The coronavirus pandemic has seen a massive surge in online shopping and the need for fast, contactless delivery. This has driven the industry towards automated delivery systems using delivery robots. But one factor to consider here is whether or not this new delivery approach is sustainable.

Researchers from the University Of Michigan examined the environmental impacts of residential package deliveries carried out by autonomous delivery vehicles and two-legged robots that complete the final delivery stage from hubs to the front door. These impacts were then compared to traditional delivery systems involving humans.

So did the delivery robots emit a lesser amount of greenhouse gases? Let’s find out.

Experimenting last-mile delivery with delivery robots

The researchers experimented with 12 scenarios in a usual suburban route, where they used various delivery systems ranging from totally autonomous to fully human-operated.

The experiment calculated the carbon emissions for each package delivered. It also considered the emissions data of delivery robots and different cargo vans from their production stage to the disposition or recycled stage.

For this, the team carried out three different delivery scenarios using four vehicle types. 

  • Fully Autonomous Delivery- In this case, autonomous delivery robots drive through the suburban route, and the robot drops the packages at the front door.
  • Partially Autonomous- Human drives the vehicles but the packages are dropped at the doorstep by robots.
  • Fully Human-operated- This involves no robots, aka the traditional delivery system. Here, humans drive the vehicles and also drop the packages to the customer.

The researchers used two types of vehicles gas-powered and battery-electric. They further used two different sizes for each type- the first was a 120-cubic-foot van that’s almost the size of a Nissan cargo van and a 350-cubic-foot van that resembles a Ford Transit cargo van.

Interestingly, they found that package delivery robots contribute less than 20 percent of a parcel’s carbon emissions. It is the vehicle that is responsible for generating most of the emissions. 

The total greenhouse gas release depends on factors like size and type of vehicles used. The researchers concluded that using electric vehicles with reduced carbon intensity could be the most impactful way to sustainable parcel delivery.

“We found that the energy and carbon footprints of this automated parcel delivery in suburban areas were similar to that of conventional human-driven vehicles. The advantages of better fuel economy through vehicle automation were offset by greater electricity loads from automated vehicle power requirements.”

said Gregory Keoleian, one of the researchers involved in the experiment.

The least carbon footprint was 167 grams of CO2 per package. This was achieved from human-operated delivery with a smaller, electric van. The maximum emission of 486 grams per package came from the partially automated delivery system that included a larger, fuel-powered cargo van and a two-legged robot.

The results suggest that robots have a significantly lesser impact on the carbon footprint of package delivery. Whether a robot or human drives the packages, the greenhouse gas emissions remain similar. 

Emissions largely depend on the size and power source of the vehicles used. If a fuel-powered engine is used, nearly double carbon is emitted than an electric vehicle. Again, a larger cargo van has a greater carbon footprint than a smaller one.

Talking about the impact of automation on different vehicles, Keoleian said, 

“Compared to the conventional scenario, full automation results in similar greenhouse gas emissions for the large gasoline-powered cargo van, but 10% higher for the smaller battery-electric van.”

The last-mile delivery of the package is usually the most expensive, most carbon-intensive part of the delivery process. While autonomous delivery robots can reduce the overall delivery costs between 10 and 40 percent in cities, their environmental impacts should be explored more. There is also scope for reduced emissions for larger-sized vehicles using automation as they have a relatively higher carbon footprint.

It is to mention that according to the researcher, Keoleian, no single automated delivery system can work for all situations. There are various other factors to be considered including life cycle costs, safety, and social sustainability.