Search

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: 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: 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]

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]

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