scholarly journals Preliminary design study of underground pumped hydro and compressed-air energy storage in hard rock. Volume 1. Executive summary. Final report

1981 ◽  
Author(s):  
◽  
Keyword(s):  
Energy Storage ◽  
Hard Rock ◽  
Compressed Air ◽  
Final Report ◽  
Preliminary Design ◽  
Compressed Air Energy Storage ◽  
Design Study ◽  
Executive Summary

Preliminary Design and Performance Assessment of an Underwater Compressed Air Energy Storage System for Wind Power Balancing

2020 ◽  
Vol 142 (9) ◽  
Author(s):  
Marco Astolfi ◽  
Giulio Guandalini ◽  
Marco Belloli ◽  
Adriano Hirn ◽  
Paolo Silva ◽  
...  
Keyword(s):  
Energy Storage ◽  
Wind Farm ◽  
Power Input ◽  
Compressed Air ◽  
Preliminary Design ◽  
Compressed Air Energy Storage ◽  
Peak Shaving ◽  
Renewable Power ◽  
And Performance

Abstract A key approach to large renewable power management is based on implementing storage technologies, including batteries, power-to-gas, and compressed air energy storage (CAES). This work presents the preliminary design and performance assessment of an innovative type of CAES, based on underwater compressed air energy storage (UW-CAES) volumes and intended for installation in the proximity of deep-water seas or lakes. The UW-CAES works with constant hydrostatic pressure storage and variable volumes. The proposed system is adiabatic, not using any fuel to increase the air temperature before expansion; a sufficient turbine inlet temperature (TIT) is instead obtained through a thermal energy storage (TES) system which recovers the compression heat. The system includes (i) a set of turbomachines (modular multistage compressor, with partial intercooling; expansion turbine); (ii) a TES system with different temperature levels designed to recover a large fraction of the compression heat, allowing the subsequent heating of air prior to the expansion phase; (iii) an underwater modular compressed air storage, conceived as a network of rigid but open tanks lying on the seabed and allowing a variable-volume and constant pressure operation. The compressor operates at variable loads, following an oscillating renewable power input, according to strategies oriented to improve the overall system dispatchability; the expander can be designed to work either at full load, thanks to the stability of the air flowrate and of the TIT guaranteed by the thermal storage, or at variable load. This paper first discusses in detail the sizing and off-design characterization of the overall system; then it simulates a case study where the UW-CAES is coupled to a wind farm for peak shaving and dispatchability enhancement, evaluating the impact of a realistic power input on performances and plant flexibility. Although the assessment shall be considered preliminary, it is shown that round-trip efficiency (RTE) in the range of 75–80% can be obtained depending on the compressor section configuration, making the UW-CAES a promising technology compared to electrochemical and pumped-hydrostorage systems. The technology is also applied to perform peak-shaving of the electricity production from an off-shore wind farm; annual simulations, based on realistic wind data and considering part-load operation, result in global RTE around 75% with a 10–15% reduction in the average unplanned energy injection in the electric grid. The investigated case study provides an example of the potential of this system in providing power output peak shaving when coupled with an intermittent and nonpredictable energy source.

scholarly journals A Coupled Thermo-Hydro-Mechanical Model of Jointed Hard Rock for Compressed Air Energy Storage

2014 ◽  
Vol 2014 ◽  
pp. 1-11 ◽  
Author(s):  
Xiaoying Zhuang ◽  
Runqiu Huang ◽  
Chao Liang ◽  
Timon Rabczuk
Keyword(s):  
Renewable Energy ◽  
Energy Storage ◽  
Gas Flow ◽  
Hard Rock ◽  
Compressed Air ◽  
Compressed Air Energy Storage ◽  
Renewable Energy Resources ◽  
Mass Source ◽  
Discrete Crack ◽  
Rock Cavern

Renewable energy resources such as wind and solar are intermittent, which causes instability when being connected to utility grid of electricity. Compressed air energy storage (CAES) provides an economic and technical viable solution to this problem by utilizing subsurface rock cavern to store the electricity generated by renewable energy in the form of compressed air. Though CAES has been used for over three decades, it is only restricted to salt rock or aquifers for air tightness reason. In this paper, the technical feasibility of utilizing hard rock for CAES is investigated by using a coupled thermo-hydro-mechanical (THM) modelling of nonisothermal gas flow. Governing equations are derived from the rules of energy balance, mass balance, and static equilibrium. Cyclic volumetric mass source and heat source models are applied to simulate the gas injection and production. Evaluation is carried out for intact rock and rock with discrete crack, respectively. In both cases, the heat and pressure losses using air mass control and supplementary air injection are compared.

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