Dynamic modelling and techno-economic analysis of adiabatic compressed air energy storage for emergency back-up power in supporting microgrid

Adiabatic compressed air energy storage technology recently attracts a great attention due to its merits of low cost, long lifetime and environmentally friendly. Several MW scale pilot plants were recently built to explore the technology deployment potential. With the encouragement of the success of these pilot plants, this paper presents the recent research in dynamic modelling and comprehensive techno-economic analysis of adiabatic compressed air energy storage in providing emergency back-up power to support microgrid operation. The dynamic modelling for key components of a MW scale adiabatic compressed air energy storage plant and the associated microgrid is carried out. The models developed are used for analyzing the system dynamic performance while it provides emergency back-up power. Then, the economic benefit estimation model is developed for conducting a comprehensive economic analysis in order to understand the economic gains of adiabatic compressed air energy storage operation with different microgrid configurations, power supply reliabilities and diesel prices. The simulation results indicate that the MW scale adiabatic compressed air energy storage can normally fully restore the power supply to important loads within several minutes. It is acceptable for the load with no strict requirement on power outage time, but its standalone operation cannot meet the requirement of uninterruptable power source. For a microgrid having low power supply reliability requirement, high diesel price and abundant renewable energy sources, using adiabatic compressed air energy storage for providing emergency back-up power can achieve higher economic benefits compared with diesel generators

Influence of Stress Anisotropy on Petrophysical Parameters of Deep and Ultradeep Tight Sandstone

Rock mechanics parameters control the distribution of in situ stress and natural fractures, which is the key to sweet spot evaluation in reservoir engineering. Combined with the distribution of in situ stress, an experimental scheme of stress on rock physical parameters was designed. The results show that rock sonic velocity is extremely sensitive to water saturation under overburden pressure. At ultrasonic frequencies, when the water saturation increases from 0% to 80%, the P-wave velocity increases first and then decreases. When the water saturation continues to increase to 100%, the P-wave velocity increases. This is due to the effect of water saturation on the shear modulus. Saturation is negatively correlated with shear wave velocity and resistivity. Different minerals have different control effects on the rock P-S wave velocity ratio. Quartz content plays a dominant role, and the two are negatively correlated, followed by feldspar and clay, and the two are positively correlated with the P-S wave ratio. The confining pressure, axial compression, stress ratio and burial depth are positively correlated with the P-S wave and negatively correlated with the P-S wave ratio; in descending order, the influencing factors of stress on the petrophysical parameters are maximum stress ratio > confining pressure > axial pressure