Topic A. Hydrogen Emissions: Constraining The Earth system Response (HECTER)

主题 A. 氢排放：限制地球系统响应 (HECTER)

• 批准号: NE/X010791/1
• 负责人: Dudley Shallcross
• 金额: $ 15.13万
• 依托单位: University of Bristol
• 依托单位国家: 英国
• 项目类别: Research Grant
• 财政年份: 2022
• 资助国家: 英国
• 起止时间: 2022 至 无数据
• 项目状态: 未结题
• 来源: https://gtr.ukri.org/projects?ref=NE%2FX010791%2F1
• 关键词: Topic; A.; Hydrogen; Emissions; Constraining

A global hydrogen economy is growing rapidly. As hydrogen usage increases, leakage to the atmosphere is inevitable, and atmospheric hydrogen levels will rise. Many aspects of hydrogen's atmospheric life cycle are poorly understood, placing large uncertainties on the environmental consequences of this shift to hydrogen. Soil microbes remove a large but uncertain proportion (50-80%) of hydrogen from the atmosphere. Atmospheric chemistry removes the rest, through reaction with the hydroxyl radical (OH). Rising levels of hydrogen thus deplete OH, lengthening methane's lifetime. Hydrogen oxidation also generates tropospheric ozone and stratospheric water vapour. In this way, hydrogen acts as an indirect greenhouse gas (GHG). There are further impacts on stratospheric ozone and changes in oxidants that will affect aerosols and clouds. The representation of how hydrogen emissions will affect all these processes in models is in its infancy.This project will improve our global modelling capabilities, assess future impacts, and identify and reduce uncertainties associated with hydrogen use. Most current global atmospheric hydrogen models prescribe surface layer mixing ratios of hydrogen and methane, rather than adding emissions. This project will develop versions of the UKESM model (already with methane emissions) to include surface fluxes (emissions and deposition) of hydrogen that will be tuned and evaluated with observations from surface sites, aircraft data, and firn ice records. We will use two chemistry schemes - a standard scheme and another with a more comprehensive description of oxidants - in order to explore how important the representation of chemistry is for quantifying hydrogen's impacts. We will also develop another UK model (STOCHEM), which additionally represents the isotopomers of hydrogen, adding further constraints on process evaluation. We will co-ordinate our modelling efforts with several other modelling groups from around the world in order to explore model diversity. We will analyse simulations with different hydrogen leakage amounts and quantify in detail how this affects the global hydrogen budget, and the resultant impacts on methane, ozone and stratospheric water vapour. Analysis of the range of model budget terms and impacts will allow us to identify commonality and differences between models, and hence identify uncertain processes, such as processes that lead to different hydrogen lifetimes. Further model experiments will explore how impacts depend upon the location and season of hydrogen leakage - we expect there to be important differences related to the proportion of hydrogen deposited to soils (e.g., dependence on hemisphere, proportion of land/ocean, and soil properties) and levels of oxidants (e.g., tropics/high-latitudes, summer/winter).We will synthesize our results and analysis of uncertainty to produce a comprehensive quantitative assessment of climate metrics (e.g., Global Warming Potential, Global Temperature Potential, and Effective Radiative Forcing) associated with hydrogen. We will incorporate this new knowledge about hydrogen into the FaIR model, which is a policy tool used for analysing a range of future scenarios. This will allow us (and policymakers) to explore a wide range of future hydrogen scenarios, including for example: (i) the extent to which hydrogen use offsets other GHG emissions; (ii) different levels of hydrogen leakage, from different world locations; (iii) differences in the representation of atmospheric chemistry; and (iv) differences in hydrogen end usage (e.g., hydrogen combustion may be accompanied by NOx emissions, which also affect oxidants). As well as being a medium to simply communicate the implications of our new modelling results to the policy community, FaIR will also allow us to co-ordinate rapidly with the other funded projects within this call, i.e. Topic B (different representations of hydrogen's soil sink) and Topic C (future scenarios).

全球氢经济正在迅速增长。随着氢的使用增加，对大气的泄漏是不可避免的，大气氢的水平将上升。氢气生命周期的许多方面都了解得很糟糕，这对向氢转移的环境后果造成了很大的不确定性。土壤微生物从大气中清除了大的但不确定的比例（50-80％）。大气化学通过与羟基自由基反应（OH）反应去除其余的。因此，氢的水平上升，因此耗尽了OH，从而延长了甲烷的寿命。氢氧化还会产生对流层臭氧和平流层水蒸气。这样，氢充当间接温室气体（GHG）。对平流层臭氧和氧化剂的变化有进一步的影响，这些氧化剂会影响气雾剂和云。氢排放将如何影响模型中所有这些过程的表示。该项目将提高我们的全球建模能力，评估未来的影响，并识别和减少与使用氢相关的不确定性。当前的大多数全球大气氢模型规定了氢和甲烷的表面层混合比，而不是添加排放。该项目将开发UKESM模型的版本（已经使用甲烷排放），包括氢的表面通量（排放和沉积），这些氢将通过表面位点，飞机数据和FIRN ICE记录的观测来调整和评估。我们将使用两种化学方案 - 一种标准方案，对氧化剂进行了更全面的描述，以探讨化学的表示对于量化氢的影响的重要性。我们还将开发另一个英国模型（Stochem），该模型还代表了氢的同位素，从而增加了对过程评估的进一步限制。我们将与来自世界各地的其他几个建模组协调我们的建模工作，以探索模型多样性。我们将分析具有不同氢泄漏量的模拟，并详细量化这对全球氢预算的影响以及对甲烷，臭氧和平流层水蒸气的影响。分析模型预算术语和影响的范围将使我们能够确定模型之间的通用性和差异，从而确定不确定的过程，例如导致不同氢寿命的过程。进一步的模型实验将探索影响的影响如何取决于氢泄漏的位置和季节 - 我们希望存在与沉积在土壤中的氢的比例相关的重要差异（例如，依赖半球，土地/海洋和土壤的比例和土壤特性）以及氧化剂的水平（例如，热带/高层/夏季冬季）的氧化剂（例如，冬季）的综合。与氢相关的气候指标（例如，全球变暖潜力，全球温度潜力和有效辐射强迫）的评估。我们将将有关氢的新知识纳入公平模型，这是一种用于分析一系列未来场景的政策工具。这将使我们（和政策制定者）​​能够探索各种未来的氢场景，包括：（i）氢的使用程度抵消了其他温室气体的排放； （ii）不同世界的不同水平的氢泄漏； （iii）大气化学表示的差异； （iv）氢末端使用的差异（例如，氢燃烧可能伴随着NOX排放，这也会影响氧化剂）。除了简单地传达我们的新建模结果的含义与政策界的含义外，Fair还将使我们能够与本呼叫中的其他资助项目（即氢土壤水槽的不同表示）和主题C（未来场景）快速协调。