Not flexible enough? Impacts of electric carsharing on a power sector with variable renewables

Electrifying the car fleet is a major strategy for mitigating greenhouse gas emissions in the transport sector. However, electrification alone will not solve all the negative externalities associated with cars. In light of other problems such as street space as well as concerns about the use of mineral resources for battery electric cars, reducing the car fleet size would be beneficial, particularly in cities. Carsharing could offer a way to reconcile current car usage habits with a reduction in the car fleet size. However, it could also reduce the potential of electric cars to align their grid interactions with variable renewable electricity generation. We investigate how electric carsharing may impact the power sector in the future. We combine three open-source quantitative methods, including sequence clustering of car travel diaries, a probabilistic tool to generate synthetic electric vehicle time series, and an optimization model of the power sector. For 2030 scenarios of Germany with a renewable share of at least 80%, we show that switching to electric carsharing only moderately increases power sector costs. In our main setting, carsharing increases yearly power sector costs by less than 100 euros per substituted private electric car. This cost effect is largest under the assumption of bidirectional charging. It is mitigated when other sources of flexibility for the power sector are considered. Carsharing further causes a shift from wind power to solar PV in the optimal capacity mix, and may also trigger additional investments in stationary electricity storage. Overall, we find that shared electric cars still have the potential to be operated largely in line with variable renewable electricity generation. We conclude that electric carsharing is unlikely to cause much damage to the power sector, but could bring various other benefits, which may outweigh power sector cost increases.