Understanding rock Fatigue mechanisms in Underground hydrogen StoragE: FUSE

了解地下储氢中的岩石疲劳机制：FUSE

• 批准号: NE/Y002970/1
• 负责人: Shangtong Yang
• 金额: $ 10.79万
• 依托单位: University of Strathclyde
• 依托单位国家: 英国
• 项目类别: Research Grant
• 财政年份: 2023
• 资助国家: 英国
• 起止时间: 2023 至 无数据
• 项目状态: 未结题
• 来源: https://gtr.ukri.org/projects?ref=NE%2FY002970%2F1
• 关键词: Understanding; rock; Fatigue; mechanisms; Underground

Green or renewable energy has become vital in achieving net zero carbon and the key enabling technology to realise green energy ambitions is energy storage infrastructure. For instance, power systems in which more than 80% of the supply is generated from renewable sources cannot be balanced using existing storage. In the UK, wind curtailment payments almost doubled in 2020 to a total of £299M and hit a record high of £507M in 2021. The energy wasted in 2020 and 2021 is enough to power 800,000 British homes. Amongst all energy storage means, underground hydrogen storage has shown great potential for large-scale and long-term storage while securing a continuous and well-defined supply stream. Underground hydrogen storage works by injecting hydrogen that is produced from renewable electricity, e.g., wind turbines, into underground geological formations, including depleted oil and gas reservoirs, salt caverns, aquifers and hard rock caverns. The stored hydrogen can then be used for power generation to balance the fluctuation in energy use as well as for fuel to meet transportation demands. Rock caverns are often regarded as the best option for underground hydrogen storage due to their low gas permeability which contributes to excellent sealing strength and capability. Once lined with concrete and a layer of gas-tight material such as stainless steel, PE or PVC, rock caverns can have excellent storage capability for high-density hydrogen with minimum environmental impact. However, the caverns' long-term structural stability and serviceability depend on their material heterogeneity and complex geometries, and the in-situ stress state. The injection and withdrawal process will generate cyclic pressure on the rock mass; as a result, the surrounding rock is subjected to cyclic tensile stress in the tangential direction, possibly together with cyclic shear stress. The cyclic tensile and shear stresses will generate fatigue of rock, i.e., strength reduction, leading to mode-I, mode-II and/or the mixed mode cracks, at (possibly much) lower level of operational pressure. This poses a great threat to the structural integrity and safety of the storage site.In this international partnership project, we aim to address how the in-situ rock is fatigued and fractured under the cyclic pressure that will be generated from the injection and withdrawal of hydrogen, and how rock fatigue may affect the integrity and safety of the hydrogen storage infrastructure. Considering the hydrogen storage working conditions, the research problem can be summarized into low-cycle rock fatigue fracture under high in-situ stress level. Moreover, material heterogeneity, stress state, complex geometries, material creep, etc. can all have effects on the fatigue behavior of rock. To ensure the safe long-term storage of hydrogen in rock caverns it is therefore critically important to have a thorough understanding of rock fatigue mechanisms.

绿色或可再生能源在实现净零碳方面已变得至关重要，而实现绿色能源雄心的关键技术是储能基础设施。例如，超过80%的电力供应来自可再生能源的电力系统无法使用现有的存储来平衡。在英国，弃风付款于二零二零年几乎翻了一番，总额达2. 99亿英镑，并于二零二一年创下5. 07亿英镑的历史新高。2020年和2021年浪费的能源足以为80万户英国家庭供电。在所有储能手段中，地下储氢在大规模和长期储存方面表现出巨大的潜力，同时确保了连续和明确的供应流。地下氢储存通过注入由可再生电力产生的氢来工作，例如，风力涡轮机、地下地质构造，包括枯竭的石油和天然气储藏、盐穴、蓄水层和硬岩洞穴。储存的氢气可以用于发电，以平衡能源使用的波动，以及用于燃料，以满足运输需求。岩石洞穴通常被认为是地下储氢的最佳选择，因为它们的低透气性有助于良好的密封强度和能力。一旦用混凝土和一层气密材料（如不锈钢，PE或PVC）衬里，岩石洞穴就可以在最小的环境影响下具有出色的高密度氢气储存能力。然而，洞室的长期结构稳定性和可用性取决于其材料的异质性和复杂的几何形状，以及原地应力状态。注采过程会对岩体产生循环压力，使围岩在切向受到循环拉应力，并可能伴有循环剪应力。循环的拉应力和剪应力会使岩石产生疲劳，即，强度降低，导致I型、II型和/或混合型裂纹，在（可能低得多）的操作压力水平下。在这个国际合作项目中，我们的目标是解决在注入和提取氢气的循环压力下，原位岩石如何疲劳和断裂，以及岩石疲劳如何影响储氢基础设施的完整性和安全性。考虑到储氢工作条件，研究问题可以归结为高地应力水平下岩石的低周疲劳断裂问题。此外，材料非均匀性、应力状态、复杂几何形状、材料蠕变等都会对岩石的疲劳行为产生影响。因此，为了确保氢在岩石洞穴中的安全长期储存，对岩石疲劳机制有透彻的了解至关重要。