There are plenty of reasons why companies such as Amazon and Google are developing delivery drones. Most obvious are cost and convenience. If a customer can receive an order in a matter of minutes and you don’t need a paid delivery driver to make it happen, profit-hungry tech giants will jump at the chance. And then there’s always the prestige that comes with being at the cutting edge as something futuristic gains traction.
Research published in Nature this week appears to provide an environmental justification for drone delivery, too. Results from a study conducted by Joshuah Stolaroff and colleagues at the Lawrence Livermore National Laboratory suggests that, “if carefully deployed, drone-based delivery could reduce greenhouse gas emissions and energy use in the freight sector.”
The study has been three years in the works. Stolaroff and his colleagues looked at the impact, in terms of emissions, between delivery by quadcopter and delivery by diesel trucks. They found that within the average 4km (2.5 mile) range that today’s delivery drones are capable of, aerial delivery used less energy per package and per kilometer than trucks. The caveat: that was the case for light deliveries weighing 0.5kg (1.1lb) and under.
Will drone delivery result in lower greenhouse gas emissions?
Getting into the detail of the study’s results, there are some important considerations to be made before drone delivery is labelled as the next big green thing. In simple terms, the answer to whether or not they would be beter for the environment is: it depends.
What’s clear is that drone delivery would shift energy use and emissions in the traditional supply chain in two main ways. First and most obvious, delivery by drone will remove emissions and energy use caused by last-mile vehicles on the ground. Instead, they will be replaced by whatever sources of electricity are used to charge the drones. This varies depending on the region. Some states in the US are greener than others, for example.
The second way that energy use and emissions would change is that same-day delivery by drone will likely need additional warehouses to store packages in locations closer to final customers. This is because the range of most delivery drones is expected to be a couple of miles at most, so new logistics centers will need to be opened. The study assumes from this that the total energy use by package warehouses could increase.
“What we found were mixed results,” said Stolaroff. “There is a possibility drones can reduce greenhouse gas emissions and reduce energy use, but you have to be careful how you deploy them.”
An interesting example to show how important location might be is the prospect of drone delivery in California compared with Missouri.
With more renewables powering California, the study suggests that a drone there would be responsible for about 430 grams of CO2 per package delivered, compared to a diesel delivery truck producing 915 grams.
But in Missouri, a state more heavily reliant on fossil fuels, that same drone delivery would be responsible for about 850 grams of CO2 per package, with a truck being responsible for 1,100 grams.
That adds up to a dramatic difference between the two states. California could see emission savings of 53% compared to Missouri’s 23%.
Stolaroff argues that retailers should take into account the entire logistics network and look for creative ways to build efficient drone delivery systems of the future.
“Charging drones only with renewable and low-carbon electricity would be the easiest way. They also might find creative ways to deliver goods from existing retail stores rather than building additional warehouses. The bottom line is to pay attention to life-cycle impacts when designing both the drone and logistics network,” he said.
Uncertainty in the air
One thing the researchers at Lawrence Livermore National Laboratory took for granted in the study was that drones would be flying as the crow flies to deliver packages. But who knows how the airspace will be divvied up when, and indeed if, the time comes.
“In the real world, depending on how they’re regulated, there might be designated routes that drones have to follow,” says Stolaroff. “Then that’s going to make the paths long, it’s going to mean you’ll need the drones to go farther, or you need more warehouses to service the same area.”
For now, what we can say is that drone delivery certainly has the potential to be a green alternative to traditional methods. But there are countless factors that will impact emissions in reality. And all of that electricity has to come from somewhere, after all.