Microbial carbon cycling under geological CO2 storage conditions: understanding the rules of life in the engineered subsurface

为了认识到化石燃料使用导致的二氧化碳(CO2)排放增加导致的全球气候危机日益严重，英国政府最近通过了一项承诺，到2050年实现净零排放。这一雄心勃勃的目标不仅要求从化石燃料过渡到可再生能源，而且还要求直接消除大气中的二氧化碳排放。要做到这一点，一个引人注目的方法是碳捕获和储存，即从源头(例如发电厂和水泥厂)捕获使用化石燃料的二氧化碳，并将其运输到地球表面以下0.8公里或更深的地方进行安全储存。为了使这种碳捕获和储存方法取得成功，捕获的二氧化碳必须永久性地注入深层地质构造，如高盐度砂岩含水层。这些地层具有合适的二氧化碳储存地质特征，许多试点项目已经证明，将大量二氧化碳注入这些地下环境是可能的。然而，最近的研究表明，这些地下环境中居住着各种活跃的微生物群落，深部地质二氧化碳储存环境中微生物活动的影响尚不清楚。微生物能够利用二氧化碳进行代谢，向深层地下环境注入二氧化碳可能会导致微生物群落的组成和功能向能够利用二氧化碳进行生长的微生物群落转移。这可能会产生积极的影响，如加强二氧化碳的封存并转化为生物质(类似于通过植树锁定二氧化碳)，或产生负面影响，如产生可能引发储水池泄漏的额外气体。我提议进行的研究旨在更好地了解微生物在地质二氧化碳储存设施中的作用，并确定利用微生物在这些环境中锁定更多二氧化碳的方法，甚至将废弃的二氧化碳转化为有用的化学品，如生物燃料。我将模拟一个深层地质二氧化碳储藏库的条件，使用定制的‘生物反应器’，允许在地下常见的高温和压力下研究微生物群落。在整个这些实验中，以及在后续的有针对性的实验中，我将应用最先进的地球化学法和‘组学’技术来监测系统的化学和微生物学的变化。这项工作的一个特别重点是了解微生物群落中的单个有机体如何在驱动新陈代谢过程中共同工作。这些相互作用发生在所有微生物群落中，但还没有被很好地理解。使用尖端工具，我将识别和描述这些相互作用，并在这样做的过程中，以前所未有的详细程度揭示这些微生物过程对二氧化碳储存的作用。这些结果将被用来开发这些微生物群落的计算机模型，从而能够预测这些微生物群落在不同条件下的作用。利用这些预测，我们可以学习如何利用地下微生物的力量，帮助英国在2050年前实现零排放目标。

In recognition of the growing global climate emergency caused by the increase in carbon dioxide (CO2) emissions from fossil fuel use, the UK government recently passed into law a commitment to reach net zero emissions by 2050. This ambitious target not only calls for a transition from fossil fuels to renewable energy, but also for the direct removal of CO2 emissions from the atmosphere. A compelling way to do this is with carbon capture and storage, whereby CO2 from fossil fuel use is captured at source (for example power plants and cement factories) and transported for safe storage 0.8 km or more beneath the surface of the Earth. In order for this carbon capture and storage approach to succeed, captured CO2 must be injected into deep geological formations, such as high salinity sandstone aquifers, on a permanent basis. These formations have the right geological characteristics for CO2 storage, and numerous pilot projects have demonstrated that the injection of large volumes of CO2 into these subsurface environments is possible. However, recent research has shown that these subsurface environments are inhabited by diverse and active communities of microorganisms, and the impacts of microbial activity in a deep geological CO2 storage environment are not known.Microorganisms are capable of using CO2 for their metabolism, and the injection of CO2 into deep subsurface environments is likely to cause a shift in the composition and function of microbial communities towards those capable of exploiting CO2 for growth. This could result in positive impacts, such as enhanced sequestration of CO2 and conversion into biomass (akin to locking away CO2 by planting trees), or negative impacts, such as the production of extra gases that may trigger leakages from the storage reservoir. The research I propose to conduct is designed to better understand the role of microorganisms in a geological CO2 storage facility, and to identify ways in which microorganisms might be harnessed to lock away more CO2 in these environments and even convert waste CO2 into useful chemicals, such as biofuels. I will mimic the conditions of a deep geological CO2 storage reservoir using bespoke 'bioreactors' that allow microbial communities to be studied under the elevated temperatures and pressures common to the subsurface. Throughout these experiments, and in follow-on targeted experiments, I will apply state-of-the-art geochemical and 'omics' techniques to monitor changes to the chemistry and microbiology of the system. A particular focus of this work is to understand how individual organisms in a microbial community work together in driving metabolic processes. These interactions occur in all microbial communities, but are not well understood. Using cutting-edge tools, I will identify and characterise these interactions and in doing so unearth the role of these microbial processes on CO2 storage in unprecedented detail. These results will be used to develop computer models of these communities, enabling predictions to be made on the role of these microbial communities under different conditions. Using these predictions, we can learn how to harness the power of microorganisms in the subsurface to help the UK reach its zero emissions target by 2050.