Both of these aspects have important beneficial consequences for the whole electrical system. By lowering this maximal imbalance, one reduces the additional residual capacity needed in the system to balance demand. In France, seasonal fleet management reduces the maximal residual demand by 6.4 GW, from 17.6 to 11.2 GW. Based on EURELECTRIC/VGB data (IEA/NEA, 2010), in France the overnight investment cost of an additional capacity of 6 GW can be estimated at USD 11.7 billion if coal plants are built coal, and at USD 7.2 billion for gas-fuelled units.