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The demand for eco-products due to the exigency of friendly and environmental production could affect the employment of the firms. This paper tests whether product and process eco-innovations boost employment in Spain differentiating by the environmental goals (material and energy efficiency and environment responsiveness), by the level of qualification of the workers, and by the dirtiness of the industries. We apply a Green Harrison model, using the Technological Innovation Panel (PITEC) for Spain from 2008 to 2016. Results show a positive relationship between all types of product eco-innovations and employment, while the influence of process eco-innovations on employment depends on the environmental goals, the level of skills, and the industry. Specifically, distinguishing by industry there is a labour-saving effect in clean industries and a labour-friendly effect for low-skilled employment in dirty industries. [ABSTRACT FROM AUTHOR]

This paper studies the diverse actions, interventions and strategies initiated to address rising energy vulnerability among low-income households in the Barcelona region over the last decade. Drawing upon recent conceptual work around the politics of energy and in-depth fieldwork conducted over more than two years, we trace the different processes and sites through which the basic socio-material conditions of domestic access to energy have become politicised. We show how this involves a two-stage movement of deconfinement and reconfinement. In a context marked by austerity, an energy inefficient urban fabric and a centralised and oligopolistic energy system, energy vulnerability emerged from the domestic and private sphere to become framed as a public problem through parliamentary debate, social protest and local authority initiatives. Yet, energy access and vulnerability have also to some extent been recontained in the space of the household through the focus of recent local policy intervention on 'low cost' measurement, audit and equipment of domestic energy use. We argue that in reprivatizing what had become a public issue and thus redistributing responsibility for change to the household level, authorities and practitioners continue to ignore the systemic factors behind energy vulnerability situations and reproduce a status quo that benefits only energy utilities. The contribution of the paper is thus to show a politics of energy access that is increasingly constituted through entangled, fluid, blurred forms of relations between domestic and collective issues. This politics allows, for example, the need for systemic change to be framed as ostensibly a concern of households and to be met through fragmented, low-cost, metrological measures at that level. [ABSTRACT FROM AUTHOR]

This paper explores whether the changes in energy intensity in Spain have led to improvements in the energy consumption levels or to a backfire effect offsetting the expected decrease. Jevon's paradox or backfire effect happens when a rebound higher than 100% causes energy efficiency improvement to raise energy consumption. To test Jevon's paradox or the backfire effect caused by energy efficiency actions, a Logarithmic Mean Divisia Index I (LMDI-I) is used for the Spanish economy. The period under consideration ranges from 2000 to 2015, when three national action plans were implemented. The main methodological novelty of this paper consists on to block the economic activity effect in a second decomposition round to better explore the effect of energy efficiency on energy consumption. As a whole, our results do not support Jevon's paradox for the sectors analyzed. However, they do warn about a possible backfire effect in the industry, transport and service sectors. Major findings follow these same findings when the activity effect is blocked. • Backfire effect caused by energy intensity is explored. • Focus is on the Spanish case from 2000 to 2015. • Main methodological novelty is to block the economic activity in a LMDI approach. • Results do not support Jevon's paradox for the sectors analyzed. [ABSTRACT FROM AUTHOR]

• The paper has a focus on energy consumption habits and trends using statistical methods. • Occupants' behavior is monitored using smart metering system and awareness surveys. • The impact of a serious game on occupant's behavior is evaluated. The paper has a focus on energy consumption habits, trends and intervention strategies in residential buildings, mainly through the serious game approach with a combination of direct consumer feedback through smart metering. More than 150 homes in France and Spain have been involved in the research experiment and the consumption habits of approximately 50 homes were deeply analyzed. The applied methods, processes, results and findings of the monitoring data analysis are presented in the paper with two aims. First, consumption profiles and trends were determined for apartment homes with regard to heating, domestic hot water and electric consumption. Second, the impact of a serious game experiment was assessed comparing energy consumption, indoor air temperature and users' habits (based on questionnaires) before and after launching the experiment. [ABSTRACT FROM AUTHOR]

Highlights • The paper describes a methodology to obtain an Urban Energy Sustainability Index (UESI). • This methodology can evaluate the global energy performance for any city. • UESI works through the measurement of 12 clearly-defined indicators and targets. • UESI is also a tool for designing effective actions towards energy-sustainable cities. • The index has been applied successfully to two Spanish cities (Malaga and Barcelona). Abstract The aim of the paper is to propose a methodology for evaluating the energy sustainability of a city based on the characterization of the energy end-use, energy systems and flows, as well as other intrinsically related concepts, such as the quality of air and the energy efficiency in transport and buildings. As a result, an Urban Energy Sustainability Index (UESI) has been proposed to measure the energy sustainability of the cities. Several indicators have been proposed to be used to build the index. These indicators have been grouped into three types depending on their influence on energy urban sustainability: basic, instrumental and complementary. For each indicator, an analysis has been done and as a result an expression for estimating it has been proposed. The value of the index is obtained from the combination of these indicators using the weighted average method. The proposed index can be used as an operational tool to improve the sustainability of cities. It also aims to have an international application as it is related to the global sustainability objectives defined by internationally recognized organizations. The proposed methodology has been used for two different Spanish cities, Barcelona and Malaga. The results show that it covers most of the issues related to the use of energy and sustainability in the cities and that it can also be applied to others cities. [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]

Countries worldwide have set national targets for energy production from renewable sources. Yet, while many governments are committed to more renewable energy, obtaining permission to site installations is becoming increasingly difficult. With large tracts of land for renewables becoming intensely contested, countries seeking to meet their renewables targets are directing attention also towards tapping the potential in the urban environment through smaller-scale facilities. These entail other challenges, and countries are seeking ways to overcome them. The focus of this paper is on one, still evolving, type of renewable energy technology: small-scale wind turbines (SSWT). The paper presents a review of current but limited international academic knowledge on the land-regulation aspects of siting SSWT in countries that already have experience with such installations, including the USA, UK and New Zealand. The paper also reports on a comparative analysis of the land-related regulations and practices in two selected Mediterranean jurisdictions – Spain (Catalonia) and Israel. The approach of this study is exploratory, relying on analysis of legal and policy documents complemented by field work through in-depth interviews with key-stakeholders in both jurisdictions. The overall aim of this study is to examine different approaches of planning systems to new technologies. The findings show that despite their shared objective factors, the two jurisdictions have adopted almost opposite approach to regulating SSWTs. The findings, therefore, suggest that the incorporation of an unknown technology within the city requires a change of mindset both among the officials and among the city residents. A more effective regulatory framework might therefore entails a combination of strategic thinking, an experimental approach and the capacity to learn from cross-national comparative experiences. [ABSTRACT FROM AUTHOR]

The purpose of this paper is to review the literature focused on the energy/electricity-growth nexus, highlighting how the focus has shifted from aggregated energy/electricity consumption towards specific energy sources. Moreover, it aims to shed light on the relationships between different energy/electricity sources and economic growth. Empirically, the paper focuses on the analysis of interactions between electricity generation in Spain under both the Special Regime ( SR ) and the Ordinary Regime ( OR ), and their relationship with economic activity. Data for Spain is studied for a time span from January 2003 to January 2016. The Toda-Yamamoto causality test is carried out to check for causality relationships. Additionally, both short- and long-run effects are assessed by using the ARDL bounds test approach. Overall, the results reveal high internal consistency when comparing the ARDL results with the causality analysis. The substitution effect was detected between OR and SR. However, the negative effect of the SR on economic activity deserves special attention by energy policymakers. This paper argues that the main challenge of renewable sources for policymakers is their cost-effectiveness. [ABSTRACT FROM AUTHOR]

Effectively utilizing low-grade thermal energy is a promising approach to mitigating greenhouse gas emissions while reducing the burden on centralized power grids. Current thermoacoustic heat pumps and power generators face challenges such as high onset temperature differentials and low performance. This paper addresses these challenges by introducing a gas-liquid resonator into a thermoacoustic combined heat and power systems to recover low-grade thermal energy in residential buildings. Through Sage modeling and calculations, the internal characteristics of the proposed system and its output performance under different operating conditions are explored. At a heating temperature of 350 °C, the system can generate 6.4 kW of output thermal power, 0.9 kW of electricity, and overall exergy efficiency is 79.3 %. Combining neural network models with case studies conducted in Spain and Finland, the system can annually save 5.6 MWh and 20.7 MWh in fuel energy, reduce emissions of 1374 kg and 5180 kg of carbon dioxide, and save a total cost of €611 and €2324, respectively. Furthermore, comparisons with other emerging micro-CHP systems highlight the efficiency of the proposed system. These results indicate the high potential of thermoacoustic combined heat and power systems in recovering low-grade thermal energy and achieving energy savings and emission reductions. • Introducing an innovative thermoacoustic micro-CHP system. • Achieving an exergy efficiency of 79.3 % under standard operating conditions. • One system can annually reduce household CO 2 emissions by 5180 kg. • Ideal for households, balancing lower output levels for both heat and electricity. [ABSTRACT FROM AUTHOR]

Decentralized and small-scale forms of organization are reappearing in Spanish's energy system. Co-operatives have a social approach based on three dimensions: the purpose of the initiative, the form of organization and ownership, and embeddedness. In this paper, we apply this analytical framework to twelve energy co-operatives in Spain. These collectively owned organizations are energy-marketing communities, and they have specific objectives: These are an ecological objective (to reduce energy consumption and generate renewable energy) and a social objective (to propose an alternative to the reality of the energy market and citizen empowerment). Energy co-operatives in Spain have been typified as social enterprises, and these social enterprises have experience in common energy service, with which they may mark their future role in local energy communities. These results show the consolidation of energy co-operatives as a sign of the maturity of Spanish society in the face of energy challenges. [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]

• We present a novel integration for reducing CO 2 emissions in blast furnaces. • It combines top gas recycling, oxy-fuel regime, power to gas and biomass pyrolysis. • The integration was modelled using the extended operating line methodology. • The best performance was found for pyrolysis at 700 °C. • The CO 2 emissions were reduced by 58% (9.8 MJ/kg CO2 energy consumption) The paper introduces a novel approach for mitigating CO 2 emissions in blast furnaces by integrating top gas recycling, an oxy-fuel regime, power to gas, and biomass pyrolysis. Various case studies were conducted, involving the adjustment of pyrolysis temperatures (300 °C, 500 °C, 700 °C, and 900 °C) and varying the quantity of blast furnace gas directed to methanation for carbon recycling. Pinus radiata, abundant and cost-effective in Chile and Spain, was chosen as the biomass source. The integration was modeled using the extended operating line methodology and evaluated through 12 key performance indicators, such as flame temperature, coke consumption, CO 2 emissions, and specific primary energy consumption per unit of CO 2 avoided. Optimal performance was observed with pyrolysis at 700 °C and no blast furnace gas recycled through methanation. This configuration achieved a 58 % reduction in CO 2 emissions, with an energy consumption of 9.8 MJ/kg CO2 , and obviated the need for geological storage. Comparing this innovative proposal with other oxygen blast furnace approaches from the literature revealed a 13 percentage point improvement in CO 2 reduction over the second-best alternative. Additionally, the required electrolysis capacity, influencing capital expenditure, was 57 % lower, and energy consumption was reduced by 44 %. [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]

The Basque Y High Speed Rail connection between Madrid and the Basque Autonomous Community is, quite exceptionally, a mixed freight and passengers HSR line, that has been presented as a fundamental step towards a more sustainable mobility. In this paper, a life-cycle assessment (LCA) is conducted to assess the environmental performance of the line throughout its lifetime, based on the latest data available, including both construction and maintenance burdens. Results show that this new corridor is not justified in terms of reducing emissions and energy consumption, mainly due to its low transport density. It also has a negligible impact on Spanish current low rail freight traffic. We conclude, therefore, that Spain needs to reconsider its AVE network expansion if aiming at increasing rail's modal share and meeting the emissions targets set by the EU. From a policy perspective, many information inconsistencies have been found regarding the demand projections of freight transport, which cast serious doubt about the decision-making process behind Trans-European transport projects. [Display omitted] • Life-cycle assessment (LCA) of the Basque Y high-speed rail line under construction in 2023. • It verifies whether this project is justified in terms of environmental impacts reductions. • Net balance of the Basque Y high-speed rail is very modest, when not detrimental. • This project would not be justified in terms of environmental impacts reductions. • Alternatives to high-speed rail in the transport hierarchy provide better environmental balance. [ABSTRACT FROM AUTHOR]

Abstract: The most widespread support system for renewable-energy-sourced electricity (RES-E) is the feed-in tariff (FIT). FITs can be divided into fixed-FIT and premium systems. The latter type may also include a cap and floor option, turning it into a variable premium system. The cap value (upper limit) aims to avoid windfall profits for the RES-E investor if the electricity price rises quickly, while the floor value (lower limit) ensures minimum revenue, reducing the risk caused by low electricity prices. This paper examines the performance of the variable premium system as established in Spain (hourly-based) and investigates the possibility of alternative novel designs. For this purpose, an analysis was undertaken of the cap & floor system established in Spain based on real market data over a three year period and its performance compared to the fixed premium system (no cap & floor limitations) and two novel cap & floor designs (monthly- and yearly-based). Two other novel alternatives were also considered: daily- and weekly-based. It is shown that the hourly-based cap & floor system did not result in a reduction of the overall RES-E revenue compared to the fixed premium system over the three year period, though revenue was more evenly distributed from year-to-year. The paper concludes that variable premium systems should be based on monthly or yearly cap & floor mechanism as opposed to an hourly one. [Copyright &y& Elsevier]

Abstract: The contribution to global energy consumption of the information and communications technology (ICT) sector has increased considerably in the last decade, along with its growing relevance to the overall economy. This trend will continue due to the seemingly ever greater use of these technologies, with broadband data traffic generated by the usage of telecommunication networks as a primary component. In fact, in response to user demand, the telecommunications industry is initiating the deployment of next generation networks (NGNs). However, energy consumption is mostly absent from the debate on these deployments, in spite of the potential impact on both expenses and sustainability. In addition, consumers are unaware of the energy impact of their choices in ultra-broadband services. This paper focuses on forecasting energy consumption in the access part of NGNs by modelling the combined effect of the deployment of two different ultra-broadband technologies (FTTH-GPON and LTE), the evolution of traffic per user, and the energy consumption in each of the networks and user devices. Conclusions are presented on the levels of energy consumption, their cost and the impact of different network design parameters. The effect of technological developments, techno-economic and policy decisions on energy consumption is highlighted. On the consumer side, practical figures and comparisons across technologies are provided. Although the paper focuses on Spain, the analysis can be extended to similar countries. [Copyright &y& Elsevier]

The energy retrofitting of residential stock is not always straightforward where heritage protected housing is concerned. In southern Europe, many examples built under the Modern Movement codes are now obsolete in terms of energy efficiency. The aim of this paper is to assess the potential for improvement of comfort conditions and energy efficiency in Mediterranean heritage residential buildings, through the incorporation of passive strategies in keeping with preserving heritage values. Long-term monitoring and field tests in representative flats of the case-study building were carried out and, focusing on a single example, adaptive comfort equations were used to assess results. The passive strategies considered are the thermal isolation of the air cavities of walls, changing window frames, optimizing window glazing, and setting up regular mechanical ventilation rates for indoor air changes. Although simulation results generally predict a better energy performance after testing retrofit strategies, the potential decrease in energy demand is more noticeable than the potential improvement in comfort conditions. • The improvement of comfort and energy efficiency in a heritage building is assessed. • Long-term monitoring and field tests were carried out in representative flats. • Passive strategies in keeping with preserving heritage values were examined. • Adaptive comfort equations were used to assess results focusing on one flat. • Energy efficiency improvements are more noticeable than those of comfort conditions. [ABSTRACT FROM AUTHOR]

Abstract: Due to the increasing energy consumption of air conditioning in buildings and the need to decrease the fossil CO2 emissions to the environment, the interest of using renewable energy sources shows up stronger than ever. We present a general study whose aim is to propose a method to evaluate an upper bound in the potential of solar cooling by using some simplified models. As an example it has been applied to the very diverse climates of Spain. In the paper it has been assumed a direct solar coupling between the solar collector field and a single effect absorption cooling machine, without any intermediate solar storage tank. An equation is obtained that shows the dependence of the generator/solar-collectors equilibrium temperature on basic design parameters of the system (absorption machine-solar collectors). The paper analyzes the effect of these on the total amount of cooling produced along a typical mean year and the peak cooling power. The paper also includes a discussion on how to estimate the values and what is their physical meaning of the parameters which define the behavior of real absorption machines. Finally tables are included for the 12climates of Spain that can be used as an example of how to make a quick pre-sizing of such direct coupled system. The classification of the Spanish climates is based on general data (average monthly total horizontal solar radiation, average monthly dry temperature, etc.) and the results could be generalized for climates with the same severity. Moreover if hourly weather data is available for any place (like tmy2, bin, epw, etc. files), the procedure can be applied without further changes. [Copyright &y& Elsevier]

Abstract: The present production and use of energy are causing depletion of resources and serious environmental problems. Accordingly, more and more countries are examining a whole range of new policies and technology issues to make their energy futures “sustainable,” thus increasing governmental incentives for technology providers and utility mandates to incorporate significant levels of renewable resources. Hand-in-hand with the sustainable development initiative, in recent years the concept of a “Smart Grid” for the delivery of energy to consumers has emerged. Existing distribution networks were not designed to accept extensive distributed generation (DG). The actual paradigm may change in the near future impelled by a worldwide increasing of DG penetration in distribution grids. This paper presents the status and content of Spanish legislation on DG. Fundamental considerations are first discussed, exclusively regarding the grid-interconnection requirement. This paper also analyses the relationship between that guidelines and recognized international standard in a systematic way. Major requirement areas include general specifications, safety and protection strategies, and power quality requirements. This study reveals the diversity of requirements for DG grid connection coexisting, considering both the national and the international context; this stresses the urgent need for international harmonization. It is interesting to note that in Spain (as in most of the European countries), protections for LV photovoltaic systems are defined but not for the rest of the distributed generation technologies in low voltage. Thus, one could conclude from this study that probably the most important barriers are the lack of adequate requirements and procedures. [Copyright &y& Elsevier]

Abstract: In the last few years the solar-powered air-conditioning systems have been in intensive development and more often are considered as the viable application for the thermal solar systems in the regions of southern Europe. This is mainly due to the increasing higher electrical consumption in many countries (especially in Spain) which is moving from the winter to summer months due to expanding usage of cooling systems in this period of the year. In this paper we will analyze the behaviour of the solar-assisted air-conditioning system installed in the CIESOL building. This system consists mainly of flat-plate solar collectors and the simple effect LiBr–H2O absorption chiller. Different operation modes were analyzed. Coefficient of performance (COP) at various generator, absorber, condenser and evaporator temperatures is investigated and experimental results show that in practice it is easy to obtain values of about 0.6. The main goal of this paper is to describe the characteristics of the developing building and the solar-assisted air-conditioning system. Another useful purpose is to find the optimum conditions and operation parameters for the solar system through analyzing various systems'' operation strategies. [Copyright &y& Elsevier]

• 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]

• Advanced climate-resilient energy retrofit technology reduces the use of non-renewable energy in the building sector. • Renewable District Heating as an optimal technology in deep energy renovation strategies. • Sustainable cities and buildings are feasible by Centralised District Heating system powered by biomass. • Key Performance Indicators (KPIs), to achieve nZEB performances established in the European legislations. This paper presents the implementation of a biomass-fuelled District Heating System (DHS), as a part of a deep energy renovation exercise to achieve a climate-resilient campus with minimum carbon dioxide emissions. The case study is carried out for the University of Valladolid, an average-sized university in Spain, with a continental weather climate. Prior to renovation, the different building blocks had a wide-ranging level of fossil fuel consumption for space heating and domestic hot water ranging between 60 and 430 kWh/m2·year. The application of this centralised heating system allows to achieve the minimum threshold for near zero-energy buildings (nZEB) of 100–120 kWh/m2, in accordance with the Spanish Standards. These values correspond to the maximum European indicators for offices in continental weather conditions. Results of this comprehensive study show that 15 out of the 19 buildings reached the nZEB target, due to the proposed strategy. The overall carbon dioxide emissions have dropped by 92.69% as compared to the original fossil-fuel powered boiler, thus bringing carbon dioxide emissions down to 1.57 kgCO 2 /m2·y. Therefore, it is shown that deep energy renovation strategies through renewable energy DHS have the potential of achieving nZEB for universities in continental weather conditions. [ABSTRACT FROM AUTHOR]

The low energy efficiency of the European building stock is both a social and environmental issue. However, plans and studies on energy retrofitting interventions do not usually evaluate the impact of these measures on households' energy affordability. This paper analyses and compares the effect of alternative retrofitting strategies on thermal energy services' affordability in Spanish vulnerable households. This analysis was carried out by applying the Required Thermal Energy Expenditure model proposed in previous studies to several 2030 residential building stock scenarios, setting 2020 as a baseline. Therefore, this work proposes a methodological approach to assess the impact of the considered energy efficiency interventions on energy poverty in winter (WEP) and summer (SEP) and carries out both a 'social cost' and a cost-benefit analysis. The dwelling's thermal-enclosure retrofitting stands out as a very WEP-reduction and social-cost effective measure. Instead, replacing old thermal systems with more efficient ones would have a higher impact on SEP. Combining both kinds of retrofitting measures could reduce heating and cooling required expenditures by, respectively, 49% and 59%, and decrease the WEP and SEP share, correspondingly, by 35% and 63%. These results might inform policymakers to enhance the targeting and design of energy efficiency programs. [ABSTRACT FROM AUTHOR]

This paper reports on the environmental impact assessment of a specific urban fabric: the housing estate. This urban-growth typology arose in the second half of the twentieth century to supply the existing needs of the time. It involved short-term processes, reduced costs, and lower comfort standards, which are far from present European guidelines. Currently, they represent situations of unsustainability in cities worldwide that are undergoing improvement. Here, the environmental impact assessment and minimization for urban organisms (EIAMUO) methodology is presented. This consists of a system of eco-indicators created specifically for estimating the impacts associated with these fabrics. Through its practical application, a snapshot of the current situation is achieved and the targets designed to minimize the environmental impact are proposed. [ABSTRACT FROM AUTHOR]

Reducing greenhouse gas emissions and energy cost in the building sector largely relies on effective energy management. Yet, when it comes to heating or cooling, energy savings may translate to uncomfortable conditions for the building users. To ensure thermal comfort with a minimal energy consumption, in this paper we propose a modular methodology that dynamically schedules the operating hours of the heating/cooling system of the building using thermal comfort forecasts. To decide on the time and mode of operation, our approach utilizes indoor air temperature and relative humidity forecasting models, as well as a data-driven algorithm that predicts thermal comfort level based on said forecasts and employs pre-heating/cooling when necessary. Our empirical evaluation, conducted in the Casal Mira-sol culture center of Sant Cugat, Spain, suggests that our approach can improve the satisfaction of the building users, while achieving significant energy savings. • A method to handle heating and cooling systems based on thermal comfort forecasts. • Optimization of the HVAC operation using indoor temperature and humidity forecasts. • A dynamic algorithm that simulates thermal comfort to pre-heat/cool the building. • Demonstration of the approach through an application to a public building in Spain. [ABSTRACT FROM AUTHOR]

This paper presents a study of the thermal performance of a single-family house located in a coastal city in northern Spain that was built according to Spanish standards during the 1990s. The study estimates an annual energy demand of around 95 kWh/m 2 and a thermal power rating of the heating system of around 16 kW. The potential energy savings that would be obtained by implementing different retrofitting measures frequently used nowadays are also quantified: installing a ventilation system with heat recovery, improving the insulation of opaque construction elements, replacing the existing windows with high-thermal performance windows, and reducing air infiltration rates. These integrated actions on the house would reduce the annual energy demand below the requirements of both the Technical Building Code (24.24 kWh/m 2 year for this case of study), which is the regulation currently in force in Spain, and the well-known Passivhaus standard (15 kWh/m 2 year), which is one of the most widespread building standards in Europe. Compliance with these requirements means that the annual energy demand and the size of the heating system would respectively be potentially reduced by 81% and 57% of the present values. [ABSTRACT FROM AUTHOR]

Generally, in most pressure irrigation systems and particularly in irrigation systems of golf courses, an efficient management of water and energy use is required. Through an efficient management of these resources the excessive consumptions are controlled and a savings in exploitation costs could be achieved. One of the tools that allow controlling and identifying the water and energy consumption is the use of management and automation indicators. With the employ of these tools, several parameters that affect in the efficiency of water and energy use of pumping systems, water network configuration, automation and the associated energy systems could be controlled. In this paper the methodology and implementation of several water, energy and automation indicators and their productivity adapted to four golf courses in south-east Spain are shown. For this purpose, some data of a developed study among 2008 and 2011 in the irrigation systems of these golf courses and their influence in the improvement of the efficiency in the water and energy use are presented. This combined methodology is particularly suitable for comparing the irrigation systems of several golf courses. Moreover, by using these indicators with automation and remote control devices for water and energy management in such irrigation systems, it is possible to reduce and control associated costs. The results demonstrate that automation is a low-cost investment (with a maximum of 2% of the total costs) compared to the large benefits and advantages. For this study, the maximum values of the automation cost per controlled water volume and energy were 0.2007 €·m −3 and 0.2233 €·kWh −1 , respectively. The percentage of automation cost in the total cost is around 1.5 percent. [ABSTRACT FROM AUTHOR]

Fuel poverty can be defined as “the inability to afford adequate warmth in the home”. The concept was firstly developed due to health risks related to cold among low income households. However, in the last few decades, especially since the summer heat wave of 2003 that caused 35,000 deaths across Europe, a lot of research has been conducted about the health risks related to high temperatures. Along with advances in knowledge related to the health risks associated with inadequate temperatures, several directives of the European Commission related to energy regulation urge Member States to develop their own fuel poverty definitions. This need of a methodological development for new definitions poses several questions. First, what should be the temperature thresholds for the overheated season? But, furthermore, are existing temperature baselines adequate for the Spanish context and climate? This paper presents a preliminary approach to define these new temperature thresholds for the Spanish context through the adaptive comfort model criteria. For that purpose, a statistically representative dwelling building typology of vulnerable household spaces was used to analyze indoor thermal temperatures and hence, to establish minimal energy requirements so as to achieve minimal habitability conditions. [ABSTRACT FROM AUTHOR]

'Energy efficiency first' is one of the key principles of the Energy Union, mainly due to it being the most cost effective way to reduce emissions, improving energy security, enhancing competitiveness and making energy consumption more affordable for all consumers. In light of the revised EU Energy Efficiency Directive, this paper discusses new developments brought by the EU together with the national case studies of Slovenia and Spain. Given that the paper has a specific focus on the industrial sector, it discusses the selected measures of the Energy Efficiency Directive, such as defined in Articles 7, 8, and 14, which are the most relevant to this sector. The paper also explores the newly issued integrated national energy and climate plans together with national measures and policies that support energy efficiency in industry, including the quantification of achieved and forecast energy savings in these two EU Member States. • The revised EU Energy Efficiency Directive is the key driver of change in Member States. • More ambitious energy efficiency targets are projected in Slovenia and Spain for 2030. • The integrated National Energy and Climate plans inspired further national developments. • Both countries committed to continue their national measures/schemes on energy efficiency. [ABSTRACT FROM AUTHOR]

This paper has two main aims: to offer an overview of Spain׳s strategy for fulfilling its Kyoto commitments and to analyze the main drivers that have influenced the recent trend in its greenhouse gas (GHG) emissions, with special emphasis on the Spanish power sector. First, the use of the Kyoto Flexibility Mechanisms in Spain and the role of the different subsectors of the country׳s economy in fulfilling the aforesaid commitment are explored, focusing on the sectors affected by the European Union Emission Trading Scheme (EU ETS). Then, based on the Stochastic Impacts by Regression on Population, Affluence, and Technology (STIRPAT) model and on the analysis of trends in Spain׳s primary and final energy intensity ratios, the main drivers in GHG emission trends are identified, with a distinction being drawn between “strategic” and “non-strategic” drivers. The results show that the trend in the level of the economy is the main “non-strategic” driver, while increased penetration of renewable energies in the Spanish power mix and improvements in final energy efficiency are the main “new-strategic” drivers which explain the downward trend observed in GHG emissions from 2006 onwards. However, changes in legislation introduced in 2012 are negatively affecting the new renewable installed power generation capacity: they seem to mean a step backward in the future Spanish strategy to reduce or limit GHG emissions. [ABSTRACT FROM AUTHOR]

Energy performance certificate databases are a key tool for mapping national building stock and thus fostering greater overall energy efficiency. This paper presents an insight into the energy performance of residential and tertiary sector buildings in Spain, through an analysis of the first 129,635 energy performance certificates issued for existing buildings, collected by the Catalan Institute of Energy. Most of the residential buildings or building units that were studied were “E” class (53.6%). Single-family houses were found to use more energy on average (248.0 kWh p /m 2 ) than individual dwellings (183.2 kWh p /m 2 ). Tertiary sector buildings were found to have slightly better energy performance (26.4% of buildings were rated “D class”), with an average energy consumption of 317.8 kWh p /m 2 . Modern buildings consume less energy, as they must meet the higher energy performance requirements stated in thermal building regulations. Residential buildings or building units located in hotter climate zones consume slightly less energy than those located in colder zones, mainly because heating accounts for a high percentage of overall energy expenditure (70–75% in residential buildings). A significant proportion of the energy consumed in tertiary sector buildings is for lighting (37.2%). This research defines the current energy consumption baseline of existing buildings in Spain. The results can help to prioritize energy conservation efforts according to building type, construction period, climate zone and specific end-uses. They may also help public authorities to plan future energy policies, and construction practitioners to identify market segments and business strategies. [ABSTRACT FROM AUTHOR]

The need for airtightness control is a reality given its impact on buildings' energy use and Indoor Air Quality (IAQ). For the past few years, this fact has resulted in energy performance regulations establishment that involves airtightness requirements in many countries in Europe and North America. In this sense, efforts should not only be focused on new buildings, but also existing ones. Considering that around 90% of the built stock in the EU is expected to still be standing in 2050 and that almost 75% of the buildings are energy inefficient, attention must be paid to retrofitting actions. Airtightness predictive models have become useful in the decision-making process and to estimate input values in energy performance simulation tools. So far, several predictive models have been developed in different countries. However, specific construction systems and practices lead to a lack of consensus regarding the impact of different factors on airtightness performance. Therefore, the applicability of existing models is limited to their specific contexts. This paper presents a predictive model for envelope airtightness, which was developed from a database that contains a fully characterised representative sample of the residential building stock in Spain. A General Linear Model (GLM) was considered to assess significant variables related to the age of the building, typology, building state, construction system, and dimensions. As a result, a predictive model is presented and validated. Overall, even if some limitations were identified, the relevance of the model proposed is warranted from the statistical point of view. The airtightness predictive model presented offers a procedure for airtightness estimation of residential buildings in Spain. • Development of a model to estimate the envelope airtightness of dwellings in Spain. • The model is based on a representative sample of existing dwellings tested. • The model allows the analysis of factors that impact the airtightness level. [ABSTRACT FROM AUTHOR]

This paper shows how exergy can be used to assess the mineral balance of a country and at the same time assess its mineral resource sustainability. The advantage of using such an approach is that the quality of the resources is taken into account, as opposed to the conventional procedure that uses tonnage as a yardstick. The exergoecology method evaluates mineral resources as the exergy required to replace them from a complete dispersed state to the conditions they were originally found with the best available technologies. The country chosen as a case study is Spain and serves as a representative example of the mineral situation in Europe. The general trend observed is that imports are increasing and domestic production is decreasing. The minerals with higher exergy replacement costs are mainly those imported, including fossil fuels and scarce minerals. In 2005, the domestic production of minerals was higher than the imports but since imports were mainly of scarce minerals, the exergy loss associated with such imports was higher compared to domestic production. As it happens to most European nations, Spain is a very dependent country regarding the supply of fossil fuels but not as much in the case of non-fuel minerals. [ABSTRACT FROM AUTHOR]

This study proposes a technical procedure based on a life cycle approach for implementation of the environmental sustainability assessment (ESA) of several waste-to-energy (WtE) plants located in Spain. This methodology uses two main variables: the natural resources sustainability (NRS) and the environmental burdens sustainability (EBS). NRS includes the consumption of energy, materials, and water, whereas EBS considers five burdens to air, five burdens to water, and two burdens to land. To reduce the complexity of ESA, all variables were normalised and weighted using the threshold values proposed in the European Pollutant Release and Transfer Register regulation. The results showed the plants studied had a greater consumption of natural resources than Spain, ranging from 1.1 to 2.0 times higher than the Spanish reference consumption. The comparison of Spain with the BREF reference on waste incineration showed that only in the variable related to materials, did Spain have a lower consumption (1.80 times lower). In terms of EBS, air and land impacts were the highest contributors to global burden. The WtE plants presented higher burdens to air and water than Spain, whereas only one plant exceeded the average burden to land of Spain. Finally, this paper demonstrated the usefulness of the ESA methodology to reduce the complexity of LCA and assist the decision-making process in choosing the best option from an environmental point of view. This procedure can be used to obtain an overview of the environmental performance of WtE plants, as well as to assess individual burdens and thereby determine the main environmental hotspots, thereby improving the critical points of the process. [ABSTRACT FROM AUTHOR]

Due to climate change, energy dependence and other energy-related issues, most developed countries are attempting to reduce fossil-fuel use in the transport sector. Accordingly, there are several instruments that have been in place for many years, such as mandatory design standards, taxes on fuels, car purchase and ownership, and energy efficiency labels. Yet it is still not clear whether consumers value energy efficiency as a characteristic of vehicles. In this paper we use the European labelling system for light vehicles, which classifies automobiles according to their relative fuel consumption levels, as a novel, alternative indicator for energy efficiency. Moreover, we use a unique database that incorporates official commercial prices along with prices obtained through ‘mystery shopping’ at a selection of Spanish car retailers. We apply the hedonic price method to this database to estimate the price functions for vehicles and thereby obtain the marginal price of vehicles rated highly in terms of energy efficiency. Our results show that vehicles labelled A and B are sold at prices 3 to 5.9 percent higher than those with similar characteristics but lower energy-efficiency labels. [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: The cut-off of any subsidy or feed-in tariff that incentives the installation of new renewable energy systems which are close to the grid parity, is a reality in most of the European countries, but in the recent years the grid parity has worsened because of the global economic crisis. In the case of Spain, in addition to the economic problems, the photovoltaic sector has been dramatically damaged through a changeable regulatory framework, an excessive bureaucracy and the inclusion of additional fees or possible back-up tolls that are very prejudicial for the deployment of this sector. Nowadays, the current Spanish legislation mentions the possibility of self-consumption (totally or partially) of the electricity generated by PV or any renewable energy systems but, up to the date of this work, the law that regulates the administrative, technical and economic conditions for the net-metering of the electrical energy produced within the consumer׳s network, is still under a draft stage. In this paper it is analyzed the case of the University of Jaen, where it has been identified and simulated several PV systems on the roofs and parking lots of the University Campus, and considering the current electrical tariffs (hourly defined for the case of high power and high voltage consumers), it has been done a cost and economic analysis. As a result, it has been obtained an average Levelised Cost of Energy around 0.125€kWh−1, a discount payback time of 17.5 years or less, a positive Net Present Value and a nominal Internal Rate of Return of 8.48% in the worst case. Beyond that, it has been carried out a sensitivity analysis of the factors that have more influence in the profitability of these systems, like the initial investment cost, the PV electricity yield, additional taxes and the variations in the electricity price market. [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]

Public Authorities are responsible for setting speed limits on roads. It is obvious that the modification of speed limits affect travel time. Also, there are many academic studies highlighting the relationship between vehicle speed and other particular isolated social costs, such as speed and accidents, speed and pollution or speed and fuel consumption. However, there are very few comprehensive studies on the subject of optimum speed limits. Furthermore, when Public Authorities modify speed limits usually they justify the measure to achieve a particular goal. The aim of this paper is to develop a comprehensive methodology that relies on cost-benefit analyses to determine the optimum speed limit for a particular road. The methodology is then applied to two recent case studies in Spain. In the first one, the Authorities decreased speed limits on national highways from 120 to 110 km per hour to save fuel. In the second case, the Authorities also reduced speed limits on the M − 30 ring road from 90 to 70 km per hour on specific days to reduce pollution. It seems that the Authorities might not always perform a technical analysis of these measures before implementing these policies. • Statutory speed limit changes by Public Authorities are usually justified by a particular goal, such as pollution or accident reduction. • Statutory speed limit changes affect other transportation costs, such as travel time. • It is possible to determine an optimum statutory speed limit that is comprehensive of all transportation costs. • In two case studies from Spain, statutory speed limit changes do not seem to be the result of a comprehensive technical analysis including the main transportation costs involved. [ABSTRACT FROM AUTHOR]

Abstract: The first objective of this paper is to map the adoption of technologies for the reduction of energy and resource consumption in production and the second is to test the relationship between the implementation of those technologies and the performance of manufacturing firms. The aim is to contribute to the identification of the characteristics of the manufacturing firms that use this kind of innovative technology in order to help policy makers promote energy and resource efficiency in a suitable manner. Our research is based on the Spanish and Slovenian subsamples of a wider European Manufacturing Survey. Our suggested models explain how significant energy efficiency is, and how much of the variability in economic performance and environmental performance it can explain. The results show that the use of energy and material saving technologies does not have a clear and significant relationship with economic performance. On the other hand a significant positive relationship is found between energy and material saving technologies and environmental performance. [Copyright &y& Elsevier]

Abstract: This paper analyses the water-energy nexus in irrigation districts (IDs) under the semi-arid conditions of south-eastern Spain. Three IDs supplied by different water sources and subjected to water scarcity over time were studied throughout a 10-year period (2002–2011). A set of performance indicators was selected to characterise water and energy relationships at three management levels: basin, irrigation district, and farm. Basin level was the largest energy consumer, representing 71–82% of the annual total consumption, which ranged from 0.95 to 1.55 kWh m−3. Basin energy consumption increased depending on the water source as follows: surface water, recycled water, groundwater, external water transfer, and desalinated brackish water. ID level involved 12–15% of the annual total consumption. The highest values were attained in periods of water scarcity, when the available sources were those with higher energy requirements. ID modernisation resulted in slight decreases in energy consumption at that level. At farm level, energy consumption was lacking when farmers took advantage of the pressure head in the ID distribution network, whereas it was from 0 to 0.19 kWh m−3 when the available pressure head was lost. Finally, water and energy productivities by the main crops were analysed. [Copyright &y& Elsevier]

Abstract: This paper presents a solar field configuration to supply thermal energy to the heating and air conditioning system of a hotel located in Almería (Southern Spain). The solar collector technology selected for the solar field is parabolic trough collector (PTC) technology, in particular a small sized PTC prototype especially designed for industrial process heat and air-conditioning systems. Each PTC collector is 8m long and its aperture length is 1m. The heat transfer fluid in the solar field is pressurized hot water. Considering the space available for the solar collector field just close to the hotel and its thermal energy demand profile, the solar field configuration proposed consists of 8 parallel rows, north-south oriented, composed of 32 PTCs connected in series. With this solar field configuration, 25% of the cooling demand is covered the hottest day of the summer and 76% of the heating demand is covered the coldest day of the winter. [Copyright &y& Elsevier]

Abstract: This paper presents a regression analysis of energy consumption in the banking sector. In our case study, the target area is the Spanish banking sector, for which we divide the available data into a prediction and a validation subset. Power models were developed using test data from 55 banks. From the analysis, three models were obtained; where the first proposed model can be used to predict the energy consumption of the whole banking sector, while the rest of the models estimate the energy consumption for branches with low winter climate severity (Model 2) and high winter climate severity (Model 3). Models 2 and 3 differ from the first model in that they need independent variables measured in situ. As a result, the uncertainty of the response variable in the function of the independent variables is reduced by 56.8% for the first model and by 65.2% and 68.5% for the second and third proposed models, respectively. The validation of the first model, which is the model with the lowest determination coefficient, shows that this model is appropriate for predicting the energy consumption of bank branches with good energy consumption performance and detecting inefficiencies in bank branches with poor energy consumption performance. [Copyright &y& Elsevier]

Abstract: Life Cycle Assessment (LCA) has been conducted for seven experimental cubicles located in Puigverd de Lleida (Spain). The objective of this experimental set-up is to test different constructive solutions in order to point out the most sustainable solution with lower energy demand during the operational phase. Therefore, different building, insulation and Phase Change Materials (PCMs) have been tested under controlled temperature conditions to examine the thermal performance of the whole system. Although some of these materials are able to reduce the energy demand and consequently the environmental impact during the operational phase, they still have high embodied energy that can cause high environmental impact during the manufacturing phase. Therefore the LCA study in this paper focuses on assessing the impact of the embodied energy needed during the manufacturing and disposal phase by highlighting and comparing the effect of using different building materials, insulating materials, and phase change materials. [Copyright &y& Elsevier]

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

Cool roofs are an inexpensive method to save energy and to improve the comfort level in buildings in mild and hot climates. A high scale implementation of cool roofs in Andalusia, in the south of Spain, could potentially save 295,000 kWh per year, considering only residential buildings with flat roofs using electrical heating. At the current energy prices, consumers can save 59 million euros annually in electricity costs and the emission of 136,000 metric tons of CO2 can be directly avoided every year from the production of that electricity. If radiative forcings are considered, Andalucía can potentially offset between 9.44 and 12 Mt of CO2. All the provinces in the rest of Spain are also studied in this paper. The biggest savings are achieved in Gran Canaria (48%), Tenerife (48%), Cádiz (36%), Murcia (33%), Huelva (30%), Málaga (29%), Almería (29%) and Sevilla (28%), where savings are greater than 2 euros per square meter of flat roof for old buildings with dark roofs. For the biggest cities the range of savings obtained are: between 7.4% and 11% in Madrid, between 12% and 18% in Barcelona and between 14% and 20% in Valencia. [Copyright &y& Elsevier]

Abstract: This paper deals with the potential of power generation resources for hydrogen production and electric grid load balancing in large scale management scenarios like the Spanish power system; much of which is currently underutilized and could deliver substantial amounts of energy, with great advantages for the reliability of the system at the same time. In this context, the production of hydrogen by electrolysis using the power grid mix is a promising option as an alternative to other operational procedures or exporting the electricity. Power generation can be controlled by the disposability of the installations and their utilization ratios; thus, we analyze the forms of generation to shape the power load curves, by using the regulation with hydrogen and getting a balance of efficiency, economy and ease of operations. To estimate hydrogen production we use the characteristic curves of electrolyzers, where the interest is that it applies to variable operations with time: i.e. the ‘surplus energy’ during over-generation periods is electrolyzed into hydrogen, which can be reconverted into electricity for ‘peak shaving’ or other uses. We establish a ‘critical ratio’, which determines the power generation for given demands, to fulfill the needs of the electric grid according to the curve profiles and the regulation with hydrogen; this ratio depends of many variables which are investigated for reaching an adequate balance: the energy gap of the generation and load curves, the capacity factor of the electrolyzers with regard to their maximum power inputs and the shape of daily generation curves. The resulting scenario is good enough for the transition of power system, as it admits 42% of energy from decarbonated sources, at the same time that shortens the payback period of fossil fuel utilities and generates hydrogen for other uses; economically, we obtain a positive cash-flow of the project after the third year, while the net incomes are 1863 M€ in the whole period; environmentally, it reduces the emissions from 236 to 210  per MWhe, while we can fuel three millions of hydrogen vehicles, with a net reduction of 4  and local air pollutants. After ordinary thermal installations are amortized, the management with hydrogen at large scales would permit the deployment of the power systems based in renewable sources, doing away with all CO2 emitting technologies which are substituted by wind, solar, hydro or nuclear. [Copyright &y& Elsevier]

Abstract: We present a novel transmission expansion planning model that explicitly considers a multi-year planning horizon. The proposed formulation is a mixed-integer linear problem that can be solved using commercially available software. The algorithm determines the best overall transmission expansion plan, reflecting both investment and operational costs. To analyze the results obtained from the model, we use a set of efficiency metrics to appraise the effect of the expansion among generators and demands, as well as congestion metrics to measure changes in nodal prices and line congestions. This paper also provides a case study that considers the expansion plan for a transmission system based on the one of mainland Spain. [Copyright &y& Elsevier]

Abstract: Energy consumption in Spanish school buildings is higher during spring seasons. Thermal inertia of buildings can help to reduce such consumption, improve comfort, and even replace HVAC systems. This thermal inertia is usually associated to heavy wall construction, but the truth is there are other parameters that can have a significant effect on this property. This paper describes a field case study of school buildings with different types of wall construction, aimed at demonstrating real thermal inertia effects on indoor conditions. Besides air temperature measurements, HAM tools were used to simulate indoor air conditions. Results showed a good agreement between simulated and experimental air temperature results, and that other building construction parameters, such as the use of permeable coverings, may have a large impact on indoor thermal conditions and energy consumption. [Copyright &y& Elsevier]

Abstract: The implementation of Directive 2001/77/EC on the promotion of electricity produced from renewable sources sets a target of 22.1% of electricity consumption in the EU in 2010, and establishes various mechanisms that member countries may adopt depending on their needs. This paper analyses these mechanisms, their implementation in Spain by means of RD 661/2007 and the degree of fulfilment of objectives. It concludes with an analysis of the effectiveness of the mechanisms adopted and recommendations on market design. [Copyright &y& Elsevier]