Can the ability of bacteria in soil to produce energy be harnessed in a realistic and even attractive way? The designers of this bio-photovoltaic panel believe so. A decorative framework based on Voronoi tessellation, a natural pattern, has been installed at the Valldaura campus of the Institute for Advanced Architecture of Catalonia. The framework houses bacteria-rich soil fed through by-products from the photosynthesis of plants, creating free electrons which are captured and stored in a battery.
So how does it work? When bacteria metabolize plant nutrients, they release hydrogen protons and electrons, and then a 'redox process' occurs transferring the free electrons in the soil from anode to cathode. A circuit with a step-down converter or capacitor can transfer this energy to electronic devices. Different variables make a significant difference in how much power is produced, from the type of plant that's grown, the type of soil that's used and how often it's watered. (See more of the technical details at DesignBoom.)
During their experiments, the researchers discovered that totally saturated soil produces the best results, since the water promotes electrolysis within the soil. Triangle containers were found to be most efficient, and coil cathodes maximize the surface for bacteria to gather around, making it ideal for collecting electrons. The Voronoi tessellation pattern used in the containers maximizes water distribution.
Could this be a viable method of producing power? Scientists have known for years that bacteria living in soil create small currents that can be harvested in a microbial fuel cell, but it's still unclear just how much power they could ultimately provide. Experiments like this one are an intriguing glimpse at potential solutions for low-cost power, especially in developing nations.