assessment, but can also be easily used in other fields, such as meteorology and climate change studies.Peer ReviewedPostprint (published version

Renewable energy auction prices: near subsidy-free?

The latest trend of low record bid prices in renewable energy auctions has raised concerns on the effective deployment of the winning projects. A survey of recent auction data from several countries, technologies and remuneration designs is analysed and compared with the corresponding levelised costs of energy (LCOEs) to draw first insights on their viability. A critical assessment of the ability of the LCOE for determining the adequate bid level is then performed and the preliminary unviable results of selected mature technologies are further investigated using improved profitability metrics as the project and equity net present value (NPV) and internal rate of return (IRR). As representative examples, the analysed Danish 2019 onshore wind and photovoltaics (PV) auctions require very specific scenarios to become viable, which cast doubts on their effective implementation. Under the assumptions of a realistic base case, the sensitivity analysis revealed that either 59% of decrease in the weighted average cost of capital (WACC), or 37% of discount on the investment cost or a 3.6% annual increment in the mean market price is needed for achieving the NPV break-even in the onshore wind case. Likewise, the PV case is unprofitable whatever the WACC may be, and either a 60% discount on the investment cost or a 6.8% annual increment in the mean market price is needed for the NPV to break-even. Although some projects could be relying on indirect revenues or additional sources of incomes beyond the auction support, it remains to see if they are finally materialised.Peer ReviewedPostprint (published version

Methodology for obtaining simplified models for the long-term energy management of renewable assets under a high degree of uncertainty

This paper addresses the attainment of a methodology aimed at obtaining simplified models embedding the regulatory constraints imposed by the country-specific remuneration mechanisms in the energy management system of long operating life renewable assets under a high degree of uncertainty. This methodology, composed of different steps in which sensitivity analysis as well as Monte Carlo simulation play a key role, is focused on a significant case study that has implemented two of the most widely used worldwide remuneration mechanisms in the promotion of renewable energies, i.e., feed-in tariffs and auctions. The earnings before interest, tax, depreciation and amortization have been used as the output variable of the energy management model, as it is essential to take into account both revenues and operating costs of these renewable assets to manage them optimally. Some valid simplified models have been achieved by applying the proposed methodology to the case study with generalized errors below 5%. Specifically, one simplified energy management system model has been obtained under the feed-in tariff scheme, which involves acting on almost 40% of the equations of the original model and reducing the initial input parameters by 22%. Meanwhile, two simplified energy management system models have been obtained under the auction scheme. The most conservative simplified model involves acting on almost 50% of the equations of the original model and reducing the initial input parameters by 35%, while in the less conservative case it involves acting on more than 50% of the equations of the original model and reducing the initial input parameters by 42%. In short, although the uncertainty on the energy assets cannot be completely eliminated, it can be considerably reduced by facilitating the assessment of its prospective financial results. The validity of the achieved simplified models demonstrates the suitability and usefulness of the proposed simplifying methodology, providing a touch of quality in the long-term judgement and decision-making of the stakeholders when optimally managing renewable energy facilities under any type of remuneration scheme.Peer ReviewedPostprint (author's final draft

A comprehensive model for the design of a microgrid under regulatory constraints using synthetical data generation and stochastic optimization

As renewable energy installation costs decrease and environmentally-friendly policies are progressively applied in many countries, distributed generation has emerged as the new archetype of energy generation and distribution. The design and economic feasibility of distributed generation systems is constrained by the operation of the microgrid, which has to consider the uncertainty of renewable energy sources, consumption habits and electricity market prices. In this paper, a mathematical model intended to optimize the design and economic feasibility of a microgrid is proposed. After a search in the state-of-the-art, weaknesses and strengths of existing models have been identified and taken into account for building the present model. The present model should be seen as a basis on which other models can be built upon, hence a complete definition of the different sub-models is stated: uncertainty modelling, optimization technique, physical constraints and regulatory framework. One of the main features presented is the generation of synthetic data in uncertainty modelling, employed to enhance the reliability of the model by taking into account a longer time horizon and a shorter time step. Results show significant details about energy management and prove the suitability of using a stochastic approach rather than deterministic or intuitive ones to perform the optimization.Peer ReviewedPostprint (published version

Reducing the environmental impact of surgery on a global scale: systematic review and co-prioritization with healthcare workers in 132 countries

Abstract Background Healthcare cannot achieve net-zero carbon without addressing operating theatres. The aim of this study was to prioritize feasible interventions to reduce the environmental impact of operating theatres. Methods This study adopted a four-phase Delphi consensus co-prioritization methodology. In phase 1, a systematic review of published interventions and global consultation of perioperative healthcare professionals were used to longlist interventions. In phase 2, iterative thematic analysis consolidated comparable interventions into a shortlist. In phase 3, the shortlist was co-prioritized based on patient and clinician views on acceptability, feasibility, and safety. In phase 4, ranked lists of interventions were presented by their relevance to high-income countries and low–middle-income countries. Results In phase 1, 43 interventions were identified, which had low uptake in practice according to 3042 professionals globally. In phase 2, a shortlist of 15 intervention domains was generated. In phase 3, interventions were deemed acceptable for more than 90 per cent of patients except for reducing general anaesthesia (84 per cent) and re-sterilization of ‘single-use’ consumables (86 per cent). In phase 4, the top three shortlisted interventions for high-income countries were: introducing recycling; reducing use of anaesthetic gases; and appropriate clinical waste processing. In phase 4, the top three shortlisted interventions for low–middle-income countries were: introducing reusable surgical devices; reducing use of consumables; and reducing the use of general anaesthesia. Conclusion This is a step toward environmentally sustainable operating environments with actionable interventions applicable to both high– and low–middle–income countries

Aportació a l'estudi de la regulació de les energies renovables, focalització en l'energia solar fotovoltaica

Des del novembre de l’any 1997, amb l’aprovació de la Llei 54/1997 del Sector Elèctric, fins l’actualitat, amb la recent aprovació del Reial Decret 413/2014 que regula l’activitat de producció d’energia elèctrica a partir de fonts renovables i desenvolupa la nova Llei 24/2013 del Sector Elèctric, el sector de les energies renovables, i en concret el de l’energia solar fotovoltaica, ha anat patint múltiples transformacions i canvis any rere any, que ha fet que cada cop sigui més difícil la interpretació dels marcs reguladors als que s’acullen les diferents instalGlacions productores d’electricitat mitjançant fonts renovables. Per aquest motiu, en aquest TFG es pretén analitzar i descriure acuradament els diferents marcs reguladors que han anat sorgint al llarg de l’esmentat període, explicant així mateix, de quina manera les instalGlacions es veien afectades, tant econòmicament com jurídicament, fent especial esment al nou marc regulador format principalment per la Llei 24/2013 i pel RD 413/2014, del qual se’n detallarà la seva formulació econòmica d’accés a mercat amb retribució específica. Finalment, s’analitzarà la prospectiva de futur del sector fotovoltaic a través del PER 2011-2020 i es proposaran alguns models basats en la dinàmica de sistemes per tal d’analitzar aquesta prospectiva

Aportació a l’anàlisi i gestió tècnica-econòmica dels sistemes de generació distribuïda amb energies renovables i microxarxes : introducció a la presa de decisions en el context normatiu actual

Agraïment: L'article de l'editorial Elsevier, MONTE-CARLO probabilistic valuation of concentrated solar power systems in Spain under the 2014 retroactive regulatory framework, es pot consultar a la web, DOI 10.1016/j.rser.2020.110670(English) In recent years, the development of a generation system based on renewable energies has become the backbone of the energy policies of most countries in the world in the search for the decarbonization of the energy sector to contain planet global warming. The remarkable progress achieved in the reconversion of the electricity generation sector worldwide towards a renewable model has been acquired in large part by the public support policies for renewable generation technologies implemented. Spain has not been an exception, but rather a particularly relevant case study due to the numerous legislative changes experienced in the regulation of renewable energies in the last two decades. Specifically, Spain went from being one of the world's leading countries in the promotion of renewable energy sources, especially solar and wind, through the implementation of legal-economic frameworks with high associated economic returns during the first decade of the 2000s, to being one of the first countries to retroactively apply containment measures to reduce the disproportionate development costs that put the financial sustainability of the Spanish electricity sector at risk, giving rise to very unfavourable conditions for renewable assets in the second decade of the 2000s. In this sense, this thesis, presented as a compendium of articles, is developed within the line of research focused on the analysis and synthesis of regulatory frameworks to optimize decision-making in the design and management of energy assets, contributing to the state of the art from three papers published in indexed journals. First of all, this project aims to provide the academy with an exhaustive review of the evolution of solar energy policy in Spain during the period 1998–2020, through the first review article. Specifically, this study focuses on solar generation technology (photovoltaic and concentrating solar power) that has the potential to become the most abundant energy resource in the world, with Spain having the most abundant solar resource in the entire European Union. This review of the academic literature integrates and evaluates all the relevant information from published research works, as well as form the regulations in force during the period 1998–2020, allowing readers to understand the importance of energy policies to promote these solar assets. In this line, and in relation to the economic analysis of these assets based on the regulatory frameworks applied, this project through the second paper analyses the impact of regulatory retroactivity on the economic valuation of Spanish concentrating solar power assets in the medium and long term by using a stochastic model, seeking to improve decision-making regarding the design and management of these assets and reduce the impact on investment risk. Finally, once the importance of regulatory frameworks on the economic results of energy assets has been verified, this work addresses in the third paper the definition of a methodology aimed at obtaining simplified models that incorporate all the variables associated with the problem in the energy management model of renewable assets with a long operating life under a high degree of uncertainty. Accordingly, it seeks to solve a real problem by facilitating operational decision-making and the management of renewable assets in the medium and long term, in order to optimize their economic results. The line of work defined and shown with this compendium of articles clearly demonstrates the importance of regulatory frameworks and the need for their incorporation in both economic and energy decision-making. The methodology and results of the thesis are currently applied to the concentrating solar power and photovoltaic assets of the Spanish generation system, improving their optimal and economically efficient management.(Català) En les últimes dècades, el desenvolupament d’un parc de generació basat en energies renovables s’ha convertit en l’eix vertebrador de les polítiques energètiques de gran part dels països del mon en la cerca de la descarbonització del sector energètic per tal de contenir l’escalfament global del planeta. El destacable progrés assolit en la reconversió del sector de la generació d’electricitat a nivell mundial cap a un model renovable s’ha adquirit en gran part per les polítiques de suport públic a les tecnologies de producció renovables implementades. Espanya no ha estat una excepció, sinó un cas d’estudi especialment rellevant pels nombrosos canvis legislatius experimentats en la regulació de les energies renovables en les darreres dues dècades. En concret, Espanya va passar de ser un dels països líders mundials en la promoció de les fonts d’energia renovable, especialment la solar i la eòlica, mitjançant la implementació de marcs juridicoeconòmics amb altes rendibilitats econòmiques associades durant la primera dècada dels anys 2000, a ser un dels primers països en aplicar retroactivament mesures de contenció per reduir els costos de promoció desproporcionats que posaven en risc la sostenibilitat financera del sector elèctric espanyol, donant lloc a unes condicions molt desfavorables per als actius renovables en la segona dècada dels anys 2000. En aquest sentit, aquesta tesi, presentada com a compendi d’articles, es desenvolupa dins la línia de recerca centrada en l’anàlisi i síntesi dels marcs reguladors per optimitzar la presa de decisions en el disseny i la gestió d’actius energètics, contribuint en l’estat de l’art a partir de tres articles publicats en revistes indexades. En primer lloc, aquest projecte pretén aportar a l’acadèmia una revisió exhaustiva de l'evolució de la política d'energia solar a Espanya durant el període 1998-2020, a través del primer article de revisió. En concret, aquest estudi es focalitza en la tecnologia de generació solar (fotovoltaica i termosolar) que té el potencial de convertir-se en el recurs energètic més abundant del món, posseint Espanya el recurs solar més abundant de tota la Unió Europea. Aquesta revisió de la literatura acadèmica integra i avalua tota la informació rellevant de treballs de recerca publicats, així com de la regulació vigent durant el període 1998-2020, permetent als lectors copsar la importància de les polítiques energètiques de promoció d’aquests actius solars. En aquesta línia, i en relació a l’anàlisi econòmic d’aquests actius en funció dels marcs reguladors aplicats, el present projecte a través del segon article analitza l’impacte de la retroactivitat regulatòria en la valoració econòmica dels actius termosolars espanyols a mig i llarg termini mitjançant un model estocàstic, en la cerca de millorar la presa de decisions relatives al disseny i la gestió d’aquests actius i reduir l’impacte en el risc d’inversió. Finalment, un cop constatada la importància dels marcs reguladors sobre els resultats econòmics dels actius energètics, aquest treball aborda en el tercer article la definició d'una metodologia orientada a l'obtenció de models simplificats que incorporin totes les variables associades al problema en el model de gestió energètica dels actius renovables de llarga vida operativa sota un alt gra d’incertesa. En aquest sentit, es busca resoldre un problema real facilitant la presa de decisions operatives i la gestió dels actius renovables a mig i llarg termini, per tal d’optimitzar els seus resultats econòmics. La línia de treball definida i mostrada amb aquest compendi d’articles demostra clarament la importància dels marcs reguladors i la necessitat de la seva incorporació en la presa de decisions tant econòmiques com energètiques. La metodologia i resultats de la tesi són d’aplicació actual sobre els actius termosolars(Español) En las últimas décadas, el desarrollo de un parque de generación basado en renovables se ha convertido en el eje vertebrador de las políticas energéticas de gran parte de los países del mundo en la búsqueda de la descarbonización del sector energético para contener el calentamiento global del planeta. El destacable progreso logrado en la reconversión del sector de la generación eléctrica hacia un modelo renovable se ha adquirido en gran parte por las políticas de apoyo público a las tecnologías de producción renovables implementadas. España no ha sido una excepción, sino un caso de estudio especialmente relevante por los numerosos cambios legislativos experimentados en la regulación de las renovables en las últimas dos décadas. En concreto, España pasó de ser uno de los países líderes mundiales en la promoción de las renovables, especialmente la solar y la eólica, mediante la implementación de marcos reguladores con altas rentabilidades económicas asociadas durante la primera década de los años 2000, a ser uno de los primeros países en aplicar retroactivamente medidas de contención para reducir los costes de promoción desorbitados que ponían en riesgo la sostenibilidad financiera del sector eléctrico español, dando lugar a unas condiciones muy desfavorables para los activos renovables en la segunda década de los años 2000. En este sentido, esta tesis, presentada como compendio de artículos, se desarrolla dentro de la línea de investigación centrada en el análisis y síntesis de los marcos reguladores para optimizar la toma de decisiones en el diseño y la gestión de activos energéticos, contribuyendo en el estado del arte a partir de tres artículos publicados en revistas indexadas. En primer lugar, este proyecto pretende aportar a la academia una revisión exhaustiva de la evolución de la política de energía solar en España durante el periodo 1998–2020, a través del primer artículo de revisión. En concreto, este estudio se focaliza en la tecnología de generación solar (fotovoltaica y termosolar) que tiene el potencial de convertirse en el recurso energético más abundante del mundo. Esta revisión de la literatura académica integra y evalúa toda la información relevante de trabajos de investigación publicados, así como de la regulación vigente durante el periodo 1998– 2020, permitiendo a los lectores entender la importancia de las políticas energéticas de promoción de los activos solares. En esta línea, y en relación al análisis económico de estos activos en función de los marcos reguladores aplicados, el presente proyecto a través del segundo artículo analiza el impacto de la retroactividad regulatoria en la valoración económica de los activos termosolares españoles a medio y largo plazo mediante un modelo estocástico, en la búsqueda de mejorar la toma de decisiones relativas al diseño y la gestión de estos activos y reducir el impacto en el riesgo de inversión. Finalmente, una vez constatada la importancia de los marcos reguladores sobre los resultados económicos de los activos energéticos, este trabajo aborda en el tercer artículo la definición de una metodología orientada a la obtención de modelos simplificados que incorporen todas las variables asociadas al problema en el modelo de gestión energética de los activos renovables de larga vida operativa bajo un alto grado de incertidumbre. En este sentido, se busca resolver un problema real facilitando la toma de decisiones operativas y la gestión de los activos renovables a medio y largo plazo, para optimizar sus resultados económicos. La línea de trabajo definida y mostrada con este compendio de artículos demuestra claramente la importancia de los marcos reguladores y la necesidad de su incorporación en la toma de decisiones tanto económicas como energéticas. La metodología y resultados de la tesis son de aplicación actual sobre los activos termosolares y fotovoltaicos del parque de generación español, favoreciendo su gestión óptima y económicamente eficiente.Postprint (published version