“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,” said Namita Shrestha, South Dakota School of Mines and Technology.
“The process also helps purify the tomato-contaminated solid waste and associated waste water,” Shrestha said. Tomatoes are a key crop in Florida, said Venkataramana Gadhamshetty, professor at South Dakota School of Mines and Technology. Florida generates 396,000 tonnes of tomato waste every year, but lacks a good treatment process, said Gadhamshetty who began the research at Florida Gulf Coast University.
“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,” he said. The team developed a microbial electrochemical cell that can exploit tomato waste to generate electric current. “Microbial electrochemical cells use bacteria to break down and oxidise organic material in defective tomatoes,” Shrestha said.
The oxidation process, triggered by the bacteria interacting with tomato waste, releases electrons that are captured in the fuel cell and become a source of electricity. The natural lycopene pigment in tomatoes, the researchers have found, is an excellent mediator to encourage the generation of electrical charges from damaged fruits. “Typical biotechnological applications require, or at least perform better, when using pure chemicals, compared to wastes,” Gadhamshetty said.