A study from the University of Michigan and Ford found that the type of transportation used to get packages around neighborhoods matters most.

Humans vs. robots: Michigan researchers study lowest emission package delivery method

Automated robots have emerged in recent years as a solution for delivering packages, especially as e-commerce booms. Some developers say the robots are more efficient and emit fewer greenhouse gases than using humans to deliver packages. 

But a study from the University of Michigan and Ford found that might not be the case. Researchers discovered similar carbon footprints using human and robot delivery methods. What matters most is the type of transportation used to get the packages around neighborhoods, they say.

The experiment

The researchers studied the full lifecycle environmental impacts from 12 advanced residential package delivery scenarios that used electric and gas-powered autonomous vehicles and two-legged robots to transport goods from delivery hubs to customers’ front doors. Those scenarios were compared to the environmental impacts from the traditional model of a human driver hand-delivering packages to the front door.

Credit: Reprinted with permission from Environmental Science & Technology. Copyright 2021 American Chemical Society.

This cradle-to-grave analysis takes into account all the emissions created not just during the delivery process, but also in manufacturing and disposing of or recycling the delivery vehicles and robots. The team tested three delivery scenarios:

  • Conventional: A human drives the vehicle and delivers each package to the doorstep.
  • Partially automated: A human drives the vehicle and a robot completes the final delivery.
  • Fully automated: A connected and autonomous vehicle drives and a robot takes parcels to doorsteps.

Each scenario included an analysis of using both internal combustion engine and battery electric powertrains on two sizes of delivery vehicles.

The results

The analysis showed that robots and automation contributed less than 20% to a package’s carbon footprint. Most of the greenhouse gas emissions came from the transporting vehicle. 

The smallest carbon footprint, 167 grams of CO2 per package, occurred during conventional delivery with a smaller, electric van. The largest footprint, 486 grams per package, occurred during the partially automated scenario that used a larger, gas-powered van and a two-legged robot.

Thus, a vehicle’s powertrain and efficiency are the most important factors in determining the package’s carbon footprint.

“For all delivery systems studied, the vehicle-use phase is the single largest contributor to greenhouse gas emissions, highlighting the need for low-carbon fuels for sustainable parcel delivery. It is critically important to decarbonize grids while deploying electrified vehicles,” Gregory Keoleian, professor of civil and environmental engineering, said in a news release.

Implications for the future

The study uncovers opportunities for reducing package delivery emissions, such as choosing the right vehicle for the job. 

“The advantages of better fuel economy through vehicle automation were offset by greater electricity loads from automated vehicle power requirements,” Keoleian said. “Results suggest that automated delivery systems could have slightly greater life cycle greenhouse gas emissions than conventional delivery systems for smaller-sized vans, but there is potential opportunity to reduce emissions for larger-sized vans. … 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.” 

Keoleian explained that no single automated delivery system exists that works well in all situations. Further research to optimize package delivery could also consider life cycle costs, safety, and social sustainability.

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