By Ryyan Hammoud
Elementary Category (Grades 4-6)
Experiment | Energy and Natural Resources, Environment
Fossil fuels have been our energy source for over a century. We have become deeply dependent on these fossil fuels in their many forms and uses. We continue to depend on them even though they are harmful to our environment as they are the primary contributors to global warming and climate change. They are also causing air and water pollution as well as health diseases.
Scientists have discovered that electricity can be generated from plants without affecting their growth. This electricity is generated by direct extraction of photosynthetic electrons. A plant produces organic matter via photosynthesis. Part of this organic matter is used for plant growth, but a large part can’t be used by the plant and is excreted into the soil via the roots. Naturally occurring micro-organisms around the roots break down the organic compounds to gain energy. In this process, electrons are released in the soil. By inserting electrodes (cathode, anode) into the soil, these electrons can be harvested as electricity.
By using living plants, we will be able to generate clean electricity around the world and keep our environment clean. However, this harvested electricity is still a weak energy source and we need to find a solution to increase the amount of energy produced.
Generating the most electricity depends on the type of electrodes inserted in the soil, the type of plants and soil. Research shows that plants that requires constant soil moisture such as rice fields, reeds and ferns will produce more electricity because water is a good conductor.
Researchers are still testing different electrode materials. By doing this project, I will conduct an experiment to find out which cathode will generate the most electricity from a plant. My project will test copper, aluminium and graphite as cathodes in combination with zinc anode in a spider plant. I will then use the best cathode material found to be the best conductor of electricity for my next experiment to light up a 1.8 V LED and to charge a smart phone from the plant. I will need to test how many plants would generate enough electricity to light up the LED and charge the smart phone.
My hypothesis was that the copper cathode will generate the most electricity from the plant because copper is commonly used as a conductor material for its high conductivity. The experimental results supported my hypothesis by showing that the copper cathode in combination with zinc anode generated the highest voltage and amperage (0.980 V and 0.233 mA) followed by graphite cathode (0.886 V and 0.156 mA), then aluminum cathode (0.331 V and 0.011 mA). My hypothesis for the second experiment was that two connected plants in series circuit will light up the LED and six plants will charge the smart phone. The results supported my hypothesis for the LED. By connecting two plants, the voltage increased from 0.913 V to 2.020 V causing the LED to light up. However, the amperage dropped from 0.520 mA to 0.480 mA. The experiment also showed that by connecting six plants, the voltage increased to 5.5 V (amount required to charge a smart phone). However, the smart phone did not charge at all. This was due to the drop of amperage to 0.222 mA. I learned that connecting more plants in series gives higher voltage. Furthermore, I learned that increasing the voltage will cause the amperage to decrease.
This experiment is important because it ensures that we may be able to solve issues caused by the use of fossil in the coming years. Generating electricity from living plants will strongly benefit all the world.