The Environmental Impacts of E-Scooters

Several articles have been written over the past two years regarding shared micromobility electric scooters’ environmental impact. Some of the more phenomenal headlines were hyper-critical of electric scooters:

            Electric Scooters Aren’t Quite As Climate-Friendly As We Thought;

            Sorry, Scooters Aren’t So Climate-Friendly After All;

            Study: Electric Scooters Increase Carbon Emissions In Most Cases.

The report cited to support these assertions is one out of North Carolina State University with a similarly eye-catching title: “Are E-Scooters Polluters? The Environmental Impacts Of Shared Dockless Electric Scooters.” The study found that the greenhouse gas emissions associated with e-scooters were derived from four primary sources. The two largest impact categories — materials & manufacturing and collection & distribution emissions — accounted for over 90 percent of emissions. The two remaining categories were the transportation to the U.S. (most scooters are manufactured in China) and the actual emissions from scooter use and maintenance.

To me, that life cycle assessment is encouraging because scooter companies can reduce those two largest categories through practices on through production and operational changes. The truth of the environmental impact of electric scooters ultimately rests on the answer to a few simple questions:

  1. How are electric scooters manufactured?
  2. How long is the use-life of an electric scooter?
  3. What types of trips are electric scooters replacing?
  4. How are electric scooters collected, charged, and distributed?

These questions are interrelated and address overlapping issues. The answers are important for the future success of shared micromobility scooters as part of a mixed-transportation system. High on the list of goals that cities have set that they hope micromobility can help them reach are reduced traffic congestion and reduced emissions.

How are electric scooters manufactured?

This part of the life cycle of scooters may be difficult for cities to internalize and pressure scooter companies to change. Since the scooters are manufactured in China, and the raw materials are sourced outside the U.S., the immediate emission effects are not internalized in the United States. The direct effects are brought to bear in China and at the communities containing the mines for component materials. The component materials of a typical electric scooter include an aluminum frame (6.0kg), steel parts (1.4 kg), a lithium-ion battery (1.2 kg), an electric motor (1.2 kg), and tires with tubing (0.83 kg). Fifty percent of the emissions associated with electric scooters come from procuring the materials and manufacturing the actual scooter.

One way to reduce the emissions per passenger mile driven is to use the parts of decommissioned scooters to refurbish and extend other electric scooters’ lives. This will extend the parts’ life and reduce the need to procure and manufacture brand new scooters with new raw materials. Most of the scooter parts can be recycled if they cannot be reused in other scooters.  Uber has committed to recycling 90 percent of used spare parts from their “Jump” line of micromobility bikes and scooters. In the future, major micromobility providers should commit to using more recycled raw materials and components and to recycling the parts of e-scooters after they have outlived their working days. We cannot let what happened to bicycles in China happen to electric scooters in the United States.

How long is the life of an electric scooter?

Closely tied to the question of what goes into an electric scooter is: how long do scooters stay on the road? The longer a scooter can remain operational, the lower the average emissions per passenger miles traveled due to the sizeable portion of emissions being created up-front from materials and manufacturing. The less time a scooter is operating on the street, the higher the emissions per passenger mile traveled. When companies first distributed scooters around the U.S., the average life cycle was between one and three months. This short life was due in part to scooters being destroyed, thrown in rivers, and generally abused as they descended on cities, in addition to the expected wear and tear from everyday use. Over time, the scooters being manufactured and distributed have been made to be more durable and long-lasting. However, this can create a tradeoff with manufacturing emissions: to make more durable scooters that enjoy a longer street-life, more durable materials, and more energy must go into manufacturing, creating more emissions. If vehicles can last for two years before being decommissioned, the average per passenger-mile traveled is decreased by roughly 30 percent, according to the NCSU study. The tradeoff between increasing manufacturing inputs to extend the life of scooters is beneficial. Micromobility providers should continue spending resources developing more robust scooters that will need less maintenance and can remain in circulation longer to drive down average emissions continually. This solution should be supplemented by reusing parts, as discussed above. Using parts from older scooters to extend scooters’ lives on the street should be a priority for cities and micromobility companies. 

What trips are electric scooters replacing?

The benefits of electric scooters on transportation sector emissions depend mostly on what other transportation methods are being displaced. Suppose scooter trips only displace trips that otherwise would have been walking. In that case, scooters will never be an emission reducing solution. If e-scooters are only replacing automobile trips, scooters would always reduce net transportation emissions even at the current life cycle emissions assessment. Replacing ride-sharing and automobile trips decreases emissions (although this may not remain true as ride-hailing providers shift to using only zero-emission vehicles). Replacing what would otherwise be walking, bicycling, or public transportation trips results in more emissions from the transportation sector.

Several cities have studied this question during their scooter pilot programs. Chicago reported 43 percent of scooter trips replaced a trip that would have used ride-sharing service or personal vehicle. Thirty percent would have been walking trips, and 15 percent would have used public transportation. Portland found that 34 percent of local riders and 48 percent of visitors took an e-scooter instead of using a ride-hailing service or driving a personal vehicle. However, the city also reported that 42 percent would have walked or biked. Suppose scooters continue to and increasingly replace personal vehicle and ride-sharing trips. In that case, they will successfully help cities meet their goals of reducing traffic congestion and transportation emissions. However, in Ann Arbor, data shared by scooter companies has shown that scooters are not serving to replace vehicle trips or as the touted first-last mile solution. They are overwhelmingly replacing trips that otherwise would all be on foot: trips between on-campus academic buildings. This widespread use for scooters in college towns is an occurrence cities will need to address to meet their goals.

How are electric scooters collected, charged, and distributed?

Scooter companies approach collection, charging, and distribution in similar ways with minor variations. They employ people (either as employees or independent contractors) to drive around and collect scooters, take them somewhere (a central charging location or their home) to be charged overnight, and then use those people to drive around in the morning to redistribute the scooters. Cities often have requirements for the starting balance of scooters across the city to provide equitable access to communities underserved by public transportation. The additional miles driven by personal vehicles to find scooters, take them to be charged, and redistribute them in the morning accounted for 43 percent of scooters’ emissions impact.

There are several ways to address this enormous source of emissions. One method would require micromobility companies to make a similar move to Lyft: require their “chargers” (as Spin calls them) to drive an electric vehicle (or at least highly fuel-efficient cars) to reduce emissions from driving around. However, this would limit the number of people eligible to work in these roles, but that will change as electric vehicle models become more ubiquitous in the market this decade. Another solution is to minimize the distance between where scooters are picked up and dropped off. This may require greater segmentation or creating grids for collection and drop off.

The solution I like best requires investment and partnership between cities and scooter companies: installing public charging and storage corrals, and develop a reward charging program. At the entrances to metro stations, near bike-share drop-off areas, and other areas where morning demand is highest, scooter companies can work with cities to install corrals where scooters can be deposited and plugged into installed chargers. By sharing demand and usage data, scooter companies and cities can determine the best morning distribution locations and work in partnership to build central hubs for charging and collection.

Instead of hiring or contracting with vehicle drivers to pick up dozens of scooters, scooter companies should create rewards programs that incentivize users to drop off low-battery scooters at this location and plug them in to be charged. There will still be a need for drivers for scooters with bone-dry batteries. Still, users can relocate scooters with 10-20 percent juice to a charging corral at the end of a day in exchange for a free ride credit for later use. With the invigoration of reward and competition type apps, micromobility companies could incorporate features that “gamify” charging on foot instead of driving around in a vehicle.

Where we go from here

The conversation around the emissions associated with shared micromobility scooters needs to be reshaped. The industry has already come a long way since the first days of descending on cities like locusts. Cities are integrating scooters into their transit options; People have accepted them and approve of them; Scooters have great potential to reshape transportation. By adopting some of the suggestions I’ve proposed above, electric scooter companies can put to rest the idea that they aren’t a part of the solution to reduce the transportation sector’s emissions.