%0 Journal Article
%T A Coupled Thermo-Hydro-Mechanical Model of Jointed Hard Rock for Compressed Air Energy Storage
%A Xiaoying Zhuang
%A Runqiu Huang
%A Chao Liang
%A Timon Rabczuk
%J Mathematical Problems in Engineering
%D 2014
%I Hindawi Publishing Corporation
%R 10.1155/2014/179169
%X 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. 1. Introduction Renewable energy such as wind, solar, tidal, and wave only produces electricity intermittently and with low power and energy density, thus, nondispatchable and difficult to use at large scales as the modern society requires [1]. That is why many renewable energy technologies are lacking the economies of scale, which reduces their competitiveness and delays the transition to a low carbon economy. Therefore, economic solutions to bulk energy storage are urgently needed in order for renewable energy to take a significant share in the total energy mix. A critical issue for renewable energy to be integrated into grids with satisfactory stability is appropriate energy storage to defer electricity demand from peak to off peak times. Most energy storage systems are expensive, either in terms of Capex and Opex or in terms of energy losses incurred in storing and retrieving the energy. For example, batteries are costly, fly wheels are suitable for short-duration storage only. The CAES, besides pumped-hydro, is the only conceivable technology able to provide the very large scale energy storage deliverability above 100£żMW in single unit sizes while free from adverse environmental effects of pumped-hydro. Hence, CAES has recently received lots of attention [2, 3] and it has been recently proposed that large-scale solar-CAES and wind-CAES deployment can enable renewable energy to compete against coal-fired electricity generation [4, 5]. In CAES, a source energy is stored in the form of
%U http://www.hindawi.com/journals/mpe/2014/179169/