Study Finds Shared E-Scooters are Not as Green as Other Modes of Transport

People believe that electric scooters (e-scooters) are eco-friendly means to travel around town. However, a recent study from North Carolina State University states that it is not that simple: shared e-scooters may be greener than the majority of cars, but they can be less green than numerous other options.

(Photo credit: John Brighenti)

“E-scooter companies tout themselves as having little or no carbon footprint, which is a bold statement,” says Jeremiah Johnson, corresponding author of the study and an associate professor of civil, construction and environmental engineering at NC State. “We wanted to look broadly at the environmental impacts of shared e-scooters—and how that compares to other local transportation options.”

To detect the impact of e-scooters, scientists studied emissions linked with four features of each scooter’s life cycle: the production of the materials and parts that are fitted into each scooter; the manufacturing process; transporting the scooter from the manufacturer to its city of use; and collecting, charging, and redistributing the scooters.

The scientists also carried out a small-scale survey of e-scooter riders to see what modes of transportation they would have used if they had not used an e-scooter. The scientists learned that 49% of riders would have walked or biked; 34% would have used a car; 11% would have boarded a bus; and 7% would not have taken the trip at all. These results were quite like those of a larger survey conducted by the city of Portland, Oregon.

So as to compare the influence of e-scooters to that of other transport options, the scientists examined formerly published life cycle studies of cars, electric mopeds, buses, and bicycles. Scientists explored four types of pollution and environmental impact: nutrient loading in water; climate change impact; respiratory health impacts associated with air pollution; and acidification. The performance results were quite like all four types of pollution.

A lot of what we found is pretty complicated, but a few things were clear. Biking—even with an electric bike—is almost always more environmentally friendly than using a shared e-scooter. The sole possible exception is for people who use pay-to-ride bike-share programs. Those companies use cars and trucks to redistribute the bicycles in their service area, which can sometimes make them less environmentally friendly than using an e-scooter.

Jeremiah Johnson, Study Corresponding Author and Associate Professor of Civil, Construction and Environmental Engineering, NC State

By the same token, the research learned that driving a car is virtually always less eco-friendly than using an e-scooter. But certain results may amaze readers. For instance, taking the bus on a route with high ridership is typically more eco-friendly than an e-scooter.

We found that the environmental impact from the electricity used to charge the e-scooters is fairly small—about 5% of its overall impact. The real impact comes largely from two areas: using other vehicles to collect and redistribute the scooters; and emissions related to producing the materials and components that go into each scooter.

Jeremiah Johnson, Study Corresponding Author and Associate Professor of Civil, Construction and Environmental Engineering, NC State

That means that two main aspects add to each scooter’s environmental footprint. First is that the less driving that is done to gather and redistribute the scooters, the lesser the influence. The second aspect is the scooters’ lifespan: the longer the scooter is in service, the more time it has to counterbalance the impact caused by manufacturing all of its constituent parts.

There are a lot of factors to consider, but e-scooters are environmentally friendly compared to some modes of transport. And there are things that companies and local governments can do to further reduce their impacts. For example, allowing—or encouraging—companies to collect scooters only when they hit a battery depletion threshold would reduce a scooter’s impact, because you wouldn’t be collecting scooters that don’t need re-charging.

Jeremiah Johnson, Study Corresponding Author and Associate Professor of Civil, Construction and Environmental Engineering, NC State

The paper, “Are E-Scooters Polluters? The Environmental Impacts of Shared Dockless Electric Scooters,” has been published open access in the journal Environmental Research Letters. First author of the paper is Joseph Hollingsworth, a former graduate student at NC State. The paper was co-authored by Brenna Copeland, an undergraduate at NC State. The research was supported, partly, by the North Carolina State University Department of Civil, Construction, and Environmental Engineering Research Experience for Undergraduates Program.


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