Following on from the Grid Study Part I conducted in 2009, this study looks at the European electricity grid in 2030 and 2050, with regards to the infrastructure required to support up to 100% penetration of renewable energies as outlined by the Greenpeace Energy [R]evolution scenarios. This time however, an attempt is made to optimize between the costs of curtailing energy and reinforcing the grid, based on power flow simulations for a “standard year” with an hourly resolution, as well as the “extreme weather scenarios”, as was done in the Grid Study Part I. Furthermore, the effectiveness of demand-side management, storage, and grid reinforcements in reducing energy curtailment are explored, and their roles in integrating renewable energies as well as contributing to the security of supply are discussed. This study was featured in the report by Greenpeace International titled “Battle of the Grids”.