indeed according to some estimates when the externalities associated with different energy sources are fully reflected in policy incentives some renewable energy sources particularly wind power are already as cost efficient as conventional energy sources as many of these technologies are still in early phases of their respective development chains further cost reductions are expected in the future especially if these technologies are appropriately supported by research development demonstration and deployment programs rddd since renewable energy generation has been growing only at an annual rate of which is lower than the growth rate of total electricity generation thus while in of total electricity was produced from renewable sources this share has declined to estimated in most of which was generated from hydro plants