Younger readers might be astonished to learn that until just 40 or 50 years ago, milk, cheese, and even ice cream were customarily delivered to your doorstep by the local dairy. The “milkman” of years past is now largely extinct, but in his place we are starting to see more and more grocery stores offering home delivery of items purchased online. There’s even a nascent resurgence in home delivery of dairy products and fresh produce by local farms. Are these emerging delivery services more environmentally friendly than personal car trips to the store or farm?
A recent study in Journal of the Transportation Research Forum calculated greenhouse gas emissions for grocery delivery in the Seattle area (1). The researchers found that the distance traveled by a delivery vehicle is shorter than the sum of the distances traveled by customers’ cars; in fact, with smart planning of the delivery route, it could be a whopping 85 to 95 percent less. Even though delivery trucks generally produce more carbon dioxide emissions per mile than cars, the increased emissions per mile are more than offset by the decreased number of miles traveled by the delivery trucks. Consequently, when personal car travel is replaced by a delivery service, carbon dioxide emissions also decrease substantially.
For maximum environmental benefit, the researchers found, delivery vehicles should group their deliveries by geographical area. In contrast, random delivery routes based on customers’ selection of date and time for delivery were considerably less efficient—although still much better than personal car travel. In other words, for the greatest reduction in greenhouse gas emissions, customers would have to adapt to a system in which the provider mandates service times for a particular region—much like municipal garbage collection services do now.
Surprisingly, the environmental benefits of a delivery service were seen not only in high population density areas but also in rural areas, where people are more spread out. Moreover, fewer personal car trips to the grocery store mean less road congestion, an improvement in the quality of life for all of us.
(1) Wygonik, E. and A. Goodchild. 2012. Journal of the Transportation Research Forum 51(2): 111–126.
David Tyler is the Charles J. and M. Monteith Jacobs Professor of Chemistry at the University of Oregon.