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Although, Spain does not obtain an official arctic strategy, it was mentioned in the paper for Spanish Polar Strategy that the Arctic region has become one of the country's national interests. The government of Spain is also deeply concerned about the problem of climate change and how it affects economic and social aspects of life. When addressing the Arctic energy issue we must make a prior delimitation, since it does not propose to study in detail, and only in general description, the internal functioning of the Arctic energy systems, that is, the one that serves to supply their populations with lighting, water, gas or electricity. [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]

The electricity production from Renewable Energy (RE) in isolated locations requires long-term energy storage systems. To that end, Hybrid Energy Storage Systems (HESS), through a combination of hydrogen and batteries, can benefit from the different advantages of both technologies. This paper presents a hybrid Power-to-Power (PtP) Optimal Power Dispatch (OPD) model for isolated systems with no electric grid access. Currently, the electricity supply in such cases is usually based on a mix of RE as the primary energy source sustained by a diesel genset acting as a backup generator. In this context, the model delivers the hourly energy flows between renewable production sources, energy storage devices and the electrical load, which minimises costs and Green House Gases (GHG) emissions. For validation purposes, the model was tested through its application to a case study in an isolated area in the Canary Islands, Spain. The results show that the algorithm calculates the hourly OPD successfully for a given plant sizing, considering the defined operational states of the different assets. These operational constraints showed a decrease in the PtP round-trip efficiency of 5.4% and a reduction of the hydrogen production of 9.7%. Finally, the techno-economic analysis of the results proves that the combination of hydrogen and batteries with RE production is a feasible alternative to phasing out fossil fuels for the selected case study – reducing the diesel generator usage down to 1.2% of the yearly energy supply. • Novel multi-state optimal power dispatch model for power-to-power energy systems. • Multi-year techno-economic evaluation of an off-grid case study. • Phasing out fossil fuels with renewable energy-based hybrid energy storage systems. • Hydrogen technology contributes to a lower levelized cost of energy. • High initial investment cost was a significant entry barrier to deploying hydrogen. [ABSTRACT FROM AUTHOR]

Residual flows are of major importance in coastal areas, driving environmental processes such as sediment transport or nutrient dispersion. Consequently, in those areas where a large tidal stream energy resource is available, prior to the installation of a tidal farm, it is imperative to assess how energy extraction affects the residual flows and, in particular, upwelling events. In this paper, the potential effects of different configurations of tidal stream farms on the residual circulation and its seasonality are analysed by means of a case study: Ria de Ortigueira, the westernmost of the Galician Rias Altas (NW Spain). For this purpose, a 3D numerical model was implemented and validated against field measurements. Next, a total of eight case studies, including the operation of bottom-fixed and floating converters under typical summer and winter scenarios, considering upwelling favourable winds, were studied. Overall, when a tidal farm operates, regardless of its configuration and the forcings considered, the resulting general residual flow pattern does not experience significant modifications. This pattern is characterized by a 2D circulation in the inner ria and a positive estuarine circulation in the middle and outer ria. The largest modifications of the residual flow are apparent in the vicinities of the plant, with maximum values of about 0.05 ms−1. Outside this area, the alteration is lower than 0.01 ms−1 and virtually negligible at some distance from the farm where upwelling events develop. [ABSTRACT FROM AUTHOR]

Food-delivery digital labour platforms started to operate in Spain in 2016. As in other national contexts, these platforms have misclassified workers as independent contractors rather than employees, shifting responsibilities and risks onto workers who have been forced to operate under marketized relationships lacking protection. This paper analyses trade unions practices and strategies targeted towards food-delivery platform workers (riders) in Spain. The findings are based on desk research and fieldwork consisting of semi-structured interviews with representatives from different trade unions and self-organized workers' associations. The article shows how trade unions' strategies resting on litigation and social dialogue ended up with the first legislation in Europe which introduced a rebuttable presumption of employment in the field of delivery platforms. At the same time, it shows the limitation of those strategies resting on institutional power resources due to the fragmentation of workers' interests and the newly platforms' strategies to circumvent labour law. [ABSTRACT FROM AUTHOR]

In December 2013, a new electricity law was approved in Spain as part of an electricity market reform including a new remuneration scheme for distribution companies. This remuneration scheme was updated in December 2019, and the new regulatory framework introduced a series of relevant modifications that aim to encourage regulated firms to reduce their power supply interruptions using a benchmarking approach. While some managerial decisions can prevent electricity power supply interruptions, other managerial decisions are more oriented toward mitigating the consequences of these interruptions. This paper examines the second type of decision using a unique dataset referring to the power supply interruptions of a Spanish distribution company network between 2013 and 2019. We focus our analysis on the effect which grid automatization has on restoration times, the relative efficiency of the maintenance staff, and the importance of its location. We estimate a bottom-up spatial model and a stochastic frontier model to examine both external and internal power supply interruptions at municipal level. While our frontier model is standard, our spatial model differs from a conventional one in that it is developed from scratch using the information of each individual power supply interruption. [ABSTRACT FROM AUTHOR]

Summary: This paper develops a multiperiod multiobjective optimization procedure to determine the optimal configuration and operational strategy of a trigeneration system assisted with solar‐based technologies and thermal energy storage. The optimization model, formulated as mixed integer linear programming problem, incorporates dynamic operating conditions through time‐dependent local climatic data, energy resources, energy demands, electricity prices, and electricity CO2 emission factors. The methodology is applied to a case study of a residential building in Spain. First, the single‐objective solutions are obtained, highlighting their fundamental differences regarding the installation of cogeneration (included in the optimal total annual cost solution) and solar‐based technologies (included in the optimal total annual CO2 emissions solution). Then, the Pareto curve is generated, and a decision‐making approach is proposed to select the preferred trade‐off solutions based on the marginal cost of CO2 emissions saved. Additionally, sensitivity analyses are performed to investigate the influence of key parameters concerning energy resources prices, investment costs, and rooftop area. The analyses of the trade‐off solutions verify the enormous potential for CO2 emissions reduction, which can reach 32.3% with only 1.1% higher costs by displacing cogeneration in favor of the heat pump and the electric grid. Besides, with a modest cost increase of 7.3%, photovoltaic panels are incorporated, promoting an even greater CO2 emissions reduction of 45.2%. [ABSTRACT FROM AUTHOR]

This paper presents the technical, environmental, and economic evaluation of integrating various combinations of renewable energy sources-based systems in the expansion of a district heating and cooling network of a Technology Park near Barcelona in Spain. At present, a combined heat and power plant running on fossil fuels serves the heating, cooling, and electricity demand of the Park. However, this energy demand is expected to increase substantially in the coming years. EnergyPRO software was used to model the energy demand growth till 2030. Validation of the software application was done by making a base model using real plant data from the year 2014. The software was then used to project the energy supply based on three 15-year scenarios, having different combinations of renewable energy technologies, from 2016 until 2030. Primary energy consumption, CO2 emissions, and the net present value obtained in each scenario were used to decide the best combinations of renewable energy sources. The results of the study showed that presently, biomass boilers combined with absorption chillers and supported with solar thermal cooling are the most competitive technologies in comparison to ground source heat pumps for large DHC networks. This is mainly because of the lower primary energy consumption (624,380 MWh/year in 2030 vs. 665,367 MWh/year), higher net present value (NPV) (222 million € vs. 178 million €), and lower CO2 emissions (107,753 tons/year in 2030 vs. 111,166 tons/year) obtained as a result of the simulations. [ABSTRACT FROM AUTHOR]

The penetration level of wind energy is continuously growing, and it is especially relevant in European countries such as Denmark, Germany, and Spain. For this reason, grid codes in different countries have been recently revised, or are now under revision in order to integrate this energy in the network taking into account the security of supply. This paper is related to reactive compensation, which is one aspect usually included in these codes. On the other hand, a great number of installed wind parks are formed by fixed speed wind turbines equipped with induction generators. The typical scheme for reactive compensation in this kind of wind parks is based on capacitor banks locally controlled in each machine. This configuration makes very difficult to follow the requirements of the new grid codes. To overcome this problem, a configuration with a central controller that coordinates the actuation over all the capacitor steps in the wind park is proposed in this paper. A central controller algorithm that is based on a dynamic programming is presented and evaluated by means of simulation. At this time, the proposed scheme has been installed at the Sotavento Experimental Wind Park (Spain) and it is currently being tested. [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]

The growth of the geothermal industry demands the constant search of techniques with the aim of reducing exploration efforts whilst minimizing subsurface uncertainty. The exploration of geothermal resources is fundamental from the exploitation point of view, especially in those regions where this energy is not as widespread as the rest of renewable sources. This research shows how geoelectrical methods can contribute to the investigation and characterization of medium–low enthalpy geothermal resources until about 800 m of depth. A 2000 m long electrical-resistivity tomography profile was performed in a region of Southern Spain with previous evidence of moderate geothermal potential. Results of this geophysical campaign (together with a preliminary geological characterization) allowed for the obtainment of a 2D profile and a pseudo-3D model with extensive information about the subsoil in terms of geological composition and formations. The interpretation of geophysical results denotes the existence of a potential formation constituted by carbonate materials with thickness greater than 300 m, crossing different fractures. Once the ideal location for the geothermal exploitation is defined, the research evaluates the contribution of the possible energy source, deducing that the energy extraction in the potential fracturing area would be double that of the one in the vicinity of the site. [ABSTRACT FROM AUTHOR]

Nowadays, Wind turbines are highly used and their costs are reduced. Although using these turbines has so many benefits, but, because of their variable nature, their participating in power market has some unpredicted problems. In this paper, new approach is presented based on neural networks to forecast the production of wind power resources. This is used for probabilistic modeling of production uncertainty. Thereafter, new method is presented for bidding strategy of wind power to the power market based on minimization of imbalance cost. To determine the optimal bid to the power market, the probabilistic optimization is used. Different aspects of participation of wind generation in power market are analyzed based on the imbalanced power prices. Finally, using the practical data of a wind farm in Spain, different conditions of bidding strategy for energy is discussed. To compare the results, besides the proposed method, an advanced method for the short terra prediction is used. [ABSTRACT FROM AUTHOR]

This study provides an in-depth assessment of the environmental performance of five public schools in the transition towards a low-carbon economy and a more sustainable model of society. Life cycle assessment (LCA) methodology is used to conduct the study. The school system includes several activities and processes clustered in three subsystems: management of the school building, training and learning activities (T&L) and mobility and transport (M&T). A detailed primary data inventory of energy and resources consumption was collected in five schools located in Spain and Portugal. Findings on climate change (CC), water depletion (WD), particular matter (PM), acidification (Ac), and human health (HH), as well as associated external cost (EC), are reported per student in one school year as reference unit, allowing the schools' individual performance comparison and identify the potential improvements. Considering the sample of schools, findings reveal that peculiarities of the schools, such as location, specialization, and level of education, are crucial for the environmental performance. Buildings are a relevant contributor to CC as well as heating and electricity needs, although their relevance is dependent on multiple factors. The M&T subsystem also has relevant weight on the metrics evaluated. Educational activities have a lower impact in absolute terms but, in some schools, it becomes the main contributor to HH due to paper and electricity consumption and manufacturing of equipment. External costs results are in the range of 11 to 38 EUR/student·year mainly caused by heating, electricity and wastes from the building subsystem, and the M&T subsystem. [ABSTRACT FROM AUTHOR]

Agriculture is one of the most energy intensive activities within the European Union. The common absence of electric infrastructure in these rural settings has led to the need for in situ generation in many cases. The existing excess pressures in large pressurised irrigation networks makes the generation of micro hydropower here a possible alternative renewable energy source. Pump-as-turbines have been proposed as a cost-effective technology for such purposes, taking advantage of the excess pressure in pipe networks to produce energy. This paper presents a methodology for the design of a plant for micro hydropower generation in an agricultural farm and outlines the predicted benefits of the installation. These predicted benefits were also compared with the measured performance of the plant for the 2019 irrigation season. The main aim of the plant was to replace a diesel generator that supplied energy to the farm. The excess pressure found in the pipe network varied between 0m and almost 60m. The nominal power of the pump-as-turbine was selected to supply the maximum energy requirements of the farm. The predicted operation time of the plant was estimated at up to 3199 h concentrated between April and September. An annual savings of approximately €2950 and 11 t eCO 2 were also estimated. The measured results showed an actual operation time of 2443 h between May and September, as in April the monitoring system was not operational. For this operation time, the savings were €2258 and 8.4 t eCO 2. Considering the April theoretical irrigation time obtained, the savings raised up to approximately €2434 and 9.1 teCO 2. The return on investment of the installation was computed to be recovered in less than ten years. • Real pilot PAT installation operating during an entire irrigation season. • Electricity was brought to remote places with no access to grid connection. • Diesel energy source was fully replaced by micro hydropower technology. • Solar and micro hydro hybrid solution was used for self-consumption. • More than 9 tCO 2 and €2400 were saved during the 2019 irrigation season. [ABSTRACT FROM AUTHOR]

This paper presents a model for optimizing the life cycle economic and environmental impacts of a hybrid renewable energy and battery storage system – as energy supply technologies (EST) for off-grid farms. Micro-hydropower and photovoltaics represent the primary renewable energy (RE) sources, with batteries and a diesel generator considered as possible back-up systems. A modified Non-dominated Sorting Genetic Algorithm II (NSGA-II) was developed and applied to a case study farm in Southern Spain and provided different EST solutions to optimize a design based on economic (life cycle costing or LCC) and environmental (life cycle assessment or LCA) constraints. The results highlighted that cases with a strong dependence on batteries could achieve minimum costs and lower impacts for climate change and energy resources (non-renewable fuels). In contrast, the optimal system for minimizing the consumption of material resources (metals/minerals) resulted in higher fuel use, which was up to 25% more expensive. The optimal EST solutions used up to 37% of the total energy generated; however, the results were sensitive to energy production-demand distributions. This methodology can help identify the most cost-effective solutions with the lower environmental impacts for decarbonizing the agricultural sector. [Display omitted] [ABSTRACT FROM AUTHOR]

In the context of the efforts toward the technological development of wave energy converters, reliable estimations of the annual energy production that can be attained with a given device are fundamental for a sound evaluation of the related levelized cost of energy, which is crucial in the investment decision-making process. The lack of reliability in estimates of devices productivity can, in turn, be exacerbated by uncertainty in the available wave energy resource. The Climate Data Store of the Copernicus Climate Change Service delivers hindcast data and projections of the wave climate along the 20 m bathymetric contours of the whole European coastline, covering the periods 1976–2017 and 2040–2100. This work addresses the presence of long-term trends in wave power and the effect of these trends on wave energy exploitability and on the energy production of different wave energy converters to be installed along the Mediterranean, North African, and European Atlantic coastlines. The results show that the monthly variation in the wave energy resource will generally increase for most of the considered areas, up to double the current values in some locations. Wave energy converters will have to face more severe wave conditions, with relevant implications in terms of survivability. At the same time, the future annual energy production of the analyzed devices is expected to increase in many areas in the Mediterranean Basin (particularly in the nearest future scenario), as well as in the Baltic Sea and along the coasts of the UK and France and the north coasts of Spain. [ABSTRACT FROM AUTHOR]

Renewable energy sources (RES) can play a significant role in economic growth. This article examines the development of the wind energy market in the EU. The applicable regulations, directives, and legal acts are reviewed, and the State's role in the development of the renewable energy market is discussed. The analyses were carried out based on the available literature and Eurostat data. The authors of the paper used basic statistics to summarize the changes in wind energy and make a prognosis. The data analysis uses the Autoregressive Integrated Moving Average Method (ARIMA). The survey found that the highest average wind cumulative installed capacities were in Germany (31026 MW), Spain (18602 MW), United Kingdom (7894 MW) and France (6108 MW). Our analysis indicates that the biggest average annual installed wind capacity was in Germany (2952.6 MW), Spain (1224.5 MW) and the United Kingdom (1363.8 MW). These same countries achieved the highest average wind gross electricity production in the years 2004–17: Germany (50.9 TWh), Spain (39.3 TWh) and United Kingdom (18.9 TWh). The study finds that wind cumulative installed capacity will increase in most countries of the EU. • The European Union onshore wind energy market seems to be stable. • Wind power plays an important role as a source of energy supply. • The most important wind gross electricity producers in the EU are: Germany and Spain. • The highest increase of wind cumulative installed capacity in 2022 will be in Croatia. [ABSTRACT FROM AUTHOR]

Wind power has been increasing its participation in electricity markets in many countries around the world. Due to its economical and environmental benefits, wind power generation is one of the most powerful technologies to deal with global warming and climate change. However, as wind power grows, uncertainty in power supply increases due to wind intermittence. In this context, accurate wind power scenarios are needed to guide decision-making in power systems. In this paper, a novel methodology to generate realistic wind power scenarios for the long term is proposed. Unlike most of the literature that tackles this problem, this paper is focused on the generation of realistic wind power production scenarios in the long term. Moreover, spatial-temporal dependencies in multi-area markets have been considered. The results show that capturing the dependencies at the monthly level could improve the quality of scenarios at different time scales. In addition, an evaluation at different time scales is needed to select the best approach in terms of the distribution functions of the generated scenarios. To evaluate the proposed methodology, several tests have been made using real data of wind power generation for Spain, Portugal and France. [ABSTRACT FROM AUTHOR]

In recent years, there has been a remarkable development in the technology and legislation related to electric and autonomous vehicles (i.e., EVs/AVs). This technological advancement requires the deployment of the most up-to-date supporting infrastructure to achieve safe operation. Further infrastructure is needed for Level 5 vehicles, namely the introduction of super-fast wireless 5G technology. To achieve harmony between the rapid technological advancement of EVs/AVs and environmental preservation, enacting legislation related to their sustainable use is vital. Thus, this manuscript provides a review of the technological development of EVs/AVs, with a special focus on carbon footprints and the implementation of additive manufacturing using recycled materials. While EVs have a 12.13% increased carbon footprint compared to conventional vehicles, AVs with basic and advanced intelligence features have an increased carbon footprint of 41.43% and 99.65%, respectively. This article emphasizes that the integration of 3D-printed components has the potential to offset this impact with a substantial 60% reduction. As a result, custom-made solutions involving 3D printing are explored, leading to greater speed, customization, and cost-effectiveness for EVs/AVs. This article also lists the advantages and disadvantages of the existing legislation in Spain, the United Kingdom, and the western Balkans, demonstrating various approaches to promoting electric mobility and the development of autonomous vehicles. In Spain, initiatives like the MOVES program incentivize EV adoption, while the UK focuses on expanding the EV market and addressing concerns about EVs' quiet operation. In the western Balkans, the adoption of legislation lags behind, with limited incentives and infrastructure for EVs. To boost sales, legal mechanisms are necessary to reduce costs and improve accessibility, in addition to offering subsidies for the purchase of EVs. To this end, an analysis of the incentive measures proposed for the development and use of renewable power sources for the supply of energy for EVs/AVs is presented. [ABSTRACT FROM AUTHOR]

Abstract: This paper presents the design and the implementation of a methodology for measuring and improving safety culture at a nuclear power plant (NPP). The study has involved the completion of a pilot project aimed at seeing how to make use of the RADAR logic (Results, Approach, Deployment, Assessment and Review) of the EFQM model as a tool for the self assessment of safety culture in a nuclear power plant. The work was aimed at finding evidence of the safety culture that was in place at the plant and at identifying both the strengths of that culture and any areas in which it could be improved. The score obtained from an analysis of those strengths and areas for improvement has made it possible to prioritise the actions to be taken. The identification of perceptions and evidence, the agreement on the strong points and areas for improvement and the quantification of the safety culture have been performed by groups comprising volunteers who work at the NPP. The advantages of this methodology are assessed in the paper. [Copyright &y& Elsevier]

• Application of the ampacity control system is necessary for wind energy integration. • DLR application reduced the time in which wind farms were out of service by 4100 h in 44 months. • DLR application increased the energy supplied by wind farms by 70.9 GWh in 44 months. • DLR application saved more than 7800 t of CO 2 in 44 months. The total renewable wind energy capacity of Spain currently accounts for more than 20% of the total installed energy capacity, which makes integration into the grid challenging for wind farm owners as well as Distribution System Operator (DSO). Electrical companies require new techniques to integrate renewable energies safety and with low investment costs. Dynamic line rating (DLR) is one of these techniques, and is used by DSOs to maximise the capacity of existing infrastructure. This paper presents a successful case of DLR application by a DSO over several years to reduce the time that wind farms were out of service due to an excess of electrical energy generated. Over the period from January 2015 to September 2018, the application of the DLR technique prevented 4,100 hours of out-of-service time, increasing the energy supplied by the wind farms by 70.9 GWh and by extension saving 7,800 tons of CO2. [ABSTRACT FROM AUTHOR]

Abstract During the last two decades, a relevant development of renewable energy sources for electricity generation has been observed in Spain. Their diffusion has provoked deep changes that at times have been controversial. The large penetration of renewables under the recent economic conditions has affected power plants, triggering changes in the regulatory framework. In Spain, the use of Combined Cycles Gas Turbines (CCGTs) for complementing intermittent renewables is meant to ensure the security of supply. This paper aims toward a better understanding of the effects of renewables deployment and the modifications of the regulatory framework in terms of resource and capacity support schemes. Highlights • A relevant development of RES has been observed in the Spanish electricity system. • A substantial loss of generation was detected for Spanish CCGT. • National regulatory framework in the field of electricity changes continuously. • A clear regulatory position should be taken in order to re-order the electricity sector. [ABSTRACT FROM AUTHOR]

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The purpose of this paper is to describe and assess a new characterization and classification method of voltage dips. The proposed method allows us to classify multistage and real voltage dips when measurement errors or transients are present in the recorded data. Different real voltage dips are used to assess this method, comparing the results with previous approaches. For visualization purposes, a voltage-space vector representation is introduced in order to clarify the global voltage dip evolution along the time. The classification of all the voltage dips, measured from a one-year field measurement campaign in wind farms located in the Spanish region of Castilla-La Mancha, is also presented and characterized according to the proposed method. [ABSTRACT FROM AUTHOR]

The number of wind power plants installed in Spain has increased dramatically, and many are located in important wildlife areas. This paper explores the geographical overlap of wind power plants with the ranges of flying vertebrate species. The list of animals studied includes bats, soaring birds, and other birds that may be killed by turbines. Results show that the 10 × 10 km UTM squares occupied by wind power plants fell within the range of more bat and bird species than squares free of these infrastructures. For species included in the Spanish Red List, there were more wind power plants than expected inside the range of two raptors (Neophron percnopterus and Circus pygargus) and less than expected in six species (Ciconia nigra, Aquila adalberti, Hieraetus fasciatus Myotis capaccinii, Rhinolophus mehelyi and Myotis myotis). The rest of endangered species (15) had a range occupation similar to that predicted by random sampling, a result that reflects a poor strategy to prevent the overlap. These patterns may be explained by the small amount of overlap of the range of many of these animals with the windiest areas in Spain, where wind power plants are concentrated today. However, this situation is changing rapidly with the densification and expansion of wind power plants promoted under the Spanish Plan of Renewable Energies. This may produce the occupation of many areas important to bird and bat conservation, and therefore preventive measures should be implemented to protect these species and their habitats. [ABSTRACT FROM AUTHOR]

There is a surge in the use of the solar chimney power plant in the recent years which accomplishes the task of converting solar energy into kinetic energy. As the existing models are insufficient to accurately describe the mechanism, a more comprehensive model is advanced in this paper to evaluate the performance of a solar chimney power plant system, in which the effects of various parameters on the relative static pressure, driving force, power output and efficiency have been further investigated. Using the solar chimney prototype in Manzanares, Spain, as a practical example, the numerical studies are performed to explore the geometric modifications on the system performance, which show reasonable agreement with the analytical model. Copyright © 2005 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

• 2050 low-carbon economy pledge and Spanish photovoltaic investment plan. • Photovoltaic spatial allocations minimising unpredictable variability. • Impact of wind energy investments on the optimal photovoltaic spatial allocation. • Allocation of photovoltaic and wind investments minimising supply–demand mismatch. • Assessment of the current photovoltaic investments in Spain. After a period of stagnation that lasted until approximately 2018, Spain has established an ambitious investment program in photovoltaics, derived from the pledge to switch to a carbon-free energy system by 2050, the sustained cost decreases of the technology, and the excellent irradiance values over its territory. This paper implements an additional criterion for the spatial allocation of these investments based on minimising the energy variability generated because of weather intermittency. The analysis is based on hourly data for the years 2005–2020 (inclusive), in various locations homogeneously spread throughout Spain. Subtracting the deterministic daily and annual irradiance cycles to estimate the variability of the random component is discussed. Failing to do that yields significantly higher and distorted values for solar energy variability, resulting in low investment proportions when combined with other energies, like wind. The first results show that a straightforward, equally-weighted allocation of investments is suboptimal. It is also shown that investing in low-irradiance locations contributes to reducing overall variability. Secondly, the study analyses overall power variability minimisation conditional on a given wind investment weight. It is found that the impact is significant spatially, and that proportions of wind energy above 10% increase aggregated variability across all levels of aggregated power generated. Nevertheless, investment proportions in wind energy below 10% reduce the overall combined variability significantly due to the negative correlation between wind and solar irradiation. The third point addressed is the minimisation of the mismatches between renewable energy supply and aggregate electricity demand. The optimal proportion for solar and wind investments becomes close to 50% in this case. However, this proportion tilts towards solar investments if variability minimisation is also considered. Finally, the current spatial distribution of photovoltaic investments in Spain is analysed, and it is shown that there is room for improvement. It is also found that the current ratio between wind and photovoltaic energy may not be optimal, and that it would be advisable to increase proportionally more photovoltaic energy. [ABSTRACT FROM AUTHOR]

Human societies face challenges in transitioning towards low‐carbon economies and sustainable management of land use and natural resources. Documenting and learning from past transitions helps policy‐makers cope with such challenges. The agricultural revolution in Cantabrian Spain (ca. 7000 cal a bp) was one major adaptation of hunter‐gatherers to a changing environment that started with the Last Glacial Maximum (ca. 24 000 cal a bp) and lasted until the Mid‐Holocene (ca. 5300 cal a bp). Classic approaches to documenting prehistoric cultural timelines are based on manufacturing and technology, thus limited in their ability to describe the sustainability of past societies. Energy regimes, a functional societal approach independent from time, investigate and consider patterns of resource and energy use in various cohabiting and cooperating cultural phases. To examine past energy regimes, a database of archaeological remains was compiled to document four indicators: mobility, economy, overexploitation and societal complexity. Statistical analyses were conducted to elucidate trends, changes and continuity in subsistence strategies by hunter‐gatherers and sedentary societies. Results show that energy regimes act as a complement to cultural phases, adding novel functional analyses of past societies to cultural stratigraphy units common in archaeology, shedding light on the sustainability of past societal transitions. [ABSTRACT FROM AUTHOR]

Solving the issue of energy security for geographical islands presents a one-of-a-kind problem that has to be tackled from multiple sides and requires an interdisciplinary approach that transcends just technical and social aspects. With many islands suffering in terms of limited and costly energy supply due to their remote location, providing a self-sustainable energy system is of utmost importance for these communities. In order to improve upon the status quo, novel solutions and projects aimed at increasing sustainability not only have to consider optimal utilization of renewable energy potentials in accordance with local conditions, but also must include active community participation. This paper analyzes both of these aspects for island communities and brings them together in an optimization scenario that is utilized to determine the relationship between supposed demand flexibility levels and achievable savings in a setting with variable renewable generation. The results, specifically discussed for a use case with real-world data for the La Graciosa island in Spain, show that boosting community participation and thus unlocking crucial demand flexibility, can be used as a powerful tool to augment novel generation technologies with savings from flexibility at around 7.5% of what is achieved purely by renewable sources. [ABSTRACT FROM AUTHOR]

Climate change, other environmental impacts due to increased energy use worldwide, and the exhaustion of energy resources are some of the major challenges facing today's society. Considering this, this paper assesses the importance of biomass-based heating and hot-water systems in the achievement of more sustainable buildings. Using a simplified calculation method, we jointly analyzed the potential operational cost savings and reduction of CO2 emissions that would be achieved when the traditional energy model, based on the use of fossil fuels, is replaced by biomass-based heating systems. Evidence stems from a case study in public buildings in the province of Pontevedra, in the northwest of Spain. The results of this research not only show a huge impact on CO2 emission reduction just by adapting the kind of fuel use, but also considerable annual cost reduction without compromising activity development and workers' comfort. Thus, the findings obtained should encourage governments to support the transition toward cleaner sources of energy, acting as first movers toward a locally produced and renewable-based energy supply. [ABSTRACT FROM AUTHOR]

On the path towards the decarbonization of the electricity supply, flexibility and demand response have become key factors to enhance the integration of distributed energy resources, shifting the consumption from peak hours to off-peak hours, optimizing the grid usage and maximizing the share of renewables. Despite the technical viability of flexible services, the reduction of greenhouse gas emissions has not been proven. Traditionally, emissions are calculated on a yearly average timescale, not providing any information about peak hours' environmental impact. Furthermore, peak-hours' environmental impacts are not always greater than on the base load, depending on the resources used for those time periods. This paper formulates a general methodology to assess the potential environmental impact of peak-hourly generation profiles, through attributional life cycle assessment. This methodology was applied to five different countries under the INVADE H2020 Project. Evaluation results demonstrate that countries like Spain and Bulgaria could benefit from implementing demand response activities considering environmental aspects, enhancing potential greenhouse gas reductions by up to 21% in peak hours. [ABSTRACT FROM AUTHOR]

Bioenergy is the form of clean energy with the greatest potential for growth in Spain, especially in those regions with a large forest area and a high potential for the utilization of forest resources for energy purposes. This is the case in Galicia (a region located in northwestern Spain), where the communal management of forest resources is widespread. Within this type of management, there is a pioneering case study in which biomass energy use activities have been initiated through an international project. The possible success of this project is of great importance since it could represent an alternative to the main energy activity in the common management of forests: the production of wind energy. In recent years, and with a special increase in 2022, Galician public opinion has expressed its opposition to the implementation of new wind farms in its forests. The aim of this article is to analyze whether or not it is profitable for forest management communities to participate in bioenergy initiatives, which is a novel analysis of the Galician geographical area. For this purpose, the main economic and financial variables of the Galician forest management communities participating in the bioenergy project, SilvaPlus Project, have been analyzed, before and during their participation in the project. In addition, a financial comparison is also made with a group of Galician forest management communities without the energy use of their resources. The evolution of the relevant variables, analyzed between 2011 and 2020, shows a generally positive trend in the values of the forest communities participating in the bioenergy generation project, resulting in a positive experience, both environmentally and financially, for the forest community. [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: As fossil fuels are not only a limited resource, but also contribute to global warming, a transition towards a more sustainable energy supply is urgently needed. Therefore, today''s environmental policies are largely devoted to fostering the development and implementation of renewable energy technologies. One important aspect of this transition is the increased use of biomass to generate renewable energy. Agricultural residues are produced in huge amounts worldwide, and most of this residue is composed of biomass that can be used for energy generation. Consequently, converting this residue into energy can increase the value of waste materials and reduce the environmental impact of waste disposal. This paper analyses the situation of biomass energy resources in Andalusia, an autonomous community in the south of Spain. More specifically, biomass is the renewable source which most contributes to Andalusian energy infrastructure. The residual biomass produced in the olive sector is the result of the large quantity of olive groves and olive oil manufacturers that generate byproducts with a potentially high energy content. The generation of agricultural and industrial residues from the olive sector produced in Andalusia is an important source of different types of residual biomass that are suitable for thermal and electric energy since they reduce the negative environmental effects of emissions from fossil fuels, such as the production of carbon dioxide. [Copyright &y& Elsevier]

Abstract: In transmission and distribution systems, the high number of installed transformers, a loss source in networks, suggests a good potential for energy savings. This paper presents how the Spanish Distribution regulation policy, Royal Decree 222/2008, affects the overall energy efficiency in distribution transformers. The objective of a utility is the maximization of the benefit, and in case of failures, to install a chosen transformer in order to maximize the profit. Here, a novel method to optimize energy efficiency, considering the constraints set by the Spanish Distribution regulation policy, is presented; its aim is to achieve the objectives of the utility when installing new transformers. The overall energy efficiency increase is a clear result that can help in meeting the requirements of European environmental plans, such as the ‘20–20–20’ action plan. [ABSTRACT FROM AUTHOR]

Abstract: Spain is a country with six LNG terminals in operation and three more scheduled for 2011. At the same time an increasing number of LNG tanks are under construction to compensate the Spanish lack of underground storage. A method for evaluating the daily boil off generated is presented in this paper. This method is applied to evaluate the increase of BOG to be handle by LNG terminals in 2016, studying the best commercially available solution to be installed. Finally, as a solution to tackle with the BOG a cogeneration plant is suggested. This option will reduce terminal’s operational costs increasing its availability. [ABSTRACT FROM AUTHOR]

Abstract: Although the Mediterranean region is blessed with abundant solar resources, photovoltaic energy currently represents a very small share of power production. In Germany however, a much less sunny country, the photovoltaic (PV) industry is booming. This country has become a front runner in the adoption of PV because of effective policy incentives. Based on a cross-case study analysis of the German, Spanish and Greek PV markets, this paper investigates factors determining the effectiveness of PV policies. Our analysis shows that, above a certain level of return, risk-related factors (such as policy instability and administrative hurdles) play a more important role in influencing investment decisions than return-related factors (such as the level of a feed-in tariff). [Copyright &y& Elsevier]

This article analyses national postal services unions' strategic capacity in Spain and Belgium in response to the effects of liberalization and changes in the postal sector. The analysis shows, first, that despite having had to operate in a hostile context, Correos and bpost unions have been able to mobilize their power resources to resist the impact of market pressures on employment and working conditions. Second, it detects the relevance of national industrial relations institutions in order to understand the strategies unions adopt. [ABSTRACT FROM AUTHOR]

The aim of this study is to estimate the environmental impacts associated with modernization measures that improve the energy efficiency of an office building listed as of cultural interest and located in northern Spain, a region with an Atlantic climate. European Climate Action for 2020-2030 sets a long-term goal of achieving neutrality of greenhouse gas emissions and towards the end of 2019 the Spanish Government presented its Integrated National Energy and Climate Plan. It is of interest to the international audience to know how energy policies can affect decisions on building retrofitting to improve sustainability: reduction in energy consumption, climate change and other environmental impacts. A life cycle assessment was carried out for the retrofitting of the building envelope and different energy supply scenarios: only electricity from the electricity mix (scenario of reference that of 2018, and decarbonisation scenarios proposed for 2020 and 2030), and the installation of heat pump and photovoltaic panels. The impacts will decrease 40% for Global Warming Potential and 15% for Cumulative Energy Demand in 2030 with respect to the reference scenario. These reductions will further increase up to 54 and 61%, respectively, if photovoltaic panels and a heat pump are implemented. [ABSTRACT FROM AUTHOR]

Analyzes the hypotheses of dematerialization based on the historical experience of energy intensification process in Spain. Association of energy use with economic growth; Conventional approach of energy intensity analysis; Use of integrated assessment in the characterization of energy metabolism and economic development.

• Fiscal policies can be potential tools to boost renewables. • Electricity self-generation is implemented and evaluated. • Removal taxes to renewables achieves price competitiveness. The sustainability of the environment implies a dire need to redesign electricity systems. The aim of this paper is to evaluate the role of alternative fiscal incentives to promote renewable electricity. To this end, a disaggregated, electricity-related Computable General Equilibrium model is developed, taking the current structure of the (renewable and non-renewable) electricity sector into account. The Computable General Equilibrium model developed presents at least two advantages: the changes are analyzed from a global perspective (including impacts on prices), and second, rebound effects are accounted for. The fiscal measures examine three scenarios of change in line with the decarbonization processes of economies. Specifically, the scenarios assess: (1) a 100% decrease in renewable electricity taxes; (2) a 23% increase in taxes paid by the non-renewable electricity sector; and, (3) both together. In addition, these fiscal measures are evaluated assuming improvements in electricity self-generation. The case study is the Spanish economy for 2016. The Computable General Equilibrium model is calibrated on a symmetric input–output table, constructed from supply and use tables. These tables disaggregate the energy and electricity sectors. Results reveal the role and strength of fiscal policy in boosting the production of electricity generation technologies using green energy resources, and reducing the production of electricity generated from brown sources. However, results suggest that these effects are limited to the energy chain sectors, with insignificant effects in the whole economy. This study also provides better information and guidance to politicians and decision-makers who wish to promote renewables, and the need to have a clear understanding of the influence price competitiveness has on the economy. Moreover, the results of this study have implications for rebound effects when electricity self-generation is implemented. [ABSTRACT FROM AUTHOR]

One of the main goals of the Catalan nationalist movement toward independence initiated in 2012 was to internationalize the conflict between, in theory, two sides: Catalonia and Spain. In the case of Catalonia, its storytelling tried to offer to the world the view of an entire society intensely mobilized in pro of freedom and independence by peaceful methods, while Spain would be incarnated in an elitist irreducible and defensive government closed to reason and negotiation. This article describes the use of strategic communication (mainly public diplomacy and public relations), a soft power and post-modern resource, by the pro-independence movement in opposition to the use of modern and hard power means by Spain's government (including appeal to courts, police, and financial pressure, among other means). It describes the efficient use of strategic communication, including para-diplomacy efforts as well as positive press coverage and even "fake news", by the Catalan pro-independence movement. Nonetheless, the movement was not able to gain the political support of supra-national organizations like the European Union (EU), the United Nations (UN) or even some major powers such as Germany, which had supported other independence processes in the past. The conclusion is that an efficient use of strategic communication seems to have its limits in the internationalization of internal conflicts and in altering the political status quo when the threatened nation state, in this case Spain, has a solid international position and good democratic credentials. [ABSTRACT FROM AUTHOR]

• A model for the optimization of energy renovation of districts is presented. • The model covers both energy supply systems and envelope design. • The model is applied to a case study district located in Northern Spain. • The designs are limited by the roof availability and economic feasibility. • The model can be used for fast design and policy making. The nearly Zero Energy Building concept should be adopted in the renovation of existing buildings and actions upscaled and applied to larger and larger urban areas. In this context, this paper presents an optimization methodology for drafting integral renovation actions at district level. The methodology is based on a MILP model that allows selecting energy saving measures, as well as the design and operation of energy supply systems amongst a very large set of potential permutations. For its application, the concept of District Equivalent Building is introduced, defined as a virtual building with a set of energy loads equal to the addition of all the individual load vectors of each building. The methodology was applied to a real residential district located in Bilbao (northern Spain). For this case study, the optimal renovation plan was obtained, considering for that three different optimization objectives: (i) Optimal-Cost, (ii) Zero Energy District (ZED) and (iii) Zero Energy District including domestic electricity consumption in the calculation of the non-renewable primary energy consumption (ZED'). Although similar solutions were adopted for each of these cases, significant differences were get attending the hourly operation of the solutions. These cases were economically assessed and the optimal-cost curve was obtained. [ABSTRACT FROM AUTHOR]

Featured Application: Featured Application: Several commercially available and free downloadable PV modelling software tools are compared with real data for three different photovoltaic power plants in operation over the past 12 years. Both annual and monthly results are analyzed. Prediction of energy production is crucial for the design and installation of PV plants. In this study, five free and commercial software tools to predict photovoltaic energy production are evaluated: RETScreen, Solar Advisor Model (SAM), PVGIS, PVSyst, and PV*SOL. The evaluation involves a comparison of monthly and annually predicted data on energy supplied to the national grid with real field data collected from three real PV plants. All the systems, located in Castile and Leon (Spain), have three different tilting systems: fixed mounting, horizontal-axis tracking, and dual-axis tracking. The last 12 years of operating data, from 2008 to 2020, are used in the evaluation. Although the commercial software tools were easier to use and their installations could be described in detail, their results were not appreciably superior. In annual global terms, the results hid poor estimations throughout the year, where overestimations were compensated by underestimated results. This fact was reflected in the monthly results: the software yielded overestimates during the colder months, while the models showed better estimates during the warmer months. In most studies, the deviation was below 10% when the annual results were analyzed. The accuracy of the software was also reduced when the complexity of the dual-axis solar tracking systems replaced the fixed installation. [ABSTRACT FROM AUTHOR]

Hot-dip galvanisation (HDG) is the method most commonly used to protect steel surfaces from corrosion. However, HDG involves very intensive consumption of energy and resources. This paper aims to evaluate the environmental performance and hotspots in the Spanish HDG sector using cradle-to-gate life cycle assessment (LCA). Two Spanish HDG industrial plants, with different galvanisation capacities and manufacturing processes, were selected for the case study. The LCA revealed that the consumption of energy, fuels and nonrenewable resources were the most relevant environmental burdens at both plants. Steel was the main contributor, as it had the greatest influence on the plants' environmental profiles. The consumption of primary zinc and natural gas, used to dry and heat the molten zinc bath, also contributed to the impact of the HDG plants. This work proposes a normalisation to compare the Spanish sector against a European reference based on the average of 66 companies in 14 countries. The impacts of the Spanish HDG plants being studied were generally below the EGGA values, although the results are strongly influenced by the type of steel and the degree of material reuse implemented in the steel manufacturing process. The study lays the foundations for improvements in the resource efficiency and productivity of galvanisation plants. We propose alternatives such as the use of secondary zinc or modifications that will extend the lifespan of pickling baths, which would contribute to a more sustainable use of resources in the galvanising industry. Image 1 • The hot-dip galvanisation (HDG) sector in Spain was assessed via LCA. • Two HDG plants with different production properties provided detailed data inventories. • The highest impacts were found in the production of steel and primary zinc. • Using secondary zinc and extending pickling bath's lifespan would improve HDG. • The impacts of the Spanish HDG plants were generally below the European average. [ABSTRACT FROM AUTHOR]

• The model estimates the biomass required to produce the syngas in a BFBGP. • The proposed FF-PSO algorithm showed to solve model dynamic Power Generation systems. • The FF-PSO model proposed for the ANN-based model has the best performance. Agriculture and forestry crop residues represent more than half of the world's residual biomass; these residues turn into synthesis gas (syngas) and are used for power generation. Including Syngas Gensets into hybrid renewable microgrids for electricity generation is an interesting alternative, especially for rural communities where forest and agricultural waste are abundant. However, energy demand is not constant throughout the day. The variations in the energy demand provoke changes in both gasification plant efficiency and biomass consumption. This paper presents an Artificial Neural Network (ANN) based model hybridized with a Particle Swarm Optimization (PSO) algorithm for a Biomass Gasification Plant (BGP) that allows estimating the amount of biomass needed to produce the required syngas to meet the energy demand. The proposed model is compared with two traditional models of ANNs: Feed Forward Back Propagation (FF-BP) and Cascade Forward Propagation (CF-P). ANNs are trained in MATLAB software using a set of historical real data from a BGP located in the Distributed Energy Resources Laboratory of the Universitat Politècnica de València in Spain. The model performance is validated using the Mean Squared Error (MSE) and linear regression analysis. The results show that the proposed model performs 23.2% better in terms of MSE than de other models. The tunning parameters of the optimal PSO algorithm for this application were found. Finally, the model was validated to predict the necessary biomass and syngas to cover the energy demand. [ABSTRACT FROM AUTHOR]