The Matrix had it all wrong. Robots won’t turn our bodies into batteries. No, no. no…they’ll use our poop. The Bristol Robotics Laboratory has a history of creating robots that can run off the decomposition of organic matter. Their latest is the Ecobot-III Bio-Regulation and Energy Autonomy with Digeston or simply the BREADbot. This robot has an ‘artificial gut’ that holds a host of sludge bacteria to decompose all kinds of waste. 48 microbial fuel cells (MFC) harness the decomposition process for small amounts of electricity. The robot is completely powered by digestion. Bristol Robotics will be presenting their findings at the Artificial Life XII conference later this month. Check out BREADbot and its predecessors in the pictures and videos below. The bio-robotic revolution has already begun, and it is nauseatingly awesome.
The central technology for Ecobots (including the BREADbot) is the microbial fuel cell. MFCs contain decomposer bacteria in a medium (often sludge or soil) that slowly release ions and electrons as they process organic materials. These ions can be harnessed to create a low electric current from the MFC. While MFCs are very inefficient -less than 1% of the chemical energy is converted to electricity – they can run as long as the bacteria are alive and have material to ‘eat’. Right now the MFCs used in Ecobots can’t even perform as well as simple alkaline batteries, but they could be improved considerably. Eventually we could use enormous numbers of these devices to transform sewage processing facilities and maybe even garbage dumps into power plants.
For now, the advantage of MFCs are that they give BREADbot the potential to run for years and years without stopping, as long as it has a good supply of wastewater. It’s that potential that has really intrigued the Bristol Robotics Lab. BREADbot and its predecessors are experiments in autonomy. Robots that can run off materials found in nature could be left alone to work for long periods of time without additional supplies or support. BREADbot itself was shown to run for 7 days on its own. It only failed because a mechanical pump in its system broke down; the MFCs and robotics functioned very well. BREADbot ‘eats’ wastewater for fuel (eww) and freshwater to replace moisture lost to evaporation. In the following video you can see how the robot travels back and forth between supplies for each along a stainless steel track. While the test environment (named EcoWorld) is very simple, it shows that robots like this could eventually harvest nature for power.
Part of the deliciously repugnant parts of BREADbot is that it purges its artificial gut every 24 hours to make room for fresh organic filled waste. This purging happens towards the middle of the track and you may be able to make out a pool of liquid waste in the video. As unappealing as a poo puddle may be, it’s actually a positive for this robot. The only by-products that the robot produces is CO2 (from the decomposition) and semi-processed liquid waste. Importantly, it doesn’t release anymore CO2 than would normally be released during natural decomposition. Robots like BREADbot are essentially run on ‘green energy’. So as we distribute these robots into the wild, they would likely have a neutral effect on their environments.
If you haven’t seen enough liquid waste yet, here’s a video of the Ecobot III (of which BREADbot is an updated version) dispensing the contents of its artificial stomach. Yummy.
As I said before, Bristol Robotics is interested in autonomy and they’ve been looking at nature-feeding robots for years. Other groups were first to explore how to power robots with MFCs, but Bristol has really bent the technology towards creating self-sufficient bots. Back when they were the Intelligent Autonomous Systems Lab, they created Slugbot, a prototype machine that would eat slugs for fuel. A mechanical claw would harvest slugs (which have no skeletons, are pests, and often plentiful) and bring them to a digestion chamber for consumption. Later, Bristol created the Ecobot-I a bot that was run off of the power generated by E. coli bacteria fed with sugar. The Ecobot-II is probably my favorite. It used sludge bacteria to harvest energy from dead flies and rotten fruit. Oxygen taken from the air helped it decompose the flies and fruit and power its 8 MFCs. Because of the low amounts of electricity, the Ecobot-II ran on pulse power. It built up charge on capacitors until it was ready to move a short distance. Powered by dead flies it was shown to be able to move towards a light and take readings along the way. Not only was Ecobot-II a predator, it was also a scientist. So cool. Check it out in the following video:
Whether they run on slugs, sugar, flies, garbage, or wastewater, robots powered by digestion are an amazing combination of the mechanical and biological. We’ve seen bots with organic parts before, but the use of microbial fuel cells really takes the concept in a different direction. With a nature-based power source robots take a step closer to autonomy. Not only that, but if we design their artificial guts for the right materials they could become a valuable balance to human consumption. Robots that ate garbage and waste could perform important tasks while negating some of the impact we have on our environment. It’s a double win. Right now the low-efficiency of MFCs greatly limits what these robots can do, but as MFCs improve, so will their capabilities. Who knows, the advanced robots of the future may use poop as a power supply. Science is awesome when it’s disgusting.