A natural battery based on lake water and its soil bank

We report a natural battery constructed by lake water and its soil bank. A DC (direct current) open-circuit electric voltage and short-circuit current is generated between two metal electrodes dipped inside lake water and its soil bank. The open-circuit voltage, short-circuit electric current and maximum output power are up to 486 mV, 70 μA and 8.2 μW, depending on the distance from the metal electrode inserted into soil to the one immersed in lake water. The small power of the battery is generated by the pH value difference between the lake water and soil bank, and the oxidation of organic matter around the electrode in soil. The natural battery provides an easy and essential method to harvest small energy from the environment for the drive of low power electronic systems.

► A natural battery has been constructed by lake water and its soil bank.
► Easy method to harvest small energy from the environment for the drive of low power electronic systems.
► Generated electric power can be sufficient to power a sensor node and some existing microcontrollers.
► The generated voltage, electric current and maximum power is 490 mV, 70 μA and 8.2 μW, respectively.
► The extension of this research to the natural systems may lead to the discoveries of other natural batteries.