Waste tomatoes tapped as source of electricity

Damaged tomatoes that are unsuitable for sale at the grocery store found to be "a particularly powerful source of energy" by US researchers(Credit: Bart, CC 2.0)

The tomato is a very versatile fruit. It can be juiced, made into cold soup, used as sauce or just eaten raw in a salad. It is a true food icon and now its usefulness could be expanding to an unexpected area as a US team is experimenting with the fruit as a source of electricity. A pilot project developed by researchers based in several American institutions involves a biological-based fuel cell that uses tomato waste from harvests in Florida, giving a new lease of life to organic material that would otherwise end up in landfills.

The process is based on a microbial electrochemical cell that uses tomato waste to generate electric current. Bacteria breaks down and oxidize the organic material, causing electrons to be released and then captured into the fuel cell to convert into electricity. Making all of this possible is a natural pigment called lycopene, which the researchers have found to be an efficient mediator to stimulate the generation of electrical charges from the fruit.

At this stage, the amount of electricity the team managed to produce with tomatoes is very small, with only 0.3 watts of electricity produced for every 10 milligrams of tomato waste. But it is believed that the technology can be scaled up and the output greatly increased. For instance, the researchers say that the tomato waste produced in Florida every year - estimated at 396,000 tonnes - could be enough to power Disney World for 90 days using an optimized biological fuel cell.

The researchers were surprised at just how well the waste performed. "Typical biotechnological applications require, or at least perform better, when using pure chemicals, compared to wastes," says research team member Venkataramana Gadhamshetty. "However, we found that electrical performance using defective tomatoes was equal or better than using pure substrates. These wastes can be a rich source of indigenous redox mediators and carbon, as well as electrons."

For now the researchers are further looking into the mechanisms of electron transfer and the interaction between tomato and microbes. Next, they need to find out which component of the process is hampering the flow of electricity and work on it.

The video below shows the researchers presenting their work last week during the 251st National Meeting & Exposition of the American Chemical Society (ACS), which took place in the San Diego Convention Center.

Source: ACS

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