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[Display omitted] • Various carbon nanotube-based devices are developed for solar energy utilization. • The water evaporation system can generate freshwater (1.28 kg m−2h−1). • The solar-thermoelectric system can output a voltage and charge a cellphone. • The supercapacitor performs an areal specific capacitance of 19.6 mF cm−2. • The hybrid energy system can produce freshwater, generate and store electric power. Nowadays, multi-functional systems driven by solar energy have been explored to alleviate the crisis of energy and freshwater scarcity. However, it remains a great challenge to integrate multi-functions into one hybrid system with a monolithic material, which can harvest, convert and store solar energy synergistically. Here, we firstly propose a multi-functional carbon nanotube paper, which starts from a material level to solve these problems. The carbon nanotube paper is fabricated by vacuum filtration. It exhibits high efficiency of solar-thermal conversion. Secondly, three types of energy conversion/storage systems (e.g., solar-thermal evaporation system, solar-thermoelectric generation system, and supercapacitor) are constructed based on the carbon nanotube paper, which extend the research to a device level. The solar-thermal evaporation system shows an evaporation rate of 1.28 kg m-2h−1 under simulated sunlight irradiation of 1 kW m−2. The solar-thermoelectric generation system demonstrates a stable electric power generation with an output voltage of 100 mV under light irradiation of 1 kW m−2. The supercapacitors perform the energy storage function with an areal specific capacitance of 19.6 mF cm−2. These devices and systems can be used in freshwater generation (0.84 kg m-2h−1, sunlight irradiation of 1 kW m−2), water purification/desalination (inorganic ions rejection larger than 99.9%) and portable solar charging system (maximum output voltage of 5 V). Finally, a hybrid energy system is innovatively proposed from the system level to simultaneously produce freshwater, generate and store electric power. Through the synergetic coupling of solar conversion and storage technologies, the hybrid energy system can supply sustainable freshwater and electricity for remote areas in daily life, highlighting the superiority of multi-energy (thermal energy, electrical energy, and electrochemical energy) complementary. [ABSTRACT FROM AUTHOR]

• Linear planning models of two types of compressed air energy storage are proposed. • A novel electricity-gas coupled energy hub for cascade utilization is structured. • Comparisons between energy-based and capacity-based energy storage are analyzed. Large-scale long-duration energy storage (LDES), like compressed air energy storage (CAES) and liquid air energy storage (LAES), is promising for high-penetration renewable energy consumption in the city-scale integrated energy system (IES). Due to high installation costs and challenges in decentralized control of distributed energy storage, this paper proposes an optimal planning model for an urban electricity-gas coordination hub (UEGCH) with centralized energy storage using large-scale LDES. Firstly, the UEGCH with energy cascade utilization is designed, where process-based linearized models of advanced adiabatic compressed air energy storage (AACAES) and LAES are established to make a trade-off between solving accuracy and speed. Then, a city-scale integrated electricity and gas system (IEGS) is constructed with multiple regions considering line-packing. Finally, a multi-scenario planning method is proposed based on X-means for scenario reduction, and the global optimum is obtained through linearization. Results show that compared with traditional gas storage tank (GST) in the UEGCH, the utilization of AACAES and LAES requires as little as 7 % and 0.7 % of the construction volume with lower carbon emissions and can be cost-competitive in terms of future advancement. As for different EESs, in contrast to the energy-based energy storage (EBES) (i.e., battery (BT)), the levelized cost of energy (LCOE) of the capacity-based energy storage (CBES), which includes AACAES and LAES, can be reduced by nearly 0.1 $/kWh, bringing an annual economic benefit of $ 3 million. Besides, the discharge duration of CBES can be increased to 13 h, demonstrating the application prospect in 100 % renewable consumption and islanding operation. Compared with AACAES, LAES can reach 11.67 times the energy density, with a drop of 6.11 % in operating cost. The abilities of EBES and CBES to locally consume renewables are respectively weaker and stronger than that of power-to-gas (P2G) combined with line-packing. Meanwhile, this paper further analyzes the impacts of temperature, discharge duration, renewable penetration, energy tariff, and demand on the operation and sizing of centralized energy storage. [ABSTRACT FROM AUTHOR]

[Display omitted] • PCM energy storage and PV/T coupled multi-source heat pump systems were combined. • The thermal performance, energy efficiency, and economy of the system were analyzed. • The performance of paraffin C17 and water as energy storage materials were compared. • The performance of six low-temperature PCMs applied to the system were analyzed. • Compared to the existing system, it saves 56 % of energy and 27.7 % of operating costs. To improve the application of renewable energy in the heating zone, as well as to address the limitations of air and water source heat pump. The study presents a PV/T (photovoltaic/thermal) coupled air–water source heat pump system integrated with phase change energy storage. A theoretical analytical model and TRNSYS simulation model of the system were developed to evaluate the thermal performance, energy efficiency and economics of the system. The performance of phase change energy storage was compared with that of water storage, and the effect of different phase change materials on the system characteristics. The results show that the coupled system achieves a seasonal performance factor of 2.3, a 56 % reduction in energy consumption, and a 27.7 % reduction in operating costs compared to a conventional gas boiler system. Comparative analysis with the water storage system showed that the system equipped with phase change materials performed well in terms of energy consumption, operating costs and heating stability. In addition, the density of the phase change material has a biased effect on the overall performance of the system. This paper can provide a reference value for the study of renewable energy heating systems in cold zone. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Energy storage systems for series hybrid excursion ships are studied. • CO2 emission are avoided during the casting-off and the docking maneuvers. • Full model using Energetic Macroscopic Representation (EMR) is described. • 1.39 kg of CO2 during the casting-off/docking maneuvers can be avoided. • Global consumption and emissions can be reduced by 20%. Abstract Ecological areas visits require appropriate management of key ecological features. In protected reserves innovative systems should be developed to facing problems of pollution, exhaust fumes and noise. These underlying conditions lead to special challenges for excursions ships. The switching to a cleaner, safer and quieter transport system seems to be a sustainable long-term solution for the problems of ecological areas, where more electric ship can be an important part of the solution and principally for the last mile. This paper presents a design approach of a hybrid Energy Storage Systems (ESS) for new generation of series hybrid excursion ship devoted to ecological areas to avoid any emission during the casting-off and the docking maneuvers. The main purpose of the paper is to show that, even if the hybrid ESS plus series-hybrid propulsion were already used to other vehicles, the gain for a ship with no regenerative capability is not evident. The proposed hybridization is built upon a fully-active parallel topology with battery and supercapacitors. The sizing methodology and the configuration of the ESS are detailed. For a real mission profile in Alster Lake (Hamburg, Germany) it is shown that a small battery pack of 2 kWh with a supercapacitor bank of 0.54 kWh are necessary to have zero-emission maneuvers. The graphical formalism Energetic Macroscopic Representation (EMR) is used to describe the model and to establish an energy analysis tool. An inversion-based control scheme is then deduced from the EMR and simulation results are provided to validate the proposed methodology. The usage of hybrid ESS avoids 1.39 kg of CO 2 during the casting-off and docking maneuvers despite increasing consumption of 0.2 l (+8%). However, the plug-in capability can be introduced and a recharge of the battery when the ship is docked could reduce the global consumption and emissions by 20% in comparison to the original ship. [ABSTRACT FROM AUTHOR]

• A comparison method between energy-only and energy and reserve model. • Higher revenue for flexible technologies was achieved for joint model. • The down reserve proved to be more required in high RES systems. • The study showed significant difference in operation between two models. The requirements for ancillary services in energy systems are growing as the amount of renewable energy sources such as solar and wind increases. On the other hand, the system can benefit from extra sources of flexibility thanks to the increased digitalization that enables successful integration of demand response and energy storage. The majority of recent energy system analysis research did not consider the regulation markets. As a result, these investigations preclude the ability to fully evaluate the advantages of energy storage and flexible cooling loads. With the method outlined in this paper, it is possible to compare the two strategies and assess the advantages of energy storage and flexible cooling loads for each strategy. In addition to the energy storage systems, the case study in this paper focuses on flexible cooling loads as a significant consumer in the system. According to the findings, the system's operating costs increased by 19.4% when reserve limitations were placed. Furthermore, the findings demonstrated that when flexible assets were permitted to participate in the reserve market, they generated significantly higher incomes. According to the findings, mechanisms that will allow energy storage and demand response to provide reserve capacities as well as the growth of reserve markets are both necessary. [ABSTRACT FROM AUTHOR]

• A CCHP system based on solar energy and thermochemical energy storage is proposed. • Increasing the share of solar energy used in combined cooling, heating and power (CCHP) systems. • The 4E analysis and parameter study of the system are carried out. • The SPECO method is done and provides direction for the optimization of the system. • The effects of the main parameters on the system performance were evaluated. The combination of calcium looping and concentrating solar power (CSP) is a promising energy conversion technology that can greatly increase the share of solar energy used in combined cooling, heating and power (CCHP) systems. This paper designs a CCHP system based on solar energy and thermochemical energy storage. The system runs all day through day and night modes. Under basic working conditions, the energy and exergy efficiencies of the system could reach 56.92 % and 35.94 %, respectively. The system is evaluated by multiple approaches including parametric sensitivity analysis and 4E (energy, exergy, economy and environment)) analyses. The results demonstrate that the system could produce 2618.09 MW of electricity, 305.56 MW of heat and 523.88 MW of cooling capacity per day, respectively. At the same time, the reductions of CO 2 emissions and fossil fuel consumption could reach 2222.76 tons and 696.41 m3 per day, respectively. Furthermore, the increasing mass flow of main turbine inlet could increase both the system efficiency and the exergy efficiency. Thus, it is beneficial to reduce the environmental impact but with the increasing investment cost. In the meanwhile, the exergoeconomic factor and exergoenvironment factor of the system were 55.65 % and 0.139, respectively. Besides, as the extraction flow rate of the intermediate pressure turbine increases, the energy efficiency increases but the exergy efficiency descends. This is unfavorable to reducing the environmental impact, yet it could decrease the investment cost of the system. These results reveal that the hybrid system has the characteristics of high efficiency and emission reduction in energy storage, power generation, heating and cooling, and has great development potential. [ABSTRACT FROM AUTHOR]

• A hierarchical energy management strategy with life balance control is proposed. • A dynamic threshold control of ultracapacitor SOC is designed for optimization. • Life-cycle average operating cost is defined to evaluate the comprehensive economy. • A hardware-in-the-loop platform is built to verify the effectiveness. • The proposed strategy has better life mileage compared with the DP strategy. Fuel cell (FC) is an ideal power source for electric vehicles with high efficiency and little pollution. However, with its weak dynamic reaction, it needs to be used in combination with other energy storage devices, and the coupling of multiple energy sources makes it difficult to fully utilize the system performance. Meanwhile, the cost and durability of FC hinder its commercialization. This paper takes the composite energy storage system composed of FC, battery (BAT) and ultracapacitor (UC) as the research object. In order to improve the system performance, a hierarchical energy management strategy is proposed based on the analysis of the relationship between UC output power and vehicle demand power under dynamic programming (DP) strategy, taking into account the vehicle energy consumption and energy source lifetime. A fuzzy control based on speed prediction and a dynamic state-of-charge (SOC) threshold control optimization algorithm of UC based on working condition recognition are designed to optimize the hierarchical control strategy. In the upper layer strategy, for realizing the online real-time distribution of UC output power, the generalized regression neural network is used to learn the relationship between UC output power and demand power under DP strategy; in the lower layer strategy, the power of the FC and BAT is distributed using an equivalent energy minimization strategy. Based on above strategy, this paper proposes a life balance control strategy for energy sources to maximize the lifetime of the composite energy storage system. Simulation and experimental results show that the proposed strategy has a comparable life-cycle average operating cost to the DP strategy with better life mileage. [ABSTRACT FROM AUTHOR]

The droop method is an advantageous technique for stand-alone AC supply systems, allowing for power sharing among various inverters with no need for communication cables. However, in stand-alone systems with multiple distributed energy storage units, the conventional droop methods are unable to control the storage unit state-of-charge (SOC) in order to change simultaneously. Existing techniques endeavor to solve this problem by changing the slope of the P – f curve however this solution compromises the power response performance. As an alternative, this paper proposes a new SOC-based droop control, whereby the P – f curve is shifted either upwards or downwards according to the battery SOC. The proposed technique makes it possible to select the time constant for the battery SOC convergence and, at the same time, to optimize the power response performance. The paper also shows how the SOC changes when the ratios between the battery capacity and the inverter rated power are different and how the proposed technique can limit the SOC imbalance. Simulation and experimental results corroborate the theoretical analysis. [ABSTRACT FROM AUTHOR]

Generally, off-grid fossil fuel generators provide energy supply to remote regions. The integration of photovoltaic (PV) plants to battery energy storage (BES) systems potentially increases reliability, the system autonomy and lifetime, reducing the generator working hours and the system environmental impact. PV–BES–Diesel generator hybrid energy systems (HESs) offer technical, economic and environmental benefits compared to traditional off-grid systems. This paper proposes a bi-objective design model for off-grid PV–BES–Diesel generator HESs. The aim is to identify the PV plant rated power, the BES system capacity and the technical configuration able to jointly reduce the levelised cost of the electricity ( LCOE ) and the carbon footprint of energy ( CFOE ) . Furthermore, the comparison of the LCOE and CFOE values of the HES against a traditional diesel generator allows determining the economic and environmental advantages coming from the described system. Despite the proposed model is general and suitable for any installation site and HES configuration, this paper exemplifies its application designing a HES to be installed in a remote village in Yakutsk, Russia. The model takes into account the hourly energy demand, the irradiation and temperature profiles of the installation location calculating the hourly PV plant yield, the battery charge–discharge processes and the required generator energy. Results highlight the technical, economic and environmental feasibility of the system for a context with a medium irradiation level, i.e. ∼1400 kW h/(m 2 year), and relatively low fuel cost, i.e. 0.7 €/l. For the best economic scenario LCOE and CFOE reductions are of about 8% and 28%, respectively. Finally, the most effective trade-off between economic and environmental performances leads to a CFOE decrease of about 48% and a slight decrease of the economic performances (−2%). [ABSTRACT FROM AUTHOR]

Concentrating solar power plant coupling with thermal energy storage is a popular technology during the solar application process. A multitude of researches focus on improving heat transfer performance of the whole system for getting the higher efficiency and lower cost. In this paper, a new storage tank for concentrating solar power has been designed, and the mathematical model of one-dimensional unsteady state heat conduction in cylindrical coordinates has been established and validated. Also, the charge time and the temperature of the tank have been investigated in the designing conditions based on this model. The results show that the new storage tank has a superior performance for the system in the charge period. The charge time from unsteady state to steady state heat conduction for the tank is about 9923 s. It can be found that there is a relatively good agreement of about 18.9% for the charge time between the mathematical model and the reference. The curve of the temperature versus the charge time for different thermal properties of the materials based on the model of this paper has been investigated. The results can provide a good reference for designing, operating, and energy-saving of thermal energy storage for concentrating solar power plants. [ABSTRACT FROM AUTHOR]

This paper presents a study evaluating the effects of charge controller operation and coulombic efficiency on stand-alone hybrid power systems. The model used in the study makes it possible to consider the uncertainty related to renewable resources, fuel cost, the battery bank's lifetime, energy demand, charge controller operation, and coulombic efficiency. As a case study, a hybrid system installed in Zaragoza, Spain, was analysed. The system includes photovoltaic panels, a wind turbine, a conventional diesel or gasoline generator, and a battery bank. First, the impact of charge controller operation and coulombic efficiency was studied through a comparative analysis of both the model presented in this paper and another that does not offer the ability to consider the charge controller operation or the relation between coulombic efficiency and the state of charge. The results show a difference between the models of approximately 33% in the number of hours of operation of a conventional generator, 31% in fuel consumption, and 31% in net present cost for hybrid power system configurations with low storage capacity. However, these differences were reduced when the capacity of the battery bank was increased because the charge currents were reduced, the acceptance of charge by the battery bank was improved, and the effect of the charge controller was minimised. Finally, a sensibility analysis was carried out for different sizes of battery banks, obtaining uncertainty in the net present cost, which depends on fuel cost and uncertainties about the battery bank's lifetime. [ABSTRACT FROM AUTHOR]

• A novel polygeneration liquid air energy storage system is presented. • An alternative strategy for cold energy utilization is proposed. • Hydrate based processes are integrated to coproduce potable water. • Electrical round-trip and exergy efficiencies of 145.57 % and 72.34 % are achieved. • The advanced system has a high positive net present value of 158.17 million USD. Energy management and freshwater production are recent social concerns due to the population explosion. However, conventional liquid air energy storage (LAES) systems and desalination approaches face low efficiency and high energy consumption challenges. The present paper proposes a novel LAES system coupled with LNG cold energy, solar energy, and hydrate based desalination (HBD) to bridge the research gap at the intersection of electricity and freshwater production. The system develops the respective integration of external cold and heat sources in energy storage and release processes to strengthen the operational characteristics. Additionally, the proposed LAES employs HBD systems in LNG regasification and energy release processes, thus taking advantage of underutilized cold energy. The non-dominated sorting genetic algorithm II is developed to obtain the optimum operating parameters regarding peak shaving and water production. The optimized system is thoroughly analyzed from the energy, exergy, and economic perspectives. The results indicate that the system with 2805.26 tons of daily freshwater production has an electrical round-trip efficiency of 145.57% and an exergy efficiency of 72.34%. A high positive net present value of 158.17 million USD is achieved. Overall, the efficient system, with superior techno-economic performance, provides an extraordinary alternative to enhance the energy management-water nexus in grid dimensions. [ABSTRACT FROM AUTHOR]

Abstract: The paper reports guidelines for the efficient design and sizing of Small-Scale Compressed Air Energy Storage (SS-CAES) pressure vessels, including guidelines for pressures that should be used in the SS-CAES system to minimize the cost of the pressure vessel. Under a specified energy storage capacity and specified maximum and minimum operating pressures in CAES, the volume of the vessel(s) can be evaluated. The present study provides guidelines for choosing appropriate shape and size for the vessels that minimize material and manufacturing cost for cylindrical vessels. The two main contributions of the paper are that it provides a methodology to determine: (a) an optimum pressure; (b) the shape, size, and number of vessel to be used in a particular application. Results suggest that pressure vessels with a length to diameter ratio of roughly three are the most economical, and that a system should be designed for a pressure of roughly three times the minimum pressure of the expansion device. [Copyright &y& Elsevier]

• Battery transport and logistics to increase renewable use and system flexibility. • Full train transport and carpooling to improve the economics of battery use. • Levelized cost of energy of battery transport & logistics is $0.045/kWh averagely. High share of variable renewable energy is challenging to the traditional power system technically and economically. This calls for a significant increase to the system flexibility, which might result in the costs associated with energy storage and costly upgrades to the traditional transmission and distribution system. This paper presents a multi-stage battery transportation and logistics optimization method to increase the renewable energy consumptions, economics, and mobilities of the battery utilization. A new approach is proposed in which the batteries are charged in the renewable power plants and transported back and forth by railways between the renewable power plants and cities. Based on the forecasts of battery supplies/demands, multiple optimization stages (full train transport and carpooling) are designed by the branch-and-bound algorithm and genetic algorithm respectively. The proposed battery transportation and logistics concept and model are performed using the Beijing-Tianjin-Hebei region in China as an example. The results show that the levelized cost of energy of the battery transportation and logistics model is $0.045/kWh averagely. Also, by the use of mobilized batteries, the proposed battery transportation and logistics model increases the system flexibilities and renewable energy deliveries to the end users without the reinforcement of transmission and distribution system and any constraint from a highly penetrated power system. [ABSTRACT FROM AUTHOR]

Abstract: This paper assesses impact of using phase change materials (PCM) in buildings to leverage its thermal energy storage capability. The emphasis is from an electricity demand side perspective with case studies that incorporates wholesale electricity market data of New Zealand. The results presented in this paper show that for space heating application significant advantages could be obtained using PCM built structures. These positive impacts include peak load shifting, energy conservation and reduction in peak demand for network line companies and potential reduction in electricity consumption and savings for residential customers. This paper uses a testing facility that consists of two identically designed and shaped offices built at Tamaki Campus location of the University of Auckland, New Zealand. The walls and ceilings of one office are finished with ordinary gypsum boards while the interior of the other office is finished with PCM impregnated gypsum boards. Controlled heating facility is provided in both the offices for maintaining temperature within the range of human comfort. This facility is equipped with advanced data acquisition equipment for data monitoring and archiving both locally within the offices and also remotely. Through actual observations and analysis this paper demonstrates two major impacts of DSM. First, the application of phase change material (PCM) in building environment enabling efficient thermal storage to achieve some reduction in the overall electrical energy consumption. Second, assessment of peak load shifting achieved for space heating in a PCM building during a typical winter period in New Zealand. [Copyright &y& Elsevier]

Highlights • Evacuated tube solar collectors integrated with phase change materials are investigated. • The phase change process and the system performance are affected by the flow rates. • Under high flow rate, the system does not achieve a thermal energy storage benefit. • A correlation is presented to express discharge time as a function of temperature. Abstract This paper presents an experimental investigation of the performance of evacuated tube solar collectors integrated with Phase Change Materials systems. The performance of these systems depends on the thermal charging and discharging of the phase change materials. One of the important heat transfer parameters concerning these systems is the phase change process. Such a process depends on the flow rate of the heat transfer fluid and the environmental conditions. In the present study, a comparative study was carried out for two finned U-tube direct flow collectors. For the first collector paraffin wax was used as a phase change material. While for the second collector the control collector was left empty. Different flow rates were applied to study their effects on both the phase change process and the system performance. It was found that low flow rates allow a complete phase change and achieve the energy storage benefit of the phase change material. When the phase change process was complete, the system delivered its best efficiency. Under high flow rates, the system did not achieve the expected thermal energy storage benefits because the phase change material remained in the solid state. However, the solid phase provided a good insulator for the useful heat and enhanced the system's efficiency. At a flow rate that caused a partial phase change, the system's efficiency deteriorated, but the storage benefit of the phase change material was achieved. A novel correlation is proposed to estimate the hot water supply period according to a required discharge temperature. This correlation is valid for the direct flow finned and U-tube evacuated tube solar collectors integrated with paraffin wax as a phase change material. [ABSTRACT FROM AUTHOR]

• An optimization model for sizing PV/energy storage/cold ironing systems is presented. • The model is based on a Life Cycle Cost (LCC) approach. • The ferry traffic of the port of Ancona (Italy) has been taken as case study. • Different scenarios have been simulated by varying initial and energy prices. • The best size is 3600 kW (PV) with 5750 kWh (energy storage) and 87% CO 2 reduction. Traditional cold ironing allows ships to shut down their auxiliary engines, during the berthing time, and to be powered by an on-shore power supply. Traditionally the energy demand is satisfied by electricity form the national grid. Alternatively, a local energy production increases the energetic self-sufficiency of the port areas and reduces the pressure on the national grid with continuous peaks of energy demand. This way the port area can be considered a microgrid, characterized by both energy producers and consumers. This paper presents an optimization model, implemented on MATLAB, to provide the best sizing for a combined photovoltaic/energy storage/cold ironing system. The ferry traffic of the port of Ancona (Italy) has been taken as case study. The proposed model returns the percentage of the energy demand covered, the interactions with the national grid, and the optimal size of the PV plant and the storage capacity basing on a Life Cycle Cost (LCC) approach. Results show that the optimal configurations are 2100 kW and 3600 kW with 5750 kWh (without and with storage system) considering lower initial and operational costs, and 3700 kW and 6400 kW with 17,350 kWh (without and with storage system) hypothesizing higher costs. All scenarios ensure an environmental saving, compared to traditional on-board diesel generators, with 87.4 % maximal CO 2 reduction achieved. [ABSTRACT FROM AUTHOR]

The integration of more-electric technologies, such as energy storage systems (ESSs) and electric propulsion, has gained attention in recent years as a promising approach to reduce fuel consumption and emissions in the maritime industry. In this context, hybrid power systems (HPSs) with direct current (DC) distribution are currently gaining a commendable interest in research and industrial applications. This paper examines the impact of using HPS with DC distribution and a battery energy storage system (BESS) over a conventional AC power system for short haul roll-on/roll-off (RORO) ferries. An electric ferry with a HPS is modeled in this study and the power management system is simulated using the Matlab/Simulink software. The result is validated using measured load profile of a ferry. The performance of the DC HPS is compared with the conventional AC system based on fuel consumption and emission reductions. An approach to estimate the fuel consumption of the diesel engine through calculation of specific fuel oil consumption (SFOC) is also presented. This study uses two optimization techniques: a classical power management method namely Rule-Based control (RB) and a meta-heuristic power management method known as Grey Wolf Optimization (GWO) to optimally manage the power sharing of the proposed HPS. Fuel consumption and emission indicators are also used to assess the performance of the two power management methods. The simulation results show that the HPS provides a 2.91% and 7.48% fuel consumption reduction using RB method and GWO method respectively. It is apparent from the result that the HPS has more fuel savings while running the diesel generator sets (DGs) at higher operational efficiency. It is interesting that the proposed HPS using both power management methods provided a 100% emission reduction at berth. Finally, it was found that using a meta-heuristic optimization algorithm provides better fuel and emission reductions than a classical method. [ABSTRACT FROM AUTHOR]

Solar energy being intermittent in nature, can provide a sustainable, steady and high density energy source when converted into electrolytic hydrogen. However, in current photovoltaic market trend with 99% conventional single junction PV panels, this cannot be achieved efficiently and economically. The advent of the multi-junction solar cells (MJCs), with cell-efficiency exceeding 46%, has yet to receive wide spread acceptance in the current PV market in form of concentrated photovoltaic (CPV) system, because of its system design complexity, limiting its application scope and customers. The objective of this paper is to develop a low cost compact CPV system that will not only eliminate its application and installation related restrictions but it is also introducing a highly efficient and sustainable photovoltaic system for common consumer, to convert intermittent sunlight into green hydrogen. The developed CPV system negates the common conviction by showing two times more power output than the flat plate PV, in tropical region. In addition, sunlight to hydrogen conversion efficiency of 18% is recorded for CPV, which is two times higher than alone electricity production efficiency of flat plate PV. [ABSTRACT FROM AUTHOR]

The reduction of automotive fuel consumption and emissions remains one of the main challenges. This paper presents the potential fuel saving in a CNG-powertrain derived from the recovery of the main energy losses. The analysis includes the kinetic energy recovery by a belt starter generator (BSG), the exhaust gas waste heat recuperation by using in a cascade approach, a thermoelectric generator (TEG) and a turbo-generator (TBG)- and the electrification of the main auxiliaries. An additional 48 V board net as well as the addition of a storage system are also included in the study. To support on the design phase of the project and in the operation strategy, a dynamic model in Matlab/Simulink® has been used. The model includes all the new components/major changes required in the vehicle- experimentally validated-. It has been used on backward simulations for the ACEA long haul mission in order to maximize the vehicle’s efficiency. Estimations at rating point (600 Nm and 1200 rpm) result in an electric production up to 4 kW h and a fuel saving of 7.5%. The most convenient technologies in the ACEA cycle turns out to be the KERs followed by the TBG. [ABSTRACT FROM AUTHOR]

• Use the P-graph approach to provide optimal and near-optimal solutions. • Integrate battery storage and hydrogen into renewable energy systems. • Hydrogen storage reduces energy system costs by 21.5% and battery storage by 5.3%. • Provide environmental cost of CO 2eq emission from the island energy system. • Sensitivity analysis can be used to support practical applications. Renewable energy systems play an important role in alleviating environmental pollution, and their characteristics, including low emissions and recyclability, are highly favourable. At present renewable energy can be costly and renewable energy systems have room for optimization, particularly systems which cater to remote and island areas. This paper develops a P-graph-based multi-period energy model, using hydrogen for energy storage to satisfy the fluctuating electrical and thermal energy demand of an island. Hydrogen can be generated from renewable energy sources during off-peak periods and can be used to serve as an energy carrier. An economic and carbon footprint analysis of the system is performed, which compares a pure renewable energy system, with hydrogen storage, and with battery storage. Within the same scenario, the results show that the renewable energy systems with hydrogen storage and battery storage are 21.5 % and 5.3 % cheaper than the renewable energy system without energy storage, with CO 2eq emissions of 1,717 t/y and 1,680 t/y. These findings show that the inclusion of energy storage systems has great potential to reduce costs within renewable energy systems. Changes in the supply of biomass were investigated (which had the greatest impact in the study area), as well as changes in the cost of hydrogen storage. In addition to the optimal solution, near-optimal solutions were also suggested to provide well-rounded guidance for implementation. [ABSTRACT FROM AUTHOR]

In this paper, cost-efficient operation problem of photovoltaic/battery/fuel cell hybrid energy system has been evaluated in the presence of demand response program. Each load curve has off-peak, mid and peak time periods in which the energy prices are different. Demand response program transfers some amount of load from peak periods to other periods to flatten the load curve and minimize total cost. So, the main goal is to meet the energy demand and propose a cost-efficient approach to minimize system’s total cost including system’s electrical cost and thermal cost and the revenue from exporting power to the upstream grid. A battery has been utilized as an electrical energy storage system and a heat storage tank is used as a thermal energy storage system to save energy in off-peak and mid-peak hours and then supply load in peak hours which leads to reduction of cost. The proposed cost-efficient operation problem of photovoltaic/battery/fuel cell hybrid energy system is modeled by a mixed-integer linear program and solved by General algebraic modeling system optimization software under CPLEX solver. Two case studies are investigated to show the effects of demand response program on reduction of total cost. [ABSTRACT FROM AUTHOR]

This paper describes a hybrid tram powered by a Proton Exchange Membrane (PEM) fuel cell (FC) stack supported by an energy storage system (ESS) composed of a Li-ion battery (LB) pack and an ultra-capacitor (UC) pack. This configuration allows the tram to operate without grid connection. The hybrid tram with its full load is tested in the CRRC Qingdao Sifang Co.; Ltd. It firstly works on the operation mode switching method (OPMS) without energy regenerative and proper power management. Therefore, an equivalent consumption minimization strategy (ECMS) aimed at minimizing the hydrogen consumption is proposed to improve the characteristics of the tram. The results show that the proposed control system enhances drivability and economy, and is effective for application to this hybrid system. [ABSTRACT FROM AUTHOR]

• Hydrogen storage systems enable flexible energy conversion and scheduling. • Hydrogen storage cost accounts for the largest proportion of system cost. • The hydrogen energy storage system has less demand for energy storage space. With global energy consumption increasing year by year, the industrial sectors of the world's countries have never been more urgent in achieving carbon reduction. Renewable energy plays a crucial role in the industrial decarbonization process. As the most mature renewable energy technology, wind and photovoltaic power generation have made significant progress in recent years. However, the intermittent characteristics hinder the efficient use of renewable energy. Existing research provides sufficient support for the flexible scheduling of large-scale renewable energy. Hence, this paper proposes a combined energy system composed of wind power-photovoltaic-energy storage salt cavern with hydrogen as the energy scheduling carrier. The system mainly realizes energy conversion through electrolytic water equipment and fuel cells. Then, Qianjiang City, Hubei Province, is taken as the analysis object, and the working conditions of each component in the system are optimized with the help of an improved particle swarm optimization algorithm. According to the results, the system's contribution to the energy system is discussed, and the system's economy and carbon reduction effect is studied. The analysis proves that the improved particle swarm optimization algorithm has a stronger solving ability. The combined energy system can effectively improve the economy and renewable energy utilization rate, meet the regional electricity demand, and significantly reduce carbon emissions. The economic analysis of the system shows that the operation and maintenance cost of hydrogen storage salt caverns accounts for the largest proportion of the total cost, about 60 %. Compared with several existing large-scale energy storage technologies, it is found that the energy efficiency of the whole system is only about 40 % due to the limitation of technology maturity. Nevertheless, the flexibility of the hydrogen storage system layout is relatively high. The required underground space volume is only equivalent to 1/6 and 1/2 of pumped storage and compressed air storage with the same scheduling capacity. The system will provide a theoretical support for the optimization of energy pattern and layout. [ABSTRACT FROM AUTHOR]

The global demands for air conditioning have increased rapidly over the last few decades leading to significant power consumption and CO 2 emissions. Current air conditioning systems use mechanical vapour compression systems which consume significant amount of energy particularly during peak times and use refrigerants that have global warming potential higher than that of carbon dioxide. This paper presents a new approach for providing air conditioning and power using liquid nitrogen produced from surplus electricity at off peak times or renewable energy sources. Thermodynamic analyses of different cryogenic cycles was carried out to achieve the most effective configuration that provides the required cooling and power for a 170 m 2 dwelling in Libya with minimum LN 2 consumption. Results showed that at today LN 2 prices, it is feasible to use LN 2 to provide for cooling and power demands of residential buildings with saving of up to 28% compared to conventional AC systems. However, as the LN 2 price decreases to around 1.3 pence per litre, the proposed technology will have significant advantages compared to AC systems with savings of up to 79% with almost 85% of the energy stored in LN 2 is recovered. [ABSTRACT FROM AUTHOR]

• A novel energy storage-based supercritical CO 2 power system with ejector is proposed. • Thermodynamic analysis and parametric optimization are carried out. • Power regulation capacities in energy storage and release conditions are examined. • Correspondence between storage tank pressure and system performance is conducted. The application of supercritical CO 2 (S-CO 2) in power generation systems shows huge advantages of compactness and high efficiency for nuclear energy utilization. However, it is difficult to achieve a quick response for reactor power regulation system in isolated power gird, and amounts of nuclear heat is wasted by bypass regulation to track the power load. In this paper, a novel energy storage-based supercritical CO 2 power system with ejector is proposed to realize the rapid energy storage and energy release in system operation to guarantee high conversion efficiency of nuclear energy. Thermodynamic mathematical models are established to examine the performance of the proposed system. The parametric analysis and optimization are performed to acquire the optimum system performance. Furthermore, the performance evaluation in energy storage conditions and energy release conditions are presented to show the power regulation capacity of the proposed system. Results show that the appropriate split ratios of recompression supercritical CO 2 power system for different main compressor outlet pressures are both about 0.3. The optimum thermal efficiency of the proposed system is 44.58% and the corresponding exergy efficiency is 66.94% under the given system conditions. In addition, 10% of mass flow rate storage for the S-CO 2 results in a decrease in power load of 41.2%, and 10% of mass flow rate release for the S-CO 2 can achieve an increase in power load of 45.59%. Furthermore, the maximum regulation capacity for the power load increases with the pressure of the high-pressure energy storage tank. Meanwhile, the energy release conditions with a low pressure of high-pressure energy storage tank and a high entrainment ratio of the ejector result in the decrease in net power output. [ABSTRACT FROM AUTHOR]

For Fuel Cell Electric Vehicles, DC-DC power converters are essential to provide energy storage buffers between fuel cell stacks and the traction system because fuel cells show characteristics of low-voltage high-current output and wide output voltage variation. This paper presents a hybrid-mode two-phase interleaved boost converter for fuel cell electric vehicle application in order to improve the power density, minimize the input current ripple, and enhance the system efficiency. Two operation modes are adopted in the practical design: mode I and mode II are used with each boost converter operating in continuous conduction mode and discontinuous conduction mode. The operation, design and control of the interleaved boost converter for different operating modes are discussed with their equivalent circuits. The boundary conditions are distinguished with respect to switching duty ratio and load conditions. Transitions between continuous conduction mode and discontinuous conduction mode are illustrated for the whole duty ratio range. The expressions for inductor current ripple, input current ripple and output voltage ripple are derived and verified by simulation and experimental tests. The efficiency and power density improvements are illustrated to verify the effectiveness of the proposed design scheme. [ABSTRACT FROM AUTHOR]

This paper aims to present a mathematical model for the design of a hybrid power system (HPS) to support a remote island with 100 thousand citizens. The goal is to reduce diesel fuel consumption by adequate expansion of wind power supply. Pumped hydroelectric storage (PHS) is used in the HPS to buffer the impact of intermittent behavior of wind energy. A superstructure is proposed for HPS design, considering all possible capital decisions (e.g. the number of wind turbines) and hourly-basis operational variables (such as the amount of surplus electricity in storage and its discharge). The HPS design problem can then be formulated as a mixed-integer linear program (MILP) based on the proposed superstructure. For a given total share of wind power, the optimal mix of diesel-based and wind power supplies as well as the required capacity of PHS are determined using a four-step optimization approach, involving minimizing (i) the consumption of diesel fuel, (ii) the number of wind turbines, (iii) the size of the upper water reservoir, and (iv) the charge/discharge rates of the PHS system. In this sequential optimization, the objective value obtained in a previous step is added as an additional constraint to the next step. The proposed HPS design model is applied to a real case study of the remote K Island on the other side of Taiwan Strait using hourly-basis, year-round historical data. Inclusion of other renewable energy sources, such as photovoltaic cells and biomass-fired power plants, as well as economic perspectives will be considered in future work. [ABSTRACT FROM AUTHOR]

Under the existing commercial framework of electricity in Malaysia, commercial and industrial customers are required to pay for the peak power demand charge every month. Usually, the peak demand charge can contribute up to 30% to their electricity bills due to the use of open-cycle gas power plants that deliver expensive electricity to the customers. Therefore, alternative means are sought after in order to reduce the peak demand for the customers. Distributed small-scaled energy storage can offer a good option to reduce the peak. This paper aims to identify the financial benefits of the energy storage system for utility companies and customers. An energy dispatch model is developed in HOMER to determine the cost of electricity. The model considers the heat rates of power plants in calculating the costs of electricity under different regulatory frameworks of natural gas with various prices of battery components. Apart from that, the cost-benefit for the customers under various electric tariff structures is evaluated. Four battery storage technologies, namely lead acid, vanadium redox flow, zinc-bromine, and lithium-ion are considered. The simulation results show that the storage system with lead acid batteries is more cost-effective than other battery technologies. The customers can reduce their electricity bills with the payback period of 2.8 years. The generation cost for the power system with energy storage is lower than that without energy storage. Besides, the system with energy storage has lower greenhouse gas emissions than that without energy storage. The deferral of the reinforcement of transmission and distribution infrastructure can be achieved with the installation of energy storage at distribution network. [ABSTRACT FROM AUTHOR]

Microgrids are small scale energy grids that can provide adequate energy supply to cover regional demand by integrating renewable energy generation and storage technologies. This paper develops a high performance dynamic model of a microgrid system comprising a wind turbine, a PV, a fuel cell, a micro gas turbine generator, an energy storage, electric loads with variable load profile and flexible AC transmission system (FACTS) devices. The FACTS devices based on static VAR compensators have been employed as a supervisory controller. Key performance indicators such as microgrid power losses, buses voltage deviations, buses power factor, buses voltage total harmonic distortion and voltage-frequency deviation are used to evaluate the performance of this microgrid in grid-connected and islanding modes. The results obtained from the Matlab/Simulink environment show that the proposed microgrid design with SVC has the ability to meet its special requirements such as bus voltages stabilization, reduction of feeder losses, power factor enhancement and mitigation of total harmonic distortion using SVC in grid-connected and islanding modes. [ABSTRACT FROM AUTHOR]

Advanced Adiabatic Compressed Air Energy Storage (AA-CAES) is a large-scale energy storage system based on gas turbine technology and thermal energy storage (TES). Electrical energy can be converted into internal energy of air and heat energy in TES during the charge process, while reverse energy conversion proceeds during discharge process. The performance of AA-CAES system requires further improvement in order to increase efficiency. In this paper, a multi-stage AA-CAES system model is established, and the influence of effectiveness and pressure loss in heat exchanger on energy conversion and utilization efficiency of AA-CAES system is analyzed theoretically based on the theory of thermodynamics. Four Cases about effectiveness and pressure loss of heat exchanger are investigated and compared with each other. It is found that effectiveness and pressure loss of heat exchanger are directly related to energy conversion and utilization in AA-CAES system. System efficiency changes with the variation of heat exchanger effectiveness and the impact of pressure loss on conversion of heat energy in TES is more sensitive than that of internal energy of air. Pressure loss can cause the complexity of system efficiency change. With appropriate selection of the values of heat exchanger effectiveness for both charge and discharge processes, an AA-CAES system with a higher efficiency could be expected. [ABSTRACT FROM AUTHOR]

This paper presents a modification of stepped solar still with continuous water circulation using a storage tank for sea and salt water. Total dissolved solids (TDS) of seawater and salt water before desalination is 57,100 and 2370 mg/l. A comparison study between modified stepped and conventional solar still was carried out to evaluate the developed desalination system performance under the same climate conditions. The effect of installing a storage tank and cotton black absorber for modified stepped solar still on the distillate productivity was investigated. The results indicate that, the productivity of the modified stepped still is higher than that for conventional still approximately by 43% and 48% for sea and salt water with black absorber respectively, while 53% and 47% of sea and salt water, respectively with cotton absorber. Also, the daily efficiency for modified stepped still is higher than that for conventional still approximately by 20%. The maximum efficiency of modified stepped still is occurring at a feed water flow rate of 1 LPM for sea water and 3 LPM for salt water. Total dissolved solids (TDS) of seawater and salt water after desalination is 41, and 27 mg/l. [ABSTRACT FROM AUTHOR]

• A novel CCHP system based on Compressed Carbon dioxide Energy Storage is proposed. • Wind turbine waste heat is utilized to optimize the system performance. • Under the designed conditions, the system power efficiency can reach 0.48. • The impact of wind turbine waste heat on the system performance is confirmed. Due to climate change and the increase in energy demand caused by population growth, considerable attention is being given to wind energy and combined cooling, heating, and power (CCHP) systems, which are known for their high energy utilization. With the rapid growth of wind power generation, the waste heat generated by wind turbines and the intermittency of wind power have emerged as problems to be addressed. Therefore, this paper proposes a low-temperature CCHP system based on transcritical compressed CO 2 energy storage which utilizes wind power and wind turbine waste heat. A mathematical model of this system is developed and applied, and system characteristics are evaluated from the perspective of thermodynamics. The performance indices (system power efficiency (SPE), system energy efficiency (SENE), and exergy density (E D)) are defined, and sensitivity analysis of the key factors affecting system performance is conducted. Based on the parameters under the design condition, the SPE of the system is 0.48, the SENE is 1.19, and the E D is 11.51 kWh/m3. Storage pressure and waste heat temperature have a great influence on the thermodynamic performance of the system, while ambient temperature only affects cooling energy, heating energy, and E D. The variation of the pressure difference at the main throttle valve mainly affects SPE and E D of the system. [ABSTRACT FROM AUTHOR]

Highlights: [•] The modified ICSSWH system are simulated and validated, in this paper. [•] The proposed system is a baffle plate type storage unit. [•] The storage unit is divided with two trapezoids volumes (top volume as VA and bottom volume as VB ). [•] For , then the present ICSSWH system efficiency is maximized. [•] Present system has the highest efficiency than the rectangular and the triangular ICSSWH systems. [Copyright &y& Elsevier]

[Display omitted] • A novel CATES-SOFC-GT energy storage system is proposed. • Compression heat is thermochemically utilized by driving methanol decomposition. • SOFC-GT is employed to improve power output and electrical efficiency. • Thermo-economic analysis and multi-objective optimization are performed. This paper proposes a novel system integrating compressed air and thermochemical energy storage with solid oxide fuel cell-gas turbine (SOFC-GT). During charging process, the compression heat drives methanol decomposition into syngas for converting its low-grade thermal energy into high-grade chemical energy and achieving hybrid storage of physical and chemical energies simultaneously. During discharging process, the SOFC-GT efficiently converts the stored energy into power based on energy cascade utilization, significantly improving the total exergy efficiency of the system. The effects of six key parameters on the thermo-economic performance of the system are studied by the sensitivity analysis, and the results show that the total exergy efficiency conflicts with the levelized cost of energy (LCOE). Therefore, the multi-objective optimization is carried out for the system from the thermodynamic and economic aspects, and the best trade-off is selected with the total exergy efficiency of 65.89% and LCOE of 126.48 $/MWh, in which the system can generate 7.22 MWh power and 2.37 MWh heating with the total energy efficiency of 89.76%. [ABSTRACT FROM AUTHOR]

Abstract: This paper presents the results of a series of parametric analysis to investigate the factors that affect the effectiveness of using simultaneously building thermal capacitance and ice storage system to reduce total operating costs (including energy and demand costs) while maintaining adequate occupant comfort conditions in buildings. The analysis is based on a validated model-based simulation environment and includes several parameters including the optimization cost function, base chiller size, and ice storage tank capacity, and weather conditions. It found that the combined use of building thermal mass and active thermal energy storage system can save up to 40% of the total energy costs when integrated optimal control are considered to operate commercial buildings. [Copyright &y& Elsevier]

Abstract: Renewable energy sources (RES) are an “indigenous” environmental option, economically competitive with conventional power generation where good wind and solar resources are available. Hybrid systems can help in improving the economic and environmental sustainability of renewable energy systems to fulfill the energy demand. The aim of this paper is to present a dynamic model able to integrate different RES and one storage device to feed a “Green” building for its thermal and electrical energy needs in a sustainable way. The system model is embedded in a dynamic decision model and is used to optimize a quite complex hybrid system connected to the grid which can exploit different renewable energy sources. A Model Predictive Control (MPC) is adopted to find the optimal solution. The optimization model has been applied to a case study where electric energy is also used to pump water for domestic use. Optimal results are reported for two main cases: the presence/absence of the energy storage system. [Copyright &y& Elsevier]

Abstract: The application of solar air collectors for space heating has attracted extensive attention due to its unique advantages. In this study, a solar air heating system was modeled through TRNSYS for a 3319m2 building area. This air heating system, which has the potential to be applied for space heating in the heating season (from November to March) and hot water supply all year around in North China, uses pebble bed and water storage tank as heat storage. Five different working modes were designed based on different working conditions: (1) heat storage mode, (2) heating by solar collector, (3) heating by storage bed, (4) heating at night and (5) heating by an auxiliary source. These modes can be operated through the on/off control of fan and auxiliary heater, and through the operation of air dampers manually. The design, optimization and modification of this system are described in this paper. The solar fraction of the system was used as the optimization parameter. Design parameters of the system were optimized by using the TRNSYS program, which include the solar collector area, installation angle of solar collector, mass flow rate through the system, volume of pebble bed, heat transfer coefficient of the insulation layer of the pebble bed and water storage tank, height and volume of the water storage tank. The TRNSYS model has been verified by data from the literature. Results showed that the designed solar system can meet 32.8% of the thermal energy demand in the heating season and 84.6% of the energy consumption in non-heating season, with a yearly average solar fraction of 53.04%. [Copyright &y& Elsevier]

• We investigate innovative technologies for energy generation for maritime applications. • We develop an innovative approach to compare energy production and storage solutions onboard. • We build an extended database with costs, volumes, weights, emissions for each solution. • We investigate two case studies (small and large size vessels). • We compare the results in terms of fuel consumptions, emissions and costs. In this paper, the authors present an innovative approach to compare the most promising innovative technologies for energy production and storage for maritime applications. The developed algorithm, which include a large database built with market and literature data, compares several possible solutions, including innovative ones, from the environmental, economic and energetic standpoints. A detailed decription of the functions implemented in the database is reported, explaining also in detail the algorithm developed to evaluate and compare the technologies. Then, the methodology is applied to two case studies to demonstrate the algorithm's potential, the reliability of the wide range of data included in the database and the impact of the scenario on the final results. The investigated case studies are: (i) a small size passenger ship operating in urban areas (ii) a large size cruise ship. Analyzing the first case study, a focus on the impact of generation unit and fuel storage systems is developed for the most promising solutions, represented by fuel cells in comparison to standard solutions. The second case study shows that, as could be expected, the most promising solutions in this range of application is the use of MDO or LNG in Internal Combustion Engines. In order to evaluate the future potential of the different alternative fuels, a sensitivity analysis is performed to evaluate the impact of the increasing emissions' importance: methanol, LNG, and ammonia are indicated as the most futurible fuels. It is worth noting that the presented approach has a general validity, thus it can be applied to other ships' typologies; the modular structure also allows for including further emerging technologies. [ABSTRACT FROM AUTHOR]

• A new model is proposed for the calculation of energy storage in the heat-supply net. • The proposed method introduced an influence θ to the improved HTES model. • The new method connected the energy stored in the heat-supply net with users indirectly. • The performance of the proposed model is tested using several cases. • The new model can guide the temperature and flow rate of the supply water in practice. The study of energy storage characteristics of heat-supply net in distributed energy system is essential to develop the control strategy of energy efficient utilization. Studying the energy storage characteristics of the heating network in the distributed energy system is the key to formulating energy-saving utilization control strategies. In this paper, the quantitative calculation model of heat transfer and energy storage (HTES) is established through the research on the energy storage characteristics of heat-supply net in distributed energy system, and the duration of thermal storage energy (TSED) of the energy storage characteristics in heat-supply net is also described. In the HTES model, the influence factor is introduced to make the temperature of the heat transfer section in the initial model more realistic, which also improves the accuracy of the model. Based on the HTES model and experimental data, the lag time of the three heat exchange stations was calculated and compared to verify the correctness of the HTES model. Through the calculation of practical cases, the TSED is obtained and analyzed, and for a best flow rate is found for the working medium. In addition, the quality and quantity regulation of central heating network under the conditions of unit shutdown and time-divided heating is calculated to achieve the purpose of guiding the actual water supply temperature and flow. [ABSTRACT FROM AUTHOR]

• A kinetic energy harvester embedded in dowty retarder is presented for the first time. • The new retarder can both provide braking resistance and harvest kinetic energy. • A special mechanism is utilized to convert two-way motion into one-way rotation. • This new design is used for self-powered applications in heavy haul railways. • Efficiencies of 55.4% and 51.9% are obtained in the simulation and bench tests. Rail transit system has been considered to have a large energy harvesting potential, and to be usable to achieve self-powering for rail-attached electrical installations. Dowty retarder is a key device installed on the side of rails to assist train braking, which can be used as a carrier for kinetic energy harvesting. In this paper, a high-efficiency kinetic energy harvester (KEH) based on a railway Dowty Retarders (DRs) is investigated. This new KEH can accumulate the kinetic energy of a decelerating train using a novel vibration rectification mechanism. The current study comprises four main components: energy input module, motion transmission module, generation module, and energy storage module. The energy input module has a screw-nut mechanism that can convert linear vibration into rotational motion. As a core component of the entire device, the motion transmission module contains a special closed-loop shaped gear train that converts the two-way rotary motion into a unidirectional rotation. The final unidirectional rotation is transferred to the generation module for power generation and the generated energy is stored in the energy storage module. Finally, both experimental and simulation approaches were performed to verify the dynamics response of the KEH mechanism. The maximum efficiencies of 55.4% and 51.9% are obtained during the simulation and experimental analyses. It is validating that the KEH mechanism is promising and practical in self-powered applications for the heavy haul railway. [ABSTRACT FROM AUTHOR]

• Techno-economic and life cycle assessments of energy storage systems were reviewed. • The levelized cost of electricity decreases with increase in storage duration. • Efficiency, lifetime, and duration of discharge influence the final costs and emissions. • A consistent system boundary is crucial for conducting life cycle assessment. • An integrated techno-economic and life cycle assessment model is recommended. Incorporating renewables in the power grid has challenges in terms of the stability, reliability, and acceptable operation of the power system network. One possible solution is to integrate an energy storage system with the power network to manage unpredictable loads. The implementation of an energy storage system depends on the site, the source of electrical energy, and its associated costs and the environmental impacts. Moreover, an up-to-date database with cost numbers, energy use, and resulting emissions is required for decision-making purposes. This paper reviews the techno-economic and environmental assessments of mechanical, electro-chemical, chemical, and thermal to give an update on recent developments and generate a relevant database for costs and emissions. We reviewed 91 publications, 58 on techno-economic assessment and 33 on life cycle assessment. We found that, because of economies of scale, the levelized cost of energy decreases with an increase in storage duration. In addition, performance parameters such as round-trip efficiency, cycle life, and cycle length highly influence the final costs and environmental footprints of various storage technologies. However, further research is required to build a bottom-up model that can handle all the technical parameters to quantify the levelized cost of energy and environmental footprints of the storage systems simultaneously. [ABSTRACT FROM AUTHOR]

• Layout for a dish-Stirling coupled to a geothermal storage system presented. • Energy performance of the cogenerative solar concentrator presented. • Influence of several physical parameters investigated to optimise the system. • Identification of a incentivisation policy for a cogenerative dish-Stirling plant. • Evaluation of energy and economic viability of the cogenerative layout. In the future, renewable energy sources will increasingly represent an efficient energy source capable of meeting the demands of residential and industrial buildings avoiding the emissions of greenhouse gases into the atmosphere. In this paper, a heat and electric power cogeneration plant implementing a field of dish-Stirling collectors, a seasonal geothermal storage and a system of water-to-water heat pumps is proposed for the first time. The cogeneration plant has been designed both to supply thermal energy to the heating system of Building 9 of the Department of Engineering in Palermo and to produce electricity. The operation of the plant has been tested by means of hourly-based numerical simulations that have been carried out using a numerical model implemented with Transient System Simulation Tool. The experimental data of a pilot dish-Stirling collector, located in the same area, has been used to carefully calibrate the numerical model. Using energy and economic performance indicators, it was possible to select the best configurations among 1440 analysed cases. Results of simulations show that with the best plant configuration, it is possible to cover 97% of the building's annual thermal loads with energy produced by the solar system. The remaining 64% of electrical energy produced by the electric engines is free to be used for other applications. Financial analyses have shown that market penetration of this type of plant would need a strong support through incentives. [ABSTRACT FROM AUTHOR]

• A standalone PV/wind/A-CAES based hybrid energy system for rural MBS is proposed. • The fan and A-CAES turbine exhaust provide cooling energy besides air conditioner. • The performance assessment of the proposed system is carried out. • The parametric sensibility and LPSP analysis are implemented. The standalone renewable powered rural mobile base station is essential to enlarge the coverage area of telecommunication networks, as well as protect the ecological environment. In this paper, a standalone photovoltaic/wind turbine/adiabatic compressed air energy storage based hybrid energy supply system for rural mobile base station is proposed. The energies from renewable sunlight and wind are the primary power sources and the adiabatic compressed air energy storage system acts as the energy buffer to manage the fluctuations in both demand and generation sides. Meanwhile, the hybrid cooling strategy is also adopted by consisting of air conditioner, fan assistant natural ventilation and turbine exhaust from adiabatic compressed air energy storage during discharge. The simulation results under design condition demonstrate that the loss of power supply probability is 0.988%, and the monthly load and individual equipment power consumption, the monthly cooling energy demand and supply and the monthly energy generation and consumption all match well. Then, the effect of photovoltaic-wind turbine configuration, the air tank volume and storage pressures of adiabatic compressed air energy storage on system performance have been implemented. Moreover, the loss of power supply probability analysis show that the required photovoltaic panels number increases with the reduced air tank volume in conditions of fixed wind power capacity and fixed 1% maximum loss of power supply probability threshold, whereas the dump load rate raises. For a certain air tank volume and maximum loss of power supply probability threshold, the dump load rate firstly reduces and then rises with the wind turbine number increases. [ABSTRACT FROM AUTHOR]