Solution:

Bacterial power plants.

In the late 1980s, microbiologists led by Derek Lovley at the University of Massachusetts Amherst, discovered electrically conducting microfilaments or “nanowires” in the rod-shaped microbe Geobacter sulfurreducens, part of a group referred to as “electrigens” for their known ability to generate an electrical charge.

Jim Yao and another team at the University have succeeded in producing electricity using a bacterial nanowire, measuring seven micrometers thick film positioned between two electrodes and exposed to the air.

This nanowire film, produced by G. sulfurreducens, absorbs water vapor present in the atmosphere, thus creating a small electrical charge through the diffusion of protons in the material.

In order to better understand this electron transfer process for energy production, Geobacter sulfurreducens was inoculated into chambers in which a graphite electrode served as the sole electron acceptor and acetate or hydrogen was the electron, or in short a microbial fuel cell

Called Air-gen, the system produces a sustained voltage of 0.5 volts at 17 micro amperes per square centimetre, generating clean energy 24/7. The system produces no waste and could (theoretically at least) work in places like the Sahara Desert which is why the team are looking to scale up to industrial-sized systems as soon as possible.

One issue is the limited amount of protein nanowire that can currently be produced by G. sulfurreducens, however, there may already be a novel solution: get genetically engineered E. coli to mass produce the nanowire.

Discover Solution 127: Protecting and feeding plants with an electric current.

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