A small company in the Netherlands called Plant-e has been developing a new technology to harvest electricity from living, growing plants, potentially opening a whole new approach to "generating"sustainable energy. Whereas existing biomass energy production systems rely on converting the stored energy of a previously living organism, Plant-e's system can be embedded in the soil or other growing substrate of active, living plant life.
The system works on the basis that all of the sugars created by plants through photosynthesis isn't used by the plant itself; in fact, about half of those sugars are excreted into the surrounding soil. Once there, the sugars are broken down by bacteria in the soil, releasing protons and electrons in the process. It is these electrons that Plant-e's system extract via electrodes inserted into the soil.