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• 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]

This paper proposes the first application of a split-range control technique on a concentrating solar collector to improve an absorption plant production. Solar absorption plants have solar power availability in phase with cooling demand under design conditions. Thus, it is a powerful cooling technology in the context of renewable energy and energy efficiency. These plants need control systems to cope with solar irradiance intermittency, reject irradiation disturbances, manage fossil fuels backup systems and dump closed-loop thermal-hydraulic oscillations. In this work, control techniques are proposed and simulated in an absorption plant in Spain. The plant consists of a concentrating Fresnel solar collector connected to an absorption chiller. The objectives are to operate with 100% renewable solar energy and avoid safety defocus events while reducing temperature oscillations and control actuators effort. Firstly, the current available plant controllers are defined, then two modifications are proposed. The first modification is a split-range controller capable of manipulating both flow and defocus of the Fresnel collector, the second modification is a PI controller to substitute the original chiller on-off controller. The results compare, through validated models, the different control systems and indicate that using both proposed controllers reduces 94% of the sum of actuators effort and 43% of the integral of absolute set-point tracking error compared to the plant's factory pre-set controllers. The suggested controllers increase 66% of energy production and 63% of exergy production. Besides, the split-range technique can be extended to any concentrating solar collector control. [Display omitted] [ABSTRACT FROM AUTHOR]

The operation of solar photovoltaic installations for many years may lead to problems such as reduced energy efficiency and aging of components. Under this framework, replacing certain components in the facility to extend the service life of the power plant is viewed, in some cases, as a feasible strategy. However, despite its enormous strategic interest for the solar PV industry, we find that revamping PV installations has been the focus of very few scientific publications, and even less so when it comes to analyzing real facilities. Thus, this paper performs a techno-economic analysis of three revamping strategies at a real PV power plant located in the south-east of Spain. The strategies consist of substituting, in each case, the PV modules, the inverter, and both components. The simulated results show that the highest production value by installed power is obtained when both the modules and the inverter are replaced. In the same vein, the economic analysis reveals this scenario as the most favorable in terms of profitability. Based on the results obtained, an interesting future line of research would be focused on the extension of the analysis at country level to study the joint impact of numerous revamping actions. • Techno-economic analysis of revamping projects of a real solar PV power plant. • Replacing modules and inverter emerges as the most feasible strategy. • Study's applicability extends to other revamping initiatives and geographical regions. • Economic outcomes allow the most cost-effective alternatives to be determined. • This research can contribute to efficient and sustainable energy planning. [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]

Abstract Recent electricity management systems such as Smart Grids and Virtual Power Plants help to better integrate distributed generation renewable resources (RDG), such as photovoltaic, small hydro or micro wind in electricity markets. In this context, an important increase of small-scale power generation technologies is expected in Spain by 2020, according to the Spanish Action Plan for Renewable Energy. This paper analyses the environmental and economic impacts of the massive integration of RDG in Spain for 2020 by using an Input-Output approach. The induced production and employment effects in every sector due to new RDG project investments as well as the CO 2 reductions attributed to a decline in conventional electricity consumption are estimated. The results indicate that investments in RDG based on photovoltaic and small-hydro have the greatest impact on employment generation. The RDG investments will lead to a decrease in emissions of 21.67% in 2020 compared with 2013. The RDG technologies become an alternative to reach a sustainable economic growth in Spain. In future research, a multi-regional input-output model and the study of the links between energy consumption, standard of living and consumption patterns will aid to delve deeper into the relationship between economic growth and the environmental impacts of small-scale renewable technologies. Highlights • RDG will be over half of total installed electricity generation capacity in 2020. • The impact of RDG deployment is quantified on Spanish economy in 2020. • The IO methodology is used to study the environmental and economic impacts. • Photovoltaic and small-hydro have the highest impact on employment generation. • RDG becomes an alternative to reach a sustainable economic growth in Spain. [ABSTRACT FROM AUTHOR]

This paper evaluates the net effect of renewable energy policy in Spain from 2002 to 2017 and calculates its cost-effectiveness in terms of CO 2 emission reductions in the production of electricity. Our conclusions indicate that although the phasing out of Feed-in Tariffs reduced the regulatory costs, it also limited renewable participation in the electricity market, leading to an increased electricity price and higher emissions. According to our results, the joint effect of (i) the value of avoided emissions due to renewable energy participation and (ii) the merit order effect was able to compensate for the regulatory costs (subsidies) up until 2010, while the sign of the net effect was reversed from 2011 to 2017. Finally, we find that the economic implications of emission reductions are highly dependent on how the social cost of carbon is measured. [ABSTRACT FROM AUTHOR]

Abstract: This paper contributes a critical view of the development of grid-connected photovoltaic systems (GCPVS) in Spain during the period 1998–2008 by looking into the different actions that were intended to promote this technology. The Spanish photovoltaic (PV) sector has undergone bullish development in the recent years, but its underlying factors still lack systematic identification and analysis. Accordingly, this paper collects and presents detailed data for describing this evolution. It also makes a special case of the particular promotion of PV systems on roof and goes further to analyze how these actions have affected GCPVS evolution as well as the magnitude of their impact on its performance. The exponential growth of installed cumulative PV power at the end of this period, which largely exceeded the target set for 2008, is canvassed by building an analogy with feedback control systems. In this approach, market response or the PV power attained is considered as the system output, while the different regulation changes are regarded as control actions aimed at enabling GCPVS to hit the energy target. Such an analysis allows determining the most significant delays and control actions that explain the system''s performance. Hence, this study suggests an alternative framework to support the formulation and assessment of energy policy as it puts the emphasis not only on the evolution of the system per se but rather on the performance of the system against the energy target. In this regard, it might contribute to enhance the promotion mechanisms of green technologies. [Copyright &y& Elsevier]

Abstract: A rigorously founded assessment of the potential of renewable energies is essential for the development of energy policies and regulations. Usually, a hierarchy of potentials are calculated which gradually include restrictions for the use of a specific renewable resource. This paper deals with the estimation of the technical potential of roof-integrated photovoltaic systems. The most restrictive step when estimating this potential for large-scale territories is the estimation of the roof available area in existing buildings, for which no direct data exists. The methodology proposed in this paper allows to estimate the roof area available for solar applications and also quantify the error made in this estimation. It is based on easily accessible data (such as land uses and population and building densities) and on a statistically representative stratified-sample of vectorial GIS maps of urban areas. The main point in this sampling process is that the stratification is done based on a finite set of average building typologies which comprises every urban area in the region of study. An interesting characteristic emerging from the proposed methodology is its scalability and the possibility of being used from regional to continental scales. This methodology is applied in this work to Spain and a mean available area for photovoltaic equipment on roofs of . with a confidence level of 95% is obtained. Additionally, results are given for the technical limit of production of roof-integrated photovoltaic energy. [Copyright &y& Elsevier]

Offshore wind energy generation has experienced an important growth in the last five years, reaching currently an installed capacity of almost 8000 MW. The most important references in this type of technology are Denmark, Holland, Sweden, Germany and United Kingdom. In Spain, previsions for technology, have been set at around 750 MW of installed power during the period 2011–2020. However, Spanish coastal features, social opposition to installations near the coast and lack of a stable regulatory environment guaranteeing the investments are factors which are restraining the development of this technology. This paper presents a brief review of the state of the art of offshore wind technology and it describes the most frequently used types of turbines, transmission systems and support structures in Europe. It also presents the current situation and the expected growth of offshore wind power facilities, introducing the characteristics of the operational – and under construction – windfarms. Finally, it analyses particular problems and solutions for its development in Spain which can be extrapolated to countries with similar circumstances. [ABSTRACT FROM AUTHOR]

From mid-2007 to September 2008, the Spanish PV sector experienced an investment boom, which led to a ten-fold increase in solar PV deployment. The concern of the government about the large increase in the associated support costs through a feed-in tariff led to the implementation of several cost-containment regulations. These included a cap on the electricity generation being eligible for support, a grid access charge, a generation charge, a shortening of the support period and the updating of tariffs below the consumer price index. The aim of this paper is to analyze the impact of those cost-containment mechanisms on the profitability of solar PV plants in Spain. The results show that these measures have had a moderate impact on the profitability of those plants, which is still relatively high, with internal rates of return which are always above 7% in all the simulated cases. However, their impact is mediated by different features of the plant, including the levels of the initial investment (upfront costs), borrowing and operation and maintenance (O&M) costs. It is also mediated by policy variables (such as changes in the tariff-updating method and the level of the grid-connection charges) and by other variables, e.g., the interest rates of loans. The specific impact of each of the cost-containment measures has also been analyzed. Our findings show that the generation charge has the greatest impact, followed by the change in the tariff-updating mechanism, the generation cap, the shortening of the support period and the grid access charge. [ABSTRACT FROM AUTHOR]

This paper estimates the impact of a hypothetical change in Spain's energy mix on a number of productive sectors. The change would be brought about by substituting power generation from natural gas with generation from biomass. The total amount of electricity supplied has been calculated to remain constant so that a crowding-out effect would be derived from the displacement of one technology with another. An input–output (IO) framework has been used to estimate the overall economic impact on 26 productive sectors included on Spain's 2007 IO Table. Based on the available literature, the consideration of net impact improves the analysis. The results show that the overall net impact across all productive sectors of this change in the energy mix would be positive and equal to about 0.5% for the period. Higher impacts were measured for the ‘Electricity power and Electricity Supply’ sector (15.4%) followed by the ‘Agriculture, Hunting, Forestry’ sector (7.1%). Only the ‘Gas generation and Gas supply’ sector showed a negative impact (–2.5%), which is consistent with the reduced use of natural gas. The overall calculated total impact for Spain's productive sector was equal to € 8074.95 million at the 2007-equivalent value. [ABSTRACT FROM AUTHOR]

Abstract: An analysis of scientific publications on solar energy was conducted to determine whether public interest in the subject is mirrored by more intense research in the area. To this end, the research published by Spain and Germany, the two EU countries with the highest installed photovoltaic capacity, was analyzed based on Web of Science data. The results show that: solar output has risen substantially; solar research has a greater impact (measured in terms of citations) than publications on other renewables such as wind power; scientific production on solar energy is high in Germany and Spain, which together account for 51% of the total in the EU-27; the pattern of topics researched in the two countries is very similar; and their international collaboration is more intense than the world average and higher than in countries such as the USA, China or Japan. Collaboration between them is likewise intense. The main conclusion is the divergence in Germany and Spain between solar energy demand/output growth, being exponential, and the growth of research papers on the subject, which is linear. [Copyright &y& Elsevier]

Abstract: This paper reviews the production and consumption of traditional and renewable energy in Spain over the past two decades. It also presents an overview on the development of renewable energy, such as solar (photovoltaic and photothermal), wind, biomass, hydropower, marine and geothermal energies in Spain. A brief overview of the legislation regulating renewable energy in Spain is offered. It was shown that the installed renewable energy of 32,472MW represented 11.6% of the country׳s primary energy consumption. Furthermore, the installed renewable energy average of electric power in Spain was 0.7kW per capita and 59kW/km2. Wind energy continues to experience a good growth rate, and does not seem to be affected by regulations, which has made it the most sustainable renewable energy in Spain. Finally, an analysis of energy production and consumption, renewable and non-renewable energy by province is made. The data indicates that highly populated and industrialised provinces made more efficient use of their energy from an electrical consumption viewpoint. This uneven growth was not motivated solely by the existence or lack of renewable energy resources but by the autonomous community or province in their socio-economic context. [Copyright &y& Elsevier]

Abstract: This paper aims to estimate the economic impacts of increasing the production capacity of the installed biofuel plants in Andalusia (southern Spain). A computable general equilibrium (CGE) approach is used to calculate the changes in the economic sectors' activity, in employment as well as in GDP and other macroeconomic variables relevant to biofuel plants in Andalusia under two distinct scenarios (i) based on an operating biodiesel plant (with 90ktoe/year of installed capacity); (ii) upgrading to 2174ktoe by 2013 in compliance with the regional ‘Plan Andaluz de Sostenibilidad Energética (PASENER) 2007–2013'. Results show that compliance with the PASENER goal would increase the activity level of the economic sectors considered by 3.04%, the total induced employment generated would reach 167,975 equivalent full-time jobs lasting one year and the GDP would increase by 9.82%. [Copyright &y& Elsevier]

Abstract: The capacity expansion planning problem of the renewable energy industry involves decisions regarding the optimal mix of different plant types, locations where each plant should be built, and capacity expansion decisions over the planning horizon for each plant. The aim of this paper is to develop a goal programming model, based on a multi-source multi-sink network, in order to locate five renewable energy plants for electric generation in five places located in the autonomous region of Cantabria, in the north of Spain. As different types of plants can be placed in each location, the goal is to locate one plant in each place, maximizing the number of plants that are matched with comparable locations, in a way that the total deviations from goals are minimized. [Copyright &y& Elsevier]

Abstract: The use of vehicles powered by hydrogen from renewable sources can be a viable alternative for Andalusia, given its accessibility to renewable energies and the problems of energy dependence and pollution resulting from the current energy model. However, the introduction of this type of technology requires an initial infrastructure that solves the classical chicken and egg problem. Given that hydrogen fueling infrastructure will require significant initial capital investment, it is reasonable to assume that a possible strategy of introduction could be the establishment of a station network that is sparse to avoid redundancy and therefore minimize costs. In this paper, we utilize Analytic Hierarchy Process to rank, on the basis of several supply, demand and environmental criteria, the more than 750 municipalities of Andalusia according to their suitability for the establishment of hydrogen fueling stations. Subsequently, we incorporate these results into an optimization problem to achieve optimal planning of the number and location of hydrogen fueling stations to provide coverage for the region. [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: This paper describes a simulation model that reproduces the performance of parabolic trough solar thermal power plants with a thermal storage system. The aim of this model is to facilitate the prediction of the electricity output of these plants during the various stages of their planning, design, construction and operation. Model results for a 50MWe power plant are presented and compared to real data from an equivalent power plant currently operated by the ACS Industrial Group in Spain. [Copyright &y& Elsevier]

Abstract: The European Union has established challenging targets for the share of renewable energies to be achieved by 2020; for Spain, 20% of the final energy consumption must be from renewable sources at such time. The aim of this paper is the analysis of the consequences for the electricity sector (in terms of excess cost of electricity, investment requirements, land occupation, CO2 emissions and overcapacity of conventional power) of several possibilities to comply with the desired targets. Scenarios are created from different hypotheses for energy demand, biofuel share in final energy in transport, contribution of renewables for heating and cooling, renewable electricity generation (generation mix, deployment rate, learning curves, land availability) and conventional power generation (lifetime of current installations, committed deployment, fossil fuel costs and CO2 emissions cost). A key input in the estimations presented is the technical potential and the cost of electricity from renewable sources, which have been estimated in previous, detailed studies by the present authors using a methodology based on a GIS (Geographical Information System) and high resolution meteorological data. Depending on the scenario, the attainment of the targets will lead to an increase in the cost of electricity from 19% to 37% with respect to 2007. [Copyright &y& Elsevier]

Abstract: In this paper, we assess the potential for the generation of electricity in Spain from agro-industrial residues. The industries considered are olive-oil mills, rice mills, wineries, dairy plants, breweries and wood, meat and nut processing plants. The methodology used is based on statistical data, and is integrated into a Geographical Information System (GIS) from which geo-referenced results are obtained. The waste-to-electricity technologies analyzed are: grate firing followed by steam turbine, co-firing in coal power plants and anaerobic digestion plus internal combustion engine. The combined potential for the agro-industrial residues in Spain is estimated at 2625ktoe/year of primary energy (1.85% of the primary-energy consumption in Spain in 2008). Olive mill and wood processing residues have the largest energy potentials. Comparisons are presented with (partial) results from other studies. Considering only profitable plants, grate-firing followed by steam-turbine cycle is the conversion option with the largest potential, totaling 653MWe and an electrical generation of 4.57TWh (1.44% of the gross electrical generation in Spain in 2008). A complete sensitivity analysis is done to investigate the influence of the different economic parameters. A reduction by 50% of the investment costs of grate firing would increase profitable power to 1102MWe (and production to 7.70TWh). [Copyright &y& Elsevier]

Abstract: This paper presents an integrated method that assesses the socio-economic impact of establishing renewable energy on a regional scale, in particular on the creation of jobs. The method proposed is based on the collection, critical analysis and presentation of the results obtained using primary information sources considering the jobs created as the most direct measure of the socio-economic potential of renewable energy sources. Its design includes contributions extracted from a prior analysis of the existing assessment methods, to lessen the uncertainty of the job ratios often used in these types of analysis. The integrated method implemented has been applied to the autonomous community of Aragon (Spain) as a pilot case, through which the method has been tested and the indicators selected to analyse the socio-economic impact of renewable energy sources on the jobs created, the quality of the jobs and other factors related to the socio-economic development of a territory: technological development, per capita income, territorial development and human capital. [Copyright &y& Elsevier]

Olive sector residues could contribute to increased use of renewable energies, especially in those areas where the olive crop is produced. This paper determines the maximum amount of electrical and thermal energy which could be obtained in Andalusia from olive sector residues, and the economic value that could be obtained from these energy uses. For this, the current data on installed power and electrical and thermal generation are compared with the calculated potential data which would be obtained at full capacity. The results show there is a 69.23% wastage of olive sector residues for energy purposes. Thus, using the resources at full capacity, 3.9 million tons of biomass per year could be obtained for energy purposes. Currently, only 2 million tons of biomass are used for energy purposes. This wastage translates into a below potential generation of electrical and thermal energy. The full use of these residues would allow 83.9% and 64.9% higher generation of electrical and thermal energy, respectively. The results obtained also show that the economic value of olive sector biomass is higher than the market price value, with the average values for each use being 248.20 €/t for domestic thermal use, 165.04 €/t for electrical use and 139.50 €/t for industrial thermal use. Thus, it is considered feasible that the olive sector biomass could be used to a greater degree than at present. In this sense, it is recommended that more electricity generation plants and thermal-generating systems be put into operation. • There is a 69.2% wastage of olive sector residues that could be used for energy purposes. • The full use of olive by-products would account for 6.2% of renewable electricity. • The full use of olive by-products would account for 26.7% of thermal generation. • Better use of residues would promote the start-up of 55 and 1762 electricity and thermal plants, respectively. • The economic value of olive sector biomass allows the value chain to be covered. [ABSTRACT FROM AUTHOR]