The Natural Gas Supply Chain: The Importance of Methane and Carbon Dioxide Emissions
The Natural Gas Supply Chain: The Importance of Methane and Carbon Dioxide Emissions
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DOI：
10.1021/acssuschemeng.6b00144
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发表时间：
2017-01-01
影响因子：
8.4
通讯作者：
Hawkes, Adam
中科院分区：
文献类型：
--
作者：
Balcombe, Paul;Anderson, Kris;Hawkes, Adam
天然气通常被认为是燃烧更清洁的化石燃料，可以在有限的碳预算中发挥重要作用。虽然天然气燃烧时排放的二氧化碳比其他化石燃料少，但其主要成分是甲烷，甲烷在短期内对气候的影响比二氧化碳强得多。天然气供应链中甲烷排放量的估计一直备受争议，原因是与估计方法、数据质量和所用假设相关的不确定性。该报告全面汇编了全球天然气供应链中的二氧化碳和甲烷排放量估计值，旨在通过总结报告的数据，定位主要不确定性领域，并确定需要进一步开展工作以减少或消除这种不确定性，为学术界，工业界和政策制定者提供平衡的见解。总体而言，整个供应链中甲烷排放量的记录估计范围很大，包括不同的地质构造，技术，工厂年龄，气体成分和区域监管，更不用说估计方法的差异。估计甲烷和二氧化碳的总排放量为2至42克二氧化碳当量/兆焦耳HHV，而仅甲烷的排放量为所产生甲烷的0.2%至10%。开采阶段的甲烷排放是最具争议的问题，可用数据有限，但与非常规天然气、液体卸载以及传输阶段的完井相关的潜在影响很大。从文献估计的范围来看，估计了一个约束范围的排放量，反映了最新和可靠的估计：供应链温室气体总排放量估计在3.6和42.4克CO2当量/兆焦耳HHV之间，中心估计值为10.5。在供应链的所有阶段都存在“超级排放者”，即造成极高排放量的少数设施或设备，造成排放量分布高度倾斜。然而，各种新技术、缓解和维护方法以及立法正在推动天然气供应链中甲烷泄漏的显著减少。
Natural gas is typically considered to be the cleaner-burning fossil fuel that could play an important role within a restricted carbon budget. While natural gas emits less CO2 when burned than other fossil fuels, its main constituent is methane, which has a much stronger climate forcing impact than CO2 in the short term. Estimates of methane emissions in the natural gas supply chain have been the subject of much controversy, due to uncertainties associated with estimation methods, data quality, and assumptions used. This Perspective presents a comprehensive compilation of estimated CO2 and methane emissions across the global natural gas supply chain, with the aim of providing a balanced insight for academia, industry, and policy makers by summarizing the reported data, locating the areas of major uncertainty, and identifying where further work is needed to reduce or remove this uncertainty. Overall, the range of documented estimates of methane emissions across the supply chain is vast among an aggregation of different geological formations, technologies, plant age, gas composition, and regional regulation, not to mention differences in estimation methods. Estimates of combined methane and CO2 emissions ranged from 2 to 42 g CO2 eq/MJ HHV, while methane-only emissions ranged from 0.2% to 10% of produced methane. The methane emissions at the extraction stage are the most contentious issue, with limited data available but potentially large impacts associated with well completions for unconventional gas, liquids unloading, and also the transmission stage. From the range of literature estimates, a constrained range of emissions was estimated that reflects the most recent and reliable estimates: total supply chain GHG emissions were estimated to be between 3.6 and 42,4 g CO2 eq/MJ HHV, with a central estimate of 10.5. The presence of "super emitters", a small number of facilities or equipment that cause extremely high emissions, is found across all supply chain stages creating a highly skewed emissions distribution. However, various new technologies, mitigation and maintenance approaches, and legislation are driving significant reductions in methane leakage across the natural gas supply chain.