Study: Delivery UAVs Can Reduce Emissions Written 14 February 2018

Forbes reports that a study by Nature Communications led by researchers at Lawrence Livermore National Laboratory and Carnegie Mellon University “finds that using relatively small quad- or octo-copters (in comparison to far larger drones used for military applications, for example) instead of diesel-burning delivery trucks could mean a reduction in both energy consumption and release of greenhouse gases that contribute to climate change.” The article mentions that DHL, Amazon, UPS, and Google are among the companies experimenting with delivery drones.
More Info (Forbes)