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Hybrid Energy Tech Could Clean Wastewater for Free

A combination of microbial fuel cell and reverse electrodialysis is efficient enough to make sewage treatment energy neutral

3 min read
Hybrid Energy Tech Could Clean Wastewater for Free

A microbial electrolysis cell

Photo: Bruce Logan
Two in One: A microbial electrolysis cell is a combination of a microbial fuel cell [chambers on left and right] and a reverse electrodialysis stack [middle]. Click on the image to enlarge.

1 March 2012—Engineers at Pennsylvania State University have combined two cutting-edge energy-generation technologies—microbial fuel cells and reverse electrodialysis (RED)—to make a hybrid device that could generate enough energy from wastewater to power its treatment and even feed some extra electricity into the grid. The engineers report their invention this week online in Science.

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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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