Student scientists build battery prototype ... out of tomatoes?

Damaged tomatoes are best kept out of salads, but they aren’t entirely useless, say researchers.

It turns out spoiled tomatoes can be turned into electricity. Inspired by the large amount of tomatoes that go to waste in Florida – 396,000 tons of tomato waste every year – a group of student researchers from South Dakota School of Mines & Technology, Princeton University, and Florida Gulf Coast University have developed a prototype fuel cell running on tomatoes.

“We wanted to find a way to treat this waste that, when dumped in landfills, can produce methane – a powerful greenhouse gas – and when dumped in water bodies, can create major water treatment problems,” said Professor Gadhamshetty Venkataramana, who is the team leader of the project, according to the Independent.  

"We have found that spoiled and damaged tomatoes left over from harvest can be a particularly powerful source of energy when used in a biological or microbial electrochemical cell," says Namita Shrestha, one of the researchers, and a PhD student from the South Dakota School of Mines and Technology. "The process also helps purify the tomato-contaminated solid waste and associated wastewater," Popular Science reports.

Here is how it works. The process is dependent on bacteria, which is significant for breaking down organic material from tomato waste, and oxidizing it to generate electric charge. The charge produced is then harnessed using a microbial, or biological, fuel cell. The waste is also neutralized in the process, to prevent it from emitting greenhouse gases.

Tomatoes contain a bright red carotene pigment which is an excellent catalyst for generating electrical charges, the researchers found. Though the power output from their device – 0.3 watts of electricity from 10 milligram of tomato waste – is quite small. The researchers say that more research can lead to increased power output. According to their calculation, the waste from Florida alone could potentially generate enough electricity to power Disney World for 90 days, reports CNN.

The team hopes that the project can be beneficial to large-scale tomato growers, and particularly in the rural areas.

"My hope for this kind of thing is that it can be used in rural areas where you have a lot of agricultural waste and you don't necessarily have access to a power supply, particularly in the developing world," said Alexander Fogg, an undergraduate chemistry major at Princeton University, according to CNN.

The findings from their initial study – showing that tomatoes are a suitable source of energy – were published in the Journal of Power Sources in 2014, and the results from the pilot project were presented at the 251st National Meeting and Exposition of the American Chemical Society in San Diego this week.