harnessing free energy from nature for efficient operation of compressed air energy storage system and unlocking the potential of renewable power generation - commercial energy storage systems

In recent years, due to the rise of renewable energy, energy storage technology has gained considerable momentum of development.
The deployment of energy storage will last until 2018 and beyond.
In the near future, compressed air energy storage (CAES)
It will become an integral part of several energy-intensive sectors.
However, the main drawback of promoting the CAES system on a large and small scale is its minimum turnover efficiency.
In the current work, the main shortcomings related to the various existing configurations of the CAES system are analyzed.
Through this analysis, interesting results of the constant temperature CAES system are obtained, and the overall turnover efficiency is improved by utilizing free energy from natural water bodies/oceans, thus a system that produces additional output energy compared to the supply input.
The optimal operating properties of the charging and discharging cycles are also discussed.
Increase the percentage of renewable energy in the current energy situation (RE)
Since RE-based power generation is inherently intermittent, the share in power generation is quite challenging.
The integration of energy storage technology with renewable energy is essential because it relieves the intermittent nature of available energy.
However, the development of efficient energy storage systems is one of the main challenges in the large-scale promotion of renewable energy.
In a variety of storage systems, electrolytic battery storage and pumped storage (PHS)
Attracted the business market.
However, the shorter cycle life makes the storage cost of the battery higher, and the PHS system involves certain geographical and site restrictions.
In addition to the above storage system, the compressed air energy storage system is not targeted at the commercial market as one of the mature systems due to the low turnover efficiency.
Therefore, the motivation of this study is to develop efficient CAES configurations with higher turnover efficiency for economic feasibility and sustainability. Kittner .
Various strategies of emerging energy storage technologies have been deployed, and a clear route has been formulated for achieving cost-effective low-carbon power.
In recent years, in order to improve the stability of the power grid and avoid the problem of transmission congestion, large-capacity energy storage is gaining great momentum of development.
Compressed air energy storage (CAES)
It is considered to be one of the large-scale energy storage systems with attractive economic benefits.
While discussing the operating principles, the energy is stored in the form of compressed air, the compressor is operated using the RE source during off-peak hours, and the stored compressed air is released through the expansion machine during peak hours, and generate electricity using an AC generator.
However, it is well known that during the entire energy transfer and conversion process considerable energy loss associated with all three phases of the storage system (
Charging, discharging and storage)are inevitable. Hartmann .
The efficiency of a fully charged and discharged cycle of several insulated compressed air energy storage structures is analyzed.
They conclude that the key factor in improving efficiency is the development of a high temperature energy storage and heat-resistant material for compressors. Kushnir .
The thermodynamic response of the underground cave reservoir was studied and used to analyze the charge/discharge cycle of the compressed air energy storage device.
Based on the conservation equation of mass and energy, the numerical and approximate analytical solutions of temperature and pressure changes in the air cavity chamber are derived. Audrius .
The CAES system with and without thermal energy storage is analyzed for fire and fire Economy (TES)
It was found that the energy efficiency increased to 86% and the efficiency of exergy increased to 55. 8% of CAES
Compared with the CAES system, the efficiency of the TES system is 48%, and the efficiency of exergy is 50. 1%. Nejad .
A thermodynamic analysis of the wind integrated CAES system was carried out, and they revealed the fact that the energy conversion process could be thermal insulation or constant temperature.
The main parameters they analyzed were storage pressure, temperature and tank volume (TV). Li .
A micro three-generation compressed air system using energy storage technology is proposed.
They also conducted a thermodynamic analysis and found that the average comprehensive efficiency in winter and summer was about 50% and 35% respectively, which seems to be much higher than the traditional three-generation system.
The numerical simulation of a nearly 4 MWh underwater CAES system is carried out, and the optimal configuration and maximum round-trip efficiency of the system are obtained.
In this system, the accumulator is placed underwater using the water pressure applied by the surrounding water body. Nielsen .
The concept of an isopressure insulated CAES system integrating a joint loop is proposed. Houssainy .
The thermodynamic analysis of the high temperature mixed CAES system is carried out, and the two heating stages are combined through separate low temperature and high temperature TES units, eliminating the need for combustion in the traditional CAES system. Safaei .
It is recommended to export the compressed heat to meet the application of space/water heating, which will help to improve the overall efficiency. Simpore .
Dynamic simulation was carried out and the feasibility of using the CAES system integrated with buildings in the case of photovoltaic power generation was observed, and this was proved. Trujillo .
Transient simulation analysis of CAES systems without any thermal energy recovery devices and auxiliary fuel systems.
In order to analyze the different configurations and performance of The CAES system, various studies have been carried out.
In 1978, the first utility-scale CAES system was put into use in Huntorf, Germany, with a power generation capacity of 290 mw and air stored in caves with a volume of 3, 10,000 m³, the working pressure range is 46-72 pressure bar.
Subsequently, in 1991, another CAES-based power grid-scale plant in Mackintosh, Alabama, was put into production with a power generation capacity of 110 mw.
In addition, Energetix Group Co. , Ltd. regards this technology as a backup power supply (
Compressed air battery-cab)
For standard and custom equipment from 3kw to 3 mw, these devices are available for standby and uninterrupted power applications.
This hybrid taxi facility is being used by BT as a third backup.
This technology is also telecom Italy (Italy), Eskom (South Africa)and Harris (US).
However, due to the low overall turnover efficiency of the system, the success rate of this technology remains difficult until today, due to the complexity of the unloading process.
In fact, without greatly improving the efficiency of turnover, it is doubtful to achieve economic feasibility.
There are mainly 4 kinds of CAES configuration in general (i)Diabatic (ii)Adiabatic (iii)
Advanced insulation and (iv)
Constant temperature system. (i)
Non-elastic compressed air energy storage (D-CAES)
The system is an energy storage system based on compressed air and stored in geological underground caves.
During operation, the available power is used to compress the air into a large storage system, such as a salt hole hundreds of meters deep, within a higher pressure range according to the depth of the hole
The stored energy is released during peak demand, and the air is heated through natural gas or fuel combustion and expanded in the turbine to generate electricity.
In a non-insulated CAES system, the compression heat is not utilized, but is dissipated as waste.
In the same system, natural gas is used for combustion, heating air before the expansion process during the discharge cycle.
As mentioned earlier, two existing commercial CAES plants are operating under this configuration, which tends to generate greater greenhouse gas emissions. (ii)
In the thermal insulation system (A-CAES)
There is a higher temperature in the compressed heat storage, so it is possible to expect a larger power output.
The thermal insulation storage system eliminates mutual cooling during compression, and simply allows the air to be heated during compression and stored in CAES tanks.
However, in reality, when the air temperature is the lowest, more air quality can be accumulated, so in this structure, in order to accommodate more air at a higher temperature, the system's demand for large-capacity tanks eventually led to an increase in investment costs. (iii)
In advanced insulation storage systems (AA-CAES)
The compressed heat storage is present in a heat storage medium, which is used to heat compressed air during expansion, and the additional heat is provided by an external source for higher power input.
As additional energy storage systems and system heating are involved, the initial investment required in this case will be slightly higher. (iv)
In the constant temperature storage configuration ,(I-CAES)
The temperature inside the tank is kept constant by removing heat during charging and supplying heat during discharge.
All of the above processes are represented in the illustration. .
Recently, attempts have been made to summarize all existing research conducted by various scientists on compressed air energy storage systems to achieve efficient utilization of intermittent renewable energy sources.
A comprehensive report through this effort is contained in ().
Over the past few years, our lab has also conducted several experimental attempts to understand the most appropriate configuration for storing energy in compressed air.
Several research groups around the world have turned their attention to this potential area.
Some of the research results mentioned below have sparked our interest in a diversified way, thus proposing a new concept conversion using the naturally available thermal energy in the ocean/large body of water as an energy source, at the same time, the RE source integrated with the CAES system is utilized.
Current research work focuses on achieving higher turnover efficiency by keeping CAES in large water bodies, thereby extracting new concepts of heat from surrounding water bodies during energy conversion.
Detailed thermodynamic analysis of the above configurations and data analysis are explained in the methods provided at the end of this paper, and the results are given in the next section.