Are e-scooters polluters? The environmental impacts of shared dockless electric scooters

Abstract

Shared stand-up electric scooters are now offered in many cities as an option for short-term rental, and marketed for short-distance travel. Using life cycle assessment, we quantify the total environmental impacts of this mobility option associated with global warming, acidification, eutrophication, and respiratory impacts. We find that environmental burdens associated with charging the e-scooter are small relative to materials and manufacturing burdens of the e-scooters and the impacts associated with transporting the scooters to overnight charging stations. The results of a Monte Carlo analysis show an average value of life cycle global warming impacts of 202 g CO 2 -eq/passenger-mile, driven by materials and manufacturing (50%), followed by daily collection for charging (43% of impact). We illustrate the potential to reduce life cycle global warming impacts through improved scooter collection and charging approaches, including the use of fuel-efficient vehicles for collection (yielding 177 g CO 2 -eq/passenger-mile), limiting scooter collection to those with a low battery state of charge (164 g CO 2 -eq/passenger-mile), and reducing the driving distance per scooter for e-scooter collection and distribution (147 g CO 2 -eq/passenger-mile). The results prove to be highly sensitive to e-scooter lifetime; ensuring that the shared e-scooters are used for two years decreases the average life cycle emissions to 141 g CO 2 -eq/passenger-mile. Under our Base Case assumptions, we find that the life cycle greenhouse gas emissions associated with e-scooter use is higher in 65% of our Monte Carlo simulations than the suite of modes of transportation that are displaced. This likelihood drops to 35%-50% under our improved and efficient e-scooter collection processes and only 4% when we assume two-year e-scooter lifetimes. When e-scooter usage replaces average personal automobile travel, we nearly universally realize a net reduction in environmental impacts.

Dockless E-Scooter: A Green Solution for Mobility? Comparative Case Study between Dockless E-Scooters, Displaced Transport, and Personal E-Scooters

“…For the manufacturing phase, due to lack of data from the Chinese factory, we followed the recommendations from Hollingsworth et al [16] and used the manufacturing of an electric bicycle (proportional to its weight) as proxy data. The transport phase was modeled based on the data from the provider, the e-scooter being transported by lorry from the factory to Shenzhen, then shipped from Shenzhen harbor to Rotterdam's harbor and, finally, by lorry from Rotterdam to Brussels.…”

“…In order to compare our PSS case study to the ownership model we have modeled another e-scooter which can be found on the market. We modeled it based on the inventory given in the appendices in Hollingsworth et al [41] who disassembled and inventoried all the materials of the different components. As the owner of an e-scooter charge it at home, no distribution phase is included in this model.…”

“…The first distance corresponds to the average single use length in Brussels, the latter corresponds to the autonomy. As the daily collection for charging represents 43% of the GWP in the Raleigh case study [16], the distance traveled by the chargers was changed adding or removing 50% of the traveled distance per e-scooter charged to test the importance of this parameter. We also tested a 100% renewable electricity mix, based on the actual Belgian renewable electricity mix.…”

“…Unlike the Brussels Mobility study, in which several answers could be selected, only one answer could be given. The modal share is also calculated in Hollingsworth et al study [16], but their sample consists of only 61 e-scooter users and the question is formulated differently: "If e-scooters were not available, what percentage of the time would you use these alternatives?" [41].…”

“…The parking of e-scooters has been the subject of one article [15]. Thus far, only one paper [16] has performed an LCA of a dockless e-scooter system. The authors assessed the dockless e-scooter in the city of Raleigh, North Carolina, USA and found a global warming potential (GWP) of 125 g CO 2 -eq/passenger-kilometer.…”