This article originally appeared in The Conversation.
Shared dockless electric scooters, or e-scooters, transport riders over short distances in cities. Ride share companies promote them as an environmentally friendly choice that reduces dependence on cars.
To properly assess these claims, it’s important to consider all relevant environmental factors, including the materials and energy required to manufacture scooters, the impacts of collecting them daily for charging and redistributing, and the electricity that charges their batteries.
I study methods for assessing environmental impacts of products and materials. In a newly published study, I show that e-scooter programs may have larger total environmental impacts than the transportation modes they displace. But if cities update their policies and mobility companies tweak some of their practices, there are opportunities to make e-scooters a greener option.
The electric scooter boom
Anyone who lives in a city or near a college campus has probably seen e-scooters. Designed for short-distance travel, these devices have a small electric motor and deck on which a single person stands. Ride share companies such as Bird and Lime rent out scooters by the minute, and riders leave them at their final destination to be claimed by the next user or picked up later for charging.
In 2017 these programs were rare, but in 2018 riders took an estimated 38.5 million trips on e-scooters. These devices fill a singular niche for some people, solving the “last mile problem” – the last leg of a trip, which sometimes can be the most difficult, since it may mean walking home from a bus stop or train station. Scooters are an alternative to driving and parking a personal automobile, and often are cheaper than a taxi or Uber.
“Your ride was carbon free” – really?
The transportation sector generates nearly one-third of U.S. greenhouse gas emissions and a large share of smog and asthma-inducing pollutants. With no tailpipes to spew emissions, it would be easy to assume that shared e-scooters are an environmentally preferable option. E-scooter companies often tout the environmental benefits of their “carbon-free” and “earth-friendly” rides.
To support these claims, Lime has pledged to purchase renewable energy credits to cover the electricity it uses for charging and carbon offsets for their operations. Bird purchases renewable energy credits and carbon offsets to cover electricity and scooter pick-up and drop-off.
However, claims of a full carbon-free ride don’t hold up when all of the actions required to have an e-scooter ready, at the right location and charged for use are considered. With North Carolina State University engineering students Joseph Hollingsworth and Brenna Copeland, I turned to a life cycle approach to fill in the gaps.
Chinese electronics company Xiaomi manufactures many of the e-scooters used in the United States. To understand what materials go into each scooter, we took one apart and inventoried the 13 pounds of aluminum, 2.5-pound lithium-ion battery, electric motor and various plastic and steel parts.
Manufacturing these scooters and other electronic products has effects at the mine site, the smelter and the factory. For e-scooters, we calculated that these production impacts often exceed half of the total impacts caused by each mile of travel on a scooter.
Shipping e-scooters from China to the U.S., however, has a trivial effect, thanks to the efficiency of the global transportation network.