A team of research students at the Institute for Advanced Architecture of Catalonia (IAAC) in Spain have recently designed and installed a bio-photovolatic wall at their Valldaura campus to generate some buzz about collecting the natural and continuous untapped energy source that constantly flows beneath our feet.
Bio-photovoltaics (BPV) describes the process of harvesting energy naturally produced by the bacteria found in soil. When plants undergo photosynthesis, they produce nutrients in the soil as a by-product that bacteria in the soil metabolize. As the bacteria digest the nutrients in soil, they release electrons. Created at IAAC’s Fablab, the team’s BPV device extracts these electrons by placing an anode and cathode inside the soil. Then by connecting the circuit with a capacitor, the harvested energy can be stored and used to power appliances and other electronic devices.
The team ran many experiments to test and improve the design. Surprisingly, they found that the actual structural design of the device had a significant effect on the efficiency; their final, optimized design is a Voronoi tessellation pattern that allows for ideal root growth as well as a ideal distribution of root nutrient by-products while still creating the maximum voltage output.
While the energy produced is not as powerful as wind or solar energy as of yet, it can still power many small appliances. Through their calculations the team estimated that one BPV panel can charge a cell phone, 8 could power a microwave and 16 could power a radiator.
Although its design seems a bit complicated, the team’s BPV tessellated panels serve as yet another avenue for harvesting energy passively from nature’s untapped excess production. On top of utilizing a sustainable and renewable resource of bacteria byproduct, BPV cells don’t constantly require the weather to be sunny, the wind to be blowing, or water to be flowing. Instead they absorb the natural energy that is produced year-round, underground.
Know a bit about engineering and electronics, and want to make a BPV cell yourself? The IAAC team outlined the detailed design, fabrication process and materials used here.