The worldwide environmental crisis brought on by rising carbon and greenhouse gas emissions has attracted the attention of most nations. Several global conventions, including the Kyoto Protocol and the Paris Agreement, have been established and executed, with over 130 countries announcing their net-zero emissions or carbon-free ecological aims. To achieve this essential sustainable development goal (SDG), efficient energy storage systems are a crucial requirement.
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What is Long Duration Energy Storage (LDES)?
Long-duration energy storage (LDES) technologies are essential for harmonizing fluctuating electrical facilities with unpredictable consumer demand and fortifying the power system against adverse weather conditions.
As per the latest article published in the Journal of Energy Storage, LDES solutions with an operating period of two hours or less can readily provide ancillary services or those services required for resolving short-term disparities between generation and load.
Energy Earthshot is a novel initiative from the US Department of Energy (DOE) that seeks to accelerate the installation of grid-scale energy storage by reducing LDES costs. In particular, the initiative aims to provide 10+ hours of capacity within the next decade. The 10+ hours of storage is supported by $1.16 billion in funding levels.
As a means of incorporating the fluctuating production across regular and seasonal phases, the importance of LDES in an efficient power system becomes particularly apparent in systems with more than 80 percent varying renewable generation.
A Novel Process Integrating Hydrogen Liquefaction Process (HLP) and Liquid Air Energy Storage (LAES)
Energy storage is a proven method for increasing sustainable energy utilization and decreasing energy waste. Liquid air energy storage (LAES) is a scalable thermomechanical preservation method. When wind and solar renewable energies are abundant, LAES technologies conserve energy and discharge it when electricity demand is high.
Researchers have published an article in Energy Conversion and Management stating that during off-peak hours, renewable energy (i.e., off-peak power) is supplied to the air liquefaction unit, where the air is liquefied at approximately 78 K and retained in insulated containers. Liquid air (LAir) can be circulated, warmed up, and expanded within turbines to produce electricity.
The research team's recommended HLP–LAES system comprises the LAES charge process (LAES–CP), the LAES draining process (LAES–DP), and the HLP. During the improvement of the HLP's technological and financial viability, the energy storage attributes of the technique were analyzed.
Before air throttling, the ambient temperature was 90 K, and the ideal temperature prior to expansion was 246.5 K. When the peak period split ratio of liquid air (PPSR) was 8.0, the average daily power generation was found to be 131.3 MWh, the system's round-trip efficiency was 58.9%, and the specific power use of liquid hydrogen was 7.25 kWh/kgLH2.
The earliest retrofitting return on investment was determined to be 9.2 years if the isolated hydrogen liquefaction facility was retrofitted to HLP–LAES, representing excellent monetary advantages.
Recent Advancements in Supercapacitors for Energy Storage
Energy storage systems are employed in a broad variety of industries as either an aggregate energy storage or a decentralized temporary energy buffer. Supercapacitors, also referred to as Electric Double-Layer Capacitors (EDLCs), are the subject of extensive research due to their advantageous properties.
Even though they have a relatively low energy density, they possess extra benefits such as minimal internal resistance, a wide operational thermal limit, and outstanding efficiency. Because of these advantages, they are ideally adapted for utilization in household electronics either alone or in combination with other high-energy devices.
The latest article in the Journal of Energy Storage focuses on supercapacitors as a viable superior energy storage option. Electrode classification is the most prevalent method for identifying supercapacitors' advantages and disadvantages. Double-layer material is utilized for both electrodes simultaneously in symmetric supercapacitors. These supercapacitors have the greatest degree of precision, finding widespread application. Asymmetric capacitors are incorporated with electrodes composed of two unique capacitance materials attaining exceptional power and energy densities.
Self-discharge is one of the main drawbacks that precludes supercapacitors from being used to store energy for periods longer than 30 minutes. Researchers discovered that 36 percent of the energy lost during the first two hours of a supercapacitor's storage was usable.
Supercapacitors are now being utilized for various applications. Batteries can be replaced or integrated with supercapacitor modules in all newly developed consumer electronic (CE) products, particularly those that operate on dc voltage or electricity.
The development of a novel DC-DC converter mechanism that functions solely on supercapacitors without a battery.
There are numerous alternatives for operating HEV techniques in close vicinity to a supplementary power source. As a secondary source of electricity, the supercapacitor is coupled with a primary source combustion engine. The secondary source meets the peak power needs for accelerated motion. This source of power is frequently used to harness regenerative braking energy and employ it for supplementary acceleration.
Although it has numerous applications, the supercapacitor requires modeling to apply its most advanced features.
Hybrid System of Carnot Battery with Low-Grade Waste Heat Recovery
Researchers from China have published their research in Elsevier, focusing on the pairing of the pumped thermal energy storage (PTES) technology and waste heat to increase the efficacy of energy storage and address the issue of low-grade waste heat consumption.
Only 34% of the initial energy intake is successfully transformed into useful energy by the energy framework, while 42% is lost as waste heat. The Carnot battery is a large-scale physical energy storage technology that stores electrical energy via thermal storage. Pumped thermal energy storage (PTES) technology is an offshoot of the Carnot battery, and research and demonstration on PTES systems have been initiated in Europe over the past few years.
Researchers have proposed the B-PTES system, the R-PTES system, and the PR-PTES system for energy storage in the article. The B-PTES consists of the heat pump (HP) cycle, the thermal storage framework, and the organic flash cycle (ORC). The HP cycle utilizes extra power to increase the temperature of waste heat. At discharge time, the stored thermal energy propels the ORC to produce electricity.
The R-PTES system is augmented with an HP recuperator and an ORC recuperator. In the HP cycle, the working fluid from the HP condenser passes through the HP recuperator and transfers power to the operating fluid expelled from the HP evaporator.
The investigators noticed that the power-to-power efficiency of the PR-PTES system was greater than that of the B-PTES system, indicating that the added components improved the efficiency and functionality of the PR-PTES system.
With the increase in waste heat temperature from the PR-PTES system, the power-to-energy conversion efficiency reached 85%. In addition, the power-to-power efficiency reached 99.3% when the waste heat input temperature was 90.0 C. This suggests that the PTES system has superior benefits compared to other energy-intensive energy storage technologies.
Flow Batteries: Aiding in Grid-Scale Energy Storage
A modeling framework created at MIT can accelerate the production of flow battery cells for large-scale, long-duration energy storage on the next-generation grid. Two different substances endure electrochemical interactions in which charges are transferred in the flow battery. The separation between where energy is stored (the containers) and where electrochemical reactions occur (the so-called reactor) is a significant advantage of this system design. Consequently, the battery's capacity, power, and the rate at which it can be charged and discharged can be adjusted independently. The selected chemistry is a crucial aspect of designing flow batteries. The two electrolytes can contain various chemicals, but the most common configuration consists of two different oxidation states of vanadium.
In short, several novel technologies are being researched and developed for energy storage systems. These technologies ensure the sustainable future of energy production and storage.
References and Further Reading
Stauffer, N. W., 2023. Flow batteries for grid-scale energy storage. [Online]
Available at: https://news.mit.edu/2023/flow-batteries-grid-scale-energy-storage-0407
Zhang, M. et. al. (2023). Carnot battery system integrated with low-grade waste heat recovery: Toward high energy storage efficiency. Journal of Energy Storage, 57, 106234. Available at: https://doi.org/10.1016/j.est.2022.106234
Satpathy, S. et. al. (2023). An in-depth study of the electrical characterization of supercapacitors for recent trends in energy storage system. Journal of Energy Storage. 57. 106198. Available at: https://doi.org/10.1016/j.est.2022.106198
Yang, Y. et. al. (2023). A novel integrated system of hydrogen liquefaction process and liquid air energy storage (LAES): Energy, exergy, and economic analysis. Energy Conversion and Management, 280, 116799. Available at: https://doi.org/10.1016/j.enconman.2023.116799
Twitchell, J., DeSomber, K., & Bhatnagar, D. (2023). Defining long duration energy storage. Journal of Energy Storage, 60, 105787. Available at: https://doi.org/10.1016/j.est.2022.10578
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