Recharge Time Research Articles

Simulation of irrigation-induced groundwater recharge in an arid area of China

Accurate estimation of irrigation return flow plays an important role in the effective management of groundwater, especially in arid and semiarid irrigation regions. However, there is a lack of sufficient research to clarify hydrological process dynamics associated with irrigation return flow. In this study, first, a two-dimensional/three-dimensional model, HYDRUS-2D/3D, was adopted to analyze two different irrigation types in the Delingha Depression, which is located at the northeastern margin of the Qaidam Basin, China. Then, a 3D saturated flow model was established. This study determined the effect of agricultural water application on the dynamics of irrigation return flow. A large difference in the irrigation return-flow coefficient (IRFC) was seen during the growing season; an IRFC of 0.3 was obtained using flood irrigation, whereas ditch irrigation resulted in an IRFC of only 0.1. The lag time of recharge was approximately 150 days. It was necessary to consider the lag time for the 3D numerical model to obtain satisfactory results. Flood irrigation led to a groundwater recharge rate of 90 mm/year. These results indicate that the lag time should be considered when groundwater recharge is estimated or modeled.

Design Considerations for Fast Charging Lithium Ion Cells for NMC/MCMB Electrode Pairs

Lithium ion cells that can be quickly charged are of critical importance for the continued and accelerated penetration of electric vehicles (EV) into the consumer market. Considering this, the U.S. Department of Energy (DOE) has set a cell recharge time goal of 10–15 min. The following study provides an investigation into the effect of cell design, specifically negative to positive matching ratio (1.2:1 vs. 1.7:1) on fast charging performance. By using specific charging procedures based on negative electrode performance, as opposed to the industrial standard constant current constant voltage procedures, we show that the cells with a higher N:P ratio can be charged to ~16% higher capacity in the ten-minute time frame. Cells with a higher N:P ratio also show similar cycle life performance to those with a conventional N:P ratio, despite the fact that these cells experience a much higher irreversible capacity loss, leading to a lower reversible specific capacity.

Optimization of recharged water quantity of Yufuhe River in Jinan City based on Hydrus-2D Software, China

Jinan, Shandong Province, China frequently faces challenges related to spring protection and water supply security, and managed aquifer recharge (MAR) presents an effective solution to these challenges. Three MAR projects with multiple sources in Yufuhe River in Western Jinan City are conductive to increasing groundwater supply and maintaining groundwater levels. In order to determine the reasonable recharge flows and time, the hydrogeological conditions of the study area were described, the river infiltration recharge processes were simulated by Hydrus-2D software, and the recharge schemes for different groundwater depths were put forward. The results show that the model can achieve the better fitting effect. When the releasing flow is small, the optimal scheme is to continuously discharge water by 286800, 282500 and 282000 m3/d for 19.5, 12.7 and 10.5 days when the groundwater depth is 42, 30, 23 m at Cuima Village respectively. This study has certain significance for the efficient water lease of the Yufuhe River recharge project in Jinan City.

Design and testing of a supercapacitor storage system for the flash recharge of electric buses

This paper proposes a hybrid storage for urban transport systems in order to reduce recharge time and increase its life and reliability. Proposed system is applied to a pre-existing electric vehicle, introducing through proposed revamping procedure a methodology for a fast integration of proposed systems on different vehicles. Finally, the system is calibrated and tested showing how the proposed control layout really simplifies the vehicle commissioning.

Design and testing of a supercapacitor storage system for the flash recharge of electric buses

This paper proposes a hybrid storage for urban transport systems in order to reduce recharge time and increase its life and reliability. Proposed system is applied to a pre-existing electric vehicle, introducing through proposed revamping procedure a methodology for a fast integration of proposed systems on different vehicles. Finally, the system is calibrated and tested showing how the proposed control layout really simplifies the vehicle commissioning.

Enabling Extreme Fast Charging Technology for Electric Vehicles

As a significant part of the next-generation smart grid, electric vehicles (EVs) are essential for most countries to achieve energy independence, secure energy supply, and alleviate the pressure on environmental protection and energy security. Although EVs have grown rapidly, the slow recharge time is still the biggest obstacle to a wider application. While gasoline vehicles can pump enough gasoline in less than ten minutes, which can carry themselves a few hundred miles. However, most of today’s fast-charging techniques take half an hour only to provide very limited miles of electric driving range.

Groundwater Recharge Estimated by Land Surface Models: An Evaluation in the Conterminous United States

AbstractEstimating diffuse recharge of precipitation is fundamental to assessing groundwater sustainability. Diffuse recharge is also the process through which climate and climate change directly affect groundwater. In this study, we evaluated diffuse recharge over the conterminous United States simulated by a suite of land surface models (LSMs) that were forced using a common set of meteorological input data. Simulated annual recharge exhibited spatial patterns that were similar among the LSMs, with the highest values in the eastern United States and Pacific Northwest. However, the magnitudes of annual recharge varied significantly among the models and were associated with differences in simulated ET, runoff, and snow. Evaluation against two independent datasets did not answer the question of whether the ensemble mean performs the best, due to inconsistency between those datasets. The amplitude and timing of seasonal maximum recharge differed among the models, influenced strongly by model physics governing deep soil moisture drainage rates and, in cold regions, snowmelt. Evaluation using in situ soil moisture observations suggested that true recharge peaks 1–3 months later than simulated recharge, indicating systematic biases in simulating deep soil moisture. However, recharge from lateral flows and through preferential flows cannot be inferred from soil moisture data, and the seasonal cycle of simulated groundwater storage actually compared well with in situ groundwater observations. Long-term trends in recharge were not consistently correlated with either precipitation trends or temperature trends. This study highlights the need to employ dynamic flow models in LSMs, among other improvements, to enable more accurate simulation of recharge.

800-V Electric Vehicle Powertrains: Review and Analysis of Benefits, Challenges, and Future Trends

Two of the main challenges for electric vehicle (EV) adoption include limited range and long recharge times. Ultrafast charging can help to mitigate both these concerns. However, for typical 400-V battery EVs (BEVs), the charging rate is limited by the practical cable size required to carry the charging current. To reach ultrahigh charge rates of 350 or 400 kW, 800-V BEVs are a promising alternative. However, the design of an 800-V EV requires careful new considerations for all electrical systems. This article reviews the current state of 800-V vehicle powertrain electrical design and performs an analysis of benefits, challenges, and future trends regarding multiple vehicle powertrain components. Specifically, detailed benefits and challenges related to the battery, propulsion motor, inverter, auxiliary power unit, and on- and off-board chargers are discussed.

Influence of thick karst vadose zone on aquifer recharge in karst formations

Vadose zone has been proven as an essential buffer zone for aquifer recharge. However, most previous researches associated with vadose zone influence of groundwater recharge concern granular porous media aquifers. Despite of the massive karst formations on surface of earth, the role of karst vadose zone on affecting recharge to the underneath karst aquifer is largely unknown. The objective of this study is to conceptualize and understand the influence of a thick karst vadose zone on groundwater recharge in a regional karst formation. In this work, an integrated field and numerical investigation on such a thick vadose zone above the regional karst aquifer is conducted, where the field component of the investigation involves survey and observation of hydraulic heads and spring discharge, and the numerical component of the investigation involves coupled unsaturated–saturated modeling exercises. The numerical simulation works are conducted by building the following three models: Model 1, a coupled saturated–unsaturated model; Model 2, a coupled saturated–unsaturated model without preferential infiltration; Model 3, a saturated flow model without vadose zone process. The influence of the vadose zone on groundwater recharge is analyzed by comparing the results of those three models. The comparison results of the spring discharge/groundwater level-time curves show that in karst area with a thick vadose zone like the study area, considering vadose zone will improve the simulation results significantly and the slow (diffusive) flow plays a major role in controlling groundwater recharge. The comparison of the recharge-time curves shows that the thick karst vadose zone has a significant buffer effect on pattern and timing of recharge. Parameters of the vadose zone, which controls the infiltration process, are analyzed and prioritized. Our analysis suggests that the infiltration rate has a great influence on groundwater recharge and the specific yield of the deep seated unconfined aquifer affects not only the amount of recharge but also its time lag.

Unsaturated Zone Flow Processes and Aquifer Response Time in the Chalk Aquifer, Brighton, South East England.

The Chalk aquifer is one of the main sources of water in South East England. The unsaturated zone in the aquifer plays an important role controlling the time and magnitude of recharge and is major pathway for contaminant transport to the water table. A range of previous work has addressed flow processes in the Chalk unsaturated zone, but physical understanding is still incomplete. Here we present the results of a study on flow mechanism in the Chalk unsaturated zone using a combination of statistical analysis and novel laboratory methods. The study was undertaken at three sites (North Heath Barn [NHB], Pyecombe East [PE], and Preston Park [PP]) on the Chalk of the Brighton block, South East England. Daily and hourly time series data of groundwater level and rainfall were correlated. The results show that a slower groundwater level response to rainfall occurs during dry seasons (summer and autumn) when the amount of effective rainfall is less than 4 mm/day, with a thicker and drier unsaturated zone. A faster response occurs during wet seasons (winter and spring) when the daily effective rainfall exceeds 4 mm/day with a thinner and wetter unsaturated zone. Periods of very rapid response (within 15 h) were observed during wet seasons at NHB and PE sites, with unsaturated hydraulic conductivity (Ku ) inferred to reach 839 mm/day. A slower response was observed at an urbanized site (PP) as a result of reduction in direct recharge due to reduced infiltration, due to presences of impermeable infrastructure covering the area around PP borehole. Laboratory measurements of Ku of the Chalk matrix using a geotechnical centrifuge show variation from 4.27 to 0.07 mm/day, according to the level of saturation. Thus, the rapid responses cannot be linked to matrix flow only but indicate the contribution of fracture and karstic flow processes in conducting water.

Evaluation of Matching Ratio Impact on Reduced Charging Time

As electric vehicles (EV) show an increased penetration into the transportation market, a challenging hurdle to overcome is a vehicle “refuel” time similar to that of refilling a gasoline vehicle tank. One pathway to accomplish this is fast charging lithium-ion cells. The majority of commercial Li-Ion cells manufactured today contain various positive electrode active materials, coupled with a graphite negative electrode. An advantage of graphite electrodes is that the lithiated graphite voltage lies close to that of Li/Li+, resulting in in increased cell voltage. This benefit also has a detrimental effect on fast charging cells with graphite electrodes, where a small polarization of the negative electrode can result in a condition favorable to lithium metal plating on the negative graphite electrodes1.While modified high rate charging procedures for commercial lithium-ion cells with conventional graphite negative electrodes, such as multistage constant current charging and boost charging, have been implemented. These procedures rely on reducing charging currents when cell voltage limits are reached 2,3. Following the development of an accelerated charging procedure based solely on negative electrode lithiation rate and polarization 4, the presented work evaluates the effect of negative to positive (N:P) matching ratio on cell fast charge performance. Two varying N:P matching ratios of 1.2:1 and 1.7:1 are evaluated and the resulted impact on fast charge performance will be presented. Utilizing an accelerated charging procedure based solely on the limiting negative electrode results in an identical charging procedure being used for multiple cell designs when charging to the same degree of negative electrode lithiation. Theoretically the applied procedure should result in a reduction in recharge time to 80% state of charge from 58 minutes to 34 minutes by altering the cell N:P ratio. Actual cell performance is altered as increased irreversible capacity loss occurs in cells with increased N:P rations, but improvements in cell charge times can be accomplished from design changes, namely cell N:P ratios. References C. Uhlmann, J. Illig, M. Ender, R. Schuster, and E. Ivers-Tiffée, Journal of Power Sources, 279, 428–438 (2015).D. Anseán et al., Journal of Power Sources, 321, 201–209 (2016).P. H. L. Notten, J. H. G. O. het Veld, and J. R. G. van Beek, Journal of Power Sources, 145, 89–94 (2005).W. Yourey, Y. Fu, N. Li, V. Battaglia, and W. Tong, J. Electrochem. Soc., 166, A1432–A1438 (2019).

Growing vertical graphene sheets on natural graphite for fast charging lithium-ion batteries

A goal of extreme fast charging less than 15 min recharge time while maintaining high energy density has been pursued to meet fast-charging and high-energy-density demand on lithium ion batteries used in electric vehicles, which is still a challenge. Here, in order to realize the goal vertical graphene sheets are grown on surface of graphite by thermal chemical vapor deposition. The vertical graphene sheets not only can greatly boost lithium-ion transport rate due to its intrinsically high electrical conductivity but also can significantly reduce tortuosity of lithium ion transport due to its highly preferential lithium-ion insertion paths. In half cells, the vertical graphene sheets/graphite can endure 3000 cycles in 3 min of charge time per cycle. More remarkably, a full cell with vertical graphene sheets/graphite anode and LiFePO4 cathode exhibits an ultrahigh energy density of 312.1 Wh kg−1 in 10 min of charge time per cycle at 4 C, indicating that the vertical graphene sheets/graphite anode possesses ability of extreme fast charging while maintaining high energy density.

Proglacial groundwater storage dynamics under climate change and glacier retreat

AbstractProglacial aquifers are an important water store in glacierised mountain catchments that supplement meltwater‐fed river flows and support freshwater ecosystems. Climate change and glacier retreat will perturb water storage in these aquifers, yet the climate‐glacier‐groundwater response cascade has rarely been studied and remains poorly understood. This study implements an integrated modelling approach that combines distributed glacio‐hydrological and groundwater models with climate change projections to evaluate the evolution of groundwater storage dynamics and surface‐groundwater exchanges in a temperate, glacierised catchment in Iceland. Focused infiltration along the meltwater‐fed Virkisá River channel is found to be an important source of groundwater recharge and is projected to provide 14%–20% of total groundwater recharge by the 2080s. The simulations highlight a mechanism by which glacier retreat could inhibit river recharge in the future due to the loss of diurnal melt cycling in the runoff hydrograph. However, the evolution of proglacial groundwater level dynamics show considerable resilience to changes in river recharge and, instead, are driven by changes in the magnitude and seasonal timing of diffuse recharge from year‐round rainfall. The majority of scenarios simulate an overall reduction in groundwater levels with a maximum 30‐day average groundwater level reduction of 1 m. The simulations replicate observational studies of baseflow to the river, where up to 15% of the 30‐day average river flow comes from groundwater outside of the melt season. This is forecast to reduce to 3%–8% by the 2080s due to increased contributions from rainfall and meltwater runoff. During the melt season, groundwater will continue to contribute 1%–3% of river flow despite significant reductions in meltwater runoff inputs. Therefore it is concluded that, in the proglacial region, groundwater will continue to provide only limited buffering of river flows as the glacier retreats.

A Model for Cost–Benefit Analysis of Privately Owned Vehicle-to-Grid Solutions

Although the increasing adoption of electric vehicles (EVs) is overall positive for the environment and for the sustainable use of resources, the extra effort that requires purchasing an EV when compared to an equivalent internal combustion engine (ICE) competitor make them less appealing from an economical point of view. In addition to that, there are other challenges in EVs (autonomy, battery, recharge time, etc.) that are non-existent in ICE vehicles. Nevertheless, the possibility of providing electricity to the power grid via vehicle-to-grid technology (V2G), along with lower maintenance costs, could prove that EVs are the most economically efficient option in the long run. Indeed, enabling V2G would make EVs capable of saving some costs for their vehicle owners, thus making them a better long-term mobility choice that could trigger deep changes in habits of vehicle owners. This paper describes a cost–benefit analysis of how consumers can make use of V2G solutions, in a way that they can use their vehicle for transport purposes and obtain revenues when injecting energy into the power grid.

Comparison of recharge from drywells and infiltration basins: A modeling study

Drywells (DWs) and infiltration basins (IBs) are widely used as managed aquifer recharge (MAR) devices to capture stormwater runoff and recharge groundwater. However, no published research has compared the performance of these two engineered systems under shared conditions. Numerical experiments were conducted on an idealized 2D‐axisymmetric domain using the HYDRUS (2D/3D) software to systematically study the performance of a circular IB design (diameter and area) and partially penetrating DW (38 m length with water table > 60 m). The effects of subsurface heterogeneity on infiltration, recharge, and storage from the DW and IB under constant head conditions were investigated. The mean cumulative infiltration (μI) and recharge (μR) volumes increased, and the arrival time of recharge decreased with the IB area. Values of μI were higher for a 70 m diameter IB than an DW, whereas the value of μR was higher for a DW after 1-year of a constant head simulation under selected subsurface heterogeneity conditions. A comparison between mean μI, μR, and mean vadose zone storage (μS) values for all DW and IB stochastic simulations (70 for each MAR scenario) under steady-state conditions demonstrated that five DWs can replace a 70 m diameter IB to achieve significantly higher infiltration and recharge over 20 years of operation. Additional numerical experiments were conducted to study the influence of a shallow clay layer by considering an IB, DW, and a DW integrated into an IB. The presence of such a low permeable layer delayed groundwater recharge from an IB. In contrast, a DW can penetrate tight clay layers and release water below them and facilitate rapid infiltration and recharge. The potential benefits of a DW compared to an IB include a smaller footprint, the potential for pre-treatments to remove contaminants, less evaporation, less mobilization of in-situ contaminants, and potentially lower maintenance costs. Besides, this study demonstrates that combining both IB and DW helps to get the best out of both MAR techniques.

Environmental isotope characteristics of water sources in the Sokoto Basin – an evaluation of the role of meteoric recharge and residence time

ABSTRACT The water sources of the Sokoto Basin are mainly of interrelated origin. The groundwater is composed of old water recharged in different climate regimes and of recent meteoric water. The recharge source is influenced by both local and regional moisture circulation given the lower slope and intercept of the local meteoric water line (LMWL) relative to those of the global meteoric water line (GMWL) and distribution of the deuterium excess d from –20 to +14 ‰. The identified interrelated water sources were confirmed by variations in tritium measured between 4.9 and <0.4 TU. The groundwater and surface water were identified to be of mixed origin, consisting of interrelated and recent types. This depicts active recharge taking place across the basin. The groundwater recharge was established to be renewable; however, rational water exploitation should be exercised considering growing water demand with the corresponding population rise.

A Multi-Protocol Home Automation System Using Smart Gateway

Smart Home is one of the most established applications of the Internet of Things. Almost every equipment we use in our daily life—appliances, electric lights, electrical outlets, heating, and cooling systems-connected to a remotely controllable network, giving the user’s ability to remotely control and monitor the house, save energy without compromising on comfort and ultimately improve the quality of experience of staying in the house. We present a cost-effective system and address a major challenge that the industry faces today-Protocol Compatibility. To address the challenge, we make use of separate gateways/bridges for each network and an open-source home automation framework called OpenHAB, where each bridge links with a single master Wi-Fi gateway, providing a single window of control through an Application or a web interface for an integrated Smart Home. We integrate an elderly health monitoring device-Beehealth with OpenHAB; addressing the paramount need of a portable, accurate, and efficient health monitoring and fall detection device. We present two methods for fall detection, namely: threshold-based and Neural Network-based, with the latter resulting in 94% accuracy for fall detection. We evaluate the Smart Home devices on parameters like syncing time, battery life, recharge time, deployability, and cost.

Recharge and residence times of groundwater in hyper arid areas: The confined aquifer of Calama, Loa River Basin, Atacama Desert, Chile

Groundwater recharge in hyper arid areas often depends on surface water infiltration and diffuse recharge of highly evaporated precipitation only contribute under favorable conditions. This happens in the Calama basin two-aquifer system, in the Central Andean area of northern Chile. A conceptual model of the groundwater system and its relationship with the Loa River is defined. We focus on the confined aquifer of the Calama basin, combining hydrodynamic, hydrogeochemical and isotopic methods. Radiocarbon (14C) activity data of dissolved inorganic carbon (DIC), in conjunction with chemical data, are applied to evaluate groundwater residence time within the confined aquifer. The Loa River recharges the Calama basin aquifers in its northeastern part, with water that has chemical and isotopic characteristics inherited from the arid environment and volcanic rocks in its upper basin. In the central and northeastern part of the confined aquifer, minor variations in chloride concentration suggest that the deep aquifer is well confined. The δ18O and δ2H values in groundwater of the confined aquifer show an increasing isotopic fractionation from the recharge area (around −10‰ δ18O) to those in the discharge area (between −8.5‰ and −8‰) in the southwestern part of the aquifer. The 14C activity continuously decreases down flow from the recharge by the Loa River. Adjusted DIC radiocarbon ages indicate a groundwater travel time between 1500 and 4000 years in the confined aquifer of Calama. Despite the limitations and uncertainties of radiocarbon in DIC to estimate groundwater transit times for the confined aquifer and considering complementary chemical and isotopic constraints, the DIC 14C provides acceptable values. The approach may be applicable in other confined aquifers in hyper-arid climates in which the formation of aquifer systems linked to river damming by geological action took place. This information is needed for sound management of the scarce groundwater resources.

The Role of Snowmelt on the Spatio-Temporal Variability of Spring Recharge in a Dolomitic Mountain Group, Italian Alps

Springs play a key role in the hydrology of mountain catchments and their water supply has a considerable impact on regional livelihood, biodiversity, tourism, and power generation. However, there is still limited knowledge of how rain and snow contribute to the recharge of Alpine springs. This study presents a four-year investigation of stable isotopes in precipitation and spring water at the scale of a 240 km2 wide dolomitic massif (Dolomites, Italian Alps) with the aim of determining the proportions of snowmelt and rain in spring water and to provide insights on the variability of these contributions in space and time. Four precipitation sampling devices were installed along a strong elevation gradient (from 725 to 2660 m a.s.l.) and nine major springs were monitored seasonally. The monitoring period comprised three extreme weather conditions, i.e., an exceptional snowpack melting period following the highest snowfall in 30 years, an intense precipitation event (386.4 mm of rain in 48 h), and one of the driest periods ever observed in the region. Isotope-based mixing analysis revealed that rain and snowmelt contributions to spring water were noticeably variable, with two main recharge time windows: a late spring–summer snowmelt recharge period with an average snowmelt fraction in spring water up to 94 ± 9%, and a late autumn–early winter period with a rain fraction in spring water up to 68 ± 17%. Overall, during the monitoring period, snowmelt produced high-flow conditions and sustained baseflow more than rain. We argue that the seasonal variability of the snowmelt and rain fractions during the monitoring period reflects the relatively rapid and climate-dependent storage processes occurring in the aquifer. Our results also showed that snowmelt fractions in spring water vary in space around the mountain group as a function of the elevation of their recharge areas. High-altitude recharge areas, above 2500 m a.s.l., are characterized by a predominance of the snowmelt fraction (72% ± 29%) over the rain contribution. Recharge altitudes of approximately 2400 m a.s.l. also show a snow predominance (65 ± 31%), while springs recharged below 2000 m a.s.l. are recharged mostly from rain (snowmelt fraction of 46 ± 26%). Results from this study may be used to develop more accurate water management strategies in mountain catchments and to cope with future climate-change predictions that indicate a decline in the snow volume and duration in Alpine regions.

Uma abordagem da dinâmica do desenvolvimento científico e tecnológico das baterias lítio-íon para veículos elétricos

O principal componente dos veículos elétricos (VE) é a sua bateria. Considerando que as baterias lítio-íon têm oferecido as melhores respostas a diferentes problemas tecnológicos, o que inclui tempo de recarga, autonomia, peso e densidade energética, questiona-se qual tem sido o seu desenvolvimento científico e tecnológico ao longo do tempo. O objetivo deste artigo é avançar na compreensão desta questão a partir de um estudo bibliométrico e de patentes das baterias lítio-íon para VE. Os resultados indicam que a dinâmica de publicação de artigos científicos e de famílias de patentes tem sido crescente, em especial a partir de 2009, motivada por preocupações ambientais e pelo interesse de uma diversidade de empresas no crescimento deste mercado. Países asiáticos tais como Japão, China, Coreia do Sul e Taiwan, além dos Estados Unidos e algumas nações europeias, ocupam a liderança nesta corrida tecnológica. Um ponto de destaque são as redes de colaboração que têm se formado entre universidades com foco na publicação de artigos científicos, e entre montadoras tradicionais e empresas do setor eletroeletrônico, para atividades de patenteamento. Este movimento evidencia a necessidade da articulação e complementaridade entre diferentes áreas do conhecimento para o avanço do desenvolvimento tecnológico das baterias de lítio-íon.