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The urgent climate situation resulting from the indiscriminate consumption of fossil fuels together with the current geopolitical instability has prompted a series of policies in Europe to boost the energy transition through the large-scale installation of renewable energy sources (RES). To combat the intermittency and fluctuations associated with their operation, renewable hydrogen is presented as a versatile solution to decarbonize different economic sectors. Hence, the design and implementation of a hybrid renewable-hydrogen power system has turn out in the first electrically self-sufficient social housing of Spain installed in the town of Novales (Cantabria, Spain). The entire process is automated and controlled by a programmable logic controller (PLC) and monitored by a SCADA system. Under this framework, the HY2RES project proposes a digital twin (DT) modeling of the pilot plant to optimize the control system and the operating parameters thanks to the application of machine learning (ML) and artificial intelligence (AI) techniques to the data collected. The paper shows some initial results of the proposed DT, which features the electrical components of the physical system. The obtained results both validate the proposed methodology and evince the possibilities brought by it. [ABSTRACT FROM AUTHOR]

The Spanish government is a strong advocate of reducing CO2 emissions and has made a clear commitment to the implementation of renewable energies. As reflected in Spain's National Energy and Climate Plan (NECP), its objective is to double the current capacity of pumped hydropower storage (PHS) plants by 2030. Therefore, the study presented here is both current and forward-looking. This paper presents the results of the analysis of the technical potential of installing floating photovoltaic (FPV) plants at 25 PHS plants in Spain, i.e., the total capacity of Spanish hydropower plants. The study was conducted using various assessment indicators: the global horizontal irradiance ratio, electrical efficiency ratio, area required ratio, pumping area ratio, volume ratio of water pumped per day, and achievable power ratio. In summary, the following conclusions can be drawn: (i) The global horizontal irradiance ratio indicates whether a FPV plant is economically viable. From this point of view, the Aguayo PHS plant and the Tanes PHS plant are not suitable, as this ratio is very low; (ii) the compliance with the electrical efficiency ratio is flexible, and all hydropower plants meet this criterion; (iii) maximising the use of the assigned grid connection capacity is one of the goals sought by electrical companies when implementing FPV plants at existing PHS plants. The following hydropower plants are not suitable for the implementation of an FPV plant in view of the following: La Muela I, La Muela II, Aguayo, Sallente, Aldeadavila II, Moralets, Guillena, Bolarque II, Montamara, and IP; (iv) if the aim is energy storage, the following hydropower plants are not suitable for the implementation of an FPV plant: the La Muela I, La Muela II, Tajo de la Encantada, Aguayo, Sallente, Aldeadavila II, Conso, Moralets, Guillena, Bolarque II, Tanes, Montamara, Soutelo, Bao-Puente Bibey, Santiago de Jares, IP, and Urdiceto; (v) if the aim is to expand an FPV plant already installed at a PHS plant, the following hydropower plants do not meet this criterion: the La Muela I, La Muela II, Aguayo, Sallente, Aldeadavila, Moralets, Guillena, Bolarque II, Montamara, and IP. There are only eight hydropower plants that meet conditions (i), (iii) and (iv): the Villarino, Torrejon, Valparaiso, Gabriel y Galan, Guijo de Granadilla, Pintado, and Gobantes. [ABSTRACT FROM AUTHOR]

The increasing demand for energy-efficient and sustainable solutions in the building sector has driven the need for innovative approaches that integrate renewable energy sources and advanced control systems. This paper presents an integrated energy management solution for solar-powered smart buildings, combining a multifaceted physical system with advanced IoT- and cloud-based control systems. The physical system includes a heat pump, photovoltaics, solar thermal panels, and an innovative low-enthalpy radiant wall and ceiling, providing self-sufficient heating and cooling. The control system makes use of advanced IoT and communication engineering technologies, using Modbus, HTTP, and MQTT protocols for seamless interconnectivity, monitoring, and remote management. The successful implementation of this solution in an average-sized model house in Paris and a deep energy retrofit of a semidetached single-family house in Oviedo, northern Spain, demonstrates increased energy efficiency, improved thermal comfort, and reduced environmental impact compared with conventional alternatives. This study illustrates the potential of integrating solar energy, IoT, and communication technologies into smart buildings, contributing to the global effort to reduce the environmental impact of the building sector. [ABSTRACT FROM AUTHOR]

In line with the decarbonization of the domestic sector to meet the 2050 climate neutrality targets, this paper describes the energy, economic, and environmental analysis of a set of different novel configurations of polygeneration installations to provide electricity, air conditioning, domestic hot water, and desalinated water for a building of 80 dwellings. All arrangements were designed to cover 100% of the five demands required in the building with renewable energy only, from photovoltaic (PV) and photovoltaic-thermal (PVT) panels and biomass backup boilers (BB). Electricity can be sold to or purchased from the grid without electrical storage with batteries. Additional electricity generation with thermoelectric generators (TEG) coupled to the PVTs, and the BB was explicitly analyzed. The choice of electrically or thermally activated technologies (heat pump, HP/single-effect absorption chiller, SEAC for cooling and multi-effect distillation, MED/reverse osmosis, RO for desalination) created four configurations from the basic structure based on solar and biomass sources. Thus, the paper has studied four designs in detail and applied them to three case studies corresponding to different locations in Spain. They were modeled with TRNSYS and included specific models for desalination technologies. Both structures provide important energy and CO2 savings concerning the conventional supply of the building demands. The novel life-cycle analysis approach further increases the lifetime CO2 savings for all configurations as well. The electric option (the combination of HP and RO for cooling and desalting) was, by far, the most attractive solution in terms of liability and lower investment required in the three case studies. [ABSTRACT FROM AUTHOR]

The current need to reduce carbon emissions makes hydrogen use essential for self-consumption in microgrids. To make a profitability analysis of a microgrid, the influence of equipment costs and the electricity price must be known. This paper studies the cost-effective electricity price (EUR/kWh) for a microgrid located at ''La Rábida Campus" (University of Huelva, south of Spain), for two different energy-management systems (EMSs): hydrogen-priority strategy and battery-priority strategy. The profitability analysis is based, on one hand, on the hydrogen-systems' cost reduction (%) and, on the other hand, considering renewable energy sources (RESs) and energy storage systems (ESSs), on cost reduction (%). Due to technological advances, microgrid-element costs are expected to decrease over time; therefore, future profitable electricity prices will be even lower. Results show a cost-effective electricity price ranging from 0.61 EUR/kWh to 0.16 EUR/kWh for hydrogen-priority EMSs and from 0.4 EUR/kWh to 0.17 EUR/kWh for battery-priority EMSs (0 and 100% hydrogen-system cost reduction, respectively). These figures still decrease sharply if RES and ESS cost reductions are considered. In the current scenario of uncertainty in electricity prices, the microgrid studied may become economically competitive in the near future. [ABSTRACT FROM AUTHOR]

The aim of this paper is to identify the drivers and barriers of on-farm adoption of renewable energy systems (RES) in Spain and to determine how the existing mix of policies (subsidies, regulation and communication) affected the decisions of the farmers. The analysis is based on the results of a national survey that was completed by 719 farmers, representing the main types of farms and production regions. Statistically significant correlations have been observed between the probability of on-farm RES adoption and variables such as the use of contract farming, interest in new technologies and risk tolerance. Findings suggest that the diffusion of on-farm RES was at an early stage. Farmers are hesitant to adopt RES because the level of economic and regulatory uncertainty is perceived as too high in relation to the return and payback time typical of RES investments. Tailored business models and financing solutions should be implemented and promoted to overcome the described issues. Furthermore, relevant and reliable information should be available within farmers' most common professional networks such as cooperatives and farmers' associations. These aspects should be combined or even prioritized over providing direct economic incentives when producing on-farm RES supporting policies. [ABSTRACT FROM AUTHOR]

Integration of renewable energy sources and water production technologies is a must when facing water scarcity problems in semiarid regions, such as Mediterranean regions. The use of additional water resources and production methods, such as reclaimed water and, more specifically, desalinated water, means present and necessary water resources to introduce in the water balances to attend to water demands within a global warming and droughting scenario. These solutions have the inconvenience of energy/power needs and costs. However, the development of renewable energies like photovoltaic solar energy, with lower and lower costs and greater efficiency, makes these economically feasible facilities, reaching competitive production costs for marine or sea desalinated water by around 50% of reduction in energy costs and 20–30% of savings in final water production cost. This paper presents a practical project or action focused on the integration of renewable energies and new water resources by introducing a Photovoltaic Energy Plant (PVEP) as an energy source to feed a Seawater Desalination Treatment Plant (SWDTP). The PV facility is designed to cover all the energy demanded using the SWDTP during the day, and even studying the possibility of selling the energy production exceeds and injecting them into the energy supply network, covering the needs of buying energy needed during the high period where there is no photovoltaic energy production. Thus, savings related to energy costs and even incomes coming from energy sales mean an important reduction in operation costs or expenditures (OPEX), which makes economically feasible and sustainable the investment and the final price of water produced within the Mutxamel SWDTP. The final reduction cost in water desalination reaches 25% on average. [ABSTRACT FROM AUTHOR]

The adoption of new global approaches in the field of energy democratization requires inquiring into how people act to shape the energy system. This is where the concept of energy citizenship (ENCI) appears as a constellation of actors that enable and/or support citizens to became active participants in the debates and energy systems both in private and public sphere, or as a collective citizen that contributes to change (Pel et al., 2021). The aim of this paper is to explore the concept of ENCI in Southern Europe. Using a mixed approach, an extensive mapping of 43 ENCI initiatives in Spain (n = 29) and Portugal (n = 14) was conducted through desktop research, and a stakeholder consultation workshop (n = 7) was carried out through a focus group. Results revealed the major presence of collective ENCI types, with the citizen-based/hybrid one standing out (e.g., energy cooperatives). Most of them were motivated by the interest to contribute to energy transition or to produce and/or use renewable energy, and aimed at promoting energy saving, energy justice and reducing the carbon footprint. The general tendency is towards active participation (in Spain) and transformative forms (in Portugal). The possibilities for citizen control in the initiatives analysed is still limited. These results were confirmed by stakeholders who, additionally, pointed out the major political, social, economic, and geographical factors related to ENCI forms. In short, various types of ENCI could be validated in the Spanish and Portuguese context, showing a commitment to sustainability, democracy, and energy justice. Other non-evidenced forms may be raised as a challenge to further in-depth research on latent forms of ENCI in Southern Europe. [ABSTRACT FROM AUTHOR]

Electric microgrids based mainly on renewable energies have seen a big expansion in recent years due to the great advantages they present against fossil fuels. Nowadays different governments are becoming aware of the use of environmentally friendly energies, so progressive investment has been granted to the consumers in Spain. Many microgrids have been installed in both connected and isolated circumstances, and this fact brings new challenges regarding the technical and economic points of view. This study aims to delve into electrical microgrids based on renewable energies applied in industrial facilities through a review of the literature associated with the study of general microgrids. It later focuses on the relationships between renewable energies and industrial environments. A brief reference is made to the use of energy storage systems in industrial installations depicting the most used systems. This paper presents a review of the state of the art of microgrids from distributed energy resources technologies to industrial microgrids optimization, with the primary objective of providing insight on current trends and directions in research and further identifying areas in need of further development. [ABSTRACT FROM AUTHOR]

• Mechanisms to encourage clean energy in Spain from 2005 to the present are analyzed. • FiT and FiP mechanisms can be effective in promoting new renewable projects. • Experience suggests that excessive support can jeopardize the entire market. • A transitional retribution scheme has proven to be effective if correctly supervised. 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. [ABSTRACT FROM AUTHOR]

• Pioneer Spain: first country to include in grid code the synthetic inertia capability. • Synthetic inertial response of a PV inverter studied based on the Spanish grid code. • Analyzed the role of power plant controller in the dynamic response of the facility. • PV system able to contribute to frequency control providing an inertial response. As the large-scale integration of renewable energy grows, inertia in power systems is reduced, which causes the rate of change of frequency to increase and worsens the frequency nadir during disturbances. There is, therefore, an urgent need to accelerate the development of international standards and regulations that require solar PV systems and other renewable installations to also contribute to stability in the network by emulating inertia. Spain is a pioneer in this field: it is currently the only country that includes the synthetic inertia technical requirement in its grid code. In this context, the present paper analyzes the synthetic inertial response of a PV system model that forms part of an actual PV power plant in Spain under two scenarios, according to its grid code: i) when measurements are conducted at the power conversion PV system level and hence only its control algorithms are executed; and ii) when measurements are conducted at the power plant level and the power plant controller also influences the response of the entire installation. Among its aims, this paper seeks to thoroughly assess the response of an actual PV power conversion system that has the capability of actively contributing to frequency regulation in a network and to critically analyze the suitability of having a power plant controller when the PV facility contributes to power-frequency control by means of an inertial response. The results reveal, at the power conversion PV system level, that the inertia emulation module significantly reduces the response times of the installation to changes in frequency -by more than 68% in the worst case under frequency increases, and by 73% under frequency decreases, thus contributing to more rapid power-frequency regulation in the network. However, at the power plant level, the power plant controller disturbs the PV power conversion system's behavior and causes the opposite effect: response times increase -up to more than 7% in the most unfavorable case when the inertia module is enabled. [ABSTRACT FROM AUTHOR]

The large penetration of renewable energy resources is demanding additional flexibility for the operation of power systems. In this sense, real world applications are proving that wind power units are able to provide part of the required flexibility. Therefore, these new sources of flexibility need to be considered by power system planners in order to make appropriate generation capacity expansion decisions. This paper proposes a generation and storage capacity expansion formulation considering that wind power units are able to participate in the reserve provision service. The proposed model is a stochastic linear program that is solved using a commercial solver. A case study based on the isolated power system of Lanzarote and Fuerteventura in Spain is solved to quantify the impact of considering the reserve provision of wind power in capacity investment decisions. [ABSTRACT FROM AUTHOR]

Climate change motivated by human activities constitutes one of the main challenges of this century. To cut carbon emissions in order to mitigate carbon's dangerous effects, the current energy generation mix should be shifted to renewable sources. The main drawback of these technologies is their intermittency, which will require energy storage systems to be fully integrated into the generation mix, allowing them to be more controllable. In recent years, great progress to develop an effective and economically feasible energy storage systems, particularly motivated by the recent rise of demand for electric transportation, has been made. Lithium-ion (Li-ion) battery prices have fallen near 90% over the past decade, making possible the affordability of electric vehicles and transforming the economics of renewable energy. In this work, a study on storage capacity demand previously presented as conference paper is expanded, including a deep analysis of the Spanish generation mix, the evaluation of the energy storage requirements for different low-carbon and carbon-free scenarios in Mainland Spain, and the calculation of the CO2 emissions' reduction and the associated storage costs. [ABSTRACT FROM AUTHOR]

This paper aims at analyzing the effect of heat treatment using Concentrated Solar Energy (CSE) on the martensitic microstructure evolution of Ti-6Al-4V alloy manufactured by Selective Laser Melting (SLM) technology. The application of CSE, a renewable energy sources, in post-processing of SLMed Ti-6Al-4V alloy is discussed based on heat treatments performed at Plataforma Solar de Almeria, Spain, using solar furnace SF40. In SLM process of Ti-6Al-4V powder because of local high heating followed by a rapid cooling the microstructure consists of an acicular martensite (α′ phase). Decomposition of α′ martensite of SLMed Ti-6Al-4V after heat treatment in solar furnace, using CSE, by SEM, EDX, TEM, SAED, and XRD analyses, was investigated. It has been found that for treatment below β-transus at 705 °C, because of low temperature, the α′ martensite was not fully converted into α + β and the β phase was not identified by XRD analysis. Heat treatments below (940 °C followed by 650 °C) and above (1050 °C) β-transus have revealed that α′ martensite was converted into a lamellar α + β mixture and also β phase was identified by XRD and TEM analysis. In the analyzed areas, middle areas of the samples contain an area fraction of β phase greater than the top areas. Area fraction of β phase, after heat treatment above β-transus, at 1050 °C, is greater than that obtained after treatment below β-transus. [ABSTRACT FROM AUTHOR]

Featured Application: This paper studies the production and amount of by-products of an emerging industry in a small region of Spain, dealing with their possible treatment and valorization through anaerobic digestion. Thus, some guidelines could be taken from it and applied in similar cases in other regions where alcoholic beverage production is an important economic resource. The industry of alcoholic beverage production has been, historically, both an important economic engine and a source of wastes and pollution (due to the production processes by themselves and to the energy requirements) in a number of countries. In the small region of Cantabria, in northern Spain, the production of alcoholic beverages as an economic sector has been growing in importance in recent years. Thus, there is a new flow of waste for which specific management plans have yet to be developed. The result is an increase in the total amount of urban waste to be disposed. Anaerobic digestion can be a suitable in-situ solution for the treatment of the generated wastes providing a source of renewable energy which can be a supply for the processes in these industries, reducing the emission of greenhouse gases associated to the use of fossil fuels, all of this benefitting both environment and economy. In this work the authors present the information gathered about waste generation and the biomethanogenic potential of the most important wastes generated in the industries. As a result, specific strategies could be designed for the industrial sector in the region, of which other small agro-industries can benefit. [ABSTRACT FROM AUTHOR]

Photovoltaic panels are promising source for renewable energy. They serve as a clean source of electricity by converting the radiation coming from the sun to electric energy. However, the amount of energy produced by the photovoltaic panels is dependent on many variables including the irradiation and the ambient temperature, leading to nonlinear characteristics. Finding the optimal operating point in the photovoltaic characteristic curve and operating the photovoltaic panels at that point ensures improved system efficiency. This paper introduces a unique method to improve the efficiency of the photovoltaic panel using Support Vector Machines. The dataset, which is obtained from a real photovoltaic setup in Spain, include temperature, radiation, output current, voltage and power for a period of one year. The results obtained show that the system is capable of accurately driving the photovoltaic panel to produce optimal output power for a given temperature and irradiation levels. [ABSTRACT FROM AUTHOR]

The European Union policy of encouraging renewable energy sources and a sustainable and safe low-carbon economy requires flexible energy storage systems (FESSs), such as pumped-storage hydropower (PSH) systems. Energy storage systems are the key to facilitate a high penetration of the renewable energy sources in the electrical grids. Disused mining structures in closed underground coal mines in NW Spain have been selected as a case study to analyze the construction of underground pumped-storage hydropower (UPSH) plants. Mine water, depth and subsurface space in closured coal mines may be used for the construction of FESSs with reduced environmental impacts. This paper analyzes the stability of a network of tunnels used as a lower water reservoir at 450 m depth in sandstone and shale formations. Empirical methods based on rock mass classification systems are employed to preliminarily design the support systems and to determinate the rock mass properties. In addition, 3D numerical modelling has been conducted in order to verify the stability of the underground excavations. The deformations and thickness of the excavation damage zones (EDZs) around the excavations have been evaluated in the simulations without considering a support system and considering systematic grouted rock bolts and a layer of reinforced shotcrete as support system. The results obtained show that the excavation of the network of tunnels is technically feasible with the support system that has been designed. [ABSTRACT FROM AUTHOR]

Estuarine dynamics are highly complex as a result of the temperature and salinity gradients, as well as the multiple interactions between atmospheric, maritime and hydrological forcing agents. Given the environmental and socioeconomic importance of estuaries and their current and future threats due to human interventions and climate change, it is of vital importance to characterize these dynamics, monitor their evolution and quantify the expected impacts derived from climate change. This paper presents a hybrid database 5 combining data obtained in six field surveys (in 2012, 2013 and 2015) and results from a physically-based 3D numerical model for the Bay of Cádiz (southern Spain), a highly anthropized mesotidal estuary. The 3D dataset includes water levels, currents, density and wave climate, allowing for an analysis of bay dynamics at different time scales ranging from intratidal processes to seasonal variabilities. The results offer an example of the potential uses of the dataset and include (1) an assessment of the spatial and seasonal variability of the estuarine dynamics and (2) an analysis of the effects of severe weather events. These examples provide convincing evidence regarding how the dataset can be employed in multiple research fields and applications, including ocean-bay interactions, water exchange between basins, longand short-wave propagation along creek systems and energy extraction of tidal waves. Therefore, this hybrid dataset may be of significant interest for stakeholders and scientists from different sectors (water engineering, ecology, urban development, energy, etc.) working on the environmental management of the Gulf of Cádiz and other tidally-dominated shallow bays. It can also serve as a benchmark test for numerical hydrodynamic models, infrastructure intervention assessments (e.g., dikes or breakwaters) or renewable energy conversion system models. [ABSTRACT FROM AUTHOR]

In this paper, a probabilistic methodology for estimating the energy costs in the market for wind generators associated with wind prediction errors is proposed. Generators must buy or sell energy production deviations due to prediction errors when they bid in day-ahead or hour-ahead energy markets. The prediction error is modeled through a probability density function that represents the accuracy of the prediction model. Production hourly energy deviations and their associated trading costs are then calculated. Three study cases based on real wind power installations in Spain are analyzed. The three study cases show that the error prediction costs can reach as much as 10% of the total generator energy incomes. [ABSTRACT FROM AUTHOR]

Wind power is one of the most important renewable energy sources worldwide. However, integrating these technologies in electricity markets faces challenges due to the intermittent wind speed, resulting in potential imbalances within power grids and subsequent inefficiencies. Traditional approaches for modeling the uncertainty simulate fixed wind power values in operational and planning models, which work well for the short term but are inadequate for medium-term decision-making due to lower forecasting accuracy and the inability to differentiate the imbalance risk faced in each simulated value. This paper proposes a novel methodology for incorporating wind energy imbalance risk into medium-term generation planning models. For this, we first simulate realistic wind power scenarios and perform a fitting distribution process to characterize the hourly wind power behavior. Then, we model the imbalance risk using quadratic-uncertainty cost functions for each simulated value. Subsequently, we conduct a temporal aggregation to reduce the computational burden, preserving the conceptual framework of the imbalance risk modeling. Finally, we propose a medium-term generation planning model that includes the imbalance risk model and the temporal aggregation strategy. Our approach is evaluated in a real-size case study formed by Spain, Portugal, and France's electricity markets, demonstrating accurate wind power imbalance risk modeling and lowered planning costs. • A new methodology to include wind energy imbalance risk in generation planning models. • Introducing a fitting process for modeling the distribution asymmetries of wind power. • Proposing a temporal aggregation method for efficient imbalance risk modeling. • The methodology is validated in Spanish, Portuguese, and French electricity markets. [ABSTRACT FROM AUTHOR]

The increased penetration of renewable energy sources (RESs) as an effective mechanism to reduce carbon emissions leads to an increased weather dependency for power and energy systems. This has created dynamic operation and degradation phenomena, which affect the lifetime estimation of the assets operated with RESs. For the reliable and efficient operation of RES it is crucial to monitor the health of its constituent components and feature selection is a crucial step for building robust and accurate health monitoring approaches. In this context, this paper presents a probabilistic feature selection approach, which probabilistically weights and selects features through a heuristic and iterative process for an improved asset lifetime estimation. Power transformers are key power grid assets and they are used to demonstrate the validity and impact of the proposed approach. The approach is tested on two different photovoltaic power plants operated in Spain and Australia. Results consistently show that the proposed feature-selection approach reduces the prediction error and consistently selects relevant features. The approach has been applied to transformer lifetime estimation, but it can be generally applied to assist in the lifetime estimation of other components operated in RESs. Part of the studies presented here as well as source codes are all open-source under the GitHub repository https://github.com/iramirezg/FeatureSelection. • Probabilistic feature selection approach for improved asset lifetime estimation. • Integration of environmental features for improved renewable-operated asset lifetime. • Systematic and robust feature weighting methodology. • Improved transformer lifetime estimation including sensor and environmental data. • Validated on two real photovoltaic power plant case studies. [ABSTRACT FROM AUTHOR]

This research delves into a case study of a photovoltaic (PV) energy community, leveraging empirical data to explore the integration of renewable energy sources and storage solutions. By evaluating energy generation and consumption patterns within real-world energy communities (a nominal generation capacity of 33 kWn) in Gipuzkoa, Spain, from May 2022 to May 2023, this study comprehensively examines operational dynamics and performance metrics. This study highlights the critical role of energy consumption patterns in facilitating the integration of renewable energy sources and underscores the importance of proactive strategies to manage demand fluctuations effectively. Against the backdrop of rising energy costs and environmental concerns, renewable energies and storage solutions emerge as compelling alternatives, offering financial feasibility and environmental benefits within energy communities. This study emphasizes the necessity of research and development efforts to develop efficient energy storage technologies and the importance of economic incentives and collaborative initiatives to drive investments in renewable energy infrastructure. The analyzed results provide valuable insights into operational dynamics and performance metrics, further advancing our understanding of their transformative potential in achieving a sustainable energy future. Specifically, our study suggests that storage capacity should ideally support an average annual capacity of 23%, with fluctuations observed where this capacity may double or reduce to a minimum in certain months. Given the current market conditions, our findings indicate the necessity of significant public subsidies, amounting to no less than 67%, to facilitate the installation of storage infrastructure, especially in cases where initial investments are not covered by the energy community. [ABSTRACT FROM AUTHOR]

The European Commission and EU Member States have recently promoted legislation (under the REPower EU Plan) to accelerate renewable energy projects by allowing the elimination or reduction of environmental assessment and public participation in the approval procedure. To avoid adverse effects on the environment, these regulations propose the exclusion of certain areas (identified through available information on protected and/or environmentally sensitive areas) from the procedure. This paper aims to evaluate whether such measures are effective to avoid damage to biodiversity from the implementation of photovoltaic energy. To this end, we studied the distribution and abundance of a threatened bird species, the Black-bellied Sandgrouse, at two geographic scales: i) regional: Andalusia (southern Spain); ii) local: Campo de Tabernas (an excellent example of the semi-arid ecosystems of southeastern Spain) and evaluated the quality of the information that Administrations have on the species by comparing it with own censuses. We also assessed the effectiveness of the environmental impact procedure for photovoltaic plants planned in Campo de Tabernas. Data from the regional Administration reveal that Andalusian protected areas cover a minimal part (17.7%) of the species' range. Moreover, neither the regional nor the national Administration have reliable and updated information on the distribution of the species in Campo de Tabernas (only 17% of the current distribution area is known). The wrong choices made by developers about where to locate the photovoltaic plants together with wrong decisions of the regional Administration (with land-use planning competences, including the planning of power plant locations) have led to the loss of 630 ha of the species' range in Campo de Tabernas. Public participation of experts prevents, through allegations to the projects, an important part of the impact on the species. Policy implications: the information that the Administrations have on this species does not allow them to make proper decisions on where to apply renewable acceleration. Obtaining complete and updated information on the distribution of endangered species to elaborate detailed wildlife sensitivity areas is essential and urgent before implementing measures to accelerate renewables. • The new EU renewable acceleration directives are analysed here for the first time. • A threatened species becomes locally extinct due to solar power plants' poor planning. • Involving experts in EIA procedure greatly reduces the impact on a threatened species. • The design of renewable go-to areas demands specific research on threatened species. • Current EU legislation to accelerate renewables will negatively affect biodiversity. [ABSTRACT FROM AUTHOR]

The energy crisis and the exacerbation of climate change, along with the associated geopolitical tensions, including the war in Ukraine, are accelerating the energy transition in Europe. A transition from fossil energy sources to renewable energy sources that have a low Energy Return Rate, involves, among many other issues, the use of wide areas to locate the necessary infrastructure for production, transport and storage, altering territories with agricultural, cultural and ecological values. This process is based on the deployment of renewable energy megaprojects in peripheric areas of the continent, mostly in the southern states creating a wide range of social conflicts and resistances. We analyse this process in the case study of the province of Granada, a peripheric territory of south-east Spain considering the category of energy colonialism and the six dimensions that characterise it, arguing that this is a proper approach to address internal colonialism related to the corporate energy transition. We also want to demonstrate the importance of using participatory methodologies for this analysis, so we have developed an online survey, semi-structured interviews and participatory cartography workshops, always focusing on the citizens and stakeholders who are resisting the deployment of renewable energy megaprojects in the province of Granada. The obtained results allow us to confirm the necessity of using participatory methodologies and the colonial aspect of this deployment, including the characteristics of social resistance, the territorial impacts, the land-grabbing process and the inequalities in the production, distribution and use of energy. We conclude with the need to articulate a decolonial energy transition where participatory methods constitute a fundamental tool both to attend the resistances and to build the alternatives. [ABSTRACT FROM AUTHOR]

The integration of a CSP tower system with a PV solar field, sharing a thermal energy storage, is modeled and discussed. The tower system uses a new-design solid particle fluidized bed receiver integrated with a thermal storage, where hot particles are directly collected to store daily energy for overnight production of electricity. The PV solar field is aimed to supply the daily energy demand; when there is a surplus of PV energy production, the electric energy is converted to heat and accumulated in the thermal storage too. The integration of the two energy systems is modeled, building efficiency functions for all the sub-components of the integrated plant (heliostat field, receiver, storage, power block, PV field). Yearly simulations are performed for two different locations, Spain and Australia, obtaining that a system with a peak power of 10 MWe CSP + 15 MWe PV can supply—with a limited curtailment—a fraction of more than 60% (respectively, 62% and 68%) of a realistic electric load with a peak demand around 10 MW, to be compared with the 45/47% of the same load obtained adopting a PV-only system with the same overall peak power. In the integrated system, PV directly supplies 40/41% of the load, the remaining 23/28% being produced by the power block (mainly fed by the CSP). [ABSTRACT FROM AUTHOR]

• Energy Communities analysis and review in Europe and, more specifically, in Spain. • Promoting energy poverty reduction and cooperation through Energy Communities. • Real case study focused on reducing energy poverty in the city of Getafe (Spain). • Selection of public buildings to implement energy community in two neighborhoods. • Significant electricity bill reductions for energy poverty households. Advancements in renewable energy technologies, a growing awareness of the need for sustainable energy solutions, and the emergence of new business models in the energy sector, have contributed to the growth of Energy Communities. Public entities can find in energy communities today an opportunity to tackle energy poverty, to increase the cooperation among citizens and to empower them to be a more active player within the energy sector. This paper analyzes energy communities in Europe and focuses specifically on Spain; considering the three beneficial aspects previously mentioned. It aims to obtain ground truth about the applications of these new citizens' arrangements. A citizen-led initiative at the city of Getafe (Madrid, Spain) is included and discussed in detail. This case study focused on reducing energy poverty of its participants. An energy community was designed and implemented as a collective PV solar self-consumption infrastructure. The roofs of various public buildings in the two case study neighborhoods were selected for locating the PV installations. Real metered data were used to evaluate the solution. A public building was selected for the energy community, considering generation on roof and dwellings proximity. The results provided that out of the 77% PV generations could be used to contribute to the demand of 100 residences; while the resulting 23% would provide approximately 60% of the energy demand of the public building. The setting up of the Energy Community not only had the technical part but also included workshops seminars and information sessions, to ensure that people prone to benefit and maximize its impact. [ABSTRACT FROM AUTHOR]

To meet water demands, pressurised irrigation networks often need pumping devices, whose power demand varies with the pump head, the flow rate delivered and the pump efficiency. To satisfy the energy demand of pumps, solar photovoltaic panels can be used as a renewable energy source. Since the electricity supply of a solar photovoltaics plant depends on irradiance, the energy that powers the pump varies with the time of the day. This study presents a strategy for scheduling water delivery by irrigation pumps, synchronising energy production in solar photovoltaic modules and minimising the installation size. An optimisation algorithm is proposed, which changes the energy required by pumping devices and adjusts them to the available solar energy supply, minimising the number of panels required. This problem applies to a pressurised irrigation network, where the utility manager may irrigate crops at all hours of the day. By adopting the proposed algorithm, irrigation will follow a rigid rotation schedule to follow the new irrigation plan. This approach improves earlier studies by employing a least-square scheduling algorithm with little computing time. This results in a tool for managers and decision-makers when evaluating the possibility of converting their irrigation network into a stand-alone system supplied by photovoltaic panels. A case study handling this issue in the University of Alicante's pressurised irrigation network in Spain is proposed to find potential energy savings by connecting the recommended scheduling irrigating plan to the present operation. [ABSTRACT FROM AUTHOR]

This paper assesses the health impact, in terms of the reduction of premature deaths associated with changes in air pollutant exposure, resulting from double-aim strategies for reducing emissions of greenhouse gases and air pollutants from the transport sector for the year 2030 in Spain. The impact on air quality of selected measures for reducing emissions from the transport sector (increased penetration of biofuel and electric car use) was assessed by air quality modeling. The estimation of population exposure to NO2, particulate matter (PM) and O3 allows for estimation of associated mortality and external costs in comparison with the baseline scenario with no measures. The results show that the penetration of the electric vehicle provided the largest benefits, even when the emissions due to the additional electricity demand were considered. [ABSTRACT FROM AUTHOR]

Highlights • Hourly-resolved model to investigate highly-renewable electricity generation in Spain. • Correlation analysis of time series to create 900 combinations used in simulations. • Transition paths evaluated based on security of supply, CO 2 emissions, and renewable share. • Short-term phase-out of nuclear and coal power plants proven to be feasible. Abstract Two alternative paths to achieve highly-renewable electricity generation in peninsular Spain are investigated in this paper. Every transition path comprises a description of the installed and decommissioned generation and storage capacities, from 2017 to 2030, as well as a hypothesis on the evolution of the electricity demand. The electricity mix for every hour within the transition path is determined through a dispatch algorithm that prioritizes electricity from renewable energy sources. The simulation is run for 900 different combinations of time series representing the hourly capacity factors of different technologies, as well as the electricity demand. This robust approach allows the evaluation of the transition paths based on the statistical distribution of several defined assessment criteria, such as security of supply, CO 2 emissions or renewable share in electricity generation. The feasibility of a Spanish power system with high renewable penetration is investigated not only in a future reference year but throughout the transition path. In particular, a progressive and simultaneous phase-out of nuclear and coal power plants in the short-term is proven to be feasible. Furthermore, the results sensitivity is analyzed including scenarios with a delayed nuclear phase-out, lower hydroelectricity generation due to more frequent and severe droughts caused by climate change and higher annual increment for the electricity demand. [ABSTRACT FROM AUTHOR]

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This paper lays out the role of the first centre in the world for the integration into the electrical grid of electricity coming from renewable energy (the Spanish acronym for which is CECRE (Centro de Control de Energías Renovables; Control Centre for Renewable Energies)) and the industrial development of large energy suppliers and wind turbine manufacturers in Spain. These two initiatives enabled the development of one of the first integrated markets for this type of energy source. The key contributions were the development of two software programs (wind management and management of solar light incidence), their visual implementation, and centralized digital control. An economic and business history approach is used to show the rise and relative failure of the Spanish wind industry during the period 2004–2015, when Spain became the fourth country after China, the US, and Germany in terms of installed capacity of renewable energy and, in relative terms, the second country after Denmark. This study is unique in that it provides an integrated vision of the reasons for the relative fall of Spain in the world ranking of wind energy producers. The methodology of the economic analysis of industrial policies makes it possible to explain the fall in the relative importance of Spain in the international panorama of wind farms. [ABSTRACT FROM AUTHOR]

More than 50% of the world's population lives in cities. Its buildings consume more than a third of the energy and generate 40% of the emissions. This makes cities in general and their buildings in particular priority points of attention for policymakers and utilities. This paper uses population density as a variable to know its influence on energy consumption and emissions produced in buildings. Furthermore, to show its effect more clearly, the influence of the climate was eliminated. The usual energy consumption in buildings is thermal and electrical. The study was carried out at the city level, both per inhabitant and per household. The area actually occupied by the city was considered. The proposed method was applied to the case of Spanish cities with more than 50,000 inhabitants. The results show that the higher the population density, the higher the energy consumption per inhabitant and household in buildings. The consumption of thermal energy is elastic, while that of electrical energy is inelastic, varying more than 100% between extreme groups. Regarding CO2 emissions, the higher the population density, the higher the emissions. Emissions of electrical origin barely vary by 2% and are greater than those of thermal origin. In addition, the proportion of emissions of electrical origin, with respect to the total, decreases with increasing population density from 74% to 55%. This research aims to help policymakers and utilities to take the appropriate measures that favor the use of renewable energies and reduce CO2 emissions. [ABSTRACT FROM AUTHOR]

This paper evaluates a parametric analysis towards compliance with the nZEB standard, which in Spain is defined by the latest update of the Technical Building Code. This regulation is critically assessed regarding its ability to promote the concept of cost optimization, promote renewable energy sources and minimize primary energy consumption in the residential sector. To this end, a virtual building was defined and multiple designs were evaluated using DesignBuilder software. A set of 170 alternative scenarios was established and parametrically evaluated for five cities representing the five climatic zones of inland Spain (Bilbao, Burgos, Seville, Madrid and Almeria). The results were evaluated focusing on cost-cost effectiveness and primary energy consumption values for the different scenarios, evaluating them in relation to the minimum requirements set by the regulation. The great potential of photovoltaic energy is highlighted, which allows negative values to be obtained for the two Equivalent Uniform Annual Costs due to the cost avoided through self-consumption. This fact makes the optimal designs tend to electrification, specifically through air and ground source heat pumps. It is worth mentioning that the new Code has only established a minimum target for renewable self-consumption in the residential sector, which should be reinforced in future updates. [ABSTRACT FROM AUTHOR]

European institutions have decided to ban the sale of Internal Combustion Vehicles (ICEVs) in the EU from 2035. This opens a possible scenario in which, in the not-too-distant future, all vehicles circulating in Europe are likely to be Battery Electric Vehicles (BEVs). The Spanish vehicle fleet is one of the oldest and has the lowest percentage of BEVs in Europe. The aim of this study is to evaluate the hypothetical scenario in which the current mobility of ICEVs is transformed into BEVs, in the geographical area of the province of Barcelona and in Spain in general. The daily electricity consumption, the required installation capacity of wind and solar photovoltaic energies, and the potential reduction of NOx and particulate matter (PM) emissions are estimated. The daily emission reduction would be about 314 tons of NOx and 17 tons of PM in Spain. However, the estimated investment required in Spain to generate the additional electricity from renewable sources would be enormous (over EUR 25.4 billion), representing, for example, 5.5% of the total national budget in 2022. [ABSTRACT FROM AUTHOR]

Energy communities using renewable energy sources directly contributes to reduction of climate change gas emissions and energy consumption in the European Union. In addition, energy communities enable citizens to transform from (passive) consumers to prosumers (active consumers and producers) and to play a proactive role in the deployment of energy transition in urban areas. As the transposition of European rules about energy communities into the national laws of EU Member States is very articulated and differentiated, this study proposes a framework to analyze and compare regulatory and financial instruments. This framework is applied to the analysis of the cases of Italy and Spain as representative of European states in which collective actions in the energy sector are not very common, with the aim of highlighting the main critical issues affecting the effectiveness of energy transition strategies and assessing the economic feasibility of energy communities. Based on analysis of regulations and procedures, including at the local level, it appears that municipalities play an important role as promoters of initiatives among citizen communities, while complex bureaucratic procedure is the most critical issue in both countries and can significantly hinder the spread of energy communities. With respect to the different financial incentives available for the formation of energy communities in Italy and Spain, a few cases studies are hypothesized, calculating the most relevant cost-effectiveness indicators, e.g., Net Present Value. It turns out that a project with the same characteristics achieves greater economic feasibility in Italy than in Spain, depending on the type and size of incentives set by national laws and, above all, that financial incentives are necessary to make the formation of energy communities cost-effective and thus to achieve direct citizen involvement in energy transition actions. [ABSTRACT FROM AUTHOR]

Even though eco-efficiency (EE) is already applied to various energy systems, so far, no study investigates in detail the hourly, marginal and seasonal impacts of a decentralized energy system. This study assesses the hourly EE of the Research Park Zellik (RPZ), located in the Brussels metropolitan area for 2022 composed of photovoltaic installations, wind turbines and batteries. A cradle-to-grave life cycle assessment (LCA) to identify the carbon footprint (CF) and a levelized cost of electricity (LCOE) calculation is conducted. An existing design optimization framework is applied to the RPZ. Consumption data are obtained from smart meters of five consumers at the RPZ on a one-hour time resolution for 2022 and upscaled based on the annual consumption of the RPZ. As the EE is presented as the sum of the CF and the LCOE, a lower EE corresponds to an economically and environmentally preferable energy system. In a comparative framework, the developed method is applied to two different case studies, namely, (i) to an energy system in Vega de Valcerce in Spain and (ii) to an energy system in Bèli Bartoka in Poland. The average EE of the RPZ energy system in 2022 is 0.15 per kWh, while the average EE of the Polish and Spanish energy systems are 1.48 and 0.36 per kWh, respectively. When analyzing four selected weeks, both the LCOE and CF of the RPZ energy system are driven by the consumption of the Belgian electricity grid mix. In contrast, due to the very low LCOE and CF of the renewable energy sources, in particular wind turbines, the RPZ energy system's EE benefits and lies below the EE of the Belgium electricity grid mix. [ABSTRACT FROM AUTHOR]

• Self-consumption in residential sector is studied under Spanish regulatory framework. • An average-day model versus a whole-year model is benchmarked. • Scheduling household appliances is analysed in a residential building. • Ex-ante and ex-post renewable energy sharing is investigated. Studies on self-consumption in residential use are constantly evolving, and society claims new solutions in response to changes to new paradigms. This paper aims to optimise the sizing of a self-consumption installation for collective self-consumption in a residential building under the Spanish regulatory framework. The study considers the current price volatility in the retail electricity Spanish market and focuses on the techno-economic analysis of self-consumption in a building consisting of 12 dwellings using photovoltaic energy and the possible support of a storage system. The three aspects analysed are the sizing of the self-consumption facility, the use of smart appliances to shift their consumption to more cost-effective times and the sharing of the renewable energy generated by the facility among the consumers participating in the collective self-consumption. This study employs two models, an average-day model and a whole-year model. The techno-economic analysis yields that between the two self-consumption modalities for residential consumption, the modality with surplus simplified compensation is more profitable than the one without surpluses. Finally, the study focuses on sharing the total renewable energy generated among the participants. The results indicate that both ex-ante and ex-post dynamic sharing brings few benefits. [ABSTRACT FROM AUTHOR]

Electricity provides a crucial service in our daily lives. However, in electricity systems mostly based on conventional, fossil-fuel fired technologies, an increase in electricity demand also leads to higher greenhouse gas emissions and, in countries without fossil-fuel resources, also increases their dependence on foreign energy sources. In more decarbonised electricity systems, with a high penetration of variable renewable energy sources, strong increases in electricity demand lead to higher system costs, given the need for back-up. Therefore, identifying the drivers of electricity demand is an academically-relevant, but also a policy-relevant exercise, since specific policy measures can be linked to those drivers. The aim of this paper is to assess the drivers of electricity demand in Spain in the period immediately after the economic crisis (2013–2017), with the help of a unique database of Spanish households and econometric modeling. Our results show that electricity demand in this period has mostly been driven by price changes. Demand has been highly price-elastic, with price elasticities being much higher (in absolute values) than in previous studies and periods. It is also negatively driven by the features of the household and its breadwinners (whether they are single-parent households or its members are foreign residents) and positively driven by income, the hours of sun and temperature changes, although the influence of these variables is much lower. In contrast, other variables do not seem to have an influence on demand, including the age of the breadwinners and their working situation (whether they are unemployed or not). These results suggest that price-based instruments, i.e., measures with an impact on electricity prices, would be the most effective to curb electricity demand. [ABSTRACT FROM AUTHOR]

The evaluation and comparative analyses of energy conversion technologies are carried out with well-established concepts, like the concept of efficiency. Today, however, new technologies based on renewable energy sources challenge conventional approaches. Accounting for fuel diversity and other inequalities can ensure that comparative analyses result in trustworthy results. This paper aims to address this issue by updating conventional efficiency for more accurate comparative evaluations of fossil fuel energy systems. Specifically, the concept of total efficiency is introduced to account for extraction, processing and transportation of fossil fuels, aspects that are not currently considered in the conventional definition of efficiency. The total efficiency is determined by studying the environmental impacts of these processes and quantifying their energy requirements in terms of additional fossil fuel use. Two case studies in Spain are presented to demonstrate the impact of using the developed method on efficiency estimates. The total efficiency is found to be lower than the convectional efficiency by 21–25% to up to 41%, in the most unfavorable cases. This shows the significant impact of the preparation steps of fossil fuels and represents a fairer comparison between fossil fuels and renewable conversion processes. • Introducing total efficiency for more accurate comparative evaluations of energy systems. • Total efficiency accounts for extraction, processing, and transportation of fossil fuels. • The developed method links environmental impacts to additional fuel input. • Fuel processing decreases the efficiencies of fossil power plants significantly. • Updated tools, like total efficiency, are necessary to achieve future energy sustainability. [ABSTRACT FROM AUTHOR]

Renewable energies play an important role as a solution to the challenge of satisfying the growing global energy demand without jeopardizing the achievements in the fight against climate change. Given this panorama, different countries, including Spain, have developed policies to promote renewable energies. One of the technologies that benefit from these policies is photovoltaics. In Spain, the number of grid-connected photovoltaic installations has increased significantly in recent years. It is interesting to analyze the panorama of these facilities and identify the trends in their design criteria. In this line, in this work, the projects of 70 grid-connected photovoltaic installations distributed across Spain were analyzed. For that purpose, benchmarking techniques were applied, facilitating the systematization of information, the intercomparison of plants and the identification of trends and efficient solutions. A set of characteristic indicators of each installation was defined, and a statistical analysis of them was developed. Likewise, a tool was developed that allows the designers of this type of photovoltaic plant to compare the design parameters chosen for their installations with those of the surrounding area. Therefore, this work provides knowledge about the current panorama of photovoltaic implementation applicable to its future advance. [ABSTRACT FROM AUTHOR]

Renewable energy sources are essential to reduce the negative impacts on the environment caused by burning fossil fuels. Using solar photovoltaic installations in recent years means that decision-makers must consider infrastructure renewal decisions. An expenditure framework to achieve the optimal renovation period of photovoltaic modules is proposed here from an economic standpoint. This approach includes not only the investment and maintenance costs but also energy and emissions savings. A sensitivity analysis was carried out using a case study in south-eastern Spain, achieving that the optimal renovation period ranges between 17.0 and 24.7 years. Many factors are studied to identify those with the greatest influence on this indicator. Installing a solar power system is always a profitable choice considering that the installation lifetime is 25 years. Neglecting the influence of these limits may cause potential savings not fully exploited. [ABSTRACT FROM AUTHOR]

Renewable energies play a fundamental role within the current political and social framework for minimizing the impacts of climate change. The ocean has a vast potential for generating energy and therefore, the marine renewable energies are included in the Sustainable Development Goals (SDGs). These energies include wave, tidal, marine currents, ocean thermal, and osmotic. Moreover, it can also be included wind, solar, geothermal and biomass powers, which their main use is onshore, but in the near future their use at sea may be considered. The manuscript starts with a state-of-the-art review of the abovementioned marine renewable energy resources worldwide. The paper continues with a case study focused on the Spanish coast, divided into six regions: (I) Cantabrian, (II) Galician, (III) South Atlantic, (IV) Canary Islands, (V) Southern Mediterranean, and (VI) Northern Mediterranean. The results show that: (1) areas I and II are suitable for offshore wind, wave and biomass; (2) areas III and V are suitable for offshore wind, marine current and offshore solar; area IV is suitable for offshore wind, ocean wave and offshore solar; (3) and area VI is suitable for offshore wind, osmotic and offshore solar. This analysis can help politicians and technicians to plan the use of these resources in Spain. [ABSTRACT FROM AUTHOR]

The relationship between water and renewable energy, as a vertebrate axis of the territory and landscape and its social acceptance in the Monachil river valley, was analysed. Qualitative interviews and surveys were designed and implemented using quantitative techniques that enabled the measure factors and dimensions of the perception of water, territory, and landscape. The main values and elements of the Monachil inventory, their links with ecosystem services, and traditional activities were identified. In addition, the influence of these premises on the acceptance of renewable energy projects was analysed. Results show that in Monachil, water is part of the territorial identity and landscape of the valley. There is also a strong link between the territory and hydroelectric power, which has generated a new energy landscape. More recently, solar energy has led them to pioneer an energy transition at the local scale. It is demonstrated how renewable energy infrastructures have been integrated into territorial practices. [ABSTRACT FROM AUTHOR]

Wind energy is a renewable system of power generation with great potential to be used and it is a sector with good growth prospects. The development of new wind turbine models assumed that the lifetime of machines is constrained, as the power supplied by the turbine is considered small for the state of wind technology. This involves replacing obsolete turbines to adjust production of wind energy to a growing demand. However, these turbines which are considered obsolete still have good performance for reuse in areas with adequate energy demand. An opportunity to reuse these machines is the isolated rural areas which are typical in northwestern Spain. In this paper is studied the feasibility of obsolete wind turbines to meet the energy needs of isolated rural areas. The methods exposed were used to facilitate the decision making process. We studied the economic feasibility and the results demonstrated that it is a viable investment. [ABSTRACT FROM AUTHOR]

Summary: The EU countries are facing a burning debate with regard to the nature and amount of decarbonized energy used within the supply mix. This study highlights the role of nuclear power and renewable energy use in achieving economic growth in Europe. Capital, labour, exports, and trade openness series are included within a multivariate framework spanning the 1986 to 2019 period and a two‐step methodology is implemented. First, a panel causality analysis over the top 10 nuclear energy‐consuming EU countries is conducted using the panel non‐causality test from Juodis, Karavias and Sarafidis (2021), robust under large cross‐sectional and time‐series dimensions, as well as heterogeneous coefficients. Second, a sub‐set of three states (Germany, Spain, and France) that are different in terms of long‐run nuclear energy policies is selected and a single‐country time‐series assessment is performed using the vector error correction model, causality tests, as well as impulse response functions. Panel EU results support the "conservation hypothesis" for both nuclear and renewable resources, without feedback effect. The country‐level estimates fail to provide homogeneous results since no causal link is found between economic growth and renewable energy use for Spain and France (confirmation of "neutral hypothesis"). A weak causality from renewable energy use to output growth is observed for Germany, while economic growth enhances the nuclear energy consumption in Spain. [ABSTRACT FROM AUTHOR]

• A systematic literature-approach to classify retrofitting is proposed. • An overview of Spain's previous guidelines on residential retrofits is presented. • A review of financial and subsidies mechanisms in Spain to renovate buildings is introduced. • A literature-based matrix on retrofitting actions is presented. • A classification of energy efficiency strategies for retrofitting is proposed. The building sector is responsible for more than 40% of final energy consumption in Europe; consequently, retrofitting existing buildings can significantly contribute to mitigate greenhouse emissions. Nevertheless, although the European Union has introduced relevant policy instruments, up to now the annual retrofit rates are considerably low with an average of 0.2% at European level. Understanding the past would support the success of the new strategies, such as the recent ones launched through the New Green Deal, which reinforces the importance of renovating existing buildings stock, as the main aim of the renovation wave. As a starting point for assessing the main challenges to allocate the Recovery funds, this paper provides a review of Spain's relevant literature to clearly define the characterization of the existing building stock, which actions have been typically considered under the scope of retrofits, and which strategies have been implemented until now, considering both, private and public initiatives and public financial schemes. The present work has a strong focus on energy-related strategies, although other interrelated actions are mentioned, such as accessibility measures and interior refurbishment of dwellings. Differences and similarities within these approaches are presented through the analysis of 27 relevant references of retrofitting actions and 52 references of financial mechanisms. As in Spain 93% of multifamily buildings were constructed prior to the national transposition of the first Energy Performance Building Directive (EPBD), and therefore are in need of deep energy renovations, the retrofitting of multifamily buildings topic has been widely addressed, even though often in a disjointed manner. The study suggests that although historically there have been several recommended strategies, few are conceived as integral actions, only 15% of the intervention packages refer passive and active energy-related measures and renewable energy incorporation. Furthermore, considering the antiquity of the building stock and the advantage of addressing the topic through clusters, only 63% of the resources directly refer these actions to specific clusters among the six distinctive periods, although in most cases focusing their recommendations on buildings constructed before 1980 where the worst energy performance buildings are concentrated. Concerning public financial and funding instruments, the research illustrates that there has been a substantial increment of programs over the last years promoting energy-related measures, renewable energy and other complementary aspects such as accessibility and interior renovations, mainly for older clusters. Nevertheless, the funds constitute only 8% of the necessary declared investments, which along with the dispersion between the different procedures and the complexity of the processes, have significantly reduced the global impact of these actions without generating robust and oriented market dynamics. Despite the several resources found, both financial instruments and guidelines tend to describe in more detail strategies related to heating demand and consumption and not delve into other relevant actions for warmer climates, fact associated both to the dynamics coming from other countries, and to a vision of the past in which people do not consume refrigeration. This clear focus on heating loads rather than cooling could present limitations for warmer regions in the near climate-change future. [ABSTRACT FROM AUTHOR]

Abstract: Climate change, added to security of supply concerns, has been leading many countries to strongly support the development of electric vehicles (EVs) not only as a cleaner and more energy efficient source of transportation but also as a flexible electricity storage option. However, the massive deployment of EVs will impose important challenges to power systems operation. In this context, this paper investigates the impact of EVs with V2G capability to power system operation. Since this impact depends on the power system considered and on the number (and type) of EVs, different scenarios for renewable energy sources (RES) generation and EV penetration are studied. A detailed analysis of the impact of EVs the Spanish power system – demand, generation, use of flexible units (pumped storage) and power reserve, and energy curtailment – is performed. For this purpose, a mid-term operation model that computes generation dispatch and simulates hourly power system operation is used. The advantage of this model is that it includes EVs in the unit commitment and represents in detail mobility and connection patterns, which allows the estimation of more realistic results. [Copyright &y& Elsevier]

Abstract: Demand response has proven to be a useful mechanism that produces important benefits for both the customer and the power system. In the context of an increasingly competitive electricity market, where prices are constantly rising and the presence of renewable energy resources is gaining prominence, this paper analyzes the flexibility potential of customers in the meat industry, based on the management of the most energy consuming process in this type of segment: cooling production and distribution. The effectiveness of the proposed actions has been successfully tested and validated in an active factory that produces cured ham in Spain, where savings of about 5% in the total annual cost of electricity have been assessed, together with power reductions in the range of 50% of the total peak demand of the studied facilities. Such results demonstrate the efficacy of these techniques, and they open the door to an innovative perspective on the evaluation of flexibility among customers which are traditionally considered rigid, providing a novel approach to the management of customer infrastructures in order to exploit their flexibility in electricity markets. [Copyright &y& Elsevier]

Abstract: Life Cycle Assessment (LCA) has been applied within the residential building sector of two buildings, one in each a developed (Spain) and a developing (Colombia) country. The main goal of this paper involves the environmental loads and also brings together the operational energy for activities during the operation phase such as HVAC, domestic hot water, electrical appliances, cooking and illumination. The present research compares two real scenarios: Situation 1, where 100% of the dwelling’s energy is supplied with electricity only and Situation 2, where dwellings can be operated with natural gas plus electricity. The results for the environmental impacts using natural gas plus electricity show that of the Spanish environmental impacts air conditioning had the highest impact with approximately 27–42% due to the electricity used to power it. In Colombian results showed that electrical appliances had the highest environmental impacts in the same order of magnitude with approximately 60% and cooking had the best reduction of emissions due to the use of natural gas, from 10% down to less than 2%. The origin of the energy source used in each Country plays an important role to minimize environmental impacts, as was demonstrated by the environmental impacts of its use in Colombia where 78% of the electricity came from hydroelectric plants whereas in Spain it is more mixed, fossil fuels represented 55%, nuclear 18% and wind 9%. In summary, LCA has been applied because this methodology supports the decision making to concern environmental sustainability. [Copyright &y& Elsevier]