High renewable and variable electricity penetration in power systems requires increased grid stabilization from balancing power plants, namely gas operated. In the future, however, stabilization might be provided by electric vehicles operating under the smart-grid framework. Departing from this, this paper discusses and quantifies to what extent electric vehicles are required to be possible to shut down gas power plants. The analysis is performed using the EnergyPLAN tool, for the case study of the Portuguese power system in 2050. The results suggest that even a small share of the fleet of electric vehicles providing load balancing could lead to important reductions in gas use and energy excess. The gas share in the electricity mix is reduced from 10.2% without electric vehicles providing for stabilization to zero with 30% of the fleet providing it; the energy excess is reduced from 1.5% to zero above 15% of electric vehicles stabilizing the grid. Therefore, to achieve a power system without fossil fuels, electric vehicles capable of supporting the grid should be developed and adopted, as should be promoted the market and regulatory conditions to allow this. (C) 2017 Elsevier Ltd. All rights reserved.