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/X010236/1
• 负责人: Alexander Archibald
• 金额: $ 67.11万
• 依托单位: University of Cambridge
• 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%2FX010236%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).

全球氢经济正在快速增长。随着氢气使用量的增加，泄漏到大气中是不可避免的，大气中的氢气含量将会上升。人们对氢的大气生命周期的许多方面知之甚少，这给氢的转变带来的环境后果带来了很大的不确定性。土壤微生物从大气中去除了大量但不确定比例（50-80%）的氢。大气化学通过与羟基自由基 (OH) 反应去除其余部分。氢含量的上升会消耗 OH，从而延长甲烷的寿命。氢气氧化还产生对流层臭氧和平流层水蒸气。通过这种方式，氢气充当了间接温室气体（GHG）。对平流层臭氧和氧化剂的变化也会产生进一步的影响，从而影响气溶胶和云。模型中氢排放如何影响所有这些过程的表示尚处于起步阶段。该项目将提高我们的全球建模能力，评估未来影响，并识别和减少与氢气使用相关的不确定性。目前大多数全球大气氢模型规定了氢和甲烷的表层混合比，而不是增加排放量。该项目将开发 UKESM 模型的版本（已包含甲烷排放），其中包括氢的表面通量（排放和沉积），该模型将根据地表观测、飞机数据和冰雪记录进行调整和评估。我们将使用两种化学方案 - 一个标准方案和另一个对氧化剂进行更全面描述的方案 - 以便探索化学表示对于量化氢的影响有多么重要。我们还将开发另一个英国模型（STOCHEM），它另外代表氢的同位素异构体，为过程评估增加了进一步的限制。我们将与来自世界各地的其他几个建模小组协调我们的建模工作，以探索模型的多样性。我们将分析不同氢气泄漏量的模拟，并详细量化这如何影响全球氢气预算，以及对甲烷、臭氧和平流层水蒸气的影响。对模型预算条款和影响范围的分析将使我们能够识别模型之间的共性和差异，从而识别不确定的过程，例如导致不同氢寿命的过程。进一步的模型实验将探讨影响如何取决于氢气泄漏的位置和季节 - 我们预计与沉积到土壤的氢气比例相关的重要差异（例如，对半球、陆地/海洋比例和土壤性质的依赖）和氧化剂水平（例如热带/高纬度地区、夏季/冬季）。我们将综合我们的结果和不确定性分析，对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）进行全面的定量评估。我们将把有关氢的新知识纳入 FaIR 模型中，该模型是用于分析一系列未来情景的政策工具。这将使我们（和政策制定者）​​能够探索各种未来的氢情景，包括：（i）氢的使用在多大程度上抵消其他温室气体排放； (ii) 来自世界不同地点的不同程度的氢气泄漏； (iii) 大气化学代表性的差异； (iv) 氢气最终用途的差异（例如，氢气燃烧可能伴随着氮氧化物排放，这也会影响氧化剂）。 FaIR 除了作为向政策界简单传达我们的新模型结果的影响的媒介之外，还将使我们能够与本次电话会议中的其他资助项目快速协调，即主题 B（氢的土壤汇的不同表示） ）和主题C（未来场景）。

项目成果

Atmospheric composition and climate impacts of a future hydrogen economy

未来氢经济的大气成分和气候影响

• DOI: http://dx.10.5194/acp-23-13451-2023
• 发表时间: 2023
• 期刊: Atmospheric Chemistry and Physics
• 影响因子: 6.3
• 作者: Warwick N

Atmospheric composition and climate impacts of a future hydrogen economy

未来氢经济的大气成分和气候影响

• DOI: http://dx.10.5194/acp-2023-29
• 发表时间: 2023
• 作者: Warwick N