The University of Michigan in Ann Arbor and Ford Motor Co. in Dearborn have modeled emissions for a single 36-item grocery basket transported to the customer via dozens of traditional and e-commerce pathways to help minimize carbon emissions.
To set a baseline, U-M and Ford researchers found that customers who drove an internal combustion-engine pickup truck to a grocery store produced the most emissions, according to the study published in the journal, Environment Science & Technology,.
When customers switched to an electric sedan, SUV, or pickup for in-store shopping, overall greenhouse gas emissions dropped between 39 and 51 percent compared to the same-style internal combustion vehicle.
“This research lays the groundwork for understanding the impact of e-commerce on greenhouse gas emissions produced by the grocery supply chain,” says Greg Keoleian, director of the Center for Sustainable Systems at U-M’s School for Environment and Sustainability. “We also emphasize the important role that consumers can serve in reducing emissions through the use of trip chaining and by making carefully planned grocery orders.”
The researchers also found that all the home delivery options had lower emissions than in-store shopping using an internal combustion vehicle, reflecting the importance of “last-mile” transportation emissions, referring to the last step of the delivery process.
For a single item delivered to customers living near a micro-fulfillment center (MFC), enabling grocers to pick up orders, a drone had the least emissions. Kroger and Walmart are among the companies testing drone delivery of grocery items.
Results from the study also includes that for the full 36-item basket, home delivery by a suitcase-sized “sidewalk robot” did best. Those four or six wheeled autonomous machines have a delivery range of two miles and are being tested in cities in the U.S., China, and Europe, but are not widely available.
For shoppers who live outside the delivery zone, curbside pickup using an EV sedan helped lower emissions. Further reductions were achieved by shopping at a grocery store with a micro-fulfillment center and by combining the grocery trip with other errands, a practice called trip chaining.
The study’s “base case” involved in-store shopping with an internal-combustion SUV. Emissions reductions were achieved when customers ordered online and either switched to an electric vehicle (emissions reductions of 18 percent to 42 percent), shopped at stores with a micro-fulfillment center (16 percent to 54 percent reductions), or used grocery-delivery services (22 percent to 65 percent reductions).
Shopping frequency and trip chaining were also important factors for households to consider, according to the researchers. Cutting shopping frequency in half reduced greenhouse gas emissions by 44 percent, while trip chaining cut emissions by about half, compared with the base case.
While grocers including Kroger use large, automated warehouses called fulfillment centers, several others, including Whole Foods, Meijer, and Albertsons, have invested in MFCs.
MFCs can serve as the hub of a hub-and-spoke distribution model. They typically service multiple stores, including the one in which they are housed.
In-store MFCs commonly fill up to 80 percent of an online grocery order, with the remaining 20 percent filled by employees picking items from store shelves. MFCs are currently used mainly to fulfill curbside pickup orders placed online.
Greenhouse gas emissions tied to grocery store operation are split mainly between lighting, refrigeration, and the HVAC system. In-store MFCs can help reduce those emissions by up to 67 percent because they are much more efficient at filling online orders than conventional stores, according to the study.
The authors say that emission-reduction opportunities identified in their study can be combined with other strategies, such as dietary shifts and reductions in food waste, to guide food-system decarbonization as part of global efforts to achieve Intergovernmental Panel on Climate Change emissions-reduction targets.
The first author of the Environmental Science & Technology study is Nicholas Kemp, a former U-M School for Environment and Sustainability master’s student. Other co-authors included several researchers at the Ford Research and Innovation Center in Dearborn.
In addition to Keoleian and Kemp, the study’s authors are former School for Environment and Sustainability master’s student Luyao Li and Ford researchers Hyung Chul Kim, Timothy Wallington, and Robert De Kleine. The research was supported by the Ford-University of Michigan Alliance Program and the Ford University Research Program