Hongyang (Ollie) Zhao
David Thompson Secondary
Floor Location : M 222 E
My project, Amp Tree, focusses on harvesting the electricity of living plants, mainly trees, without permanently damaging or killing them. The objective of Amp Tree is to harvest a useful amount of energy from living plants to power or charge remote devices, mainly sensors and transmitters. However, it can also power any electrical devices including GPSs, phones, or other smaller gadgets and equipment. The energy harvested is very consistent and great enough to power medium to large sensors along with transmitting the data.
A series of experiments were performed to determine the following. When an electrode is inserted into a tree and grounded, an electric current will form due to the pH difference between the tree and the ground amongst a few other factors. There is no electrochemical effect nor any other living organisms involved, except the tree. The output of electricity is solely dependent on the metabolism of the plant. Therefore, Amp Tree will reliably and continuously generate electricity as long as the tree is alive, which will likely be for decades.
The reason behind the fact that no one has successfully utilized the electricity generated by plants is that the output of electricity is absolutely tiny. The output voltage of plants ranges from 10mV to 440mV, averaging 250mV. Meanwhile, the output current ranges from 600nA to 20µA, averaging 5µA. Outputs of these minuscule levels can’t be processed by any existing boosters or integrated circuits. Meaning that it is impossible to increase the voltage to a usable level. Furthermore, even if converters or boosters can process such low inputs, the current of several µA won’t even be enough for dissipation. Thus, electricity from plants can’t be used to power any electric devices with any existing methods. In order to solve these challenges, Amp Tree is divided into three main components: Power Input, Power Management, and Power Conversion.
Power input is the process of harvesting unrefined electricity from the tree. Multiple electrodes, inserted at optimal locations on the tree, are used to multiply the output of electricity. When a sufficient output is achieved, the electricity is then directed to Power Management. Power Management stores the output of the tree in a super-capacitor for a period of time before releasing the short, but concentrated, burst of electricity to Power Conversion. Two TPL5111 Watch Dogs and a TPS22860 I.C. Switch keep track of time and release the charge at designated intervals. They’re personally designed and created to consume an unprecedented little amount of power. Using a DC/DC converters as well as a transformer, the self-created Power Conversion system boosts the voltage of the short, but concentrated, bursts of electricity (9mA at 0.08V) to an astounding 5V. This is then stored in a battery or capacitor that can power any small electrical devices.