Energy Storage

Why are hydroelectric power plants always built at reservoirs? Because the reservoir always holds enough water, no matter how much the power plant currently needs for the electricity supply. If the hydroelectric power plant is located on a river, it can only ever produce as much electricity as there is water available from the river. The reservoir is refilled whenever the water demand is smaller than the inflow into the lake. The water level then rises. If the power plant's demand is greater than the water inflow, the water level falls. As a store, the reservoir thus decouples the available energy (available water) from the energy demand (water demand) of a system via its fill level.

In electrical circuits, too, it is advantageous to use stores. If, for example, a battery-powered temperature sensor sends a measured value to a smartphone via Bluetooth at fixed intervals, it needs a lot of power for a short time to transmit via Bluetooth. The power demand of the rest of the temperature sensor, by contrast, is very low. A store that is slowly refilled from the battery and briefly supplies the Bluetooth module with power could decouple the load and the source.