Recent study complicates understanding of e-scooters’ environmental impact.
By Kai McNamee
After taking Santa Monica and Los Angeles by storm, shared electric scooters were touted by many as a solution to the climate crisis. Bird and Lime, two of the largest producers of dockless e-scooters, both market their services as a way to reduce carbon emissions in urban settings. But a recent study published by researchers at North Carolina State University suggests that these devices aren’t as environmentally friendly as they might seem.
The study found the majority of the scooters’ greenhouse gas emissions — the chemicals responsible for global warming — come from the initial manufacture of scooters, and the vehicles people use to collect and distribute them during the charging process.
Jeremiah Johnson, a co-author of the study and Associate Professor at NC State, explained that the study analyzes the scooters’ “cradle to grave” impacts through a process called life cycle assessment. “The work that we do uses a tool called life cycle assessment to quantify environmental impacts, particularly to quantify hidden aspects of environmental impacts that might be a little bit less obvious,” Johnson said.
Johnson’s team found that the baseline electric scooter produces the equivalent of 202 grams of carbon dioxide per passenger-mile. This measurement accounts for the carbon dioxide emissions associated with the scooters’ manufacture, transport, collection and distribution. According to the Environmental Protection Agency, driving a typical automobile produces over 400 grams of carbon dioxide per mile.
While riding a scooter is significantly better for the environment than driving a car, surveys show that scooter use frequently replaces walking — in these cases, scooter use replaces a significantly greener mode of transit.
The researchers surveyed 61 riders in Wake County, North Carolina and analyzed survey data published by the Portland Bureau of Transportation to determine the replacement effects of shared scooters. The study reported that 49 percent of survey respondents would have biked or walked had e-scooters not been available, and 11 percent would have taken a public bus.
In January, the City of Santa Monica conducted its own study, surveying approximately 3,000 scooter riders. The Santa Monica survey found 50 percent of scooter rides replaced a car trip, 37 percent of rides replaced walking, and 3.8 percent of rides replaced a bus trip.
“If you’re a user and one of your motivations for using the scooters is to reduce your environmental impact, the more you can substitute car rides with scooter rides the better,” Johnson said. “If you are displacing car rides, that is a clear environmental win. For users who are substituting walking and biking…the environmental argument is a little harder.”
Since Bird’s launch in 2017, the company has reported over ten million rides, claiming to have “prevented more than 12 million pounds of carbon emissions from being released into the air.” Lime has similarly tallied over ten million rides, reporting that 27 percent of those rides were to or from public transit hubs; in June alone, Lime boasted providing 15,000 free rides to help Europeans vote.
The study found that environmental impact is dependent on the typical scooter’s lifespan, which Johnson’s team estimated to be between 6 months and two years. The team found that 50 percent of a scooter’s carbon footprint is due to the manufacturing process, meaning scooters that last longer before replacement produce less per passenger-mile emissions.
A study conducted by Quartz found that the first generation of Bird scooters in Louisville, Kentucky had an average lifespan of less than a month.
In additional to suffering daily wear from regular use and charging, scooters are frequently vandalized. The viral Instagram account Bird Graveyard has over one hundred thousand followers and over 300 posts depicting people trashing Bird and Lime scooters by kicking them over, throwing them off of buildings, and even setting them on fire. According to Slate, the city of Oakland removed 60 electric scooters from Lake Merrit in October alone. On the Westside, scooters are frequently thrown into the water near the Venice Canals and the Venice Pier, as reported by Yo! Venice.
Since Bird’s launch, however, the company has improved its scooters’ durability and resistance to vandalism. Bird’s first proprietary scooter, Bird Zero, has been on the streets since October 2018 and has a lifespan of eight to twelve months; the company expects its most recent Bird Two model to last two years. Lime, which launched in early 2018, has similarly improved scooter durability with proprietary designs; Lime’s newest Gen 3 scooter is expected to have a lifespan of one year.
In addition to the environmental impact due to scooter production, a large portion of scooter emissions are associated with the collection and charging process. Users of shared scooter apps can sign up to become chargers — chargers typically drive around urban areas picking up scooters to charge at home, earning anywhere between $3 to $20 per scooter. Once the scooters are charged, chargers drop the scooters off at designated locations. The NC State study showed that chargers drive 0.6-2.5 miles per scooter during the collection and distribution process.
According to the study, collection and distribution make up 43 percent of the scooters’ environmental impacts.
A Lime spokesperson said “sustainability is core to Lime’s mission…we’ve already taken steps to reduce our environmental impact, including streamlining our charging operations, powering our scooters with 100% renewable energy, offsetting the emissions from fleet vehicles, and establishing a robust repair and reuse program to extend the life cycle of our products.”
Bird has taken similar action. In 2018, the company partnered with sustainability consultant 3Degrees to purchase Renewable Energy Credits (RECs) and carbon offsets to mitigate its emissions impact — RECs allow the company to charge its fleet with renewable energy, and offsets fund projects that reduce greenhouse gas emissions.
Both companies have also been testing features that allow chargers to reserve scooters before picking them up; reservation features aim to streamline the collection process and reduce the amount of time chargers drive in search of scooters.