Generating Electricity from Ambient Water with Microbial Biofilms or Their Protein Nanowires

Water sources in both gaseous and liquid forms are ubiquitous. The electrostatic and hydrokinetic energy associated with this water is a large reservoir that potentially could be transformed into a sustainable source of energy for powering electronics. We have found that useful amounts of electricity can be generated from water with microbial materials. For example, protein nanowires harvested from the microbe <i>Geobacter sulfurreducens</i> are the functional material in ‘Air-gen’ devices that continuously generate electricity from the ambient humidity that is available literally anywhere on earth. We also found that devices fabricated from microbial biofilms can generate electricity from evaporating liquid water, achieving energy densities higher than those possible with traditionally engineered materials. These two types of devices for generating electricity from water are complementary, closing the loop for broadly harvesting electricity from all distributed water forms on earth. We further demonstrate the practical application of both types of devices for continuous, sustainable powering of wearable electronic devices that monitor important human physiological functions.