From KurzweilAI:
Plants could soon provide our electricity. In a small way they already are doing that in research labs and greenhouses at project Plant-e — a university and commercially sponsored research group at Wageningen University in the Netherlands. The Plant Microbial Fuel Cell from Plant-e can generate electricity from the natural interaction between plant roots and soil bacteria. It works by taking advantage of the up to 70 percent of organic material produced by a plant’s photo-synthesis process that cannot be used by the plant — and is excreted through the roots. As natural occurring bacteria around the roots break down this organic residue, electrons are released as a waste product. By placing an electrode close to the bacteria to absorb these electrons, the research team — led by Marjolein Helder PhD — is able to generate electricity. Helder said: “Solar panels are making more energy per square meter — but we expect to reduce the costs of our system technology in the future. And our system can be used for a variety of applications.”
Plant Microbial Fuel Cells can be used on many scales. An experimental 15 square meter model can produce enough energy to power a computer notebook. Plant-e is working on a system for large scale electricity production in existing green areas like wetlands and rice paddy fields.
More here.