Small drones carrying light packages produce fewer greenhouse gas emissions per package a kilometre than even electric trucks, researchers have found. But it’s not all good news for this novel form of transport: conventional trucks still beat large drones carrying heavy packages when all the emissions along a supply chain are taken into account.
In British Columbia, transport is the largest source of emissions, with some nine percent of emissions overall coming from light and medium-duty delivery trucks. And since 2007 truck emissions have increased 13.5%, according to Transportation Futures researchers with the Pacific Institute for Climate Solutions.
Having noticed that companies such as Amazon, DHL and UPS were beginning to experiment with drone delivery of packages, scientists with the Lawrence Livermore National Laboratory wanted to explore the environmental impact of such a transition from trucks to drones.
After three years of investigating the possibilities of two different types of drone, quadcopters and octocopters, they found that despite the high energy-intensity of getting airborne, surprisingly drones beat trucks—but only up to a point.
Within a four-kilometre range, battery-powered drones consumed less energy per package per kilometre for light packages up to 0.5kg—such as iPhones, medicines, or glasses—than any delivery truck or van, regardless of how it was powered. They were better than diesel, gasoline, natural gas and even electricity in a place such as California with a relatively low-carbon electricity system.
But due to their limited range, even to achieve the emissions reduction of small copters, the number of urban warehouses would need to be increased along with “way-stations”, where drones at the limit of their range pass on their package to another drone. But buildings need heating, typically coming from natural gas, and electricity as well.
Once these additional life-cycle emissions are taken into account, large drones carrying heavy packages begin to be more carbon-intensive than electric trucks. This is because in addition to the emissions from warehouses and way-stations, a greater amount of electricity is needed to fly, and even clean electricity still produces some emissions.
The researchers concluded drones could be one part of an emissions reduction strategy for delivery systems, but only alongside electrification of trucks and decarbonization of heating and electricity.
One environmental website responding to the findings suggested a better option would simply be to use cargo bikes or e-bikes instead, without any need for more warehouses or way-stations. This this would reduce emissions still further, they argued, noting that Whole Foods (a subsidiary of Amazon) is already experimenting with such a system.
But unlike the drone researchers, the website’s authors did not appear to have performed a full life-cycle emissions analysis of these options, and even bikes and their riders consume energy and resources, producing GHGs. So it is unknown whether this is actually a better option. However, PICS is currently supporting research into the life-cycle emissions of bikes and e-bikes, including those from feeding the riders. So watch this space.
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