Additional Storage Capacity Research Articles

Functional Protection of Exfoliated Black Phosphorus by Noncovalent Modification with Anthraquinone.

Few and monolayer black phosphorus (phosphorene) is currently an intensively researched material. Shear exfoliated black phosphorus (BPSE) nanosheets were functionalized with the redox active antraquinone (AQ) that can provide additional charge storage capacity. The noncovalent interaction of BP with AQ occurs due to van der Waals interactions. X-ray photoelectron spectroscopy results show that AQ coverage of BPSE nanosheets led to a stabilization against BPSE degradation. Electrochemistry of the BPSE-AQ shows that AQ is stably anchored onto BPSE and exhibits redox peaks stable for more than 100 cycles. The surface coverage by AQ on BPSE is estimated to be 1.25 nmol AQ/mg BP and electron-transfer rate constant ( kET) of 33 s-1. Furthermore, the proposed modification greatly increases the gravimetric capacitance of BPSE-AQ with respect to the starting BPbulk. Such coating of BP not only protects BP from degradation but also brings electroactive functionality to this two-dimensionally layered material.

Contribution of Model Predictive Control in the Integration of Renewable Energy Sources within the Built Environment

Integrating intermittent renewable energy sources has renders the power network operator task of balancing electricity generation and consumption increasingly challenging. Aside from heavily investing in additional storage capacities, an interesting solution might be the use predictive control methods to shift controllable loads towards production periods. Therefore, this paper introduces a systematic approach to provide a preliminary evaluation of the thermo-economic impact of model predictive control (MPC) when being applied to modern and complex building energy systems (BES). The proposed method applies an e-constraint multi-objective optimization to generate a large panel of different BES configurations and their respective operating strategies. The problem formulation relies on a holistic BES framework to satisfy the different building service requirements using a mixed integer linear programming technique. In order to illustrate the contribution of MPC, different applications on the single and multi-dwelling level are presented and analysed. The results suggest that MPC can facilitate the integration of renewable energy sources within the built environment by adjusting the heating and cooling demand to the fluctuating renewable generation, increasing the share of self-consumption by up to 27% while decreasing the operating expenses by up to 3% on the single building level. Finally, a preliminary assessment of the national-wide potential is performed by means of an extended implementation on the Swiss building stock.

Economic benefits of combining self-consumption enhancement with frequency restoration reserves provision by photovoltaic-battery systems

Residential and commercial photovoltaic (PV) battery systems are increasingly being deployed for local storage of excess produced PV energy. However, battery systems aimed at increasing self-consumption are not constantly put to use. Additional battery storage capacity is available for a second application to improve the profitability of an energy storage system. One of these options is the provision of frequency restoration reserves (FRR) to the electricity balancing market. This provision can be either negative to compensate for excess power supply, or positive to compensate for excess demand on the power market. This study assesses the benefits for residential and commercial PV-battery systems by combining PV energy storage for higher self-consumption with provision of FRR. Six battery storage dispatch strategies were developed and assessed on the technical and economic performance of 48 residential and 42 commercial PV-battery systems. These systems were modelled over their economic lifetime with a time resolution of 5 min and with historical energy consumption measurements and market prices. FRR provision results in a small drop in the self-consumption rate of 0.5%. However annual revenues are significantly increased. Using battery storage systems only for self-consumption is not profitable with the assumptions used in this study. Provision of negative FRR substantially reduces the electricity bought with the consumption tariff and increases investment attractiveness substantially. Prioritizing the provision of FRR over self-consumption enhancement results in even higher revenues, but significantly reduces self-consumption. We recommend FRR provision to economically investment in residential battery storage systems. Commercial systems need prioritization of both positive and negative FRR provision over self-consumption for a cost-effective investment. In conclusion, combining enhancement of PV self-consumption with the provision of frequency restoration reserves leads to profitable investments.

Encapsulating Silica/Antimony into Porous Electrospun Carbon Nanofibers with Robust Structure Stability for High-Efficiency Lithium Storage.

To address the volume-change-induced pulverization problems of electrode materials, we propose a "silica reinforcement" concept, following which silica-reinforced carbon nanofibers with encapsulated Sb nanoparticles (denoted as SiO2/Sb@CNFs) are fabricated via an electrospinning method. In this composite structure, insulating silica fillers not only reinforce the overall structure but also contribute to additional lithium storage capacity; encapsulation of Sb nanoparticles into the carbon-silica matrices efficiently buffers the volume changes during Li-Sb alloying-dealloying processes upon cycling and alleviates the mechanical stress; the porous carbon nanofiber framework allows for fast charge transfer and electrolyte diffusion. These advantageous characteristics synergistically contribute to the superior lithium storage performance of SiO2/Sb@CNF electrodes, which demonstrate excellent cycling stability and rate capability, delivering reversible discharge capacities of 700 mA h/g at 200 mA/g, 572 mA h/g at 500 mA/g, and 468 mA h/g at 1000 mA/g each after 400 cycles. Ex situ as well as in situ TEM measurements confirm that the structural integrity of silica-reinforced Sb@CNF electrodes can efficiently withstand the mechanical stress induced by the volume changes. Notably, the SiO2/Sb@CNF//LiCoO2 full cell delivers high reversible capacities of ∼400 mA h/g after 800 cycles at 500 mA/g and ∼336 mA h/g after 500 cycles at 1000 mA/g.

Convertible Operation Techniques for Pump Stations Sharing Centralized Reservoirs for Improving Resilience in Urban Drainage Systems

Pump stations prevent backwater effects from urban streams and safely drain rainwater in urban areas. Urbanization has increased the required capacity of centralized reservoirs and drainage pumps; yet, their respective designs are based on the runoff of the target watershed at the time of design. In Korea, additional pump stations are constructed to supplement the insufficient capacity of centralized reservoirs and drainage pumps. Two pump stations in the same drainage area share centralized reservoirs, and there are gates between them. Operation of the gates and drainage pumps is based on the water level in the connected centralized reservoirs. The convertible operation is based on changes in flow between two pump stations with different effluent streams in shared centralized reservoirs. Efficient distribution of inflow to both pump stations provides additional storage capacity in centralized reservoirs and rapid drainage. For a rainfall event in 2010, flooding volumes for current and convertible operations were 58,750 and 7507 m3, respectively. For an event in 2011, the corresponding figures were 3697 and 471 m3. This shows that resilience increased by 0.10829 and 0.00756, respectively, for the two events. Accordingly, a new technique to operate multiple pump stations for reducing urban inundation is proposed.

CO2 Storage as Dispersed Trapping in Proximal Areas of the Pearl River Mouth Basin offshore Guangdong, China

The Pearl River Mouth Basin aquifer is vast but only small hydrocarbon fields are present in proximal areas. Some of them are not filled to spill which could be due to poor cap rock quality. The sustainable CO2 column heights of the HZ21-1 field were calculated to estimate the CO2 storage capacity. If the lack of large hydrocarbon fields is due to insufficient cap rocks, CO2 storage capacity estimations based on volumetrics for the aquifer will lead to a capacity overestimation. Instead, hydrocarbon fields and additional storage capacity in the overburden due to dispersed trapping should be considered.

Binding SnO2 nanoparticles onto carbon nanotubes with assistance of amorphous MoO3 towards enhanced lithium storage performance

We report the synthesis of a novel SnO2/MoO3/carbon nanotubes (CNTs) hybrid (denote as SMC) via hydrothermally treating aqueous SnCl4-Na2MoO4-CNTs suspension. The hydrolysis of SnCl4 promotes the precipitation of Na2MoO4, resulting in the simultaneous coprecipitation of the amorphous MoO3 and SnO2 nanoparticles which attach onto the CNTs (Note that no MoOx is produced in the absence of SnCl4). When used as anode materials for lithium ion batteries (LIBs), the as-prepared SMC hybrid delivers a high reversible capacities of 1032 and 887mAh/g after 50 cycles at current densities of 200 and 500mA/g, respectively, and still retains a reversible capacity of 496mAh/g even after 200 cycles at a higher rate of 2A/g, which shows much better lithium storage performance than that of the counterpart hybrid of SnO2/CNTs (denote as SC, with only 569mAh/g after 50 cycles at 200mA/g). The enhanced electrochemical performance of SMC can be attributed to a synergistic effect, namely, MoO3 not only confines SnO2 nanoparticles onto the CNTs but also brings additional lithium storage capacity, while the flexible conductive CNT networks facilitate the charge transfer and electrolyte diffusion.

Seasonal storage and alternative carriers: A flexible hydrogen supply chain model

A viable hydrogen infrastructure is one of the main challenges for fuel cells in mobile applications. Several studies have investigated the most cost-efficient hydrogen supply chain structure, with a focus on hydrogen transportation. However, supply chain models based on hydrogen produced by electrolysis require additional seasonal hydrogen storage capacity to close the gap between fluctuation in renewable generation from surplus electricity and fuelling station demand. To address this issue, we developed a model that draws on and extends approaches in the literature with respect to long-term storage. Thus, we analyse Liquid Organic Hydrogen Carriers (LOHC) and show their potential impact on future hydrogen mobility. We demonstrate that LOHC-based pathways are highly promising especially for smaller-scale hydrogen demand and if storage in salt caverns remains uncompetitive, but emit more greenhouse gases (GHG) than other gaseous or hydrogen ones. Liquid hydrogen as a seasonal storage medium offers no advantage compared to LOHC or cavern storage since lower electricity prices for flexible operation cannot balance the investment costs of liquefaction plants. A well-to-wheel analysis indicates that all investigated pathways have less than 30% GHG-emissions compared to conventional fossil fuel pathways within a European framework.

Climate change enhances interannual variability of the Nile river flow

Nile basin countries are expected to double their population by 2050. Observations and climate model projections now suggest water resources may be additionally stretched by a 50% (±35%) increase in interannual Nile flow variability in the twenty-first century. The human population living in the Nile basin countries is projected to double by 2050, approaching one billion1. The increase in water demand associated with this burgeoning population will put significant stress on the available water resources. Potential changes in the flow of the Nile River as a result of climate change may further strain this critical situation2,3. Here, we present empirical evidence from observations and consistent projections from climate model simulations suggesting that the standard deviation describing interannual variability of total Nile flow could increase by 50% (±35%) (multi-model ensemble mean ± 1 standard deviation) in the twenty-first century compared to the twentieth century. We attribute the relatively large change in interannual variability of the Nile flow to projected increases in future occurrences of El Nino and La Nina events4,5 and to observed teleconnection between the El Nino–Southern Oscillation and Nile River flow6,7. Adequacy of current water storage capacity and plans for additional storage capacity in the basin will need to be re-evaluated given the projected enhancement of interannual variability in the future flow of the Nile river.

Investment decisions in imperfect power markets with hydrogen storage and large share of intermittent electricity

This paper analyzes the impact of hydrogen as energy storage on production and investment decisions in an electricity market when individual participants behave strategically. We develop a game-theoretic model on investment and generation game à la Cournot under the open-loop information structure. This framework is implemented as a mixed complementarity problem and applied to the German case assuming the phase-out of the German nuclear power plants, rising renewable energy supply and increasing energy demand for electric vehicles. The numerical results of our analysis indicate that utilization of energy storage has a positive effect on energy systems with large amount of intermittent electricity and inelastic demand. We find that additional hydrogen storage capacities improve system reliability, increase overall welfare and decrease GHG emissions. Adding demand for hydrogen as a fuel for FCEVs allows for a synergetic use of the technology and changes the investment incentives for energy storage. Although the power-to-gas technology has a price-smoothing effect the overall generation capacity is higher with energy storage providing additional supply security in markets with a large amount of intermittent energy production.

Mechanical and thermal evaluation of different types of PCM–concrete composite panels

The thermal mass of construction materials can be used to reduce the energy required for heating and cooling buildings. The heat storage capacity of concrete can be increased by incorporating phase change materials (PCMs) and hence providing a latent heat storage capacity. However, the addition of PCMs to concrete can reduce its conductivity due to the low conductivity of the PCMs. This hinders the efficient utilisation of the additional heat storage capacity provided by the PCM. Two types of PCM–concrete composite panels were manufactured. Firstly, a panel was formed by adding microencapsulated paraffin to fresh concrete during the mixing process. Secondly, butyl stearate was vacuum impregnated into lightweight aggregate which was then included in the concrete mix. In order to counteract the reduction in conductivity caused by the PCM, a second group of PCM–concrete composite panels were made using ground granulated blast-furnace slag (GGBS) as a partial cement replacement. The use of GGBS results in a denser cement paste which, for a given aggregate type, increases the conductivity of the concrete. This study aimed to establish which type of PCM–concrete composite material was most effective at improving the thermal mass behaviour of the panel and also to evaluate the effect that the PCM had on the relevant properties of concrete. The effect of GGBS on the thermal performance of the panels is reported.

Scientifically advanced woody media for improved water quality from livestock woodchip heavy-use areas

Overwintering cattle on pastures in many areas can damage the pasture and lead to impaired water quality. During these times, use of a woodchip heavy-use area (HUA) presents advantages such as a soft, supportive, and dry foot surface for animals and protection of the pasture and pasture soils. However, woodchip HUAs can also be a centralized source of high nutrient loads due to their drainage outflows. A column study was conducted to assess the nutrient load reduction potential of: 1) six types of wood media (including torrefied wood media and biochar) that could be used in a woodchip HUA versus a gravel control, and 2) providing a 48 h retention time within the wood media to enhance nitrogen removal through denitrification. The woody media provided significant liquid waste volume reduction compared to the gravel in simulated events (53%–61% vs. 39% reductions, respectively), and there may be additional liquid storage capacity in the woodchips not utilized during these rapid events. Substantial total nitrogen removal by the wood treatments (mean removal efficiencies >50%) was observed across the simulated events, although nitrate leaching also occurred. Nitrate removal was enhanced during the 48 h retention test which showed removal was governed by availability of labile carbon (i.e., fresh woodchips exhibited >70% nitrate removal). The retention test also indicated biochar mixtures provided some of the best total phosphorus removal, but the greatest benefits across all parameters was provided by the Mixed Hardwood treatment.

Automated Moving Object Classification in Wireless Multimedia Sensor Networks

The use of wireless multimedia sensor networks (WMSNs) for surveillance applications has attracted the interest of many researchers. As with traditional sensor networks, it is easy to deploy and operate WMSNs. With inclusion of multimedia devices in wireless sensor networks, it is possible to provide data to users that is more meaningful than that provided by scalar sensor-based systems alone; however, producing, storing, processing, analyzing, and transmitting multimedia data in sensor networks requires consideration of additional constraints, including energy, processing power, storage capacity, and communication. Furthermore, as multimedia sensors produce much more data than scalar sensors, more manpower is required to analyze multimedia data. To overcome these constraints and challenges, this paper aimed to propose a system architecture and a set of procedures for WMSNs that facilitate automatic classification of moving objects using scalar and multimedia sensors. Methods and standards for detecting and classifying a moving object, as well as transmission of the results, are described in detail. The hardware for each sensor node includes a built-in camera, a passive infrared motion sensor, a vibration sensor, and an acoustic sensor. An application using our proposed methods was developed and embedded in the multimedia sensor node. In addition, a sink station was set up and the data produced by the sensor network was collected by this server. The classification performance of the application was tested using video recorded by the sensor node. The effect of the proposed methods on power consumption was also tested and measured. The experimental results show that the proposed approach is sufficiently lightweight to be used for real-world surveillance applications.

Long-term safety of the extended SFR - Methodology and conclusions from the SR-PSU project

ABSTRACTSince 1988 the Swedish Nuclear Fuel and Waste Management Co. operates a repository for low- and intermediate-level short-lived radioactive waste, SFR, in Forsmark, Sweden. Due to decommissioning of the nuclear power plants additional storage capacity is needed. In December 2014, an application to extend the repository was therefore submitted. One key component of this application was an assessment of post-closure safety of the extended SFR. For this safety assessment, a methodology based on that developed by SKB for the spent nuclear fuel repository was used and the impact of the degradation of repository components, the evolution of the surface system and changes of future climate on the radiological safety of the repository was assessed over a period of 100,000 years. The central conclusion of the SR-PSU safety assessment is that the extended SFR repository meets requirements on protection of human health and of the environment that have been established by the Swedish radiation safety authority for the final disposal of radioactive waste. Furthermore, the design of the repository was shown suitable for the waste selected and the applied methodology suitable for the safety assessment.

Opportunities for increasing CO2 storage in deep, saline formations by active reservoir management and treatment of extracted formation water: Case study at the GreenGen IGCC facility, Tianjin, PR China

Carbon capture, utilization and storage (CCUS) seeks beneficial applications for CO2 recovered from fossil fuel combustion. This study evaluated the potential for removing formation water to create additional storage capacity for CO2, while simultaneously treating the produced water for beneficial use. The process would control pressures within the target formation, lessen the risk of caprock failure, and better control the movement of CO2 within that formation. The project plans to highlight the method of using individual wells to produce formation water prior to injecting CO2 as an efficient means of managing reservoir pressure. Because the pressure drawdown resulting from pre-injection formation water production will inversely correlate with pressure buildup resulting from CO2 injection, it can be proactively used to estimate CO2 storage capacity and to plan well-field operations. The project studied the GreenGen site in Tianjin, China where Huaneng Corporation is capturing CO2 at a coal fired IGCC power plant. Known as the Tianjin Enhanced Water Recovery (EWR) project, local rock units were evaluated for CO2 storage potential and produced water treatment options were then developed. Average treatment cost for produced water with a cooling water treatment goal ranged from 2.27 to 2.96 US$/m3 (recovery 95.25%), and for a boiler water treatment goal ranged from 2.37 to 3.18 US$/m3 (recovery 92.78%). Importance analysis indicated that water quality parameters and transportation are significant cost factors as the injection-extraction system is managed over time. The study found that in a broad sense, active reservoir management in the context of CCUS/EWR is technically feasible. In addition, criteria for evaluating suitable vs. unsuitable reservoir properties, reservoir storage (caprock) integrity, a recommended injection/withdrawal strategy and cost estimates for water treatment and reservoir management are proposed.

Cost assessment of storage options in a region with a high share of network congestions

In Germany’s federal state of Schleswig–Holstein (S–H) the installed capacity of distributed electricity generation from renewable energy sources has been growing faster than the transmission capability of the distribution and transmission networks. Currently, this causes network congestions and requires corrective measures such as curtailment. Hence, around 3.5% of renewable production in S–H was curtailed in 2012. As one potential option for reducing these yield losses, energy storage has been suggested. Costs of different storage technologies used for this purpose are investigated in this paper. Detailed empirical data from recent years is used to assess the characteristics of curtailment actions. The analysis shows that storage’s cycling intensity is low while the power intensity is potentially high on the distribution grid level. From a transmission grid perspective, congestions are analysed studying the residual load exepected in a 2025 scenario in combination with current and future capacities to and from S–H. The results suggest that considerable amounts of surplus situations for a potential utilisation by energy storage only occur with current transfer capacities and diminish with the planned transmission grid expansion. By looking at the cost assessment results on both the distribution and transmission grid level, it is obvious that solely utilising current and 2025 levels of curtailed energy does not allow the cost recovery for any of the considered storage technologies. Hence, additional storage capacity in S–H for reducing curtailment losses is only viable if complementary use cases can be found or parts of the investment costs can be socialised or if the costs of storage technologies drop significantly.

Feasibility analysis of using closely spaced caverns in bedded rock salt for underground gas storage: a case study

A closely spaced caverns design for large-scale underground gas storage (UGS) is proposed, in which four caverns compose one group. The pillar widths between adjacent caverns are 0.7D in the same group and 1.5D between different adjacent groups (D is the maximum diameter of the cavern). Caverns in the same group operate with the same injection–production mode to decrease the negative effects of running parameters on the pillar safety. Thicknesses of salt between the cavern and the upper and lower mudstone layers are about 15 m. To verify the design, a three-dimensional geomechanical numerical model is built by ANSYS software, taking into account Jintan salt mine strata characteristics, mechanical behavior properties and running of the UGS, to monitor the deformations and stresses of the model. The deformations, volume shrinkages, plastic zone extension and configuration, equivalent strain, and safety factor are studied with the three-dimensional geomechanical numerical model. The results obtained by the numerical simulations and the model experiments show that the three-dimensional geomechanical numerical model has a high accuracy, the safety of the closely spaced caverns UGS can be ensured under different running conditions, and the proposed design has a good feasibility. This design can double the number of caverns of the original design and provide additional storage capacity of about 10 × 104 m3 for a single cavern. This approach can be implemented for similar projects in other places.

Evaluation of Multiple Stress Creep and Recovery (MSCR) Data for Arizona

In the recently released AASHTO M332 asphalt binder specification, the Multiple Stress Creep and Recovery (MSCR) test replaces the current modulus and phase angle based method used for high temperature characterization. In anticipation of possible future adoption of this standard, the Arizona Department of Transportation (ADOT) has cataloged Multiple Stress Creep and Recovery (MSCR) test results on more than 375 different asphalt binder samples dating back to 2008. In this paper, this database is reviewed to evaluate potential implications of the adoption of a revised grading procedure based on the outcomes from the MSCR test. The database is graded in both the current and the M332 system to compare temporal changes in asphalt binder under both systems. The standard is then evaluated for its ability to detect polymer modified asphalt binder supplied in Arizona, and for the interaction between grade and temperature. It is found that under the M332 system the number of required grades for the state of Arizona would increase from the current number of eight to a total of fourteen. Future work includes the reduction of the total number of grades through engineering judgment and knowledge of asphalt binder selection based on local Arizona conditions. Under this review, Arizona asphalt binder suppliers may not necessarily have to add additional storage capacity to their facilities to accommodate a transition to the M332 standard.

Combination of genetic network programming and knapsack problem to support record clustering on distributed databases

This research involves implementation of genetic network programming (GNP) and standard dynamic programming to solve the knapsack problem (KP) as a decision support system for record clustering in distributed databases. Fragment allocation with storage capacity limitation problem is a background of the proposed method. The problem of storage capacity is to distribute sets of fragments into several sites (clusters). Total amount of fragments in each site must not exceed the capacity of site, while the distribution process must keep the relation (similarity) between fragments within each site. The objective is to distribute big data to certain sites with the limited amount of capacities by considering the similarity of distributed data in each site. To solve this problem, GNP is used to extract rules from big data by considering characteristics (value ranges) of each attribute in a dataset. The proposed method also provides partial random rule extraction method in GNP to discover frequent patterns in a database for improving the clustering algorithm, especially for large data problems. The concept of KP is applied to the storage capacity problem and standard dynamic programming is used to distribute rules to each site by considering similarity (value) and data amount (weight) related to each rule to match the site capacities. From the simulation results, it is clarified that the proposed method shows some advantages over the conventional clustering algorithms, therefore, the proposed method provides a new clustering method with an additional storage capacity problem.

Origin of the Increased Li+‐Storage Capacity of Stacked SnS2/Graphene Nanocomposite

AbstractThere has been strong recent interest in using SnS2/graphene nanocomposites for reversible Li+ storage. Although SnS2 and graphene are 2D nanomaterials, many of their composites reported to date have a random 3D structure. We present here a stacked SnS2/graphene nanocomposite that retains many of the original 2D features of the graphene nanosheets. As a result, significantly improved Li+‐storage properties were shown including: 1) good cycle stability (delithiation capacity of 1063 mAh g−1 for 100 cycles at 200 mA g−1 and 918 mAh g−1 for 500 cycles at 1 A g−1); 2) high first‐cycle coulombic efficiency (89.7 %); 3) high reversibility of the conversion reaction SnS2+4 Li++4 e−→Sn+2 Li2S (87.5 %); and 4) high rate performance (712 mAh g−1 at 5 A g−1). Such good performance corresponds well with a 2D construction, in which Sn nanoparticles are firmly held by graphene nanosheets. The conversion reaction becomes more reversible in the presence of the Sn nanoparticles to contribute to the additional storage capacity.