The team of EU-funded scientists behind the EcoBot series (I, II, III) of robots has generated energy by feeding the machine food waste and raw materials. They have now set their sights on converting energy from urine for the same outcome.

The EcoBot-III project received EUR 320,000 in funding under the EU's Sixth Framework Programme (FP6) and Dr Ioannis Ieropoulos, Professor John Greenman, Professor Chris Melhuish, and other researchers from the Bristol Robotics Laboratory (BRL) in the UK are responsible for a succession of experiments undertaken with EcoBots I, II and III.

Their unique approach has been to create an artificial digestion system for the robot. This gut is designed around novel microbial fuel cell (MFC) technology, which draws on bacterial cultures to break down food in order to generate power.

Access to energy is one of the greatest obstacles to widespread use of autonomous robots, particularly in remote areas. The scientists believe that for a robot to be truly autonomous it must not only use its energy wisely but also generate this energy from its own surroundings. This means being able to search, collect and digest waste materials to replenish its energy reserves. This, in turn, has the potential to contribute significantly to the waste management issue.

The latest challenge that underlies the team's current undertaking is to use urine for MFCs. Dr Ieropoulos explained that urine is rich in nitrogen and possesses chloride, potassium, bilirubin and other compounds - all of which make it ideal for MFCs. Preliminary tests have already shown it to be a very effective waste material.

The first step for the researchers is to enable MFCs to work together in a series of cells that are linked under a continuous flow system known as a 'stack'. A stack of linked MFCs are both more efficient and produce more energy than the same quantity of individual MFCs.

The team is working towards producing a prototype portable urinal that would use urine to create power from fuel cells. Although the project is in its initial stages, the scientists believe that a machine of this type could be used at outdoor events such as musical festivals.

As part of the EcoBot project, the researchers are concurrently looking into the possibility of using MFC power generation technology underwater. The apparatus would act as an artificial gill, where organic matter would be used as the biomass fuel for the bacteria and oxygen.