How Sustainable Is Micromobility?

Micromobility is a useful addition to cars and public transport. E-bikes, e-scooters and the like are becoming increasingly common, especially in cities. But what is their environmental footprint? 

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The largest proportion of global traffic-related CO₂ emissions comes from road vehicles, which caused 12 % of the total global greenhouse gas emissions in 2021. This means that road traffic is the second largest producer of CO₂ emissions, after coal-fired power generation. Cars are the main source of emissions from traffic.

Can shared e-scooters and e-bikes reduce the emissions of urban transportation systems? To answer this question, the Fraunhofer Institute for Systems and Innovation Research (Fraunhofer ISI) conducted a study aimed at presenting a snapshot of case studies in six cities (Berlin, Düsseldorf, Paris, Stockholm, Melbourne, and Seattle) and evaluating data from 4,167 users. The data were collected and shared by the micromobility provider Lime, on the basis of a questionnaire developed by Fraunhofer ISI. 

Potential for CO₂ Reduction Is at Hand

The study’s findings show that the latest generation of shared e-scooters and e-bikes can indeed reduce net carbon emissions in the cities surveyed. The net effect is calculated as the difference between the life cycle assessment emissions per passenger kilometer (pkm) of the shared micromobility mode and the modes people would have used if shared e-scooters or e-bikes had not been available. This analysis was carried out for transportation systems in the six cities surveyed.

The largest effects for shared e-scooters were observed in Melbourne (-42.4 g/pkm) and Seattle (-37.7 g/pkm), which can be explained by a considerably higher CO₂ intensity of electricity used for public transportation and electric cars compared to the European cities. Dusseldorf (-22.1 g/pkm), Paris, and Stockholm (-20.7 g/pkm) also show effects of reduced emissions, while e-scooters in Berlin show smaller reductions (-14.8 g/pkm).

In all cities, the net carbon impact of shared e-bikes is less positive than shared e-scooters. Significant emission reductions are estimated for Dusseldorf (-20.4 g/pkm), Paris (-15.4 g/pkm), Seattle (-15.2 g/pkm), and Melbourne (-13.7 g/pkm), while the estimated emissions for Berlin increase (+13.0 g/pkm). This can be explained by the smaller proportions of shared e-bike trips that replace individual motorized modes of transportation, by the slightly higher theft rate, and by the lower usage intensity compared to shared e-scooters. 

Changing Mobility through Moral Appeals?

Micromobility can therefore be part of the solution to avoid traffic gridlock in our cities. E-scooters and e-bikes can also help to make traffic in cities more sustainable. But the question arises as to whether this can be left solely to market forces – or whether behavioral changes among road users can also be deliberately initiated. A field experiment carried out by the Leibniz Center for European Economic Research (ZEW) examined the question of whether car usage can be reduced by social comparisons and moral appeals in the context of a mobility budget. In the experiment, 341 participants – all employees of a large German company – received emails from their employer over a period of eight weeks. In these emails, randomly selected employees were informed that they had spent a smaller or larger amount on public transportation than other employees. For other randomly selected recipients, this social comparison was supplemented by a moral appeal asking them to give preference to public transportation or another climate-friendly means of transportation in order to combat climate change.

Based on the change in mobility spending, the researchers were able to demonstrate a significant effect of this information on the individual use of transportation. "The combination of social comparisons and moral appeals contributes in particular to reducing car use", said Wolfgang Habla, co-author of the study. "At the same time, there is an increase in the use of micromobility, for example e-scooters or bike sharing."

This is a partly automated translation of this German article.