School student generates electricity from scrap tyres

ERJ staff report (DS)

Edmonton, Canada -- A young Canadian student named Kyle Schole has now finished his 11th grade school exams, but it was about a year ago he thought up a natural process which dissolves tyres in a kind of soup and uses the bacterial energy produced to generate electricity.

You read that correctly. Schole has developed a system which will take chunks of tyres, dissolve them with no significant energy input and generate electricity in the process.

There is much room for improvement and a lot of ground to cover yet. For example, the microbial cell produces only 0.5 volts. Still, considering the challenges he faced as a high school student, it is astounding what Schole has discovered.

The endeavour was designed as a project for a competition in the science fair programme - and it has won a series of cash and trip prizes for its young author, as well as funding for a college place.

The system is based on bacteria - those in a microbial fuel cell (mfc).

Schole visited a local tyre storage site to gather some soil samples. The site has existed for more than his own 17 years of life. If tyre-eating bacteria exist anywhere, he reasoned, they are going to exist underneath a years-old pile of tyres.

He was right. The cultures from the soil sample were put into a series of enrichment procedures, with not much more than rubber as the potential food. Anything which could not eat the rubber died.

Kyle currently uses large tyre chunks in the mix, simply because that is what the recycling centre produces. He also knows that the process would be faster and more efficient with fine crumb - the bacteria can act only on the surface, for example.

Initially, the idea was to cut up the tyres by hand with a pair of shears, but he quickly discovered thta tyres are too tough for that.

After nine weeks of trials, Schole came up with a pair of micro-organisms, which appear to have some kind of symbiotic relationship. Neither can eat a tyre on its own, but together, they can. Schole put the cultured bacteria in a vessel with carefully measured chunks of tyre mass and left the culture to do its thing. Three weeks later, the mass of the tyre had fallen by over a third.

The story does not end there. Schole set up a microbial fuel cell. That works a bit like an electrolytic cell. An anode in one pot and a cathode in the other, separated by a membrane will produce electricity when the bacteria are consuming their food. A top-class microbial fuel cell can produce roughly 2 volts. Kyle's cell, at first attempt and with minimal optimisation, generates 0.5 V. He chose not to comment on the current it might produce.

On the downside, there is a lot he does not yet know. Some of the things still to do include identification of the bacteria; improving the yield efficiency and optimising the fuel cell.

On the upside, the system delivers interesting results, with no optimisation.