• Energy Research

The energy flows of the double skin, glass-glass façades have been analysed, establishing a mathematical model to determine the energy savings provided by this construction solution in 10 cities in Spain. It has been found that the two climatological variables that most influence energy savings are outdoor temperature, as it is directly related to the demand for heating, and solar irradiation, as it is the source of energy from which savings are extracted. Energy savings in winter vary between 11.1% and 20.5%, depending on the weather. A linear relationship between the annual average outdoor temperature and the useful energy provided by the double- skin façade has been determined. It was verified that the maximum energy saving occurs when the façade is offset a few degrees to the east from the pure south orientation. It deviates further east, the higher the annual average temperature. A linear relationship has been established between the outside temperature and the azimuth of the façade with which the maximum energy saving occurs. To obtain savings percentages greater than 20%, the ratio between the double-skin façade surface and the total heated surface of the building must be less than 7.

The current EU 2020 reference framework has set a 20% goal for energy coming from non-exhaustive resources. In general, it can be said that the national action plans for renewable energy sources and the biennial control provided in Directive 2009/28/EC, regarding the promotion of the use of energy from renewable sources, have been adequate in encouraging clarity for venture capitalists and other stakeholders and, thus, have favored a rapid development of renewable energy from 10.4% in 2007 to 17% in 2015. Between 2005 and 2013, the Spanish government implemented a renewable aid plan that induced an important boost in the number of wind energy projects facilitated by companies. This scheme was modified in 2013, resulting in a drastic decrease in the investments on wind energy capacity. The reason that this regime was modified not only because of the worldwide economic downturn since 2010 but also owing to the shortcomings of this scheme. The expected venture capitalist behavior with respect to the current energy regime is still uncertain. Given the limited support provided by the Spanish government, any remarkable development seems unlikely. This research suggests that a sudden change in the decreased investments on wind energy capacity is unlikely and the wind energy targets for 2020 will not be achieved if no new policies are implemented. 3,632 12,11 Q1 Q1 SCIE

Abstract Energy needs increases day by day in those areas of the world where the electrical distribution lines are not available. This situation limits the industrial and economic development of these areas as well as the establishment of the population, so that it facilitates the exodus and the uprooting of people. At the moment the electrical energy supply in remote areas is based on solutions with generator sets, consuming great amounts of fuel with a great environmental damage. The technological development of renewable energies and the new concepts for their management, make possible proposing off-grid generation solutions for providing great amount of energy with high quality and reliability. Along this paper, a smart-grid configuration is proposed which is developed with products of proved reliability and which uses renewable energies as main generation source. This configuration allows having “standard” grid services anywhere, without the need of connection to the traditional grid. Environmental, economic and operation benefits of using these technologies against traditional solutions are also presented in this paper. This proposed solution allows the economical development and exploitation of areas where due to the lack of energy or to the energy cost it has not been possible until now.

Buildings are one of the most important energy consumers in modern economy countries. The massive use of electrical vehicles could help decarbonizing the economy by using electricity produced using renewable energy. Combined use of Vehicle to Grid (V2G), Vehicle to Home (V2H) and Vehicle to Building (V2B) is one of the strategies to increase the number of electrical vehicles, ensure a better coupling between energy generation and consumption, reducing peak demand and increasing global energy efficiency. This research presents a novel approach of combined use of V2H and V2B that can be applied in different scenarios such as when the building workers own EVs, company shared car fleets or leasing, among others. Recharged energy at workers homes during night hours is delivered in the building during daily working hours lowering peak demand, reducing carbon intensity and energy cost savings. The results show that the methodology is feasible and can be extended to other cases and greatly contribute to better energy efficiency, reduces peak demand in buildings and increase electric vehicles penetration in transport to workplaces.

The penetration of electric vehicles is a key instrument in the operation of smart grids. Their active participation in the electrical system is proposed as a tool to increase security of supply, successfully reducing the large differences that occur between periods of higher and lower electricity demand. This research presents an analysis of the vehicle-to-grid impact in low capacity electrical systems, as in the case of islands, aiming to establish a charge/discharge pattern that facilitates the penetration of electric vehicles in weak grids. In such a way, a comprehensive scenario needs to be assessed in order to obtain significant results to be applied not only in islands and outermost regions but also in scaled systems such as minigrids. To achieve this objective, a theoretical method for the efficient charge/discharge management of electric vehicles is proposed, defined by a multi-objective model based on criteria of mobility and technical requirements. The proposed model is applied to the island of Tenerife, which quantifies the electric vehicle penetration in a real case. The results show that grids in islands can assimilate “low” or “transition” penetrations of electric vehicles, so their use as storage systems allow to significantly reduce the amplitude difference between valleys and peaks of the electric energy demand curve and thereby to contribute to the efficient management of smart grids.

Energy policy is becoming a key aspect of the everyday worldwide agenda, and the decisions in this field are directly affecting many aspects, such as energy security, energy supply, and consumer final prices, as well as environmental aspects, among others, and will also affect conditions in the coming years with regard to aspects such as energy resource availability decay, climate change effects, or air contamination. During the last decades, many specific efforts in energy planning research have been carried out by different scientists around the world, but very few of their scientifically based conclusions and recommendations have been transferred into energy planning and energy policy. As a consequence, the energy availability and the environmental situation of the world are worsening; the objectives which aim to achieve a maximum of a 1.5 °C increase are far from being achieved, and many different regions are suffering energy supply disruptions and lack of accessible and secure energy access. This paper analyzes how current energy policy is based more on the direct influence of stakeholders, energy politics, and citizens’ beliefs or preferences than on a scientific approach. It also proposes a different approach that would combine scientific energy planning as a driver for stakeholders and the political decisions which are necessary to consider as soon as possible; this is the only possible way to ensure a sustainable future.

This paper presents the application of a business case model for the implementation decisions to be done by utility companies. The goal is to modernize the grid and their business, leveraging the potential of the smart grid (SG) for the benefit of the company and the customers (economically and socially), as well as the environment. The company selected for this research is a spanish distribution and retail utility Empresa de Alumbrado Electrico de Ceuta (EAECSA). Being an isolated power system with limited extension, it proves useful as an example for larger systems and to test the proposed model. From the characteristics of the grid and the regulatory and strategy mandates, the best alternatives are calculated using a model based on the relation between each of the SG functions parameters and a prioritization factor, detailed in the paper. The assessment of actually available technologies and functions is first presented with a strategic and business approach, as a way of filtering appropriate technologies for implementation. The second step is to assess the case for each technology and function, in order to select the most impactful solutions in cost to benefit ratio. The resulting roadmap is a guide for technology implementation in the best economic, environmental and social way, proving the model a useful tool for an integrated approach to the introduction of SG technologies.

Abstract The present research explains and analyses a technically feasible and economically profitable alternative for concentrated solar power plants recently constructed in Spain. The proposed solution is hybridization with biogas. The method is more economical than investment in salt storage systems, used to improve operation time and a better electrical production control. This alternative proposes new income alternatives for plants by using residual heat in flue gases from boilers and in the cooling circuit in the power block, thereby achieving an effective reduction in the final cost of electric power generation. Current commercial technologies used in the bio-digestion process of organic waste are studied and practical cases that can be best integrated are analyzed. Presented case studies are presented for solar power plants without storage analyzing waste availability for biogas production. Areas with the greatest potential for the implementation of the proposed alternative and improvements aimed at increasing the overall performance of future hybrid plants are also determined, and an economic evaluation of the proposed solution versus salt storage is conducted. To improve research results a sensitivity analysis to evaluate the feasibility in different economic scenarios is performed. Results show that the proposed method of hybridization through the use of biogas provides an alternative solution for an important part of renewable generation power plants with a limited ability for dispatchability. In terms of environmental issues the solution places a value on certain types of waste that today, in addition to not being utilized properly, pose a serious problem for society.