Are e-scooters polluters?
People think of electric scooters, or e-scooters, as environmentally friendly ways to get around town. But a new study from an environmental engineering faculty member finds it’s not that simple: Shared e-scooters may be greener than most cars, but they can be less green than several other options.
“E-scooter companies tout themselves as having little or no carbon footprint, which is a bold statement,” says Dr. Jeremiah Johnson, corresponding author of the study and an associate professor in the Department of Civil, Construction, and Environmental Engineering (CCEE). “We wanted to look broadly at the environmental impacts of shared e-scooters — and how that compares to other local transportation options.”
To capture the impact of e-scooters, researchers looked at emissions associated with four aspects of each scooter’s life cycle: the production of the materials and components that go into each scooter; the manufacturing process; shipping the scooter from the manufacturer to its city of use; and collecting, charging and redistributing the scooters.
The researchers also conducted a small-scale survey of e-scooter riders to see what modes of transportation they would have used if they hadn’t used an e-scooter. The researchers found that 49 percent of riders would have biked or walked; 34 percent would have used a car; 11 percent would have taken a bus; and seven percent wouldn’t have taken the trip at all. These results were similar to those of a larger survey done by the city of Portland, Ore.
In order to compare the impact of e-scooters to that of other transport options, the researchers looked at previously published life cycle analyses of cars, buses, electric mopeds and bicycles. Researchers looked at four types of pollution and environmental impact: climate change impact, nutrient loading in water, respiratory health impacts related to air pollution and acidification. The performance results were similar for all four types of pollution.
“A lot of what we found is pretty complicated, but a few things were clear,” Johnson says. “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.”
By the same token, the study found that driving a car is almost always less environmentally friendly than using an e-scooter. But some results may surprise you. For example, taking the bus on a route with high ridership is usually more environmentally friendly than an e-scooter.
First author of the paper is Joseph Hollingsworth, a former graduate student in CCEE. The paper was co-authored by Brenna Copeland, an undergraduate in the department.
Return to contents or download the Fall/Winter 2019 NC State Engineering magazine (PDF, 2.3MB).
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