What is the future of public charging infrastructure for electric vehicles?

Electric vehicles are able to reduce local and global emissions from the transport sector and thereby could help to slow down global warming if they achieved significant market shares. As all other vehicles, they need a charging or refuelling infrastructure to be built up simultaneously to vehicle market penetration. With the current disability to store energy for long distance trips in batteries, the need for a dense charging infrastructure appears to be even higher. On the other hand, many car users could charge at home in their private garages. The question therefore is whether domestic charging infrastructure is sufficient to trigger market penetration of electric vehicles. Or in other words: Do we need public charging infrastructure for a mass market diffusion of electric vehicles and if so, how much? Here we discuss technical and economic aspects of this question. Large data sets of German driving profiles are analysed to estimate the share of vehicles that could technically be operated as electric vehicles. In addition, the driving behaviour is combined with a simple market diffusion model for electric vehicles and their corresponding charging infrastructure where each user is assumed to choose the fuel option with the lowest total costs of ownership. We can thereby quantify the share of vehicles that can be replaced by electric vehicles and estimate the market diffusion of public charging points. We find that this technical and economic analysis does not justify a large development of public charging infrastructure which is confirmed by empirical user behaviour data in pilot projects where not more than 10 % of all electricity for driving is charged publicly.