Are Drones Energy-Efficient?
- February 16, 2018
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Slightly more than two years after Amazon CEO Jeff Bezos introduced the idea of e-commerce drone delivery, a study by researchers at the Lawrence Livermore National Laboratory has come up with mixed results regarding the energy efficiency of drones. The study, whose results were published in Nature Communications, found that delivery drones are more energy-efficient than trucks (which are the dominant mode of transportation for deliveries) over short distances. “Results suggest that, if carefully deployed, drone-based delivery could reduce greenhouse gas emissions and energy use in freight sector,” the study’s authors wrote.
The careful deployment of drones for delivery requires consideration of several factors.
Location is one. The researchers found that drone delivery is far more energy-efficient in a green market like California than a place like Missouri. This is because California has a higher composition of renewable energies in its electric grid than the Midwestern state. In their study, the study’s authors found that emissions in California are 430 gms of carbon dioxide for a 915 gram package. In Missouri, the same package would result in 850 grams of carbon dioxide emissions.
The number and quantities of warehouses is another factor that makes a difference in overall energy consumption for drones. Trucks can carry large parcels and make multiple delivery stops along the same route over a long route. On the other hand, drones are constrained by range. The study’s authors assumed the drones could travel up to 4 km without stopping. This meant that they would need to be recharged or would have to stop their flight at this distance. In turn, it multiplied the number of warehouse hops for delivery. More warehouses equal more energy consumption. The study’s authors have suggested that e-commerce companies might want to consider building drone warehouses for deliveries.
Then there is drone size. Small drones are more energy-efficient as compared to larger ones. Part of the reason for this is the prevalence of multi-rotor design, which are complex in design and function, in drones that makes the devices less energy-efficient. The package size also makes a difference. According to Joshua Stolaroff, one the study’s lead authors, a light package (such as a pair of sunglasses) saves more energy and greenhouse gas emissions as compared to one that involves delivery of a computer system. He said larger drones are 9% better than a diesel truck in California and 50% worse than a diesel truck in Missouri.
“To realize the environmental benefits of drone delivery, regulators and firms should focus on minimizing extra warehousing and limiting the size of drones,” the study’s authors write. The good news is that they have time. A Gartner report last year found that drones will be responsible for less than 1% of all deliveries in e-commerce by 2020.