The benefits of unmanned aerial vehicles (UAVs) for businesses and consumers alike are well-documented.  Thanks to drones, businesses can reduce their labor costs and improve the efficiency and safety of their operations.  Consumers, including those in need of emergency medical care, can receive more timely and responsive service.  It’s a win-win, right?  Well, not necessarily.  Even the obvious advantages of drones can come at an unexpected cost.  And one of those costs, depending on how they’re deployed, could be their environmental impact, some researchers say.

Drone observers are accustomed to thinking of UAVs, which are generally battery-powered, as more sustainable than vehicles that rely on fossil fuels.  That may be true in the abstract.  But according to researchers at the University of Washington (UW), who compared the carbon emissions of package delivery drones with those from grocery delivery trucks in and around Los Angeles, much could depend on the size of the drone payload and the number of trips involved.

For large cargo deliveries over long distances, the emissions from drones tended to exceed truck emissions, and by a considerable amount, their research showed.  It was only for shorter deliveries of lighter packages that drones realized their potential to be more energy efficient, they argue.  While many observers might find this finding surprising, it makes logical sense, UW researchers say.  First, a drone consumes enormous energy just taking-off, more than commonly thought.  And with limited battery storage, drones typically must circle back to a charging or refueling station and then repeat the same pattern  numerous times in the course of a full day.  Grocery trucks, already fueled up, can generally move forward along their route, stopping only to make their deliveries.

Second, trucks have the capacity to store a large amount of cargo of different kinds compared to limited storage and carrying capacities of most delivery drones.  Even a large drone would have difficulty delivering furniture and other large consumer purchases.  In a head-to-head competition, drones, on balance, are simply no match for delivery trucks when it comes to both time and energy efficiency.

But the UW researchers also noted that the complete opposite is true for short-distance small package deliveries.  Trucks and their drivers waste large amounts of time and fuel compared to drones which can briefly hover and drop their packages at prearranged collection zones.  Moreover, drones can make deliveries to remote and inaccessible areas that road-bound trucks cannot reach at all.  On balance, each delivery system has its advantages and disadvantages, the researchers concluded.

What’s the solution?  A division of labor perhaps.  Use trucks to deliver large cargo to regional storage and distribution centers, then switch to drones for subsequent deliveries, especially to remote areas.  To date, the UW team’s research findings, first released early last year, haven’t gained much currency in the UAV industry.  But they couldn’t be more timely. Companies like Amazon and Wal-Mart are gearing up to implement a nationwide drone-based package delivery system.  A decade ago, a similar effort foundered due to consumer fears and disenchantment with the proposed service.  At a time of growing concern over climate change, the latest incarnation of the service must observe the high sustainability performance consumers have come expect from large corporations – or it risks failing once again.