ABSTRACT

The use of low-NOx compressed natural gas (CNG) medium-duty vehicles (MDVs) and heavy-duty vehicles (HDVs) has the potential to significantly reduce NO_x emissions and yield improvements in regional air quality. However, the extent of air quality improvement depends on many factors including future levels of vehicle deployment, the evolution of emissions from other sources, and meteorology. An analysis of the impacts requires modeling the atmosphere to account for both primary and secondary air pollutants, and the use of health impact assessment tools to map air quality changes into quantifiable metrics of human health. Here, we quantify and compare the air quality and health impacts associated with the deployment of low-NO_x CNG engines to power future MDV and HDV fleets in California relative to both a business-as-usual and a more advanced fleet composition. The results project that reductions in summer ground-level ozone could reach 13 ppb when compared to a baseline fleet of diesel and gasoline HDV and MDV and could reach 6 ppb when compared to a cleaner fleet that includes some zero-emission vehicles and fuels. Similarly, for all CNG cases considered reductions in PM_2.5 are predicted to range from 1.2 ug/m³ to 2.7 ug/m³ for a summer episode and from 3.1 ug/m³ to approximately 7.8 ug/m³ for a winter episode. These improvements yield short-term health benefits equivalent to $47 to $56 million in summer and $38 to $43 million in winter during episodes conducive to poor air quality. Additionally, the use of zero emission vehicle options such as battery electric and hydrogen fuel cell trucks could achieve approximately 25% to 31% higher benefits for an equivalent fleet penetration level due to the additional emission reductions achieved.

Implications: The paper provides a quantitative estimate of the air quality and human health benefits that can be achieved through the use of novel compressed natural gas engines (i.e., low-NO_x CNG) in medium- and heavy-duty vehicles and provide a comparison with zero emission vehicles. Thus, our findings will provide support for policy development seeking to transform the trucking sector to meet clean air and climate goals given the current struggle policymakers have with selecting between alternative truck technologies due to variance in factors like cost and technical maturity.

摘要

使用低NOx的压缩天然气（CNG）中型车辆（MDVS）和重型车辆（重型车）具有显著潜在减少NO _X排放量和产量的提高在区域空气质量。然而，空气质量改善的程度取决于许多因素，包括未来车辆部署水平、其他来源排放的演变以及气象。对影响的分析需要对大气进行建模以考虑主要和次要空气污染物，并使用健康影响评估工具将空气质量变化映射为人类健康的可量化指标。在这里，我们量化和比较低NO的部署相关的空气质量和健康的影响_XCNG 发动机为加州未来的 MDV 和 HDV 车队提供动力，相对于常规业务和更先进的车队构成而言。结果表明，与柴油和汽油 HDV 和 MDV 的基线车队相比，夏季地面臭氧的减少可达到 13 ppb，与包括一些零排放车辆和燃料的更清洁车队相比，可减少 6 ppb。类似地，对于所有考虑到的 CNG 案例，预计夏季期间PM _{2.5 的}减少范围为 1.2 ug/m ³至 2.7 ug/m ³和 3.1 ug/m ³至约 7.8 ug/m ³为冬季剧集。这些改进产生的短期健康收益相当于夏季 47 至 5600 万美元，冬季在导致空气质量不佳的情况下相当于 38 至 4300 万美元。此外，由于实现了额外的减排，使用零排放车辆选项（例如电池电动和氢燃料电池卡车）可以在同等车队渗透水平下实现约 25% 至 31% 的收益。

影响: 本文提供了对在中型和重型车辆中使用新型压缩天然气发动机（即低 NO _x CNG）可以实现的空气质量和人类健康益处的定量估计，并提供了比较与零排放车辆。因此，鉴于当前政策制定者由于成本和技术成熟度等因素的差异而在替代卡车技术之间进行选择，我们的研究结果将为寻求改变卡车运输行业以实现清洁空气和气候目标的政策制定提供支持。