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Thermal energy storage (TES) plays a key role in concentrating solar power (CSP) plants by enhancing dispatchability and improving overall system efficiency. This study presents a comparative techno-economic analysis of three TES configurations integrated into CSP plants: (i) the conventional two-tank molten salt system, (ii) a phase change material (PCM)-based system with a cascade arrangement, and (iii) a concrete-based system. While technical performance simulations indicate similar annual energy production across all cases, significant differences emerge in economic viability. The PCM TES system demonstrates the lowest levelized cost of electricity (LCoE) at $14.35/kWh, leveraging its high energy density and reduced material requirements, despite lower efficiency (93 % compared to 99 % in molten salt). Conversely, the concrete TES system, while capable of extended discharge at partial loads, incurs higher parasitic losses and investment costs, resulting in a higher LCoE ($16.16/kWh). The cost analysis further highlights the cost-performance quotient (CPQ) as a valuable metric for assessing TES competitiveness, with PCM exhibiting the most favorable CPQ of $1.04/kWh. These findings underscore the necessity of integrating economic assessments into TES selection for CSP plants. Moreover, the study identifies opportunities for cost reduction in concrete TES through optimized modular designs and improved material formulations. This work provides valuable insights for policymakers, engineers, and industry stakeholders aiming to enhance the financial feasibility of next-generation CSP storage solutions. This study receives funding from the Ministerio de Ciencia e Innovación – Agencia Estatal de Investigación (MCIN/AEI/10.13039/501100011033) through the PCI2020-120695-2 project and the European Union “NextGenerationEU”/PRTR“. CSP-ERA.NET is supported by the European Commission within the EU Framework Programme for Research and Innovation Horizon 2020 (Cofund ERA-NET Action, N° 838311). This work was partially funded by the Ministerio de Ciencia e Innovación de España TED2021-132216A-I00 funded by MCIN/AEI/10.13039/501100011033 and the European Union by NextGenerationEU/PRTR. This work was partially funded by the Ministerio de Ciencia e Innovación – Agencia Estatal de Investigación (AEI) (PID2021-123511OB-C31 – MCIN/AEI/10.13039/501100011033/FEDER, UE) and (RED2022-134219-T). This work is partially supported by ICREA under the ICREA Academia programme. The authors from University of Lleida would like to thank the Departament de Recerca i Universitats of the Catalan Government for the quality accreditation given to their research group (2021 SGR 01615). GREiA is certified agent TECNIO in the category of technology developers from the Government of Catalonia.

The aim of this study was to examine whether impaired balance control is partly responsible for the increased energy cost of walking in persons with a lower limb amputation (LLA). Previous studies used external lateral stabilization to evaluate the energy cost for balance control; this caused a decrease in energy cost, with concomitant decreases in mean and variability of step width. Using a similar set-up, we expected larger decreases for LLA than able-bodied controls. Fifteen transtibial amputees (TT), 12 transfemoral amputees (TF), and 15 able-bodied controls (CO) walked with and without external lateral stabilization provided via spring like cords attached to the waist. Effects of this manipulation on energy cost, step parameters, and pelvic motion were evaluated between groups. TT (-5%) and CO (-3%) showed on average a small reduction in energy cost when walking with stabilization, whereas TF exhibited an increase in energy cost (+6.5%) The difference in the effect of stabilization was only significant between TT and TF. Step width, step width variability, and medio-lateral pelvic displacement decreased significantly with stabilization in all groups, especially in TT. Contrary to expectations, external lateral stabilization did not result in a larger decrease in the energy cost of walking for LLA compared to able-bodied controls, suggesting that balance control is not a major factor in the increased cost of walking in LLA. Alternatively, the increased energy cost with stabilization for TF suggests that restraining (medio-lateral) pelvic motion impeded necessary movement adaptations in LLA, and thus negated the postulated beneficial effects of stabilization on the energy cost of walking.

The modelling of a compressed air energy storage system (CAES), suitable for real-time simulation in the electromagnetic transients (EMT), RSCAD/RTDS simulation environment, is considered in this paper. The combined use of an averaged value model representation of the interfacing converter and reduced order representation of the motor/generator pair is employed to reduce model complexity and increase the useable time-step. Numerical simulations are used to assess the numerical properties of the developed model.

Research on why firms should outsource and how they should do it has proliferated in the past two decades, but few consistent findings have emerged concerning the benefits of outsourcing. We argue that this is in part due to the lack of an adequate framework for measuring the effects of outsourcing. To address this, we present such a framework based upon the Cobb–Douglas productivity function. We explain how our framework can be used to unpack one component of the Cobb–Douglas productivity function, the ‘total factor productivity’, which represents the other numerous sub-variables that affect outsourcing productivity, beyond the capital and labour expenditures. We also demonstrate the framework using a simple illustrative example.

Abstract In the European Union F-gas Regulation limited the use of some refrigerants in several applications. Regarding the domestic refrigeration sector, the F-gas Regulation banned the use of refrigerants with GWP values higher than 150. This fact led the scientific community to search for a replacement of R-134a, that is the most common refrigerant used in domestic refrigerators in USA. In this work, a comprehensive environmental analysis of the drop-in substitution of R-134 with a low GWP refrigerant (R-152a) in a no-frost domestic refrigerator was performed. The comparison, based on experimental data, between the environmental performance of the refrigeration system with the two refrigerants was carried out developing two different evaluation methods, which led to the evaluation of TEWI and LCCP, respectively. Both these metrics consider both direct and indirect contributions to global warming. Historical data of different countries were used to forecast the carbon intensity values for the next 15 years, which were then used to evaluate indirect emissions of the system during its lifetime. Considering the Italian case study, the results showed that the refrigerator working with an optimal charge of R-152a, identified as the mass charge that minimises TEWI and/or LCCP index, has better environmental performance than the system working with R-134a, with a reduction of TEWI and LCCP values of 10.3% and 9.4%, respectively. The same comparison, in terms of LCCP, was also performed for other European countries, showing a strong dependence of the LCCP index on carbon intensity values.

Sustainability and Internationalization are key factors within educational programmes and institutions nowadays. Offering programmes which focus on these factors at undergraduate level has been a priority at the School of Engineering of Vilanova i la Geltrú (EPSEVG) since the introduction of the European Project Semester (EPS) in 2008. In line with its policy to increase Internationalization and Sustainability in its programmes, the School of Engineering of Vilanova i la Geltrú (EPSEVG) has designed and coordinated a new Erasmus mobility programme, the International Design Project Semester (IDPS), which started in February 2012. IDPS trains engineering students by applying Project Based Learning in intercultural groups. The working language is English and the programme is designed for degree students in their 7th or 8th semester. The IDPS programme offered at the EPSEVG emphasises the introduction of competences in sustainability and human technology. The main objective of the IDPS is to improve the learning outcomes and competences of industrial design engineering students especially in areas of sustainability. It is divided into two parts. One part covers four three (ECTS) credit core courses in specialist fields of study such as Eco Design , Human Centred Design , Sustainable Value Design and Visual Language and Grammar and the second part involves working on a project (worth 18 ECTS. Additional seminars and workshops compliment the courses and vary from programme to programme. The projects are proposed by local companies and research groups. This paper shows the design methodology used in the IDPS programme its structure and the sustainability competences to be achieved by the students. Peer Reviewed

Artículos en revistas This work proposes a dynamic model to devise the optimal risk-averse investment policy in a portfolio of complementary renewable sources for a generation company in the Brazilian power system. The proposed method merges a static energy-contracting model, based on a hybrid robustand- stochastic optimization approach, with a mean reverting binomial lattice model for real-option valuation. The proposed merge extends previous works by providing support to riskaverse investment decisions in complementary renewable sources dynamically distributed over time. The most important results of the model are: how much capacity to invest or build from each renewable source, how much to sell from the energy portfolio in bilateral contracts, and the optimal timing to invest. Unlike previous reported works, our model takes into account three classes of uncertainties simultaneously: renewable production of candidate sources and prices in the spot and contract markets. A case study with realistic data from the Brazilian power system is presented to illustrate the value of our model. info:eu-repo/semantics/publishedVersion

Many coastal sand dune systems in the UK and other parts of the world have experienced a decline in bare sand extent and dune mobility over the past 70 years, accompanied by increased coverage of coarse grass, scrub and woodland vegetation. This has raised concerns amongst nature conservationists about the survival of dune specialist species. Opinions are divided, however, regarding what management interventions should be made to counteract these trends. This paper reviews the factors which have contributed to progressive dune system stabilization at Sandscale Haws, located on the Irish Sea coast in Northwest England, considers the implications for the site of UKCP18 future climate change projections, and discusses the options and plans for future adaptive management. Analaysis of aerial photographs indicated a large reduction in bare sand area between 1946 and 1988 (from >34% to 9% of the dune system), since when there has been a further decline to 1.7%. Consideration of the evidence suggests that a trend towards a warmer, slightly wetter and less windy climate has been the main driver of stabilization, although atmospheric nitrogen deposition, increasing atmospheric CO2 concentrations, reduced grazing intensity, reduced human disturbance from the mid-1980s onwards and a tendency for shoreline progradation on the west-facing coast have played contributing roles. Some species characteristic of open habitats can still be found in good numbers in parts of the dune system, but without increased management it is likely they will decline further and some may become locally extinct. Since the site is of national and international importance for a number of nationally scarce plant and animal species it is considered that there is both a legal and an ethical duty to attempt to maintain suitable habitat for their survival. As a National Nature Reserve Sandscale Haws provides a suitable ‘natural laboratory’ within which to research the effectiveness of different intervention methods. A number of small-scale dune rejuvenation methods have been trialled since 2015, and options for larger scale interventions, including turf stripping and possible dune notching, are currently being evaluated as part of the nation-wide Dynamic Dunescapes project.

The equilibrium data of the quaternary system water-ethanol-acetone-sodium chloride at 25 °C have been determined. All equilibrium regions have been systematically studied. Tie-line and tie-triangle data for this system have been correlated using a modification of the Eisen-Joffe equation.