In Australia, various City Councils, including the City of Adelaide, are pursuing carbon neutrality at municipal-scale based on their operational greenhouse gas (GHG) emissions. As passenger transport is a major component of city operational GHG emissions, there is an opportunity for shared mobility services to play a role in reducing those emissions. This preliminary carbon modelling report has focussed on the GHG benefit from expanding shared mobility services in the Adelaide Local Government Area, although the results should be equally valid in other similar inner-urban precincts.
The Adelaide Shared Mobility (ASM) GHG model was constructed in Microsoft EXCEL using only publicly available data from the City of Adelaide’s annual community GHG emissions reporting and the Vehicle-Kilometres-Travelled (VKT) projections published in a report titled, Carbon Neutral Adelaide – Foundation Report. Seven shared mobility services were considered with regard to their potential impact over a 20-year period on reducing operational or embodied emissions or acting as a catalyst to reduce GHG emissions including – ridehailing, carsharing, carpooling, bikesharing, ridesplitting and using autonomous vehicles.
The results of the modelling showed that the current state-wide decarbonising strategy of reducing electricity grid emissions coupled with the expected uptake of electric vehicles will have a significant impact on reducing transport GHG emissions, and to a certain degree will cannibalise the potential emission impact of shared mobility services. The combined GHG savings of the considered sharing economy mobility services was found to be less than 1% of the total Adelaide LGA transport emissions for each of the modelled years. The opportunities for shared mobility services for lowering embodied emissions or being a catalyst to reduce other GHG emissions related to the Carbon Neutral Adelaide goal were also found to be not significant.
The possible reasons for the low GHG impact from expanding sharing economy mobility services included:
- Not all shared mobility trips provide a net GHG emission benefit (e.g ridehailing);
- Some shared mobility trips displace low carbon modes such as walking and public transit (e.g bikesharing);
- Some shared mobility trips are a displacement of other shared mobility modes (e.g e-scooters); and
- The ASM GHG model used conservative growth factors of expanding carshare and bikeshare services consistent with their low growth history to date in the Adelaide LGA.
While the modelling found that expanding shared mobility services had little impact on reducing the direct emissions from private car usage, there is scope to develop the ASM GHG model further to include a more detailed analysis of the embodied emissions from firstly, reducing the number of vehicles and secondly, reducing the related road and parking infrastructure in Adelaide. The ASM GHG model has focussed primarily on reducing private car usage. As more drivers move to using public transit in the future, the ASM GHG model could be expanded from its private car focus to include a detailed analysis of public transit modes to better understand the mode-switching within and between the private usage, public transit and shared mobility sectors.
The opportunities for the future research with the ASM GHG model include:
- Integrate public transit data into the shared mobility GHG model to better understand the mode-switching within and between the private usage, public transit and shared mobility sectors; and
- Investigate the benefit of the first mile shared mobility at selected Adelaide suburban transit stations to delay/avoid the future construction of car parking buildings for ‘Park n Ride’ commuters.