  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.
