Robot stomachs: powering machines with garbage and pee

Robohub • 14 May 2021

The Seinfeld idiom, “worlds are colliding,” is probably the best description of work in the age of Corona. Pre-pandemic, it was easy to departmentalize one’s professional life from one’s home existence. Clearly, my dishpan hands have hindered my writing schedule. Thank goodness for the robots in my life, scrubbing and vacuuming my floors; if only they could power themselves with the crumbs they suck up.

The World Bank estimates that 3.5 million tons of solid waste is produced by humans everyday, with America accounting for more than 250 million tons a year or over 4 pounds of trash per citizen. This figure does not include the 34 billion gallons of human organic materials that is processed in water treatment centers across the country each year. To the fictional Dr. Emmett Brown, this garbage is akin to “black gold” – ecologically powering cities, cars, and machines. In reality, the movie, “Back to The Future II” was inspired by the biomass gasification movement of 20th century in powering cars with wood during World War II when petroleum was scarce. The technology has advanced so much that a few years ago the GENeco water treatment plant in the United Kingdom built a biomethane gas bus that relied solely on sewage. In reflecting on the importance of the technology, Collin Field of Bath Bus Company declared, “We will never, ever, ever, while we are on this planet, run out of human waste.”

Less than twenty miles away from the GENco plant, Professor Loannis Leropoulos of the University of Bristol’s Robotics Laboratory is working on the next generation of bio-engineered fuel cells. Last week, Dr. Leropoulos demonstrated his revolutionary Microbial Fuel Cells (MFCs) for me. As witnessed, he is not just inspired by nature, but harnessing its beauty to power the next generation of robots. The MFCs mimic an animal’s stomach with microbes breaking down food to create adenosine triphosphate (ATP).


The Bristol lab began building MFCs to power its suite of EcoBots. “I started this journey about twenty years ago with the main purpose of building sustainable autonomous robots for remote area access,” reflects Leropoulos. He was inspired by Dr. Stuart Wilkinson’s Gastrobot in the early 2000s that first promoted the idea of “an intelligent machine that digests real food for energy.” At the time the media hyped Wilkinson’s invention as a flesh-eating robot, when in reality it digested sugar cubes, turning the carbohydrates into electrical energy. Unfortunately, the Gastrobot’s clumsy oversized form factor suffered from long charging times with an 18-hour “carbo-loading” process for every 15 minutes of power....


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