Life cycle cost analysis of electricity storage facilities in flexible power systems

Global efforts towards de-carbonization have opened the pathway for a test environment of electrical energy storage (EES) topology. In this work, the feasibility of 17 EES facilities applied to 24 individual applications of flexible power networks has been investigated in terms of levelized cost of storage (LCOS) in $/kW. Electricity storage facilities were modelled and evaluated via a life-cycle cost analysis, based on the most realistic EES characteristics and practical applications’ requirements. The results showed that pumped-hydro constitutes the least-cost and most reliable system for large-scale/long-duration applications. Zn-air and vanadium redox (VRB) offer great potential in demand-shifting and reactive support but, due to their wide LCOS range, considerable risk is added in such an investment. Electrochemical double-layer capacitor (EDLC) holds almost the exclusivity in fast-response/frequently-cycled applications, while for medium-term/medium-scale applications and where the large footprint is a prohibitive factor, valve-regulated Pb-acid (VRLA) and hydrogen fuel cells (H₂-FC) are more favourable options. However, efficient tools still lack the ability of quantifying all benefits derived from electricity storage, maintaining stakeholders’ concerns for investment. It is apparent that, further research and development implies the decrease of the uncertainty governing the majority of EES technologies, increasing EES implementations and vice versa.     

Thermodynamic analysis of a novel compressed carbon dioxide energy storage system with low-temperature thermal storage

Research projects on new electrical energy storage (EES) systems are underway because of the role of EES in balancing the electric grid and smoothing out the instability of renewable energy. In this paper, a novel compressed carbon dioxide energy storage with low-temperature thermal storage was proposed. Liquid CO₂ storage was employed to increase the storage density of the system and avoid its dependence on geological formations. Low-temperature thermal energy storage technology was utilized to recycle the heat of compression and reduce the challenges to system components. The system configuration was introduced in detail. Four evaluation criteria, the round trip efficiency (RTE), exergy efficiency (η_Ex), thermal efficiency (η_TE), and energy density (ρ_E) were defined to show the system performance. Parametric analysis was carried out to examine the effects of some key parameters on system performance and the genetic algorithm was adopted for system optimization. The calculated results show that, for the novel EES under the basic working condition, its RTE is 41.4%, η_TE is 59.7%, η_Ex is 45.4%, and ρ_E is 15 kWh m⁻³. The value of ρ_E increases with the increasing pump outlet pressure for a fixed value of pressure ratio, and the changes of RTE, η_TE, and the total exergy destruction of the system (E_D,total) with pump outlet pressure are complicated for different values of pressure ratio. When both pressure ratio and pump outlet pressure are high, the values of RTE and ρ_E can be maximized whereas the value of E_D,total can be minimized. Besides, no matter how pump outlet pressure and pressure ratio change, the exergy destruction of the system mainly come from compressors and regenerators, which accounts for about 50% of the total exergy destruction.     

Economics of electricity and heat production by gasification or flash pyrolysis of short rotation coppice in Flanders (Belgium)

Short rotation coppice (SRC) seems attractive as an energy crop on degraded land. Gasification and flash pyrolysis are promising technologies for the conversion of SRC into energy or chemicals. A model has been developed to calculate the net present value (NPV) of the cash flows generated by an investment in gasification or flash pyrolysis of SRC for the production of electricity or for combined heat and power production. The NPV has been calculated and compared for (combined heat and) power stations with an electrical capacity (P_e) between 5 MW and 20 MW. Furthermore the minimal amount of heat that has to be sold to make combined heat and power production more profitable than pure electricity production has been determined. By performing Monte Carlo simulations, key variables that influence the NPV have been identified.In the case of small scale SRC conversion, i.e. at an electrical capacity of 5 MW-10 MW, flash pyrolysis is more profitable than gasification. At the smallest scale of 5 MW it is necessary to invest in combined heat and power production, as the sole production of electricity is not profitable at this low scale. At an electrical capacity of 10 MW flash pyrolysis for the sole production of electricity becomes profitable, but gasification for electricity production is still not viable. At this capacity however, the extra investments required in the case of combined heat and power production are already paid back if only 25% of the produced heat can be sold. At a higher capacity of 20 MW, the technology choice becomes unclear taking into account the most uncertain variables, i.e. investment cost parameters and energetic efficiencies.     

The evaluation of hydrogen production via a geothermal-based multigeneration system with 3E analysis and multi-objective optimization

In this study, a novel geothermal-based multigeneration system is designed and evaluated in energy, exergy and economic (3E) analyses. Besides 3E analyses, multi-objective optimization has been assessed to reach the highest exergetic effectiveness and the lowest total cost rate. To evaluate the designed plant, thermodynamic balance equations are assigned to all sub-systems found in the design. These equations are solved by using Engineering Equation Solver (EES) software. According to the analyses' results, with base parameters, total power production is 1951 kW, the hydrogen generation rate is 0.0015 kg/s, and the whole energy and exergy efficiencies are 59.53% and 53.17%. The economic analysis performed for the multigeneration system indicates that the total cost rate is 186 $/h, and the levelized energy cost is 0.102 $/kWh. These results indicate that the designed geothermal-based multigeneration system performs better than a single-generation plant in terms of efficiency and cost.     

Commercial and research battery technologies for electrical energy storage applications

Developing green energy solutions has become crucial to society. However, to develop a clean and renewable energy system, significant developments must be made, not only in energy conversion technologies (such as solar panels and wind turbines) but also regarding the feasibility and capabilities of stationary electrical energy storage (EES) systems. Many types of EES systems have been considered such as pumped hydroelectric storage (PHS), compressed air energy storage (CAES), flywheels, and electrochemical storage. Among them, electrochemical storage such as battery has the advantage of being more efficient compared to other candidates, because it is more suitable in terms of the scalability, efficiency, lifetime, discharge time, and weight and/or mobility of the system. Currently, rechargeable lithium ion batteries (LIBs) are the most successful portable electricity storage devices, but their use is limited to small electronic equipment. Using LIBs to store large amounts of electrical energy in stationary applications is limited, not only by performance but also by cost. Thus, a viable battery technology that can store large amounts of electrical energy in stationary applications is needed. In this review, well-developed and recent progress on the chemistry and design of batteries, as well as their effects on the electrochemical performance, is summarized and compared. In addition, the challenges that are yet to be solved and the possibilities for further improvements are explored.     

Investigation of green hydrogen production and development of waste heat recovery system in biogas power plant for sustainable energy applications

In this study, biogas power production and green hydrogen potential as an energy carrier are evaluated from biomass. Integrating an Organic Rankine Cycle (ORC) to benefit from the waste exhaust gases is considered. The power obtained from the ORC is used to produce hydrogen by water electrolysis, eliminate the H₂S generated during the biogas production process and store the excess electricity. Thermodynamic and thermoeconomic analyses and optimization of the designed Combined Heat and Power (CHP) system for this purpose have been performed. The proposed study contains originality about the sustainability and efficiency of renewable energy resources. System design and analysis are performed with Engineering Equation Solver (EES) and Aspen Plus software. According to the results of thermodynamic analysis, the energy and exergy efficiency of the existing power plant is 28.69% and 25.15%. The new integrated system's energy, exergy efficiencies, and power capacity are calculated as 41.55%, 36.42%, and 5792 kW. The total hydrogen production from the system is 0.12412 kg/s. According to the results of the thermoeconomic analysis, the unit cost of the electricity produced in the existing power plant is 0.04323 $/kWh. The cost of electricity and hydrogen produced in the new proposed system is determined as 0.03922 $/kWh and 0.181 $/kg H₂, respectively.     

Electric energy storage systems in a market-based economy: Comparison of emerging and traditional technologies

Unlike markets for storable commodities, electricity markets depend on the real-time balance of supply and demand. Although much of the present-day grid operate effectively without storage technologies, cost-effective ways of storing electrical energy can make the grid more efficient and reliable. This work addresses an economic comparison between emerging and traditional Electric Energy Storage (EES) technologies in a competitive electricity market. In order to achieve this goal, an appropriate Self-Scheduling (SS) approach must first be developed for each of them to determine their maximum potential of expected profit among multi-markets such as energy and ancillary service markets. Then, these technologies are economically analyzed using Internal Rate of Return (IRR) index. Finally, the amounts of needed financial supports are determined for choosing the emerging technologies when an investor would like to invest on EES technologies. Among available EES technologies, we consider NaS battery (Natrium Sulfur battery) and pumped-storage plants as emerging and traditional technologies, respectively.     

Challenges for rechargeable batteries

Strategies for Li-ion batteries that are based on lithium-insertion compounds as cathodes are limited by the capacities of the cathode materials and by the safe charging rates for Li transport across a passivating SEI layer on a carbon-based anode. With these strategies, it is difficult to meet the commercial constraints on Li-ion batteries for plug-in-hybrid and all-electric vehicles as well as those for stationary electrical energy storage (EES) in a grid.Existing alternative strategies include a gaseous O₂ electrode in a Li/air battery and a solid sulfur (S₈) cathode in a Li/S battery. We compare the projected energy densities and EES efficiencies of these cells with those of a third alternative, a Li/Fe(III)/Fe(II) cell containing a redox couple in an aqueous solution as the cathode. Preliminary measurements indicate proof of concept, but implementation of this strategy requires identification of a suitable Li⁺-ion electrolyte.     

An off-peak energy storage concept for electric utilities: Part I—Electric utility requirements

The water battery, a reversible water electrolyser device being developed in a long-term research effort at Battelle's Columbus Laboratories, was evaluated in an analytical and conceptual design study as a load-levelling system for an electric utility. During periods when off-peak electrical power was available, the water battery would produce hydrogen and oxygen by electrolysis of water; during peak demand periods the water battery would be operated in the reverse mode, functioning as a fuel cell by producing electrical power through the recombination of the oxygen and hydrogen held in its storage vessels.The analysis involved characterisation of the PSE&G system demand requirements now and in the future, its current off-peak energy availability, the typical sizing and placement of energy storage units and the approximate break even economics and potential advantages to the utility of a water battery energy storage system. In the economic analysis, the water battery was compared with the gas turbine and the fuel cell for cost effectiveness in meeting peak and intermediate power demands, respectively.Compared with a ‘reformer-type’ fuel cell (costed at $300/kW for intermediate duty) the break even capital cost of a 50% efficient water battery would be $100/kW plus about $200/kW for each increase of $1/10⁶ Btu above the reference cost of $1/10⁶ Btu for fossil fuel. The available margin would increase about $50/kW for each decrease of 1 mill/kWh in off-peak energy cost below the reference cost of 8 mills/kWh. In a similar comparison with the gas turbine (costed at $135/kW) for peaking duty, the break even cost of a 50% efficient water battery would be $100/kW. The break even cost could rise about $100/kW for each increase in fossil fuel cost of $1/10⁶ Btu and about $20/kW for each decrease in off-peak energy cost of 1 mill/kWh.     

A review of electrical energy storage technologies for renewable power generation and smart grids

储能技术是突破可再生能源大规模开发利用瓶颈的关键技术,是智能电网的必要组成部分.在储能市场商业化雏形阶段,系统性的比较分析各类储能技术的性能特点,为未来市场发展提供筛选技术路线的框架基础至关重要.本文阐述了储能技术在可再生能源发电和智能电网中的作用,对物理储能(抽水蓄能,压缩空气储能,飞轮储能),电化学储能(二次电池,液流电池),其它化学储能(氢能,合成天然气)等储能技术进行了系统的比较与分析,最后提出储能技术的发展趋势.     

Self-discharge characteristics and performance degradation of Ni-MH batteries for storage applications

The needs for onboard energy storage are practically dependent on the Ni-MH and Li-ion battery packs, because these two power-assisting systems have features of proper energy density, longer cycle lifetime, quick charge acceptance, and proper operating windows for both voltage and temperature. In particular, the Ni-MH power system has a proper tolerance mechanism for overcharge and overdischarge, a lower cost for battery pack maintenance, and a slightly longer cycle lifetime profile. We studied the self-discharge characteristics, state-of-health, state-of-charge, and energy efficiencies at various charge input levels. The end-of-voltages during charge and discharge were evaluated for the Ni-MH storage batteries. The impedance measurements and data analysis have also been conducted for equivalent circuit simulations. The performance deterioration and capacity decay are fundamentally analyzed and discussed in details, including electrode side-reactions, structure degradations, separator weakening, and level changes of electrolyte saturation in the battery. Further battery quality enhancement through cycle duration improvement for onboard energy storage potentially provides more suitable power and energy delivery in order to obtain higher efficiency, save more fuels, and reduce CO₂, SO₂, and NO_x emissions.     

储能与液流电池技术

大规模高效储能技术是解决可再生能源发电不连续、不稳定、不可控特性的重要途径,也是构建坚强智能电网的核心技术。本文对各种储能技术进行了综合分析,并对适用于大规模储能的抽水储能、压缩空气储能、钠硫电池、锂离子电池、铅酸电池和液流电池的技术特点、优劣势、发展前景进行了深入阐述;最后,对储能技术的发展思路进行了探讨,认为坚持技术开发与应用示范并重,进一步降低储能设备成本,提高其可靠性和稳定性并辅以一定的鼓励政策,是推进储能技术的产业化和实用化的重要途径。     

Development of the all‐vanadium redox flow battery for energy storage: a review of technological,financial and policy aspects

The commercial development and current economic incentives associated with energy storage using redox flow batteries (RFBs) are summarised. The analysis is focused on the all‐vanadium system, which is the most studied and widely commercialised RFB. The recent expiry of key patents relating to the electrochemistry of this battery has contributed to significant levels of commercialisation in, for example, Austria, China and Thailand, as well as pilot‐scale developments in many countries. The potential benefits of increasing battery‐based energy storage for electricity grid load levelling and MW‐scale wind/solar photovoltaic‐based power generation are now being realised at an increasing level. Commercial systems are being applied to distributed systems utilising kW‐scale renewable energy flows. Factors limiting the uptake of all‐vanadium (and other) redox flow batteries include a comparatively high overall internal costs of $217 kW^?1 h^?1 and the high cost of stored electricity of ≈ The commercial development and current economic incentives associated with energy storage using redox flow batteries (RFBs) are summarised. The analysis is focused on the all‐vanadium system, which is the most studied and widely commercialised RFB. The recent expiry of key patents relating to the electrochemistry of this battery has contributed to significant levels of commercialisation in, for example, Austria, China and Thailand, as well as pilot‐scale developments in many countries. The potential benefits of increasing battery‐based energy storage for electricity grid load levelling and MW‐scale wind/solar photovoltaic‐based power generation are now being realised at an increasing level. Commercial systems are being applied to distributed systems utilising kW‐scale renewable energy flows. Factors limiting the uptake of all‐vanadium (and other) redox flow batteries include a comparatively high overall internal costs of $217 kW^?1 h^?1 and the high cost of stored electricity of ≈ $0.10 kW^?1 h^?1. There is also a low‐level utility scale acceptance of energy storage solutions and a general lack of battery‐specific policy‐led incentives, even though the environmental impact of RFBs coupled to renewable energy sources is favourable, especially in comparison to natural gas‐ and diesel‐fuelled spinning reserves. Together with the technological and policy aspects associated with flow batteries, recent attempts to model redox flow batteries are considered. The issues that have been addressed using modelling together with the current and future requirements of modelling are outlined. Copyright © 2011 John Wiley & Sons, Ltd.     

Performance analysis of various hybrid renewable energy systems using battery,hydrogen, and pumped hydro‐based storage units

The aim of this research is to analyze the techno‐economic performance of hybrid renewable energy system (HRES) using batteries, pumped hydro‐based, and hydrogen‐based storage units at Sharurah, Saudi Arabia. The simulations and optimization process are carried out for nine HRES scenarios to determine the optimum sizes of components for each scenario. The optimal sizing of components for each HRES scenario is determined based on the net present cost (NPC) optimization criterion. All of the nine optimized HRES scenarios are then evaluated based on NPC, levelized cost of energy, payback period, CO₂ emissions, excess electricity, and renewable energy fraction. The simulation results show that the photovoltaic (PV)‐diesel‐battery scenario is economically the most viable system with the NPC of US$2.70 million and levelized cost of energy of US$0.178/kWh. Conversely, PV‐diesel‐fuel cell system is proved to be economically the least feasible system. Moreover, the wind‐diesel‐fuel cell is the most economical scenario in the hydrogen‐based storage category. PV‐wind‐diesel‐pumped hydro scenario has the highest renewable energy fraction of 89.8%. PV‐wind‐diesel‐pumped hydro scenario is the most environment‐friendly system, with an 89% reduction in CO₂ emissions compared with the base‐case diesel only scenario. Overall, the systems with battery and pumped hydro storage options have shown better techno‐economic performance compared with the systems with hydrogen‐based storage.     

Performance evaluation of direct methanol fuel cells for portable applications

This study examines the feasibility of powering a range of portable devices with a direct methanol fuel cell (DMFC). The analysis includes a comparison between a Li-ion battery and DMFC to supply the power for a laptop, camcorder and a cell phone. A parametric study of the systems for an operational period of 4 years is performed. Under the assumptions made for both the Li-ion battery and DMFC system, the battery cost is lower than the DMFC during the first year of operation. However, by the end of 4 years of operational time, the DMFC system would cost less. The weight and cost comparisons show that the fuel cell system occupies less space than the battery to store a higher amount of energy. The weight of both systems is almost identical. Finally, the CO₂ emissions can be decreased by a higher exergetic efficiency of the DMFC, which leads to improved sustainability.     

An innovative approach for geothermal-wind hybrid comprehensive energy system and hydrogen production modeling/process analysis

In this paper, the energy, exergy, economic, environmental, steady-state, and process performance modeling/analysis of hybrid renewable energy (RE) based multigeneration system is presented. Beyond the design/performance analysis of an innovative hybrid RE system, this study is novel as it proposes a new methodology for determining the overall process energy and exergy efficiency of multigeneration systems. This novel method integrates EnergPLAN simulation program with EES and Matlab. It considers both the steady-state and the process performance of the modeled system on hourly timesteps in order to determine the overall efficiencies. Based on the proposed new method, it is observed that the overall process thermodynamic efficiencies of a hybrid renewable energy-based multigeneration system are different from its steady-state efficiencies. The overall energy and exergy efficiencies reduce from 81.01% and 52.52% (in steady-state condition) to 58.6% and 39.33% (when considering a one-year process performance). The integration of the hot water production with the multigeneration system enhanced the overall thermodynamic efficiencies in steady-state conditions. The Kalina system produces a total work output of 1171 kW with a thermal and exergy efficiency of 12.23% and 52% respectively while the wind turbine system produces 1297 kW of electricity in steady-state condition and it has the same thermal/exergy efficiency (72%). The economic analysis showed that the Levelized cost of electricity (LCOE) of the geothermal energy-based Kalina system is 0.0103 $/kWh. The greenhouse gas emission reduction analysis showed that the proposed system will save between 1,411,480 kg/yr and 3,518,760 kg/yr of greenhouse gases from being emitted into the atmosphere yearly. The multigeneration system designed in this study will produce electricity, hydrogen, hot water, cooling effect, and freshwater. Also, battery electric vehicle charging is integrated with process performance analysis of the multigeneration system.     

Size optimization of a PV/wind hybrid energy conversion system with battery storage using response surface methodology

This paper aims to show the use of the response surface methodology (RSM) in size optimization of an autonomous PV/wind integrated hybrid energy system with battery storage. RSM is a collection of statistical and mathematical methods which relies on optimization of response surface with design parameters. In this study, the response surface, output performance measure, is the hybrid system cost, and the design parameters are the PV size, wind turbine rotor swept area and the battery capacity. The case study is realized in ARENA 10.0, a commercial simulation software, for satisfaction of electricity consumption of the global system for mobile communications (GSM) base station at Izmir Institute of Technology Campus Area, Urla, Turkey. As a result, the optimum PV area, wind turbine rotor swept area, and battery capacity are obtained to be 3.95 m², 29.4 m², 31.92 kWh, respectively. These results led to $37,033.9 hybrid energy system cost, including auxiliary energy cost. The optimum result obtained by RSM is confirmed using loss of load probability (LLP) and autonomy analysis.     

Optimal design of an integrated renewable-storage energy system in a mixed-use building

The rise of mixed-use buildings contributes to the sustainable development of cities but are still met with challenges in energy management due to the lack of energy efficiency and sustainability guidelines. The use of integrated renewable-storage energy systems is a more beneficial solution to this problem over individual solutions; however, most design studies only focused on single-type buildings. Thus, this study aims to optimally design an integrated energy system for mixed-use buildings using HOMER Grid. The objective is to minimize the net present costs, subject to capacity limits, energy balances, and operational constraints. Economic metrics were used to evaluate and compare the proposed system to the varying design cases such as business-as-usual, stand-alone renewable source, and stand-alone energy storage. The case study considered a mixed-use building in a tropical area, with a solar photovoltaic system as the renewable energy source and lithium-ion battery as the energy storage system technology. The results show that the integrated system is the most financially attractive design case. It has a levelized cost of electricity of 0.1384 US$ kWh⁻¹, which is significantly less than the 0.2580 US$ kWh⁻¹ baseline. The system also provides electricity cost savings of 294 698 US$ y⁻¹, excess electricity of 35 746 kWh, and carbon emission reduction of 550 tons annually for a mixed-use building with daily average consumption of 4557-kWh and 763-kW peak demand.     

A fast classification method of retired electric vehicle battery modules and their energy storage application in photovoltaic generation

The fading characteristics of 60 Ah decommissioned electric vehicle battery modules were assessed employing capacity calibration, electrochemical impedance spectroscopy, and voltage measurement of parallel bricks inside modules. The correlation between capacity and internal resistance or voltage was analyzed. Then, 10 consistent retired modules were packed and configured in a photovoltaic (PV) power station to verify the practicability of their photovoltaic energy storage application. The results show that the capacity attenuation of most retired modules is not severe in a pack while minor modules with state of health (SOH) less than 80% bring about the retirement of the whole pack as a result of the buckets effect. There is no obvious correlation between capacities of retired battery modules and their lithium-ion diffusion coefficients or charge transfer resistance or ohmic resistance, whose reliability is low as the consistency indexes of decommissioning battery modules. The maximum off load voltage difference ΔU_max at low state of charge (SOC) values has a good negative linear correlation with the capacity of retired modules, suggesting that the ΔU_max value at low SOC values can be considered as a characteristic index for fast classification of retired battery modules for large-scale second-life application. A PV power station equipped with retired battery energy storage system (RBESS) can maximize the photovoltaic self-utilization rate. It is an important way to reutilization of retired battery that RBESSs are configured with distributed PV power stations.     

Application of ANFIS-PSO algorithm as a novel method for estimation of higher heating value of biomass

One of the important parameters in economic study of energy sources and bioenergy is higher heating value (HHV). In this investigation, adaptive neuro fuzzy inference system (ANFIS) was applied as a novel method to predict HHV of biomass in terms of fixed carbon (FC), ash content (ASH), and volatile matters (VMs). Due to the fact that experimental investigations are time- and cost-consuming, this investigation was selected purely computational and a total number of 350 experimental data were extracted from literature for different steps of modeling. The proposed algorithm was evaluated by statistical indexes such as coefficient of determination (R²), root mean squared error (RMSE), and average absolute relative deviation (AARD), which are 0.90757, 1.1792, and 5.266, respectively. The reported indexes showed that ANFIS-particle swarm optimization can be used as a novel computational approach for prediction of HHV as function of proximate analysis.