For a long time now, shipping companies have been promising customers that they could soon receive packages via drone delivery. These deliveries promise to be faster than ever, and well frankly, awesome! Already test programs have been conducted in towns and cities in North America, Europe, and Australia. Several of these trials have led to a permanent drone delivery model. Meanwhile, the rest of the world patiently awaits the authorities to finalize any logistical issues and give permission for drones to make deliveries on a broader basis. One of the big questions that this concept has brought up is whether or not deliveries made by drones will have a positive impact on the environment or be purely a gimmick. A professor from the University of Washington set out recently to determine just that.

Dr. Anne Goodchild is a Professor of Civil and Environmental Engineering and the Director of the Supply Chain Transportation and Logistics Center and Research Group for the University of Washington. In 2016 as a part of the Supply Chain Transportation and Logistics Center she went on to launch the Urban Freight Lab “to bring together the public and private sectors to address the challenges of the urban freight system by engaging in innovative research,” as stated in her bio. Last summer Dr. Goodchild and one of her graduate students, Jordan Toy, released a paper titled Delivery by drone: An evaluation of unmanned aerial vehicle technology in reducing CO2 emissions in the delivery service industry. One of the many points that advocates of drone deliveries use to sell their platform is that drones will help reduce air pollution. The paper begins by stating, “This research paper estimates carbon dioxide (CO2) emissions and vehicle-miles traveled (VMT) levels of two delivery models, one by trucks and the other by unmanned aerial vehicles (UAVs), or ‘drones.'” What Dr. Goodchild and Toy found was that it really depends on where the drones are traveling to compared to the number of trips they need to make.

The models they set up used 10 hypothetical drones compared to data from 10 real world truck delivery scenarios in Los Angeles, CA within 330 service zones. The number of customers in the model varied from 50 to 500 within each zone. At first Dr. Goodchild was sure the drones would have little impact on reducing pollution. “Flight is so much more energy-intensive — getting yourself airborne takes a huge amount of effort. So I initially thought there was no way drones could compete with trucks on carbon dioxide emissions,” she said. “In the end, I was amazed at how energy-efficient drones are in some contexts. Trucks compete better on heavier loads, but for really light packages, drones are awesome.”

Another group of researchers wrote a paper for the journal Nature Communications titled Energy use and life cycle greenhouse gas emissions of drones for commercial package delivery with similar findings. In this paper the multiple authors point out, “Although drones consume less energy per package-km than delivery trucks, the additional warehouse energy required and the longer distances traveled by drones per package greatly increase the life-cycle impacts. Still, in most cases examined, the impacts of package delivery by small drone are lower than ground-based delivery. Results suggest that, if carefully deployed, drone-based delivery could reduce greenhouse gas emissions and energy use in the freight sector.” What both articles agree on is that trucks are still needed for the bulk of deliveries as they can carry far more freight and make many stops along a route. A drone can only carry a single light package and will need to return to base after each delivery.

Drone delivery from a designated store to a customer carrying small items is one way this could work. Another way is within a closed campus like a military base or the successful drone delivery program in place at the WakeMed hospital campus in Raleigh, NC. There drones are working along preset flight paths to make life saving deliveries more rapidly than a truck could. Dr. Goodchild said, “Given what we found, probably the most realistic scenario is for drones doing the last leg of the delivery. You’re probably not going to see these in downtown Seattle anytime soon. But maybe in a rural community with roads that are slow and hard for trucks to navigate and no air space or noise concerns.”

Another idea that some are toying with is to install drone charging and docking stations on delivery trucks. A truck could be loaded with a variety of packages. Depending on the route the driver can send out a drone from the truck to start delivering some of the smaller packages while they deliver the larger ones. But what impressed Dr. Goodchild in her research the most was the engineering that has gone into drone development. So many resources have been put into designing drones that are light enough to not only support a battery while remaining airborne, but packages as well. “We haven’t applied the same level of effort to engineering lightweight trucks — they’re excessively heavy and the on-road fleet doesn’t look much different than it did a few decades ago,” she said. “If we took the same amount of energy we’ve put into making drones light and efficient, applied that to trucks and got them on the street, we could do so much good for the transportation industry and the environment.”