Electric Vehicles and their impact to the electric grid in isolated systems

Energy systems are frequently based on imported fossil fuels, and this is a problem in different dimensions including, the environmental, the economic and the security of supply, the latter being particularly relevant for any isolated system, like Islands. Renewable energy is regarded as a solution to this problem, particularly considering its transformation in electricity but this does not include the impact of the transportation sector, which represents a significant component of the imported fuels consumption. The other main limitations associated to renewable electricity consists on the need to increase the storage capacity that might attenuate the effect of renewable energy sources intermittence and disparity between supply and demand. In both these main problems associated with renewable energy management, the plug-in electric vehicles (EV) could be a part of the solution in that the use of the vehicle to grid (V2G) technology can provide storage of electric energy during low demand times and use it to match the demand in peak hours and/or to avoid fossil fuel consumption. However, could the large scale EV penetration lead to increasing the fraction of electricity from renewable? Is the usage of EV batteries like as a storage system truly the best solution? Is the EV a better solution for the vehicle's owner than the internal combustion vehicle from an economical point of view? This paper analyses a case study in the Island of Sao Miguel in Azores, where energy systems modeling is used to assess how far large scale EV penetration may lead to increasing the potential for the use of renewable electricity, and discusses the possible revenues for EV owners from providing vehicle to grid power.