Department of Civil Engineering, Kansas State University, Manhattan, Kansas 66506, United States.
Department of Systems Engineering and Management, Air Force Institute of Technology, 2950 Hobson Way, Wright Patterson AFB, Dayton, Ohio 45433, United States.
Environ Sci Technol. 2020 Jun 16;54(12):7533-7541. doi: 10.1021/acs.est.0c00176. Epub 2020 May 27.
Environmental footprinting methods provide a means to relate the environmental externalities of electricity production to electricity consumers. Although several methods have been developed to connect the environmental footprint of electricity generation to end users, estimates produced by these methods are inherently uncertain due to the impossibility of actually tracing electricity from the point of generation to utilization. Previous studies rarely quantify this uncertainty, even though it may fundamentally alter their findings and recommendations. Here, we evaluate the sensitivity of water and carbon footprints estimates among seven commonly used methods to attribute electricity production to end users. We assess how sensitive water and carbon electricity footprint estimates are to attribution methods, how these estimates change over time, and the main factors contributing to the variability between methods. We evaluate and make available the water and carbon footprints of electricity consumption for every city across the contiguous United States for all assessed methods. We find significant but spatially heterogeneous variability in water and carbon footprint estimates across attribution methods. No method consistently overestimated or underestimated water and carbon footprints for every city. The variation between attribution methods suggests that future studies need to consider how the method selected to attribute environmental impacts through the electrical grid may affect their findings.
环境足迹方法为将电力生产的环境外部性与电力消费者联系起来提供了一种手段。尽管已经开发了几种方法将发电的环境足迹与最终用户联系起来，但由于实际上不可能从发电点追踪到用电点，这些方法产生的估计值存在固有的不确定性。尽管这可能从根本上改变他们的研究结果和建议，但以前的研究很少量化这种不确定性。在这里，我们评估了将电力生产归因于最终用户的七种常用方法中水资源和碳足迹估计的敏感性。我们评估了水资源和碳电力足迹估计对归属方法的敏感性，这些估计值随时间的变化情况，以及导致方法之间变化的主要因素。我们评估并提供了美国所有评估方法中每个城市的电力消费的水资源和碳足迹。我们发现，在归因方法方面，水资源和碳足迹估计值存在显著但空间上不均匀的变化。没有一种方法始终高估或低估每个城市的水资源和碳足迹。归因方法之间的差异表明，未来的研究需要考虑通过电网归属环境影响的方法选择如何影响他们的研究结果。
