在加州, 重型 汽车是全球变暖排放的主要贡献者. 生物甲烷是一种潜在的天然气替代品 有机物分解, has been proposed as a lower-carbon alternative to diesel in 重型 vehicles—but how much of a dent can it make?
The good news is that biomethane offers a pathway to reduce global warming emissions from landfills, 污水处理中心, 和奶牛场, which all generate significant amounts of methane that goes largely uncaptured today.
The bad news is that there’s a limited amount of biomethane from waste compared to existing energy and fuel use in California—and we shouldn’t encourage creating more waste than we already do.
Meeting California’s diesel demand would require all of the potential sources of waste-based biomethane in the United States. And biomethane from waste in California could meet just 3 percent of the state’s demand for natural gas. Increasing biomethane production will require expansion of natural gas infrastructure and improvements in waste management.
鉴于生物甲烷的数量有限, a large scale shift to natural gas 重型 vehicles could increase California’s reliance on natural gas and the local impacts of extracting and delivering it, 最终破坏了该州的617888九五至尊娱乐目标.
生物甲烷与天然气相比如何?
生物甲烷和天然气具有相似的化学成分. They consist primarily of methane–a potent global warming gas—and can be used interchangeably. 在汽车的排气管处，它们产生同样的排放物.
但, 生物甲烷和天然气的来源确实不同, 这导致了不同的“上游排放”." This means that although biomethane and natural gas combust in similar ways, 它们的总体(“生命周期”)排放量是不同的.
Natural gas is a fossil fuel that comes from ancient (fossilized) plant and animal matter found beneath Earth’s surface, 必须被提取出来.
生物甲烷是植物或动物物质分解产生的, 比如在奶牛场发现的那种, 堆填区及污水处理设施. Upstream emissions are lower for biomethane than natural gas because its use offsets emissions from waste.
生物甲烷的排放效益取决于它的使用方式
Biomethane generates lower life cycle global warming emissions than natural gas in a vehicle, and it results in even lower emissions when used to make electricity or hydrogen for battery or fuel cell electric vehicles. 这在很大程度上要归功于电动汽车的更高效率.
同样的, using biomethane to power battery and fuel cell electric vehicles results in lower emissions of smog-forming nitrogen oxides (NOx) than using the biomethane in a compressed natural gas (CNG) vehicle.
While biomethane should be used to displace consumption of fossil fuels, wide-scale adoption of battery and fuel cell electric vehicles is ultimately needed to meet climate and air quality goals.
公共汽车生命周期氮氧化物排放量，按车辆和燃料类型分列. The lowest life cycle emissions of nitrogen oxides (NOx) from biomethane results from generating electricity or hydrogen for use in battery or fuel cell electric vehicles. 来源:Chandler, Espino, and O’dea 2017.(/标题)
电动汽车 在重型应用中越来越可用. With zero tailpipe emissions and the potential to be powered by plentiful sources of renewable energy like wind and solar, 电动汽车为加州带来了最大的好处.
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