Electricity from the marshes

Bio-electricity from plants could produce as much as 3.2 Watt per square metre of plant growth

An unexpected source of new, clean energy has been found: the Plant-Microbial Fuel Cell that can generate electricity from the natural interaction between living plant roots and soil bacteria. The technique already works on a small scale and will soon be applied in larger marshland areas throughout the world. On 23 November, researcher Marjolein Helder will defend her PhD research on generating electricity via plants at Wageningen University, part of Wageningen UR. She has also founded a spin-off company called Plant-e with her colleague David Strik.

The Plant-Microbial Fuel Cell draws electricity from the soil while the plants continue to grow. Plants produce organic material via photosynthesis. The roots excrete up to 70 % of this material (unused) into the soil. Bacteria around the roots break down the organic residue, thereby forming a new source of electricity. The degradation processes causes electrons to be released. Marjolein Helder and her colleagues placed an electrode close to the bacteria to absorb these electrons and generate electricity via the potential difference thus created.

The Plant-Microbial Fuel Cell can currently generate 0.4 Watt per square metre of plant growth. This is more than is generated by fermenting biomass. In future, bio-electricity from plants could produce as much as 3.2 Watt per square metre of plant growth. This would mean that a roof measuring 100 m2 would generate enough electricity to supply a household (with an average consumption of 2,800 kWh/year). Plants of various species could be used, including grasses such as common cordgrass and, in warmer countries, rice.