What is the future of public charging infrastructure for electric vehicles? – A techno-economic assessment of public charging points for Germany

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. Introduction Motorised transport is responsible for a large share of global greenhouse gas (GHG) emissions. Where the specific CO2 emissions of internal combustion engine vehicles are fundamentally limited, electric vehicles offer large emission reduction potentials when using low-carbon electricity from renewable energy sources. However, electric vehicles (EVs) are not fully comparable to conventional vehicles: battery electric vehicles with prices of the order of similar conventional vehicles have a range that is significantly smaller and plug-in hybrid or range extended EVs reach high electric driving shares only when used within a limited range. Public charging infrastructure appears to be a remedy for these limitations just as fuel stations allow refuelling for trips which are much longer than the normal range of internal combustion engine vehicles. Charging infrastructure thus seems a supporting or even necessary instrument for a large scale introduction of EVs. However, public charging infrastructure is rather expensive to install and major public investments seem necessary as long as viable business models are absent. Taken together, we face a wish for public charging infrastructure for EVs in contrast to much uncertainty about financing and the future developments of the number of available charging options which are required as input for designing business models. Thus, the aim of the present paper is to answer the following question: Which future development of (mainly public) charging infrastructure seems likely, taking into account costs, technological options and actual user behaviour? For the rest of the paper we will use the term “electric vehicle (EV)” throughout for plug-in electric vehicles (with four wheels). This includes battery electric vehicles (BEVs), plug-in hybrid electric vehicles (PHEVs), range extender electric vehi