Using vanadium redox flow batteries for the electricity storage towards the electric vehicles fast charging process

This work was later revised, extended and published as a full journal paper in ENERGY. Please use the journal version for citation purposes: Álvaro Cunha, Jorge Martins, Nuno Rodrigues, Vítor Monteiro, João L. Afonso, Paula Ferreira, F. P. Brito, Assessment of the use of Vanadium Redox Flow Batteries for Energy Storage and Fast Charging of Electric Vehicles in Gas Stations, Energy, 115-2, (2016), 1478–1494, DOI:10.1016/j.energy.2016.02.118. journal article available at: http://www.sciencedirect.com/science/article/pii/S0360544216301803The multitude and magnitude of the problems deriving from the use of fossil fuels for road transport is widely known. Therefore, electric mobility associated with renewable energy sources seems to be a good solution for minimizing these problems. However, the time required to charge the batteries of Electric Vehicles (EVs) and the availability of charging stations are seen as critical factors for their market viability. The use of fast charging stations is a possibility to mitigate the long time required to charge the batteries, but the high cost for power availability makes their operation very expensive. Moreover, it might be difficult to find suitable and affordable locations for installing these stations, so gas stations seem to be good candidates for this purpose. This paper assesses the use of fast charging stations for EVs in conjunction with Vanadium Redox Flow Batteries (VRFBs). Taking into account the low energy density of VRFBs, they are especially suited for situations where volume and weight are not limiting factors. Moreover, their liquid nature allows their installation inside deactivated underground fuel tanks located at gas stations. A preliminary assessment of a VRFB system for EVs fast charging stations taking advantage of existing gas stations infrastructures is presented. An energy and cost analysis of this concept is outlined, including a sensitivity analysis which shows that the project is technologically and economically viable for the conditions tested, although with long payback times.MOBI-MPP (MIT-Pt/EDAM-SMS/0030/2008) supported by the MIT Portugal Program and FEDER funds through the Programa Operacional Factores de Competitividade e COMPETE and National Funds through FCT e Foundation for Science and Technology. Post-doctoral grants SFRH/BPD/ 51048/2010 and SFRH/BPD/89553/2012 supported by the MIT Portugal EDAM and FCT, respectivelyinfo:eu-repo/semantics/publishedVersio

PATs Behavior in Pressurized Irrigation Hydrants towards Sustainability

[EN] Sustainability and efficiency in irrigation are essential in the management of the water- energy-food nexus to reach the Sustainable Development Goals in 2030. In irrigation systems, the reduction of energy consumption is required to improve the system efficiency and consequently the sustainability indicators of the water network. The use of pumps working as turbines (PATs) has been a feasible solution to recover the excess of energy where pressure reduction valves are installed. This research demonstrates the use of PATs under steady and unsteady conditions by analyzing the application in a real irrigation networks located in Vallada (Valencia, Spain). The study shows the possibility of recovering 44 MWh/year using PATs installed upstream of the irrigation hydrants. The real behavior of the PAT operation in a stand¿alone recovery energy solution allowed analysis of the flow, head and efficiency variation as a function of the rotational speed, as well as the minimum capacitance to self-excite the generator and the resistive load of the electrical circuit. The PAT limit is examined in terms of the overpressure induced by a fast closure manoeuvre of hydrants, and the runaway conditions due to the disconnection from the electrical load.This work was supported by FCT-Foundation for Science and Technology, through CERIS, IP, and IDMEC, under LAETA, project UIDB/50022/2020. This research is also supported by the Program to support the academic career of the faculty of the Universitat Politècnica de València 2019/2020 in the project A STEP AHEAD IN SUSTAINABILITY OF WATER SYSTEMS FOR THE ENERGY TRANSITION IN COMMUNITIES of the Modesto Pérez- Sánchez. The authors wish to thank the project REDAWN (Reducing Energy Dependency in Atlantic Area Water Networks) EAPA_198/2016 from INTERREG ATLANTIC AREA Fluids PROGRAMME 2014-2020 and CERIS, the Hydraulic Laboratory, for the support in the conceptual developments and the experiments on PATs.Pérez-Sánchez, M.; Fernandes, JF.; Costa Branco, P.; López Jiménez, PA.; Ramos, HM. (2021). PATs Behavior in Pressurized Irrigation Hydrants towards Sustainability. Water. 13(10):1-17. https://doi.org/10.3390/w13101359S117131

Optimal energy efficiency of isolated PAT systems by SEIG excitation tuning

[EN] The use of pump working as turbine (PAT) was identified by many researchers as a way to improve the energy efficiency in the water systems. However, the majority of the researches consider the hydraulic machine connected to the electrical grid, which may not fit best when these recovery systems are located in rural or remote areas. To improve the efficiency in these recovery systems for rural areas, this research contributes for a further study and optimization of the off-grid PAT systems with induction generators. The current manuscript proposes a methodology to obtain the best efficiency of the PAT-SEIG (Self-Excited Induction Generator) system when operating under different speeds and loads. For these systems, the selection of capacitors for the SEIG is critical to maximizing the energy efficiency. A methodology is proposed to estimate and select the correct SEIG model parameters and, thus, compute the best capacitor values to improve the PAT-SEIG energy efficiency. Special attention is given to the impact the SEIG parameters have in the efficiency of the recovery system. The accuracy of the analytical model improved, reducing the error between analytical and experimental results from 50.8% (for a model with constant parameters) to 13.2% (with parameters changing according to the operating point of the system). These results showed an increase of the overall PAT system efficiency from 26% to 40% for the analyzed case study.This work was supported by FCT, through IDMEC, under LAETA, project UID/EMS/50022/2019 and the project REDAWN (Reducing Energy Dependency in Atlantic Area Water Networks) EAPA_198/2016 from INTERREG ATLANTIC AREA PROGRAMME 2014-2020 and CERIS (CEHIDRO-IST), the Hydraulic Laboratory, for experiments on PATs.Fernandes, JF.; Pérez-Sánchez, M.; Ferreira, F.; López Jiménez, PA.; Ramos, HM.; Costa Branco, P. (2019). Optimal energy efficiency of isolated PAT systems by SEIG excitation tuning. Energy Conversion and Management. 183:391-405. https://doi.org/10.1016/j.enconman.2019.01.016S39140518

Branch and bound based coordinate search filter algorithm for nonsmooth nonconvex mixed-integer nonlinear programming problems

Publicado em "Computational science and its applications – ICCSA 2014...", ISBN 978-3-319-09128-0. Series "Lecture notes in computer science", ISSN 0302-9743, vol. 8580.A mixed-integer nonlinear programming problem (MINLP) is a problem with continuous and integer variables and at least, one nonlinear function. This kind of problem appears in a wide range of real applications and is very difficult to solve. The difficulties are due to the nonlinearities of the functions in the problem and the integrality restrictions on some variables. When they are nonconvex then they are the most difficult to solve above all. We present a methodology to solve nonsmooth nonconvex MINLP problems based on a branch and bound paradigm and a stochastic strategy. To solve the relaxed subproblems at each node of the branch and bound tree search, an algorithm based on a multistart strategy with a coordinate search filter methodology is implemented. The produced numerical results show the robustness of the proposed methodology.This work has been supported by FCT (Fundação para a Ciência e aTecnologia) in the scope of the projects: PEst-OE/MAT/UI0013/2014 and PEst-OE/EEI/UI0319/2014

Energy Transition in Urban Water Infrastructures towards Sustainable Cities

[EN] The world's water infrastructures suffer from inefficiencies, such as high energy consumption and water losses due to inadequate management practices and feeble pressure regulation, leading to frequent water and energy losses. This strains vital water and energy resources, especially in the face of the worsening challenges of climate change and population growth. A novel method is presented that integrates micro-hydropower plants, with pumps as turbines (PATs), in the water network in the city of Funchal. Sensitivity analyses evaluated the microgrid's response to variations in the cost of energy components, showing favorable outcomes with positive net present value (NPV). PV solar and micro-wind turbines installed exclusively at the selected PRV sites within the Funchal hydro grid generate a combined 153 and 55 MWh/year, respectively, supplementing the 406 MWh/year generated by PATs. It should be noted that PATs consistently have the lowest cost of electricity (LCOE), confirming their economic viability and efficiency across different scenarios, even after accounting for reductions in alternative energy sources and grid infrastructure costs.This research was supported by Foundation for Science and Technology of Portugal, grant number UIDB/04625/2020; HY4RES-Hybrid solutions for Renewable Energy Systems: achieving net-zero Atlantic area energy consumers & communities, Interreg project EAPA_0001/2022; and Spanish State Research Plan Scientific and Technical and Innovation 2017-2020 PID2020-114781RAI00.Ramos, HM.; Pérez-Sánchez, M.; Mullur Gurupr, PS.; Carraveta, A.; Kuriqui, A.; Coronado-Hernández, OE.; Fernandes, JF.... (2024). Energy Transition in Urban Water Infrastructures towards Sustainable Cities. Water. 16(3). https://doi.org/10.3390/w1603050416

Different methods of cell quantification can lead to different results : a comparison of digital methods using a pilot study of dendritic cells in HIV-positive patients

Although new digital pathology tools have improved the positive cell quantification, there is a heterogeneity of the quantification methods in the literature. The aim of this study was to evaluate and propose a novel dendritic cells quantification method in squamous cell carcinoma comparing it with a conventional quantification method. Twenty-six squamous cell carcinomas HIV-positive cases affecting the oropharynx, lips and oral cavity were selected. Immunohistochemistry for CD1a, CD83, and CD207 was performed. The immunohistochemical stains were evaluated by automated examination using a positive pixel count algorithm. A conventional quantification method (unspecific area method; UA) and a novel method (specific area method; SA) were performed obtaining the corresponding density of positive dendritic cells for the intratumoral and peritumoral regions. The Mann-Whitney U test was used to verify the influence of the quantification methods on the positive cell counting according to the evaluated regions. Data were subjected to the ANOVA and Student?s t-test to verify the influence of the tumour location, stage, histological grade, and amount of inflammation on the dendritic cells density counting. The cell quantification method affected the dendritic cells counting independently of the evaluated region (P-value <0.05). Significant differences between methods were also observed according to the tumour features evaluations. The positive cell quantification method influences the dendritic cells density results. Unlike the conventional method (UA method), the novel SA method avoids non-target areas included in the hotspots improving the reliability and reproducibility of the density cell quantification

New Limonoids from Dictyoloma vandellianum and Sohnreyia excelsa: Chemosystematic considerations

Molecular phylogenetic studies separated and united a group of genera that constituted the Spathelia-Ptaeroxylon clade, in which Dictyoloma and Sohnreyia have been included. Our taxonomic interest in the Dictyoloma vandellianum and Sohnreyia excelsa stimulated an investigation of both species searching for limonoids. Leaves from D. vandellianum afforded the new limonoid 1,2-dihydro-1α-hydroxy-8,30-epoxy-cneorin R, and heartwood yielded the new rearranged limonoid dictyolomin. Leaves from S. excelsa afforded the new protolimonoid 3β-angeloyloxy-7α,24,25-trihydroxy-21,23-oxide-14,18-cycloapotirucall-21-methoxycetal and the new cycloheptanyl ring C limonoid with carbonate substituent and named as sohnreyolide. The new limonoids from Sohnreyia and Dictyoloma show similarities with those from Rutaceae and Meliaceae, providing support for moving Spathelia-Ptaeroxylon clade near to these associated large families. ©2019 Sociedade Brasileira de Química

Evaluation of turbulent dissipation rate retrievals from Doppler Cloud Radar

Turbulent dissipation rate retrievals from cloud radar Doppler velocity measurements are evaluated using independent, in situ observations in Arctic stratocumulus clouds. In situ validation data sets of dissipation rate are derived using sonic anemometer measurements from a tethered balloon and high frequency pressure variation observations from a research aircraft, both flown in proximity to stationary, ground-based radars. Modest biases are found among the data sets in particularly low- or high-turbulence regimes, but in general the radar-retrieved values correspond well with the in situ measurements. Root mean square differences are typically a factor of 4-6 relative to any given magnitude of dissipation rate. These differences are no larger than those found when comparing dissipation rates computed from tetheredballoon and meteorological tower-mounted sonic anemometer measurements made at spatial distances of a few hundred meters. Temporal lag analyses suggest that approximately half of the observed differences are due to spatial sampling considerations, such that the anticipated radar-based retrieval uncertainty is on the order of a factor of 2-3. Moreover, radar retrievals are clearly able to capture the vertical dissipation rate structure observed by the in situ sensors, while offering substantially more information on the time variability of turbulence profiles. Together these evaluations indicate that radar-based retrievals can, at a minimum, be used to determine the vertical structure of turbulence in Arctic stratocumulus clouds

Low-diffusion Xe-He gas mixtures for rare-event detection: electroluminescence yield

High pressure xenon Time Projection Chambers (TPC) based on secondary scintillation (electroluminescence) signal amplification are being proposed for rare event detection such as directional dark matter, double electron capture and double beta decay detection. The discrimination of the rare event through the topological signature of primary ionisation trails is a major asset for this type of TPC when compared to single liquid or double-phase TPCs, limited mainly by the high electron diffusion in pure xenon. Helium admixtures with xenon can be an attractive solution to reduce the electron diffu- sion significantly, improving the discrimination efficiency of these optical TPCs. We have measured the electroluminescence (EL) yield of Xe–He mixtures, in the range of 0 to 30% He and demonstrated the small impact on the EL yield of the addition of helium to pure xenon. For a typical reduced electric field of 2.5 kV/cm/bar in the EL region, the EL yield is lowered by ∼ 2%, 3%, 6% and 10% for 10%, 15%, 20% and 30% of helium concentration, respectively. This decrease is less than what has been obtained from the most recent simulation framework in the literature. The impact of the addition of helium on EL statistical fluctuations is negligible, within the experimental uncertainties. The present results are an important benchmark for the simulation tools to be applied to future optical TPCs based on Xe-He mixtures. [Figure not available: see fulltext.]

Energy calibration of the NEXT-White detector with 1% resolution near Q ββ of 136Xe

Excellent energy resolution is one of the primary advantages of electroluminescent high-pressure xenon TPCs. These detectors are promising tools in searching for rare physics events, such as neutrinoless double-beta decay (ββ0ν), which require precise energy measurements. Using the NEXT-White detector, developed by the NEXT (Neutrino Experiment with a Xenon TPC) collaboration, we show for the first time that an energy resolution of 1% FWHM can be achieved at 2.6 MeV, establishing the present technology as the one with the best energy resolution of all xenon detectors for ββ0ν searches. [Figure not available: see fulltext.