Hydro power station is a solution for the gap created by solar and wind power generators. At time when sun light is strong or air flow is powerful, the energy created by these generators can be stored by pumping water to a higher storage. When solar and wind power generation is in a low level, the water in a higher storage can then be used to generate hydro power to compensate the gap, by flowing the water to a lower storage. This becomes a closed loop. If engineered properly, a pumped hydro power station should cause minor environmental impact compared with other types of power station.