Compressed energy storage (CES) of air, CO₂, or H₂ in porous formations is a promising means of energy storage to abate the intermittency of renewable energy production. During operation, gas is injected during times of excess energy production and extracted during excess demands to drive turbines. Storage in saline aquifers using CO₂ as a cushion or working gas has numerous advantages over typical air storage in caverns. However, interactions between CO₂ and saline aquifers may result in potential operational limitations and have not been considered. This work utilizes reactive transport simulations to evaluate the geochemical reactions that occur during injection and extraction operational cycles for CES in a porous formation using CO₂ as a cushion gas. Simulation results are compared with similar simulations considering an injection-only flow regime of geologic CO₂ storage. Once injected, CO₂ creates conditions favorable for dissolution of carbonate and aluminosilicate minerals. However, the dissolution extent is limited in the cyclic flow regime where significantly smaller dissolution occurs after the first cycle such that CO₂ is a viable choice of cushion gas. In the injection-only flow regime, larger extents of dissolution occur as the fluid continues to be undersaturated with respect to formation minerals throughout the study period and porosity increased uniformly from 24.84% to 33.6% throughout the simulation domain. For the cyclic flow conditions, porosity increases nonuniformly to 31.1% and 25.8% closest and furthest from the injection well, respectively.

中文翻译：

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评估压缩储能系统中利用CO2作为气垫气的地球化学局限性

多孔结构中的空气，CO ₂或H _2的压缩储能（CES）是一种有希望的储能方式，可减少可再生能源生产的间歇性。在运行过程中，在产生过多能量时会注入气体，而在驱动涡轮机的过度需求时会抽取气体。与在洞穴中进行典型的空气存储相比，使用CO ₂作为缓冲层或工作气体存储在含盐含水层中具有许多优势。但是，CO ₂之间的相互作用盐水层可能会导致潜在的操作局限性，因此尚未考虑。这项工作利用反应输运模拟来评估在以CO ₂为缓冲气体的多孔地层中CES的注入和萃取操作循环过程中发生的地球化学反应。考虑地质CO ₂储存的仅注入流态，将模拟结果与类似模拟进行比较。注入后，CO ₂创造了有利于碳酸盐和铝硅酸盐矿物溶解的条件。但是，溶解度受到循环流态的限制，在该循环流态下，在第一个循环后发生的溶解度大大降低，从而使CO ₂是缓冲气的可行选择。在仅注入流态下，由于在整个研究期间流体相对于地层矿物而言持续不饱和，因此发生了更大程度的溶解，并且在整个模拟域中，孔隙率从24.84％均匀增加到33.6％。对于循环流动条件，孔隙度不均匀地增加到距注入井最近和最远的31.1％和25.8％。