Increased Storage Capacity Research Articles

Changes in bark properties and hydrology following prescribed fire in Pinus taeda and Quercus montana

AbstractIn the eastern United States, the use of prescribed fire as a silvicultural technique to manage for desirable upland tree species is increasing in popularity. Bark physical properties such as thickness, density, and porosity have known associations with fire tolerance among species. These physical properties simultaneously influence rainfall interception and canopy storage and thus are of interest across a range of disciplines. Furthermore, while these characteristics are innate to a species, it is unknown whether repeated exposure to fire facilitates physical change in bark structure and whether these changes are consistent among species. To answer these questions, bark samples were collected from mature pine (Pinus taeda L.) and oak (Quercus montana Willd.) trees from sites across the Bankhead National Forest in Alabama, USA under three different burn regimes: 3‐year cycle, 9‐year cycle, and no fire. Samples were analysed in the laboratory for bulk density, porosity, water storage capacity, and hygroscopicity (the amount of atmospheric water vapour absorbed by bark during non‐rainfall conditions). Drying rates of saturated samples under simulated wetting conditions were also assessed. Oak bark had higher bulk density, lower porosity, and dried slower than pine bark. Interestingly, bark from both species had lower bulk density, higher porosity, greater water storage capacity, and dried faster in stands that were burned every 3 years compared to other fire regimes (p < 0.001). In summary, this study demonstrates that prescribed fire regimes in an eastern US forest alter bark structure and thus influence individual tree control on hydrological processes. The increase in bark water storage capacity, coupled with faster bark evaporation times may lead to less water inputs to the forest floor and drier overall conditions. Further investigation of this fire‐bark‐water feedback loop is necessary to understand the extent of these mechanisms controlling landscape‐scale conditions.

Scouring effect of the middle and lower reaches of the Yangtze River and its impact after the impoundment of the Three Gorges Project

三峡及其上游干支流梯级水库建成运用后,大坝下游“清水下泄”引起了长江中下游河道发生长时间、长距离的冲刷。2001-2021年期间宜昌至长江口已累计冲刷了50.3亿m³,需厘清河道冲刷对河势、防洪、航运等方面产生影响。分析表明:三峡工程运用后,长江中下游河势总体稳定,弯道段出现切滩撇弯、汊道段出现塞支强干等现象;河道槽蓄量的持续增加,进一步增大了河道调蓄和行洪能力,但水流顶冲点的变化和近岸河床的冲刷下切,使得河道崩岸频发,并影响河势稳定和防洪安全;在河道冲刷、河势控制与航道工程综合作用下,长江中下游航道条件总体得到改善,但河道不均衡冲刷使得坝下游砂卵石河段出现“坡陡流急”,沙质河段出现洲滩散乱、航槽移位等现象,影响航道条件;同流量下枯水位呈下降态势,逢极枯年份影响长江中下游用水安全;江湖关系发生新变化,“三口”分流道由原淤积转为冲刷,两湖湖区水位不同程度的降低,枯水位出现时间有所提前,不利于湖区水资源和生态环境的安全与可持续发展;三峡工程实施枯水期补水调度和“压咸潮”调度以及长江口北支淤积减缓,对于遏制长江口咸潮入侵有利,入海泥沙显著减少引起长江口近岸河床冲刷,影响沿岸码头的安全运行。;After the construction of cascade reservoirs in the Three Gorges and its upper reaches, the downstream clear water of the dam was discharged, and a long-term and long-distance erosion occurred in the middle and lower reaches of the Yangtze River. From Yichang to the Yangtze Estuary, a total of 5030 million m³ was scoured. Under the background of large-scale erosion in the middle and lower reaches of the Yangtze River, it has a profound impact on river regime, flood control and shipping. The analysis shows that the river regime in the middle and lower reaches of the Yangtze River is generally stable, and the river regime in some parts of the river changes greatly, resulting in the phenomenon of beach cutting and bending, and the phenomenon of strong trunk. The increase of channel storage capacity increases the capacity of river discharge and flood storage, but the change of flow top scour point and the erosion of nearshore riverbed also make the river bank collapse frequently, affecting the stability of river regime and flood control safety. Under the combined action of channel scour, river regime control and channel engineering, channel conditions in the middle and lower reaches of the Yangtze River improved overall. However, due to the unbalanced scouring of the river channel, the sandy pebble river section in the downstream of the dam has a 'steep slope and rapid flow’, and the sandy river section has phenomena such as scattered beaches and channel displacement, affecting the channel conditions; the continuous erosion of river bed results in the decrease of low water level, which affects the water supply safety of life, production and ecology along the middle and lower reaches of the Yangtze River in extremely dry years. The relationship between rivers and lakes has undergone new changes. The three diversion channels have changed from original siltation to erosion. The water levels in the two lakes have decreased to varying degrees, and the low water level has appeared earlier, which has adversely affected the water resources and ecological environment in the lake area. The regulation of water replenishment and saltwater intrusion in dry season of the Three Gorges Project and the slowing down of siltation in the north branch are beneficial to the control of saltwater intrusion in the Yangtze Estuary. The sediment discharged into the sea from the Yangtze Estuary is significantly reduced and the riverbed near the Yangtze Estuary is scoured strongly. It seriously threatens the safety of the main structure of coastal enterprise wharf.

Decadal Changes in Soil Water Storage Characteristics Linked to Forest Management in a Steep Watershed

Soil water storage properties, which are affected by land management practices, alter the water balance and flow regimes in watersheds; thus, it is highly plausible to clarify the influence of such management practices on the water storage condition by analyzing the long-term variations in discharge. In this study, the changes in soil water storage characteristics of the Ogouchi Dam watershed, which had undergone intensive forest management through the decades, were investigated using two approaches. Reported results from the rainfall–runoff correlation analysis show a gradual and steady increase in the soil water storage capacity at weaker continuous-rainfall events, i.e., uninterrupted wet days accumulating less than 70 mm. Meanwhile, the second approach utilizing the parameter calibration in the SWAT discharge model illustrated a constant trend in the runoff potential and the high possibility of a steady improvement in the soil available water capacity. Overall, the established decadal trends were able to prove the capability of sustainable forest management, i.e., thinning, regeneration cutting, multi-layer planting, deer-prevention fences, and earth-retaining fences (lined felled trees), in improving the water conservation function of the catchment.

Analysing the Economic Viability of Implicit Demand Response Control of Thermal Energy Storage in Hot Water Tanks

Demand-responsive control of electrically heated hot water storage tanks (HWSTs) is one solution, already present in the building stock, to stabilise volatile energy networks and markets. This has been put into sharp focus with the current energy crisis in Europe due to reduced access to natural gas. Furthermore, increasing proportions of intermittent renewable energy will likely add to this volatility. However, the adoption of demand response (DR) by consumers is highly dependent on the economic benefit. This study assesses the economic potential of DR of centralised HWSTs through both an analysis of spot price data and an optimisation algorithm approximating DR control. The methods are applied to a case study apartment building in Norway using current pricing models and examine the effect of the demand profile, electricity prices, heating power and storage capacity on energy cost and energy flexibility. Unit cost savings from DR are closely linked to the variation in unit energy price during the optimisation period. Increasing the storage capacity or the heating power increases the flexibility with a diminishing rate of return. However, increasing storage capacity does not result in cost savings as additional heat losses are greater than the saving from shifting demand, except for during highly volatile electricity price periods. Changing the minimum setpoint temperature improves the cost curve as a greater thermal storage capacity can be achieved without increasing heat loss. Systems utilising a smaller heating power are more economical due to the dominant role of the monthly price related to the peak energy demand of the system.

Energy Storage System based on Biomimetic Strategies: Concept Design and Performance Assessment in Buildings

Due to the constant growth in energy demand worldwide, renewable systems require more maintenance and electrical energy generation, which also involves an increase in storage capacity. Solar energy is one of the renewable sources with the greatest opportunity to cover this increasing demand as it promises in areas of power generation for residential, commercial, and industrial applications. Currently, there are several conventional electricity energy storage systems whose contributions have been presented at a building scale; batteries being the last the most used in the market for their ability to react instantly to changes in energy demand, but they are not totally eco-friendly. Nowadays, alternatives are being searched to reduce the ecological footprint that continues affecting the environment. To decrease carbon emissions and propose a “green” storage system, this research implements biomimetic strategies following the steps of the problem-based approach with the operating principle of lithium-ion batteries as a basis. As a result, a preliminary design of an equivalent circuit is presented that simulates the behavior of a natural cell based on the energy admission and storage processes of an oriental hornet, as well as the discharge mechanism of an electric eel.

Analysis and Design of Multivalued High-Capacity Associative Memories Based on Delayed Recurrent Neural Networks.

This article aims at analyzing and designing the multivalued high-capacity-associative memories based on recurrent neural networks with both asynchronous and distributed delays. In order to increase storage capacities, multivalued activation functions are introduced into associative memories. The stored patterns are retrieved by external input vectors instead of initial conditions, which can guarantee accurate associative memories by avoiding spurious equilibrium points. Some sufficient conditions are proposed to ensure the existence, uniqueness, and global exponential stability of the equilibrium point of neural networks with mixed delays. For neural networks with n neurons, m -dimensional input vectors, and 2k -valued activation functions, the autoassociative memories have (2k)n storage capacities and heteroassociative memories have min {(2k)n,(2k)m} storage capacities. That is, the storage capacities of designed associative memories in this article are obviously higher than the 2n and min {2n,2m} storage capacities of the conventional ones. Three examples are given to support the theoretical results.

Improving the Endurance of Next Generation SSD’s using WOM-v Codes

High density Solid State Drives, such as QLC drives, offer increased storage capacity, but a magnitude lower Program and Erase (P/E) cycles, limiting their endurance and hence usability. We present the design and implementation of non-binary, Voltage-Based Write-Once-Memory (WOM-v) Codes to improve the lifetime of QLC drives. First, we develop a FEMU based simulator test-bed to evaluate the gains of WOM-v codes on real world workloads. Second, we propose and implement two optimizations, an efficient garbage collection mechanism and an encoding optimization to drastically improve WOM-v code endurance without compromising performance. Third, we propose analytical approaches to obtain estimates of the endurance gains under WOM-v codes. We analyze the Greedy garbage collection technique with uniform page access distribution and the Least Recently Written (LRW) garbage collection technique with skewed page access distribution in the context of WOM-v codes. We find that although both approaches overestimate the number of required erase operations, the model based on greedy garbage collection with uniform page access distribution provides tighter bounds. A careful evaluation, including microbenchmarks and trace-driven evaluation, demonstrates that WOM-v codes can reduce Erase cycles for QLC drives by 4.4×–11.1× for real world workloads with minimal performance overheads resulting in improved QLC SSD lifetime.

The mechanism and sorption kinetic analysis of hydrogen storage at room temperature using acid functionalized carbon nanotubes

The present work investigates the effect of acid functionalization of multiwalled carbon nanotubes (MWCNTs) on the physisorption based mechanism of hydrogen storage at room temperature. For this purpose, a suite of functionalized CNT samples is synthesized and subjected to a comprehensive range of material characterization techniques and hydrogen storage measurements. Nitric acid (HNO3) and the mixture of sulphuric acid and nitric acid (H2SO4:HNO3) are used for the synthesis at oxidation temperatures of 80 °C and 100 °C. Electron microscopy and X-ray photoelectron spectroscopy results reveal that acid functionalization causes major alternation in the physicochemical properties of the CNTs due to the varied concentration of oxygen functional groups. Particularly, the H2SO4:HNO3 functionalized sample at 100 °C is found to have the highest interlayer spacing, oxygen to carbon ratio (26.09 at. %), defect content, and specific surface area (215.3 m2/g). These features collectively contribute to substantially improved hydrogen storage properties, including a ∼150% increase in the hydrogen storage capacity at 298 K and 50 bar. Furthermore, kinetic analysis shows that the desorption follows a multiple diffusion process which is sensitive to the oxygen functional groups and structural defects, hence reducing the rate of desorption; whereas the adsorption is controlled by a more rapid, three-dimensional diffusion process.

Sustainable groundwater management through an optimal water supply system using a coupled simulation-optimization approach.

Meeting people's water supply needs in cities is an urgent challenge. Especially in coastal cities, surface water sources are usually inadequate and so groundwater is frequently over-exploited, resulting in its rapid decrease and intrusion of saltwater. Conjunctive use of surface water and groundwater is the best alternative approach to mitigate the overuse of groundwater through effective distribution of surface water sources. It requires numerous runs of the simulation-optimization model to select an optimal pattern of water distribution by keeping the groundwater levels under control. In this study, a new simulation-optimization model is developed using wavelet support vector regression (WSVR) and genetic algorithm (GA) to propose an optimal water distribution system to Visakhapatnam city on the East Coast of India, fulfilling the constraints of surface water quantity, aquifer pumping, and drawdown. Estimation of groundwater pumping and groundwater level variation in spatial context is challenging in urban environment. To overcome this, the calibrated modular finite-difference flow (MODFLOW) model for this study area has been used to prepare the spatial and temporal variation of model inputs such as groundwater pumping and groundwater levels. The WSVR-GA model's performance to reduce the groundwater pumping is evaluated in three distinct cases. The surface water resources from three sources are distributed to different wards in the city source-wise in case I and centralized in cases II and III, while the source-wise surface water constraints are limited to monthly in cases I and II and annual in case III. The WSVR-GA management model suggested ward-wise groundwater pumping restrictions, resulting in 9.57 MCM, 11.64 MCM, and 12.54 MCM increase in total groundwater storage capacity in cases I, II, and III respectively. Cases II and III offer 21% and 25%, respectively, more storage than case I. Thus, centralized distribution systems have increased the sustainability of groundwater supplies by preventing overdrafts caused by a lack of surface water resources. Validation of results using MODFLOW indicates a substantial rise in groundwater levels in the study area.

Electrical resistivity imaging of an enhanced aquifer recharge site.

Enhanced aquifer recharge (EAR) is defined as any engineered structure or enhanced natural feature designed to convey stormwater, surface water or wastewater directly into an aquifer (e.g. aquifer storage and recovery (ASR) wells) or into the vadose zone eventually percolating to an aquifer (e.g. spreading basins, dry well, etc.; USEPA 2021). Identifying the storage and flow capabilities of complex aquifers can improve the efficacy of many conceptual site models (CSM) for sites considered for ASR projects. In a karst setting, the EAR process may be able to take advantage of natural surficial features and the increased storage capacity of karst aquifers to improve recharge to groundwater. However, the suitability for an EAR project in a karst setting depends on the maturity of the karst and its preceding epikarst. The focus of flow within the epikarst causes enlargement of fractures and karst conduits. Thus, the storage and transmissivity within the karst vary greatly. Electrical resistivity imaging (ERI) is a well-known geophysical tool for mapping fractures and sinkholes, typical in karst settings. Locating enhanced water conveyance structures of a karst aquifer can improve the design and operation of an EAR site. This study investigated the hydraulic connection between shallow and deep groundwater using ERI to identify potential flow pathways and to improve our understanding of the storage mechanisms of the epikarst. The results presented in this paper validate the effectiveness of ERI in characterizing karst/epikarst and delineating soil, bedrock and local faults and fractures in the subsurface.

Real-time controlled rainwater harvesting systems can improve the performance of stormwater networks

Real-Time Control (RTC) technology is increasingly applied in Rainwater Harvesting (RWH) systems to optimise their performance related to water supply and flood mitigation. However, most studies to date have focussed on testing the benefits at an individual site scale, leaving the potential benefits for downstream stormwater networks largely untested. In this study, we developed a methodology to predict how at-source RTC RWH systems influence the behaviour of a stormwater network. Simulation was enabled by coupling the drainage model in SWMM with an RTC RWH model coded using the R software. We modelled two different RTC strategies across a range of system settings (e.g. storage size for RWH and proportion of storage to which RTC is applied) under two different climate scenarios—current and future climates. The simulations showed that RTC reduced flooding volume and peak flow of the stormwater network, leading to a potential mitigation of urban flooding risks, while also providing a decentralised supplementary water supply. Implementing RTC in more of RWH storages yielded greater benefits than simply increasing storage capacity, in both current and future climates. More importantly, the RTC systems are capable of more precisely managing the resultant flow regime in reducing the erosion and restoring the pre-development conditions in sensitive receiving waters. Our study suggests that RTC RWH storages distributed throughout a catchment can substantially improve the performance of existing drainage systems, potentially avoiding or deferring expensive network upgrades. Investments in real-time control technology would appear to be more promising than investments in detention volume alone.

Understanding the hydrological regime based on the runoff events in a mountainous catchment with seasonally frozen soil in the Qinghai‐Tibet plateau

AbstractSeasonal thawing of frozen soil will significantly affect the hydrological regime, water storage capacity and ecosystem services in the future, which contributes to the uncertainty of regional water resources. However, based on the scale of runoff events, the mechanism of seasonal frozen soil thawing on the hydrological regime are still unclear. In this study, we systematically analysed the runoff characteristics and interactive effects of environmental factors and pre‐event catchment state on runoff processes based on the runoff event scale, using data sets of air temperature, precipitation, runoff, soil moisture, and soil temperature observed in a mountainous catchment with seasonally frozen soil distribution on the Qinghai‐Tibet Plateau from 2010 to 2019. It was found that the event runoff coefficient did not increase significantly with the increase of precipitation. Event runoff coefficients exhibited strong seasonality. The catchment exhibited a gradual increase in the event runoff coefficient with increasing pre‐event baseflow and antecedent soil moisture, especially during stable period (August to November). Event runoff generation through infiltration excess as the result of intensive rainfall seemed to be only possible in the stable period, while heavy precipitation events were common during this period. Normalized event peak discharge and event runoff coefficient showed positive trends with changes in pre‐event catchment state indicators, which were commonly observed phenomena in runoff events. For this catchment, the increased storage capacity pre‐event saturation may be the main mechanism of event runoff generation, as it was unlikely that a single precipitation event would lead to catchment saturation. Soil temperature affects runoff processes through both direct effects on runoff processes and indirect effects on pre‐event catchment state. Temperature indicators were the most important predictors of runoff changes in the Qinghai‐Tibet Plateau.

Modeling of hydrogen production system for photovoltaic power generation and capacity optimization of energy storage system

Hydrogen production using solar energy is an important way to obtain hydrogen energy. However, the inherent intermittent and random characteristics of solar energy reduce the efficiency of hydrogen production. Therefore, it is necessary to add an energy storage system to the photovoltaic power hydrogen production system. This paper establishes a model of a photovoltaic power generation hydrogen system and optimizes the capacity configuration. Firstly, the mathematical model is modeled and analyzed, and the system is modeled using Matlab/Simulink; secondly, the principle of optimal configuration of energy storage capacity is analyzed to determine the optimization strategy, we propose the storage capacity configuration algorithm based on the low-pass filtering principle, and optimal time constant selection; finally, a case study is conducted, whose photovoltaic installed capacity of 30 MW, verifying the effectiveness of the proposed algorithm, analyzing the relationship between energy storage capacity and smoothing effect. The results show that as the cut-off frequency decreases, the energy storage capacity increases and the smoothing effect is more obvious. The proposed algorithm can effectively reduce the 1 h maximum power variation of PV power generation. In which the maximum power variation of PV generation 1 h before smoothing is 4.31 MW. We set four different sets of time constants, the maximum power variation of PV generation 1 h after smoothing is reduced to 0.751, 0.389, 0.078, and 0.04 MW, respectively.

Application of modified Gaussian plume algorithm in hazard assessment of toxic chemicals in nuclear power plants

The leakage or explosion of hazardous chemicals will seriously affect the operation safety of nuclear power plants. Therefore, in the nuclear safety review, it has been clearly proposed that the environmental risks of off-site toxic chemicals should be evaluated. When calculating the toxic chemical leakage accident, as HABIT model calculation result is based on the 2 min concentration limit condition assumed in RG1.78, and the longest duration is only 7.5 min, so it cannot be applied to the safety assessment of offsite toxic hazards. This paper presents a detail analysis of the impact on toxic chemical release using modified Gaussian plume algorithm model in ALOHA. The Gaussian plume algorithm is mainly used to calculate the plume diffusion emitted by continuous point sources, assuming that its concentration distribution obeys the empirical model of normal distribution. The plume is transported downwind at an average wind speed, ignoring turbulent diffusion downwind, with vertical and horizontal lateral diffusion described by diffusion parameters. The Gaussian plume algorithm has many advantages such as high computational efficiency and simple calculation method. Therefore, it has a wide application in the field of atmospheric diffusion. Calculation shows for the chlorine and ammonia leakage accident, chlorine’s influence area is much larger than ammonia. For ammonia, safe distance is about 3.5 km, but for chlorine, hydrogen fluoride and hydrazine, with the increase of storage capacity, their safety distance change slower at 8 km, which is consistent with HAD101/04. The storage amount of liquid ammonia shows an exponential increase, indicating that for liquid ammonia, the chemical safety control distance will not exceed 3.5 km. Conclusion of this paper has a long last meaning to NPP environmental assessment and safety evaluation, and full filled area of toxic chemicals quantitative analysis.

Numerical study of high-temperature cascaded packed bed thermal energy storage system

The thermal energy storage system (TES) in the form of packed bed with encapsulated phase change materials (EPCMs) can further improve the thermal performance of ordinary TES. This study presents a numerical model for a three-dimensional cascaded packed bed thermal energy storage system (PBTES), in which an effective thermal conductivity model is used by consisering the natural convection effects in each EPCM based on its volume average liquid fraction. To examine the system-storage thermal energy and exergy in PBTES accurately, a thermodynamic analysis approach is also given. The high-temperature PCMs are grouped as KNO3, NaNO3, and NaNO2 according to the phase transition temperature from high to low in the packed bed stage. The effects of element stages on the thermal performance of PBTES are studied. Results show that the total thermal energy storage of cascaded-PBTES is 38.5% higher than that of single-PBTES (KNO3), and the total thermal exergy storage is 30.8% higher than single-PBTES. The average exergy efficiency possessed by cascaded-PBTES is 5% higher than that of single-PBTES. Furthermore, the effects of heat transfer fluid (HTF) inlet temperature and mass flow rate on the thermal performance of cascaded-PBTES are discussed. The increase of inlet temperature and mass flow rate can promote the charging process and influence the exergy efficiency. However, increasing the inlet mass flow rate will not lead to an increase in maximum thermal energy and exergy storage capacity.

Magnetically Recyclable -SO3--Coated Nanoparticles Promote Gas Storage via Forming Hydrates.

Efficient gas enrichment approaches are of great importance for the storage and transportation of clean energy and the sequestration of carbon dioxide. Of special interest is the regulated gas hydrate-based method; however, its operation requires adequate additives to overcome the low-storage capacity issue. Thus, this method is not economically feasible or environmentally friendly. In this work, a novel recyclable hydrate promoter of copolystyrene-sodium styrenesulfonate@Fe3O4 (PNS) nanoparticles with an integrated core-shell structure was synthesized through emulsion polymerization. This was found to effectively reduce the induction time of methane hydrate formation by one-third compared with the widely used sodium dodecyl sulfate (SDS); the corresponding gas storage capacity was also comparable, up to 155 v/v. In addition, the PNS nanoparticles showed a good performance in foam inhibition upon hydrate decomposition, which frequently occurred with the use of SDS and other surfactant-based promoters. In particular, the new promoters contributed to a more than 30% increase in CO2 storage capacity, coacting with the fine sediments that mimic a marine environment. This provided further possibilities of sequestering CO2 in the form a gas hydrate under the seafloor. The underlying mechanism was proposed to involve anchored surfactants on the surface and tiny channels between the nanoparticles that lead to rapid hydrate nucleation and controlled growth. The results showed that the integrated magnetically recovering nanoparticles developed in this study could improve the efficiency of gas storage by forming gas hydrates; the excellent recycling performance paved the way for solving the economic and environmental problems encountered in additive usage.

Microstructure and work hardening behavior of Al–Cu–Li alloy (AA2198) in different temper conditions

In this paper, Al–Cu–Li alloy (AA2198) sheets have been imparted under different temper conditions to obtain different precipitate morphologies. The tensile testing of the samples in the solution treated, peak-aged, and over-aged conditions at ambient and cryogenic temperatures has been carried out to compare the hardening behavior. The strain hardening in the alloy is a strong function of the nature of obstacles present in individual temper conditions and extrinsic factors such as temperature. The decreased strain hardening capacity of peak-aged and over-aged samples is manifested in terms of a considerable decrease in uniform elongation. The effect of temperature is mainly manifested in terms of a decrease in dynamic recovery parameter and increase in dislocation storage capacity, irrespective of temper condition.

Enhancement of the performance of a proton battery

The present paper reports on experiments to improve theoretical understanding of the basic processes underlying the operation of a ‘proton battery’ with activated carbon as a hydrogen storage electrode. Design changes to enhance energy storage capacity and power output have been identified and investigated experimentally. Key changes made were heating of the overall cell to 70 °C, and replacement of the oxygen-side gas diffusion layer with a much thinner titanium-fibre sheet. A very substantial increase in reversible hydrogen storage capacity to 2.23 wt%H (598 mAh g−1, 882 J g−1) was achieved. This capacity is nearly three times that of the earlier design, and more than double the highest electrochemical hydrogen storage using an acidic electrolyte previously reported. It is hypothesised that the main cause of the major gain in storage is an enhanced water formation reaction on the O-side through reduced flooding. In addition, an alternative mode of discharging a proton battery has been discovered that allows direct generation of hydrogen gas from the hydrogenated carbon material, by a ‘hydrogen-pump’ type of reaction. The hydrogen gas evolved is high purity, and thus may ultimately create opportunities for use of this storage technology in hydrogen supply chains for fuel cell vehicles.

Growth in the Economic and Hydraulic Engineering Capacities Drives Water Quality Improvement in the Eastern Region of Nansi Lake, China

Knowledge of the extent of water pollution along a diversion channel is essential for ensuring the security and effectiveness of water diversion projects. Thus, identifying the trends in the water quality and the factors which influence the trends along a diverted river is a prerequisite to ensuring the safety of the water diversion. As an important control unit of the Eastern Route of the South to North Water Diversion Project, the hilly eastern region of Nansi Lake Basin (ENLB) suffers excess water pollution in the water transferred into Nansi Lake during the flood season. The comprehensive pollution index (CPI), the Mann-Kendall trend test and analysis of variances were used to characterize the spatiotemporal variation of water quality in the three main mountainous rivers of the ENLB. The contribution of different factors which influencing the variation of the water quality parameters may be explained using ridge regression analysis. The results showed that the CPI for the three major rivers decreased significantly from 2000 to 2012. The rivers had problems in compliance, and this was most noticeable in the Guangfu River. The main pollutants exceeding the water quality standards were the chemical oxygen demand and total phosphorus. The GDP per capita was the largest factor which influenced the changes in the regional water quality, with the average contribution being 30%. An increase in the water storage capacity was shown to have a positive effect on improving the water quality. The results provided a scientific basis for establishing a regional pollution control strategy and would give support to the planning of future water diversion projects.

Life cycle assessment (LCA) of a concentrating solar power (CSP) plant in tower configuration with different storage capacity in molten salts

Although studies on the levelized cost of energy (LCoE) of concentrating solar power (CSP) plants were published in recent years, these studies were not related to the environmental impact generated. To fill this literature gap, this study compares the environmental impacts generated by four tower solar thermal plants with different storage capacities, 3, 6, 9, and 17.5 equivalent hours in nominal conditions were considered, being the plant of 17.5 h, a plant in operation. Results show that the environmental impacts generated throughout its useful life decrease when storage capacity increases. But when the storage capacity goes from 9 h to 17.5 h, the impacts generated are practically the same. Of the four plants analyzed, the most environmentally efficient plant is the one with a storage capacity of 9 h.