How to Make Electricity With Bacteria-Coated Rubber

Bacterial spores that respond to changes in humidity power a Lego generator

1 min read
How to Make Electricity With Bacteria-Coated Rubber
Images: Xi Chen/Columbia University

A new electric generator has a modest and unexpected energy source: A small strip of latex rubber coated with bacterial spores.

The contraption makes use of the harmless soil bacterium Bacillus subtilis, which has a neat survival trick. When nutrients are scarce, it turns itself into a tough little spore that can withstand heat, desiccation, chemical assaults, radiation, and anything else the world can throw at it. These spores respond to changes in humidity. When the air dries they shrivel up like grapes turning into raisins; when the air is moist they plump up again. Researchers from Harvard's Wyss Institute and several other universities realized they could harness that physical movement, and could make an actuator to generate electricity.  

In the experiment, published this week in Nature Nanotechnology, the researchers slathered one side of a sheet of rubber with the bacterial spores. When the sheet dried it curled up, much like a leaf does after it falls from a tree. Increasing the humidity caused the sheet to straighten out again. Researcher Ozgur Sahin then built a humidity driven generator out of Legos, in which the spore-coated rubber acts as a cantilever that flips back and forth, driving a rotating magnet to produce electricity. 

Such a device, properly scaled up, could use the natural evaporation of water to generate useful amounts of clean electricity, the researchers say. 

Images and video: Xi Chen/Columbia University

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This Dutch City Is Road-Testing Vehicle-to-Grid Tech

Utrecht leads the world in using EVs for grid storage

10 min read
This photograph shows a car with the words “We Drive Solar” on the door, connected to a charging station. A windmill can be seen in the background.

The Dutch city of Utrecht is embracing vehicle-to-grid technology, an example of which is shown here—an EV connected to a bidirectional charger. The historic Rijn en Zon windmill provides a fitting background for this scene.

We Drive Solar

Hundreds of charging stations for electric vehicles dot Utrecht’s urban landscape in the Netherlands like little electric mushrooms. Unlike those you may have grown accustomed to seeing, many of these stations don’t just charge electric cars—they can also send power from vehicle batteries to the local utility grid for use by homes and businesses.

Debates over the feasibility and value of such vehicle-to-grid technology go back decades. Those arguments are not yet settled. But big automakers like Volkswagen, Nissan, and Hyundai have moved to produce the kinds of cars that can use such bidirectional chargers—alongside similar vehicle-to-home technology, whereby your car can power your house, say, during a blackout, as promoted by Ford with its new F-150 Lightning. Given the rapid uptake of electric vehicles, many people are thinking hard about how to make the best use of all that rolling battery power.

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