GigaWatt-Hour Subsurface Thermal Energy storAge: Engineered structures and legacy Mine shafts: STEaM

英国最后一座深煤矿于2015年关闭。英国煤炭管理局有17.7万个已知煤矿的记录。这一建议探讨了利用废弃矿井以热能形式储存减少的风能的潜力。2020年，英国的弃风费用为2.82亿英镑，足以为125万户家庭供电，相当于每兆瓦时发电4英镑。仅在东艾尔郡就有120吉瓦的“备用”电力。热储存以前已经研究过，但受到尺寸和绝缘需要的限制。被水淹没的矿井在英国的大部分地区都是普遍存在的，然而，在矿井内储热的机会从未被探索过。竖井周围的岩体是绝缘体，我们联盟的试点工作表明，随着岩石升温，在短短三年内，热量提取的效率就会大大提高。我们将研究利用刮风天气的多余电力来加热废弃矿井中的水，在寒冷的天气里通过热泵将水抽出来供家庭和企业使用的可行性。英国到处都是煤矿时代留下的矿井——我们想把这些地洞变成储热库，以帮助平衡电网，并为家庭和企业脱碳。矿井用混凝土或砖砌成衬里（有时没有衬里）。为了安全有效地利用这些遗留的地下基础设施，我们需要了解加热矿井中的水对矿井水体的影响：矿井中的水体可能是自然分层的，并且含有可能导致污染或结垢的矿物质；关于衬里材料，在矿山关闭后的几十年里，衬里材料很可能已经退化；在周围的岩石和它们所含的水（在孔隙和裂缝中）。我们将开发复杂的热-液压-化学-机械（THCM）耦合模型，根据我们从英国竖井分析中开发的案例研究以及从测试现场收集的数据。我们还将采用一种整体系统的方法，考虑到这样一个项目的经济效益，以及在建设和运营过程中产生的碳排放，来研究这样一个储能系统如何在更广泛的能源系统中发挥作用。我们计划在一个地点进行测试，在那里我们钻入一个竖井，提取水样本和盖层材料进行分析，然后监测热量的注入，以验证我们的模型。我们提议的矿井范例是男爵煤矿，它曾经是苏格兰最深的矿井。我们的项目合作伙伴，东艾尔郡议会已经为靠近现场的观测孔提供了资金，该观测孔将为建模和观察我们的实验进展提供数据基线。这项工作的成果将适用于评估英国煤田矿井地点的矿井热储资源，与利用该资源相关的任何风险，以及在当地能源系统中使用该资源的最佳方式。我们还将提供有用的新数据，以更好地理解从矿山开采中提取天然地热补充热量的概念；考虑放弃活动矿井的最佳方法，使它们成为热储存的准备；建立了矿井与围岩的全耦合THCM模型；并开发了第一个包含地下基础设施和地质的综合能源系统模型。

The last deep coal mine in the UK closed in 2015. The Coal Authority has a record of 177,000 known mine entries. This proposal examines the potential to use abandoned mine shafts for interseasonal storage of curtailed wind energy in the form of thermal energy. In 2020, wind curtailment payments in the UK were £282M: enough to power 1.25 million homes and equivalent to £4 per MWh of energy generated. There is 120GW of 'spare' electricity in East Ayrshire alone. Thermal stores have been studied previously but are limited by size and the need to insulate. Flooded mine shafts are ubiquitous across much of the UK, yet the thermal storage opportunity within shafts has never been explored. The rock mass around the shafts are insulators and pilot work by our consortium has shown that as the rocks heat up the efficiency of the heat extraction rises considerably in as little as three years. We will investigate the feasibility of using the spare electricity on windy days to heat up water in abandoned mine shafts, to be extracted on cold days by heat pumps into homes and businesses. The UK is peppered with mine shafts from the days of coal mining - we want to turn these holes in the ground into thermal stores to help balance the electrical grid and to decarbonise homes and businesses. Mine shafts were lined with concrete or brick (sometimes unlined). To safely and efficiently utilise this legacy subsurface infrastructure we need to understand the effect of heating up the water in the mine shafts on: the water body in the shaft, which may be naturally stratified and will contain minerals that could cause contamination or scaling; on the lining material, which is likely to have degraded in the decades since mine closure; on the surrounding rocks and the water they contain (in pores and fractures). We will develop sophisticated coupled thermal-hydraulic-chemical-mechanical (THCM) modelling informed by case studies we develop from an assay of the UK's shafts, as well as data collected from a test site. We will also take a whole-systems approach to looking at how such an energy store could sit within the wider energy system, taking into account the economics of such a project, and any carbon emissions generated through construction and operation of a site. We are planning a test at a site where we drill into a shaft to retrieve samples of water and capping materials for analysis, and then monitor the injection of heat to validate our models. The example shaft that we are proposing to work on is the Barony colliery, once the deepest in Scotland. Our project partners, East Ayrshire Council have funding for an observation hole close to the site that will provide a baseline of data for the modelling and for observing the progress of our experiment. The outputs of this work will be applicable for assessing the mine shaft thermal store resource at mine shaft sites across UK coalfields, any risks associated with utilising that resource, and the optimal way to use that resource within the local energy system. We will also provide useful new data for the more well-understood concept of extracting natural geothermally recharged heat from mine workings; for consideration of the best way to abandon active mines so that they are thermal storage-ready; produce a fully coupled THCM model of mine shafts and the surrounding rock mass; and develop the first integrated energy system model to include subsurface infrastructure and geology.