Evaluation of energy storage potential within shape memory rubber nanocomposite films

Hierarchical porous hollow carbon spheres derived from spirofluorene- and aniline-linked conjugated microporous polymer for phase change energy storage

One-pot in situ synthesis of expandable graphite-encapsulated paraffin composites for thermal energy storage

Air separation units (ASUs) are power-intensive devices on the electricity demand side with significant potential for large-scale energy storage. Liquid air energy storage (LAES) is currently a highly promising large-scale energy storage technology. Coupling ASU with LAES equipment can not only reduce the initial investment for LAES, but also significantly lower the operating electricity costs of the ASU. This study proposes a novel modular-integrated process for coupling an externally compressed ASU (ECAS) with LAES. The core advantages of this integrated process are as follows: the liquefaction unit’s storage capacity is not constrained by the ASU surplus load capacity and it integrates cold, heat, electricity, and material utilization. Taking an integrated system with 40,000 Nm3/h oxygen production capacity as an example, under liquefaction pressure of 90 bar and discharge expansion pressure of 110 bar, the system achieves its highest electrical round trip efficiency of 55.3%. Its energy storage capacity reaches 31.32 MWh/104 Nm3 O2, exceeding the maximum capacity of existing energy storage systems of the ECAS by 1.7 times. Based on a peak-flat-valley electricity price ratio of 3.4:2:1, an optimal economic performance is attained at 100 bar liquefaction pressure, delivering a 7.21% in cost saving rate compared to conventional ASUs. The liquefaction unit’s payback period is 6.39 years—68.1% shorter than conventional LAES. This study aims to enhance both the energy storage capacity and economic performance of integrated systems combining ECAS with LAES.

In order to solve the problems of increased voltage fluctuation and increased peak load caused by the high proportion of distributed photovoltaic (PV) and electric vehicles (EVs) connected to the distribution network, it is helpful to increase the storage efficiency and reduce the incremental cost of energy storage system (ESS) to carry out the energy storage supplement planning based on the aggregation of the EVs. Firstly, the “distributed energy storage +” resource partition hierarchical control topology and the economic incentive model of on-board energy storage aggregation are established, including on-board energy storage and distributed energy storage system (DESS). The mathematical models of on-board energy storage, DESS and the calculation model of the potential of on-board energy storage are established. Then, a DESS supplement planning model is built, which is including on-board energy storage participating in system peak shaving and valley filling. And the solution flow is given. Finally, an example is given based on IEEE-33 bus distribution network. It is verified that the supplementary planning based on the aggregation of existing resource is effective for cost reduction and efficiency increase of energy storage resource.

BaTiO3-based materials show great promise for energy storage capacitors, but their low breakdown strength and high remnant polarization currently result in relatively low energy density. Here, we report a novel (1–x)BaTiO3–xBi(Li0.5Ta0.5)O3 (0.06 ≤ x ≤ 0.12, BT–xBLT) lead-free ceramic with electric field (E) ∼ 280 kV cm–1, discharge energy density (We) ∼ 2.2 J cm–3, charge–discharge efficiency (η) > 89% that is thermally stable up to 160 °C and with a fast discharge time (≤0.5 μs). Multilayers of compositions with x = 0.1 also exhibited high We = 4.05 J cm–3 and η = 95.5%, demonstrating their potential for energy storage.

Nanoporous activated carbons derived from bio-waste are gaining consideration due to their exceptional potential for energy storage and CO2 adsorption. Herein, we put forward a straightforward, low-cost method for preparing a highly efficient nanoporous biocarbon from ginger using solid-state activation approach. Ginger was pyrolyzed at various temperatures before activating using different amounts of KOH as an activator to produce nanoporous biocarbon. The prepared samples possess high specific surface areas and large pore volumes. By simply adjusting the pyrolysis temperature, the microporosity and surface oxygen functionalities can be finely tuned. The best sample exhibits a high Brunauer-Emmett-Teller-specific surface area of 2,330 m2/g and a large pore volume of 1.10 cm3/g and offers excellent specific capacitance of 244 and 119 F/g when tested in a three-electrode and two-electrode, at a current density of 0.5 A/g. Additionally, the optimized material demonstrates a high CO2 uptake capacity of 4.87 mmol/g at ambient pressure and 25.8 mmol/g at 0 °C and 30 bar. These interesting adsorption and energy storage performances of the nanoporous biocarbon underscore the potential of converting food waste into high-performance CO2 adsorbents and supercapacitors.

The extent to which long-duration energy storage (LDES) will support grid decarbonisation by enabling large penetration of renewable generation is subject to the achievement of suitable technical and economic performance. This study investigates the potential of established and novel thermo-mechanical energy storage (TMES) technologies to meet LDES targets, benchmarks TMES current and future techno-economic performance and highlights critical research developments. Results justify the priority of ensuring low storage costs over high roundtrip efficiency for LDES, thus endorsing novel concepts based on thermochemical energy storage. Besides adiabatic compressed air energy storage, novel TMES using metal oxidation/reduction and CaO hydration/dehydration reactions can potentially already meet the 20 USD/kWh cost target at 200 h duration, with current technology performance. The need for suggested and wide-ranging enhancements at material, device and system level is discussed, which may lead to TMES costs below 14 USD/kWh – competitive with long-duration solutions like hydrogen for covering the energy balancing needs of future low-carbon energy systems.

Energy storage will become indispensable to complement the uncertainty of intermittent renewable resources and to firm the electricity supply as renewable power generation becomes the mainstream new-built energy source and fossil fuel power plants are phased out to meet carbon-neutral utility targets. Current energy storage methods based on pumped storage hydropower or batteries have many limitations. Thermal energy storage (TES) has unique advantages in scale and siting flexibility to provide grid-scale storage capacity. A particle-based TES system is projected to have promising cost and performance characteristics to meet the future growing energy storage needs. This paper introduces the system and components required for particle TES to become technically and economically competitive. The system integrates electric particle heaters, particle TES within insulated concrete silos, and an efficient air-Brayton combined-cycle power system to provide power for storage durations up to several days via low-cost, high-performance storage cycles. Design specifications and cost estimation of major components in a commercial-scale system are presented in this paper. A techno-economic analysis based on preliminary component designs and performance indicates that particle TES integrated with an air-Brayton combined-cycle power system has a path to achieve the targeted levelized cost of storage of 5 ¢/kWh-cycle at a round-trip efficiency of 50% when taking low-cost energy-specific components and leveraging basic assets from existing thermal power plants. The cost model provides insights for further development and economic potentials for long-duration energy storage.

<p>Three-dimensional porous matrices loaded with phase change materials (PCMs) offer significant potential for photothermal energy conversion and storage. However, the composite materials prepared via vacuum impregnation suffer from low thermal conductivity. A novel phase change composite aerogel (PCCA) material is designed that simultaneously exhibits excellent thermal insulation and efficient photothermal energy conversion and storage, by leveraging the inherently low thermal conductivity of both porous materials and PCMs. PCCA constructed using biomass-derived templates demonstrates outstanding photothermal performance, achieving surface temperatures as high as 86 °C under 1 sun. A quantitative uniform coating impregnation method is developed based on the unique solid-liquid phase transition of stearic acid/ethanol mixture, which facilitates the quantitative regulation of porosity when loaded with stearic acid. PCCA50 achieves a porosity of 50%, a melting enthalpy of 182.1 J g<sup>-1</sup>, a crystallization enthalpy of 174.5 J g<sup>-1</sup>, and a thermal conductivity of 0.112 W m<sup>-1</sup> K<sup>-1</sup>, contributing to remarkable thermal insulation and energy storage capacity. Moreover, the nanoconfined space in PCCA provides kinetic constraints for the loading of stearic acid, leading to the coexistence of sub-stable and bulk-stable polymorphs. This enables PCCA to effectively resist temperature fluctuations across a broader photothermal temperature range.</p>

Introduction The power grid controls their electric power supply by maintaining voltage, frequency, and transient stability, by predicting the electricity demand at any given time. However, recent large-scale implementation of photovoltaics (PV) makes it difficult to meet them because the gap between power supply and demand will be widening. The suppression of any power sources including solar power generation with sacrificing some electricity is sometimes adopted to avoid large-scale blackouts, and the situation is expected to be a common event at the 2030s. An effective solution to such situations is called as “leveling power”, which is the ability to maintain a balance between power supply and demand. Leveling power needs to be introduced not only into the centralized power grid but also into distributed energy systems. The major candidate of leveling power at distributed energy systems is electrochemical energy storage technology such as secondary batteries or hydrogen Power-to-Gas-to-Power (P2G2P). A smart energy system called Ene-swallow has been developed by our research group, and applied to Ookayama campus at the Tokyo Institute of Technology. This system manages 1400 kW-PV, 100 kW-FC, 70 kW gas engine and 100 kWh storage battery with a 10,000 kW-class electricity demand. Ene-Swallow also accumulates the power demand data in 1-sec intervals and PV power generation data in 1-min intervals. We previously carried out a techno-economic analysis of a hydrogen energy storage system to level the annual gap of power supply and demand [1]. Here we evaluated the potential of electrochemical energy storage as a leveling power with using the annual data from those data. Method We analyzed the current situation requirements for leveling power (analysis-1) and the applicability of a distributed energy storage system (analysis-2). For analysis-1, we analyzed 1-hour data of power generation and consumption published from power companies across Japan (Fig. 1a), and 1-min data of PV power generation (Fig. 1b) and 1-sec data of power demand (Fig. 1c) at Ookayama campus. For analysis-2, we set a tentative distributed grid with a 10,000 kW-class electricity demand, a given amount of primary power generation by PV and the power supply from the grid. In this work, we set no leveling power by the grid, which supplied constant power. Then, we determined the entire gap between power supply and demand during a single year based on the actual 1-minute data of PV power generation and power demand from April, 2017 to March, 2018. Then we estimated the required amount of energy storage, and thus determined the required number of P2G2P devices with alkaline electrolysis cell (AEC), solid oxide fuel cells (SOFC), H2 tanks and compressors, and lithium-ion batteries (LIB). In the system, the balance of power generation and consumption in a day is controlled as shown in Fig. 2. During the daytime, the surplus power from PV is leveled by an AEC. If AEC capacity is not sufficient, it is leveled by LIB. At night, the required power for demand is generated by an SOFC and/or an LIB. By optimizing the capacity of each component device in the distributed system, we evaluated the total system cost. We specified the expected technical parameters in the future (for the year 2030), such as unit price, efficiency and lifetime as shown in Table 1. Results From analysis-1, the 1-hour data showed that the supply fluctuation of PV power generation during the day strongly impacts the power grid when the energy mix ratio of PV to total annual demand reached about 10% when keeping nuclear power generation constant. The 1-minute data showed large fluctuations in PV generation within in a short time period (< 1 hr) during weather such as a cloudy day (Fig. 1b). Power fluctuations with different time scales have to be leveled by using electrochemical energy storage technologies. Analysis-2 showed that the total system cost could be reduced by using a combined system of P2G2P and LIB by utilizing their different characteristics. The combined system of P2G2P can reduce their total energy cost with dividing the role by power generation and the storage when the cost targets shown in Table 1 can be achieved. [Acknowledgements] A part of this study is supported by the New Energy and Industrial Technology Development Organization (NEDO) and MIRAI program of Japan Science and Technology Agency (JST). Reference [1] T.Okubo et al., 234th ECS Meeting AiMES 2018, (September 30-October 4, 2018) Figure 1

Liquid Air Energy Storage (LAES) is at pilot scale. Air cooling and liquefaction stores energy; reheating revaporises the air at pressure, powering a turbine or engine (Ameel et al., 2013). Liquefaction requires water & CO2 removal, preventing ice fouling. This paper proposes subsequent geological storage of this CO2 - offering a novel Carbon Dioxide Removal (CDR) by-product, for the energy storage industry. It additionally assesses the scale constraint and economic opportunity offered by implementing this CDR approach. Similarly, established Compressed Air Energy Storage (CAES) uses air compression and subsequent expansion. CAES could also add CO2scrubbing and subsequent storage, at extra cost. CAES stores fewer joules per kilogram of air than LAES - potentially scrubbing more CO2 per joule stored. Operational LAES/CAES technologies cannot offer full-scale CDR this century (Stocker et al., 2014), yet they could offer around 4% of projected CO2 disposals for LAES and < 25% for current-technology CAES. LAES CDR could reach trillion-dollar scale this century (20 billion USD/year, to first order). A larger, less certain commercial CDR opportunity exists for modified conventional CAES, due to additional equipment requirements. CDR may be commercially critical for LAES/CAES usage growth, and the necessary infrastructure may influence plant scaling and placement. A suggested design for low-pressure CAES theoretically offers global-scale CDR potential within a century (ignoring siting constraints) - but this must be costed against competing CDR and energy storage technologies.

Asymmetric supercapacitors (ASC) meet the high power and energy demand in energy storage devices; however, the low capacitance of the anode materials severely hinders the development of ASCs. MoO3 with its high theoretical capacity is an ideal anode material, but its low electrical conductivity limits the application of capacitive energy storage. Herein, abundant oxygen vacancies Ce‐doped MoO3 (OV‐MoO3/Ce) ultrathin nanoflakes anode materials with a thickness of 1.51‐2.01 nm are constructed by a simple hydrothermal method. It is found that the nanostructure of MoO3 can be controllably changed from thick nanobelts into ultrathin nanoflakes by adjusting the Ce doping concentration. And Ce doping in the OV‐MoO3 lattice can additionally introduce abundant oxygen vacancies without introducing Ce oxide and other impurities. Benefiting from the synergy of ample oxygen vacancies, high specific surface area, and accelerated ion diffusion and charge mobility, the optimized OV‐MoO3/Ce electrode achieves a high specific capacitance (1439.0 F g‐1 at 2 mV s‐1 and 1446.3 F g‐1 at 5 A g‐1) and good cycle stability. More impressively, the ASC assembled using optimized OV‐MoO3/Ce as anode materials can provide an ultrahigh energy density of 150.0 Wh kg‐1 at a power density of 800 W kg‐1, and the practical demonstration of the assembled ASC device highlights its great potential for high energy storage.

There is universal agreement between the United Nations and governments from the richest to the poorest nations that humanity faces unprecedented global challenges relating to sustainable energy, clean water, low-emission transportation, coping with climate change and natural disasters, and reclaiming use of land. We have invited researchers from a range of eclectic research areas to provide a Roadmap of how superconducting technologies could address these major challenges confronting humanity.

New energy storage, as an important technology and a basic component for supporting new power systems, is of vital importance in promoting green energy transformation and high-quality energy development. It is imperative to explore customer-side energy storage as a business model and for its cost-effectiveness as an important part of new energy production. To this end, considered factors include settling peak tariff, energy storage investment and construction costs, operation and maintenance costs, financial cost, charging/discharging modes, and utilization hours. This paper establishes a cost-effectiveness analysis model for customer-side energy storage to measure the cost-effectiveness of the adoption of single/dual-system tariffs for customer-side energy storage under the independent or PV-storage integration mode in China's provinces. It was determined that, under the current electricity purchasing mechanism, the potential of the customer-side energy storage using the dual-system tariff is greater than that of the single-system tariff and the cost-effectiveness of the PV-storage integration mode is better than that of the independent customer-side energy storage mode.

Effective thermochemical energy storage (TCES) at MWh or GWh scales through reduction of oxides requires materials with 1) thermodynamic potential for significant energy storage, 2) fast reversible surface chemistry for oxygen removal, 3) rapid oxide-ion diffusion through the bulk lattice, and 4) phase and structural integrity of high-surface area structures. As reported in our previous papers (1-4)and by others (5, 6) A-site doped Ca1-xSrxMnO3-δ (x <= 0.20) provides thermodynamics for significant reduction and reversibility during redox cycles for TCES at high temperatures ≥ 700ºC. With Sr-doping levels of 5 and 10%, Ca1-xSrxMnO3-δ has demonstrated thermodynamic limits for specific TCES of 664, 737, and 877 kJ/kg at 1000ºC at P O2 ≈ 0.21, 0.01, and 10-4 bar respectively (from a zero reference state of fully oxidized Ca1-xSrxMnO3 in air at a cold temperature of 500ºC) (3). Ca0.90Sr0.10MnO3-δ and Ca0.95Sr0.05MnO3-δ were synthesized as porous particles through solid state reactive sintering to 1225ºC and tested for bulk reduction and re-oxidation at temperatures up to 1000ºC and P O2down to »10-4bar to calibrate material models for predicting specific TCES in limited residence time reactors. The particles, illustrated in Figures 1, with diameters < 450 μm, porosity ≈ 0.6, and grain sizes from 1 to 10 mm were packed into annular beds and tested in isothermal and non-isothermal redox cycling between oxidizing and reducing gases. Isothermal redox cycling of the porous particles in conjunction with TGA/DSC measurements provided the basis for fitting thermodynamically consistent surface reaction rate expressions and bulk ionic transport sub-models to measured evolution in δ. Figures 2 shows 10-cycle-averaged isothermal reduction and re-oxidation plots for a 0.6 cm bed of porous Ca0.9Sr0.1MnO3-δparticles cycled between P O2 of 0.17 and 10-4 bar. Similar results between other P O2 illustrate the significantly faster reoxidation rates that approach thermodynamic limits based on sweep-gas flow rates, suggest that neither bulk ionic diffusion nor O2 adsorption are rate-limiting at conditions tested. The packed bed experiments were simulated using a two-level internal and external dusty-gas-model for porous media transport based on measured particle and bed properties. The results showed that for typical grain sizes of 5 mm, bulk-ion transport only impacted reduction rates at temperatures ≤ 700 ºC. As such, it was difficult to fit accurately ionic diffusion parameters and further testing is required to assess more accurately ambipolar bulk diffusion models for these materials. Fitted surface chemistry rates to the experimental measurements as shown in Figure 2 does capture both the slow reduction and the fast reoxidation with a thermodynamically consistent reversible rate expression adopted from previous studies (7). The surface kinetics fitted for Ca0.9Sr0.1MnO3-δwere implemented in a one-dimensional indirect particle solar receiver model based on a narrow fluidized bed concept (8, 9)to explore the potential for how thermochemical energy storage in these particles could be coupled to designs and operating conditions for GWh energy storage systems for thermal power plants. The counterflow particles and fluidizing sweep gas at low P O2 provides a basis for reduction but rapid buildup of O2 in the gas-phase near the bottom of the bed thermodynamically inhibits reduction. As shown in Figure 3, conditions that produce particle temperatures above 1000 ºC and reduction levels with δ > 0.1 and thus provide significant specific TCES. These conditions at relatively low solid flow rates result in high wall temperatures and thus lower solar efficiency (approaching 80%) due to the wall radiation losses. Material models for Ca1-xSrxMnO3-δ permit further exploration of receiver designs to find optimal geometries and operating conditions to achieve high δ at higher solar efficiency approaching targets of 90%. References K.J. Albrecht, G.S. Jackson, and R.J. Braun, Solar Energy, 167, 179-193 (2018). L. Imponenti, K.J. Albrecht, R.J. Braun, and G.S. Jackson, ECS Transactions, 72(7), 11-22 (2016). L. Imponenti, K.J. Albrecht, R. Kharait, M.D. Sanders, and G.S. Jackson, Applied Energy, 230, 1--18 (2018). L. Imponenti, K.J. Albrecht, J.W. Wands, M.D. Sanders, and G.S. Jackson, Solar Energy, 151, 1-13 (2017). B. Bulfin, J. Vieten, D.E. Starr, A. Azarpira, C. Zachaus, M. Havecker, K. Skorupska, M. Schmucker, M. Roeb, and C. Sattler, Journal of Materials Chemistry A, 5(17), 7912-7919 (2017). N. Galinsky, A. Mishra, J. Zhang, and F.X. Li, Applied Energy, 157, 358-367 (2015). R. Merkle, Y.A. Mastrikov, E.A. Kotomin, M.M. Kuklja, and J. Maier, Journal of the Electrochemical Society, 159(2), B219-B226 (2012). G.S. Jackson, L. Imponenti, K. Albrecht, D. Miller, and R.J. Braun, Journal of Solar Energy Engineering, doi:10.1115/1.4042128 (2018). D.C. Miller, C.J. Pfutzner, and G.S. Jackson, International Journal of Heat and Mass Transfer, 126, 730-745 (2018). Figure 1