Solar-plus-storage benefits for end-users placed at radial and meshed grids: An economic and resiliency analysis

[EN] A resilient photovoltaic system, which comprises from the joint use of photovoltaic solar panels and electrochemical storage that is able to operate both with and without grid connection, is capable of providing an added service both during normal grid-connected operation and when a blackout occurs (as opposed to a traditional solar system). When the conventional power grid is in normal operation, resilient photovoltaic systems are able to generate revenue and/or reduce the electricity bill. During blackouts, resilient photovoltaic systems are capable of providing critical emergency power to help backup diesel generator systems. The research presented here evaluates the technical and economic feasibility of systems based on photovoltaic solar energy and electrochemical storage in three critical infrastructures which have to account with a typical backup diesel generator. To this end, the research presented here assigns a monetary value to the cost of avoiding a blackout. Thus, the REopt Lite software has been used to optimally select and dimension different resilient schemes. For each of the cases evaluated the resilient systems were able to obtain benefits associated with the substitution of the energy use of the electricity grid, the reduction of charges for the use of energy during peak energy periods, and the modification of energy purchase periods from periods of high cost to periods of low cost. For all cases the model found the optimal combination of technologies capable of minimizing the cost of energy throughout the life cycle of the project. The obtained results show that assigning a value to the cost of blackouts can have a major impact on the economic viability of a resilient solution. For all cases the net present value of a system was always higher when a value was assigned to resilience. The values assigned to resilience were higher for users plugged to radial networks, which are more prone to blackouts, and lower for users connected to meshed grids, usually more reliable. Despite the fact that for the investigation presented here only three types of infrastructures were assessed, similar results could be expected for other critical infrastructures with similar loads and electricity tariffs. Resilient systems using photovoltaic solar installations that are limited in size could provide both economic savings during normal grid-connected operation and limited emergency power during blackouts. When these systems based on photovoltaic solar energy and electrochemical storage are used in conjunction with an emergency diesel generator, these resilient “hybrid” systems are capable of satisfying critical loads during short- and long-term blackouts.[ES] Un sistema fotovoltaico resiliente, que comprende el uso conjunto de paneles solares fotovoltaicos y un almacenamiento electroquímico que sea capaz de funcionar tanto con conexión a red como sin ella, es capaz de dar un servicio añadido tanto durante el funcionamiento normal conectado a red como cuando se produce un apagón ( a diferencia de un sistema solar tradicional). Cuando la red eléctrica convencional está en funcionamiento normal, los sistemas fotovoltaicos resilientes pueden generar ingresos y/o reducir la factura eléctrica. Durante los apagones, los sistemas fotovoltaicos resistentes son capaces de proporcionar energía de emergencia crítica para ayudar a respaldar los sistemas de generadores diésel. La investigación aquí presentada evalúa la viabilidad técnica y económica de sistemas basados en energía solar fotovoltaica y almacenamiento electroquímico en tres infraestructuras críticas que deben contar con un típico generador diésel de respaldo. Para ello, la investigación aquí presentada asigna un valor monetario al costo de evitar un apagón. Por lo tanto, el software REopt Lite se ha utilizado para seleccionar y dimensionar de manera óptima diferentes esquemas resilientes. Para cada uno de los casos evaluados los sistemas resilientes lograron obtener beneficios asociados a la sustitución del uso energético de la red eléctrica, la reducción de cargos por el uso de energía durante los períodos pico de energía y la modificación de los períodos de compra de energía de los períodos de alto costo a periodos de bajo costo. Para todos los casos el modelo encontró la combinación óptima de tecnologías capaces de minimizar el coste de la energía durante todo el ciclo de vida del proyecto. Los resultados obtenidos muestran que asignar un valor al costo de los apagones puede tener un impacto importante en la viabilidad económica de una solución resiliente. En todos los casos, el valor actual neto de un sistema siempre fue mayor cuando se asignó un valor a la resiliencia. Los valores asignados a la resiliencia fueron mayores para los usuarios conectados a redes radiales, que son más propensos a sufrir apagones, y menores para los usuarios conectados a redes malladas, generalmente más confiables. A pesar de que para la investigación aquí presentada sólo se evaluaron tres tipos de infraestructuras, se podrían esperar resultados similares para otras infraestructuras críticas con cargas y tarifas eléctricas similares. Los sistemas resilientes que utilizan instalaciones solares fotovoltaicas de tamaño limitado podrían proporcionar ahorros económicos durante el funcionamiento normal conectado a la red y energía de emergencia limitada durante los apagones. Cuando estos sistemas basados en energía solar fotovoltaica y almacenamiento electroquímico se utilizan junto con un generador diésel de emergencia, estos resistentes sistemas “híbridos” son capaces de satisfacer cargas críticas durante apagones de corto y largo plazo.S

Effectiveness and efficiency of support schemes in promoting renewable energy sources in the Spanish electricity market

[EN] This research paper delves into the central mechanisms implemented in Spain to foster the adoption of clean energy projects. The study scrutinizes various mechanisms established from 2005 onwards, evaluating their efficacy in achieving the desired outcome of supporting clean energy project implementation. The aim is to comprehensively assess the associated costs, effectiveness, and attainment of renewable energy objectives stemming from implementing diverse support schemes. This paper explores the effectiveness of feed-in tariffs and feed-in premium mechanisms in promoting the integration of new renewable energy generation into the power system. However, the Spanish experience suggests that exhaustive planning control is imperative to prevent excessive support costs that could jeopardize the entire market and cause a significant rise in final energy costs. The research studies the support schemes and associated market distortion and presents the roadmap from regulated tariffs to a “total market” for wind and solar energy. The findings demonstrate that, under proper supervision and planning, a transitional retribution scheme effectively promotes renewable energy plant integration. Finally, the analysis examines the need to regulate the excess benefits that non-emitting power sources receive in a marginal price market, as this can lead to market imbalances and a substantial increase in final costs. These plans serve as a crucial tool in achieving the decarbonization objectives of the European Power System.SISchool of Economics and Management of the University of Porto (Post-doctoral research project titled “ELECTRICITY BALANCING AND SUPPORT SCHEMES FOR RENEWABLES IN THE EUROPEAN UNION” (07/11/2022 to 06/11/2023)

The green hydrogen-water-food nexus: Analysis for Spain

[EN] This research presents a novel approach that analyzes the water requirements for hydrogen production associ- ated with a nationally adopted Green Hydrogen strategy. Green Hydrogen production is one of the most relevant technologies for massive renewable energy integration in transport systems, industries, or heating systems. European Union has launched a strategic roadmap for green hydrogen generation and integration in the energy chain. Spain aims to be one of the most important producers and exporters and has approved a Hydrogen Roadmap for next years, but no previous research has focused on the water requirements. This research finds that Spain’s Green Hydrogen Roadmap, and a similar European one, is based on electrolyzers’ peak capacity, and this causes a large uncertainty in real hydrogen production and associated water requirements. Spain represents a case study that can be a reference worldwide as it suffers from increasing droughts, has considerable tourist pressure, and is one of the most important producers of greens and fruits. This study proposes a methodology to quantify actual hydrogen production and associated water requirements and proves that current large-scale planning based on peak generation will produce a large uncertainty and could directly impact water supply security. One of the most relevant findings is that hydrogen production and water requirements must be included in these strategies to avoid future water supply tensions. An analysis of alternative water supply using desali- nated water analyzes its feasibility and the effects on final cost. The outcomes are an example to be applied in similar scenarios worldwide and prove the need for an integrated energy-water-food strategy to deploy green hydrogen systems.SIPublicación en abierto financiada por el Consorcio de Bibliotecas Universitarias de Castilla y León (BUCLE), con cargo al Programa Operativo 2014ES16RFOP009 FEDER 2014-2020 DE CASTILLA Y LEÓN, Actuación:20007-CL - Apoyo Consorcio BUCL

Biomethane Microturbines as a Storage-Free Dispatchable Solution for Resilient Critical Buildings

[EN] Climate-change-related events are increasing the costs of power outages, including losses of product, revenue, and productivity. Given the increase in meteorological disasters in recent years related to climate change effects, the number of costly blackouts, from an economic perspective, has increased in a directly proportional manner. As a result, there is increasing interest in the use of alternators to supply dependable, instantaneous, and uninterruptible electricity. Traditional research has focused on the installation of diesel backup systems to ensure power requirements without deeply considering the resilience capabilities of systems, which is the ability of a system to recover or survive adversity, such as a power outage. This research presents a novel approach focusing on the resiliency impact of backup systems’ storage-free dispatchable solutions on buildings and compares the advantages and disadvantages of biomethane microturbines, natural gas engines, and diesel engines backup systems, discussing the revenue resulting from the resilience provided by emergency generators. The results show that, for several diesel fuel and natural gas safety assumptions, natural gas alternators have a lower probability of failure at the time of a blackout than diesel generators, and therefore, resilience increases.S

Multi-dimensional barrier identification for wind farm repowering in Spain through an expert judgment approach

.Spain was one of the pioneers in the deployment of wind energy systems worldwide and thus since 2014 has a potential for repowering that reaches between 3.3 and 8.7 GW in 2021 (12%–32% of its current installed wind capacity). However, despite the technical and economic advantages, we have observed little interest from promoters in the repowering of already amortized wind farms. The aim of the proposed study is to depict the background framework of barriers for repowering wind farms, which is specially affecting to Spain, but that can also extend to other EU countries. Therefore, we conducted a systematic survey study with academics, promoters, financial experts, manufacturers, operators, maintainers and policymakers to identify and understand the existing real and practical barriers. As a result, we have identified 34 major barriers covering five categories: technical issues, economics, environmental considerations, social concerns, and regulatory and administrative hurdles. We then asked the experts to rate these barriers based on their impact or relevance. We found that the experts agree that regulatory and administrative barriers have the maximum impact, while economic, environmental and technical barriers have only a mid-high impact. Therefore, we can conclude that, in general, the Administration must develop a concise and stable regulatory framework for all RES, especially for repowering projects, and carry out a review of both the technical requirements and the incentives schemes, with a focus on energy efficiency.S

Sustainable microgrids with energy storage as a means to increase power resilience in critical facilities: An application to a hospital

[EN] This manuscript proposes to study different cases that require the use of renewable energies in addition to diesel generators and energy storage systems with the aim of increasing the resilience of a microgrid feeding critical facilities. The aim of the work here presented is to quantify the benefits provided by an improvement of the energy resilience that could be achieved by installing a microgrid in a hospital fed by renewable energy sources. The microgrid will use a scheme based on solar PV in addition to diesel generators and an energy storage system based on electrochemical batteries. First, it has been evaluated how the implant of the microgrid increases the resilience of the power supply when a power failure occurs, considering that the main application in a hospital, even in the event of breakdowns, is to ensure the continuity of the surgical procedures and safely store drug stocks. Thus, these have been defined as the critical loads of the system. The components sizes have been optimized by considering both economic profitability but also the resilience capacity, observing that, by installing solar photovoltaic modules, Li-ion batteries and diesel generators, according to simulations performed in REopt® software, the microgrid could save approximately $440,191 on average over a 20-year life cycle of the facility (both considering the mitigation of energy provide by the power grid and the avoided losses during probable power services interruptions), while increasing the minimum resilience of the installation more than 34 h.[ES] Este manuscrito propone estudiar diferentes casos que requieren el uso de energías renovables además de generadores diésel y sistemas de almacenamiento de energía con el objetivo de aumentar la resiliencia de una microrred que alimenta instalaciones críticas. El objetivo del trabajo aquí presentado es cuantificar los beneficios proporcionados por una mejora de la resiliencia energética que se podría lograr mediante la instalación de una microrred en un hospital alimentado por fuentes de energía renovables. La microrred utilizará un esquema basado en energía solar fotovoltaica además de generadores diésel y un sistema de almacenamiento de energía basado en baterías electroquímicas. En primer lugar, se ha evaluado cómo el implante de la microrred aumenta la resiliencia del suministro eléctrico cuando se produce un fallo eléctrico, considerando que la principal aplicación en un hospital, incluso en caso de averías, es asegurar la continuidad de los procedimientos quirúrgicos. y almacenar de forma segura las existencias de medicamentos. Por tanto, éstas han sido definidas como las cargas críticas del sistema. Los tamaños de los componentes se han optimizado considerando tanto la rentabilidad económica como la capacidad de resiliencia, observándose que, mediante la instalación de módulos solares fotovoltaicos, baterías de Li-ion y generadores diésel, según simulaciones realizadas en el software REopt®, la microrred podría ahorrar aproximadamente$ 440.191. en promedio durante un ciclo de vida de 20 años de la instalación (considerando tanto la mitigación del suministro de energía por la red eléctrica como las pérdidas evitadas durante probables interrupciones del servicio eléctrico), al tiempo que se aumenta la resiliencia mínima de la instalación a más de 34 h.S

Electricity balancing challenges for markets with high variable renewable generation

[EN] This research studies how the process of equalizing the supply and demand of electrical energy can be improved in a foreseeable scenario characterized by a high share of renewable energy and distributed energy plants. The increase in the number of distributed energy resources can intensify the difficulties in balancing supply and demand but, at the same time, can help to enable an efficient settlement of active power imbalances. In the European market the distributed energy resources, either independently or in aggregate, have a modest contribution to the equalization process. This research focuses on an analysis of prevailing configurations for balancing the supply and demand of electrical energy in Europe and on checking its suitability for a prospective scenario with a much higher share of renewable energy than the present one. The results show that the ongoing configuration in Europe is an inheritance that constraints present choices. Furthermore, the study compares the current configurations in the European Union and the United States and highlights the challenges that the European Union is facing, mainly due to infrastructure bottlenecks between member states.SIUniversidad de Porto (Portugal

A Techno-Economic Appraisal of Green Diesel Generation through Hydrothermal Liquefaction, Leveraging Residual Resources from Seaweed and Fishing Sectors

[EN] This study examines the economic viability of an emerging technology for potential up- scaling and commercialization in a specific location: the village of New Stuyahok, Alaska. The proposed technology is hydrothermal liquefaction, which utilizes kelp macroalgae and fishing waste as feedstock. These materials were chosen due to their easy availability in the village and their alignment with the local economy. The economic evaluation is based on the net present value (NPV) and sensitivity models. Different feedstock ratios (on a dry basis), such as 100:0, 50:50, and 30:70 of kelp and fishing waste, respectively, were evaluated to determine the optimal combination. The results indicated that the process is economically viable only when a high proportion of fish- ing waste is used. This can be ascribed to the constrained output yield of the kelp biomass and the relatively negligible influence exerted by alginate production on the NPV. However, the ratio 50:50 appears to be economically promising if the costs can be reduced by at least 13.5% or the benefits can be increased by 12.1%. Nevertheless, government support could play a crucial role in expediting the implementation of this technology once it becomes market-ready. This means being practical, scalable, and economically viable, enabling reduced investments or increased benefits that signify its readiness. Utilizing such a tool offers valuable insights into the framework of the proposed technology and the use of local natural resource

Teaching Using Collaborative Research Projects: Experiences with Adult Learners in Distance Education

[EN] This research studies the acquisition and improvement of specific cognitive, functional, and social competencies of the students enrolled in a university module in which we applied Collaborative Research Project (CRP) strategy. The module was Research Methodology for a master’s degree in research in electrical engineering, electronics and industrial control given at the National Distance Education University (UNED) in Spain. This practice was applied to a research project in which the private sector was interested in. We have been aiming at increasing academia–industry interaction while promoting active learning; both are principles advocated by the European Higher Education Area (EHEA). Having applied this strategy, the module learning outcomes were evaluated following the guideline standards set by the National Agency for Quality Assessment of Universities (ANECA) of the Spanish Government. The results from this evaluation indicated that CRP, even when carried out by using distance learning, has encouraged the students’ interest in both research and the module. It has also fostered collaboration between students and lecturers while increasing their degree of satisfaction. We highlight the difficulties in merging all the outcomes from the students’ research as the main drawback

Optimized design method for storage systems in photovoltaic plants with delivery limitation

Versión aceptada para publicación. No contiene los cambios menores recogidos tras el proof reading.[EN] It results widely common for distribution network operators to impose restrictions on delivered solar photovoltaic generated power when the power plant rated power is greater than the maximum allowed due to the distribution network capacity. Thus, a feasible solution to maximize the performance of the solar power plant is the integration of battery energy storage systems. Although this configuration has been extensively studied in the existing literature, an optimal design method to determine the proper size and operation of the energy storage system needs to be developed. In this paper, a novel method to help power plants designers to determine the optimal battery energy storage capacity to integrate into any solar photovoltaic power plant is provided. The proposed algorithm minimizes the potential power curtailment and optimizes the utilization rate of the batteries storage system. The algorithm can be applied to any grid connected solar photovoltaic power plant under delivery power restrictions, regardless of power capacity and location. The algorithm has been implemented to a simulated power plant with delivery limitations based in a real case, and results with the optimal battery capacity show that the system would be able to recover up to the 83% of the curtailed energy and a yearly average capacity utilization of 56%. Moreover, the BESS operation has been validated with a scaled model run in Simulink and laboratory measurements, achieving 98% of curtailed energy recovery rate and a 57% of average capacity utilization.[ES] Resulta muy habitual que los operadores de las redes de distribución impongan restricciones a la potencia generada por energía solar fotovoltaica suministrada cuando la potencia nominal de la central es superior a la máxima permitida debido a la capacidad de la red de distribución. Por ello, una solución factible para maximizar el rendimiento de la central solar es la integración de sistemas de almacenamiento de energía en baterías. Aunque esta configuración ha sido ampliamente estudiada en la literatura existente, es necesario desarrollar un método de diseño óptimo para determinar el tamaño y funcionamiento adecuados del sistema de almacenamiento de energía. En este trabajo se presenta un método novedoso para ayudar a los diseñadores de centrales eléctricas a determinar la capacidad óptima de almacenamiento de energía en baterías para integrar en cualquier central solar fotovoltaica. El algoritmo propuesto minimiza el posible recorte de potencia y optimiza la tasa de utilización del sistema de almacenamiento en baterías. El algoritmo puede aplicarse a cualquier planta de energía solar fotovoltaica conectada a la red bajo restricciones de potencia de entrega, independientemente de la capacidad de potencia y la ubicación. El algoritmo se ha aplicado a una central eléctrica simulada con limitaciones de suministro basada en un caso real, y los resultados con la capacidad óptima de las baterías muestran que el sistema sería capaz de recuperar hasta el 83% de la energía restringida y una utilización media anual de la capacidad del 56%. Además, el funcionamiento del BESS se ha validado con un modelo a escala ejecutado en Simulink y mediciones de laboratorio, y se ha conseguido recuperar el 98% de la energía restringida.S