Electric scooter companies like to tout their green credentials, frequently reminding riders that every two-wheeled trip they take can help reduce carbon emissions and fight climate change — but the truth is much more complicated.

A new study from North Carolina State University found that shared e-scooters may be more environmentally friendly than most cars, but they can be less green than several other options, including bicycles, walking, and certain modes of public transportation. Riders tend to think they’re making the right move by hopping on a scooter that’s electric and thus carbon-free. But what they don’t see are all of the emissions that are produced by the manufacturing, transportation, maintenance, and upkeep of dockless scooters.

“if you take a step back, you can see all the other things that are a bit hidden.”

“If you only think about the segment of the life cycle you can see, which would be standing on the scooter where there’s no tailpipe, it’s easy to make that assumption,” said Jeremiah Johnson, corresponding author of the study and an associate professor of civil, construction and environmental engineering at NC State. “But if you take a step back, you can see all the other things that are a bit hidden in the process.”

Johnson and his team “took a step back” by conducting what’s called a “life cycle analysis” of the dockless scooter industry. That meant looking at all of the emissions associated with each aspect of a scooter’s life cycle: the production of the materials, like the lithium-ion battery and aluminum parts; the manufacturing process; shipping the scooter from its country of origin (mainly China) to its city of use; and collecting, charging, and redistributing scooters as part of the dockless service.

The study’s conclusions were equal parts obvious and surprising. Driving a car was the least environmentally friendly option, but using the bus — especially a diesel-powered one along a highly trafficked route — was a better option than riding an e-scooter. Walking and riding a bike, or even an e-bike, were also vastly superior to using an e-scooter.

Overall, the average greenhouse gas emissions per scooter mile traveled is just over 200 grams of CO2. By comparison, the life cycle emissions for the average automobile is just over 400 grams of CO2. So riding a scooter is a clear winner over taking a car.

the average greenhouse gas emissions per scooter mile traveled is just over 200 grams of CO2

The problem is that only one-third of scooter trips are replacing car trips. The NC State team conducted a survey of riders to find out how people were using scooters and what kinds of trips they were displacing by choosing to ride an electric two-wheeler. Their findings — which are backed up by other surveys of scooter riders — were 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 7 percent wouldn’t have taken the trip at all.

Even though about 63 percent of electricity in the US is generated from fossil fuels, the environmental impact of the electricity used to charge each scooter is fairly small — around 5 percent of the overall impact, the researchers found. The main culprits were the materials used to build each scooter, mostly the aluminum, and the carbon produced by the vehicles used by independent contractors to gather up and recharge the scooters every night.

There are some simple solutions to these problems that the scooter companies are already trying to tackle. The first is to cut down on all of the driving done by freelancers who collect scooters at night for charging. Lime is trying to do this by introducing a new feature that allows its “juicers” to reserve a scooter ahead of time, thus reducing the amount of unnecessary driving that takes place when juicers are out searching for scooters to collect.

“If you can make these things last two years, it would have a very large impact.”

Another way to reduce the environmental impact would be to build a better scooter that lasts longer than the models that were deployed in the early days of the scooter boom.

“If the scooter companies are able to extend the life of their scooters without doubling the impacts of materials and manufacturing, that would reduce the per-mile burden,” Johnson said. “If you can make these things last two years, it would have a very large impact.”

The scooter companies are doing this, too. Bird recently unveiled its latest next-generation scooter with a longer-lasting battery and more durable parts. Lime has also rolled out newer models that it claims improve the unit economics of the scooter business.

But ultimately, the claim that scooter riding is the greenest option available is just not true. And the scooter companies appear aware of that, at least on the surface. Last year, Lime said that in order to make its entire fleet of electric bikes and scooters completely “carbon free,” the San Francisco-based company will begin to purchase renewable energy credits from new and existing projects.

This is a fine idea (although there is some skepticism about the effectiveness of carbon offsets), but it doesn’t address the main problem with the dockless scooter industry’s business model: the use of freelancers to collect and charge a fleet of electric scooters. Lime says it hopes to eventually account for those emissions in its carbon-neutral program, but it hasn’t yet.