Plants and bacteria generate electricity A recent EU research project developed a proof-of-concept fuel cell (FC) that generated power using growing plants and bacteria. Scientists are now looking at advancing this concept towards commercial application. Energy © Thinkstock A plant microbial fuel cell (Plant-MFC) is an electrochemical system in which plants harvest light and carbon dioxide (CO2), and releases organic matter into the soil. There, specific bacteria convert the organic matter while electrons are released resulting intoelectricity. While early results in this field have been promising, work is needed to improve energy output. As such, the EU-funded PLANTPOWER project aimed to improve the net power output of the Plant-MFC from 0.0067 watts per square metre (W/m2) to 3.2 W/m2. To achieve this, scientists needed to optimise every aspect of the system and improve knowledge of how the various components interact. Researchers settled on grasses as the most promising type of plant as they are fast-growing, abundant and did not lose vitality while growing in the Plant-MFC. In addition, Plant-MFCs with grasses produced high power and high biomass for other applications. Genetic differences in the rate of chemical release by the plants were investigated, and point to physical root traits as being the most important factor. The team also chose the most promising bacterial species in order to develop a Plant-MFC inoculum. Modelling was used to optimise and speed up the Plant-MFC system. The model included growth rates, exudation (the release of the chemicals into the medium), root turnover and energetic performance.More work is needed to produce a useful Plant-MFC, including improving the electrodes, up-scaling and real-world testing. Environmental and economic analyses are also required to help PLANTPOWER produce a commercial FC. Keywords Plant microbial fuel cell, electrochemical, bacteria, exudation, grasses, bioenergy
