the same review also shows that under these and even less ambitious renewable energy scenarios it is expected that a global share of more than per cent of intermittent modern renewable power will be reached by this will require some sort of smart grid to deal with load balancing which in turn means that these scenario plans assume the rebuilding of the existing power grids in most large economies within the next years an extraordinarily ambitious undertaking comparable undertakings in previous energy transitions took more than years in this scenario demand for all types of energy increases in nonoecd countries while in oecd demand for coal and oil declines