The paper reviews different approaches, technologies, and strategies to manage large-scale schemes of variable renewable electricity such as solar and wind power. We consider both supply and demand side measures. In addition to presenting energy system flexibility measures, their importance to renewable electricity is discussed. The flexibility measures available range from traditional ones such as grid extension or pumped hydro storage to more advanced strategies such as demand side management and demand side linked approaches, e.g. the use of electric vehicles for storing excess electricity, but also providing grid support services. Advanced batteries may offer new solutions in the future, though the high costs associated with batteries may restrict their use to smaller scale applications. Different “P2Y”-type of strategies, where P stands for surplus renewable power and Y for the energy form or energy service to which this excess in converted to, e.g. thermal energy, hydrogen, gas or mobility are receiving much attention as potential flexibility solutions, making use of the energy system as a whole. To “functionalize” or to assess the value of the various energy system flexibility measures, these need often be put into an electricity/energy market or utility service context. Summarizing, the outlook for managing large amounts of RE power in terms of options available seems to be promising.

https://research.aalto.fi/files/6557604/lund_et_al_review.pdf

Review of energy system flexibility measures to enable high levels of variable renewable electricity

Renewable Energy Sources have been growing rapidly over the last few years. The spreading of renewables has become stronger due to the increased air pollution, which is largely believed to be irreversible for the environment. On the other hand, the penetration of renewable energy technologies causes major problems to the stability of the grid. Along with the fluctuations of the renewable energy technologies production, storage is important for power and voltage smoothing. Energy storage is also important for energy management, frequency regulation, peak shaving, load leveling, seasonal storage and standby generation during a fault. Thus, storage technologies have gained an increased attention and have become more than a necessity nowadays. This paper presents an up to date comprehensive overview of energy storage technologies. It incorporates characteristics and functionalities of each storage technology, as well as their advantages and disadvantages compared with other storage technologies. Comparison tables with several characteristics of each storage method are included, while different applications of energy storage technologies are described as well. Finally, several hybrid energy storage applications are analyzed and different combinations of energy storage technologies are reviewed.

Energy storage for electricity generation and related processes: Technologies appraisal and grid scale applications

Energy Storage Technology and Cost Characterization Report

Assessment of energy storage technologies: A review

An updated review of energy storage systems: Classification and applications in distributed generation power systems incorporating renewable energy resources

With the increase of power generation from renewable energy sources and due to their intermittent nature, the power grid is facing the great challenge in maintaining the power network stability and reliability. To address the challenge, one of the options is to detach the power generation from consumption via energy storage. The intention of this paper is to give an overview of the current technology developments in compressed air energy storage (CAES) and the future direction of the technology development in this area. Compared with other energy storage technologies, CAES is proven to be a clean and sustainable type of energy storage with the unique features of high capacity and long-duration of the storage. Its scale and cost are similar to pumped hydroelectric storage (PHS), thus CAES has attracted much attention in recent years while further development for PHS is restricted by the availability of suitable geological locations. The paper presents the state-of-the-art of current CAES technology development, analyses the major technological barriers/weaknesses and proposes suggestions for future technology development. This paper should provide a useful reference for CAES technology research and development strategy.

Overview of Compressed Air Energy Storage and Technology Development

Power generation from renewable energy has become more important due to the increase of electricity demand and pressure on tough emission reduction target. This has brought great impact on grid reliable operation. Wind curtailment often happens when grid can not accommodate more wind power. Various solutions are under investigation and energy storage (ES) is one of the recognized potential ways forward. Among all the ES technologies, Compressed Air Energy Storage (CAES) has demonstrated its unique merit in terms of scale, sustainability, low maintenance and long life time. The paper is to provide an overview of the current research trends in CAES and also update the technology development. The paper has also given a comprehensive review to the work conducted by the researchers in China.

https://tandfonline.com/doi/pdf/10.1080/21642583.2017.1377645

Current research and development trend of compressed air energy storage

Rocks are continuously affected by dry–wet cycles, which leads to intensified weathering and deterioration of the mechanical properties and often triggers engineering disasters. This study analysed the changes in the mechanical properties and microstructure of sandstone under dry–wet cycles. Based on the box dimension theory and the associated dimensions, the fractal dimension and correlation dimension were developed through digital images and time-series parameters to analyse the microstructural features and acoustic emission (AE) in MATLAB. The degree of microstructure damage under different dry–wet cycles was determined, and the relationship between the microstructure characteristics, fracture development trend, fractal dimension, and correlation dimension was established. The uniaxial compressive strength , elastic modulus , p-wave velocity, and resistivity of the sandstone decayed in distinct stages as the number of dry–wet cycles increased. The degree of microstructure damage was observed to be directly proportional to the fractal dimension. The physical and mechanical properties of the sandstone exhibited a significant relationship with the fractal dimension; it could be used to quantitatively describe the parametric characteristics of the sandstone. The change law of AE energy is consistent with the damage process of sandstone. Based on the analysis of the correlation dimension and sandstone microscale failure, its variation characteristics could be used to quantitatively evaluate the trend of sandstone fracture development and microstructural characteristics . The research results provide a reference for further exploration of the deterioration mechanism and engineering application of the sandstone during dry–wet cycles. • Changes in p-wave velocity, resistivity, uniaxial compressive strength, and elastic modulus of the sandstone under dry-wet cycles are studied. • Fractal dimension is used to quantify the degree of microstructure damage. • Degree of microstructure damage was observed to be directly proportional to the fractal dimension. • Acoustic emission technology is used to study the damage characteristics of the sandstone under dry-wet cycles. • Complexity of sandstone failure can be described by correlation dimensions. 

Quantification and acoustic emission characteristics of sandstone damage evolution under dry–wet cycles

The relationship between baseline axial length and axial elongation in myopic children undergoing orthokeratology

The utility model discloses a testing system based on the research of vortex formula expander low -grade energy recovery system, including high pressure gasholder, air outlet manually -operated valve, duct insert heater, relief pressure valve, pressure sensor, temperature sensor, flow sensor, air compressor machine, vortex expander, torque sensor, generator etc. The gas holder is high -pressure storage tank for storage compressed air and provide high -pressure gas for the system, air outlet manually -operated valve is this testing system's opening device to the flow that can be used to control of gases, the relief pressure valve can be used to control access to the gaseous pressure of vortex formula expander to ensure vortex formula expander intake pressure's stability, thereby ensure that the generator moving is stable, vortex formula expander includes quiet whirlpool dish and moves the whirlpool dish that passing through gases move whirlpool dish acting, realize the transformation of compression potential energy to mechanical energy, the generator is the high -speed engine, realizes that mechanical energy is to electric transformation of energy. This experimental system regards as energy conversion device to have advantages such as efficient, that little, the noise of vibration is low, compact structure, small, light in weight, control are simple with vortex formula expander, and whole test bench is rationally distributed, the adjustability good, the operation is safe convenient, green clean, has good using value and wide application prospect.

Kunpeng Lu

Papers

Overview of Compressed Air Energy Storage and Technology Development

Current research and development trend of compressed air energy storage

Quantification and acoustic emission characteristics of sandstone damage evolution under dry–wet cycles

The relationship between baseline axial length and axial elongation in myopic children undergoing orthokeratology

Low -grade energy recuperation's combined test system based on vortex formula expander