E-scooters: not so green

E-scooters may lure travelers away from biking or walking, says research from NC State.

August 9, 2019 

Are e-scooters the way to go green?

E-scooter companies like Lime and Bird have penetrated many major cities in the United States, promising to reduce the carbon emissions of the “last-mile”—the short trips that get you exactly where you need to go, like from your car to the coffee shop, or the bus to your office.

But aside from the other issues associated with e-scooters, do they actually reduce carbon emissions? A recent study from North Carolina State University says not. Researchers took a look at the energy costs of manufacturing the scooters and the driving associated with collecting and redistributing them around a city. 

In fact, the study claims that e-scooters may even increase emissions, if you take into account the more environmentally-friendly options riders would have used without the option of an e-scooter. About half the riders surveyed in the study would have biked or walked (and created no emissions in the process). Only a third would have taken their cars.

“It’s more about what the e-scooter is replacing,” said Jeremiah Johnson, Ph.D., lead researcher on the study. “If you’re substituting a car, then e-scooters look pretty good. They use about half the C02. But if you’re substituting walking or biking, it’s not so good.”

Here’s what the researchers found:

Manufacturing e-scooter parts accounts for half the global warming impacts

The team from NC State, including Johnson and his graduate students Jospeh Hollingsworth and Brenna Copeland, purchased an e-scooter from Chinese company Xiamoi, (which makes most e-scooters used in the US) and took it apart.

They took stock of each component, calculating how much energy it would take to produce. Each scooter contains 13 pounds of aluminum, a lithium-ion battery, an electric motor and an assortment of plastic and steel components. They found that the energy it takes to produce these parts account for about half of the scooter’s global warming impact. And e-scooters don’t survive the streets for very long.

The research team assumed a lifespan of less than six months, due to regular wear-and-tear and vandalism (some people have lots of hate for e-scooters).  The energy that it takes to manufacture an e-scooter isn’t balanced out by a long lifespan.

Redistributing e-scooters requires driving

The other main reason e-scooters aren’t as green as they claim to be is the energy involved in redistributing them around a city. Both Bird and Lime pay independent contractors (called “juicers” in the Lime vernacular, for Bird, charging is “nesting”) to drive around picking up e-scooters. Contractors bring the scooters home and charge them in regular outlets before driving them back to hot spot locations.

The amount of driving that it takes to accomplish this work accounts for about 43 percent of the carbon emissions of e-scooters. In comparison, actually charging the scooters only accounts for 5 percent of emissions, and both Lime and Bird have promised to buy renewable energy credits to offset those costs. Overseas shipping accounts for even less energy than charging.

Policies to make e-scooters more energy efficient

The study authors recommend a few fixes to these problems. One is for cities and companies to enforce better anti-vandalism policies to increase the lifespan of scooters. They also recommend a more streamlined approach to charging and redistributing them, moving away from the decentralized, crowdsourced method. Study authors note that in areas where taking the e-scooter is preferable to driving, e-scooters would be a win, environmentally. If e-scooters displace driving a car half the time, they’d be worth the cost.

But in the meantime, riding your bike or taking a stroll is your best choice for carbon-free transportation.

—Rossie Izlar

Rossie Izlar is a digital producer on the UNC-TV Science team.