Qin Yue, Wagner Fabian, Scovronick Noah, Peng Wei, Yang Junnan, Zhu Tong, Smith Kirk R, Mauzerall Denise L
Woodrow Wilson School of Public and International Affairs, Princeton University, Princeton, NJ 08544.
Andlinger Center for Energy and the Environment, Princeton University, Princeton, NJ 08544.
Proc Natl Acad Sci U S A. 2017 May 9;114(19):4887-4892. doi: 10.1073/pnas.1703167114. Epub 2017 Apr 24.
Facing severe air pollution and growing dependence on natural gas imports, the Chinese government plans to increase coal-based synthetic natural gas (SNG) production. Although displacement of coal with SNG benefits air quality, it increases CO emissions. Due to variations in air pollutant and CO emission factors and energy efficiencies across sectors, coal replacement with SNG results in varying degrees of air quality benefits and climate penalties. We estimate air quality, human health, and climate impacts of SNG substitution strategies in 2020. Using all production of SNG in the residential sector results in an annual decrease of ∼32,000 (20,000 to 41,000) outdoor-air-pollution-associated premature deaths, with ranges determined by the low and high estimates of the health risks. If changes in indoor/household air pollution were also included, the decrease would be far larger. SNG deployment in the residential sector results in nearly 10 and 60 times greater reduction in premature mortality than if it is deployed in the industrial or power sectors, respectively. Due to inefficiencies in current household coal use, utilization of SNG in the residential sector results in only 20 to 30% of the carbon penalty compared with using it in the industrial or power sectors. Even if carbon capture and storage is used in SNG production with today's technology, SNG emits 22 to 40% more CO than the same amount of conventional gas. Among the SNG deployment strategies we evaluate, allocating currently planned SNG to households provides the largest air quality and health benefits with the smallest carbon penalties.
面对严峻的空气污染问题以及对天然气进口依赖的不断增加，中国政府计划提高煤基合成天然气（SNG）的产量。虽然用SNG替代煤炭有利于空气质量，但会增加一氧化碳排放。由于各行业空气污染物、一氧化碳排放因子及能源效率存在差异，用SNG替代煤炭会带来不同程度的空气质量改善和气候惩罚。我们估算了2020年SNG替代策略对空气质量、人类健康和气候的影响。在居民部门使用所有生产的SNG，每年可减少约32,000例（20,000至41,000例）与室外空气污染相关的过早死亡，其范围由健康风险的低估值和高估值确定。如果将室内/家庭空气污染的变化也包括在内，减少量会大得多。SNG在居民部门的部署导致过早死亡率的降低分别比在工业或电力部门部署时高出近10倍和60倍。由于当前家庭煤炭使用效率低下，居民部门使用SNG产生的碳惩罚仅为在工业或电力部门使用时的20%至30%。即便在SNG生产中采用当今技术进行碳捕获与封存，SNG排放的一氧化碳仍比等量的传统天然气多22%至40%。在我们评估的SNG部署策略中，将目前计划生产的SNG分配给家庭可带来最大的空气质量和健康效益，同时产生最小的碳惩罚。
