Large amounts of damaged tomatoes are thrown away in the US because they are not considered fit for grocery stores. This inspired Namita Shreshtha of South Dakota School of Mines & Technology to collaborate with researchers from Princeton University and Florida Gulf Coast University to devise a pilot fuel cell running on tomatoes.
“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, who is working on the project. “The process also helps purify the tomato-contaminated solid waste and associated waste water.”
Shrestha is a graduate student in the lab of Venkataramana Gadhamshetty, Ph.D., P.E., at the South Dakota School of Mines & Technology. They are collaborating on this project with Alex Fogg, an undergraduate chemistry major at Princeton University. Other project collaborators include Daniel Franco, Joseph Wilder and Simeon Komisar, Ph.D., at Florida Gulf Coast University.
Tomato
es are a key crop in Florida, notes Gadhamshetty. He stresses that the project is important to the state because Florida generates 396,000 tons of tomato waste every year, but lacks a good treatment process. “Microbial electrochemical cells use bacteria to break down and oxidize organic material in defective tomatoes,” Shrestha explains.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 the damaged fruits.
At the moment, the power output from their device is quite small: 10 milligrams of tomato waste can result in 0.3 watts of electricity. But the researchers note that with an expected scale up and more research, electrical output could be increased by several orders of magnitude. According to calculations by Shrestha, there is theoretically enough tomato waste generated in Florida each year to meet Disney World’s electricity demand for 90 days, using an optimized biological fuel cell.
Gadhamshetty notes that,”Our research question at this time is to investigate the fundamental electron transfer mechanisms and the interaction between the solid tomato waste and microbes.” They plan to improve the cell by determining which of its parts—electrode, electricity-producing bacteria, biological film, wiring—are resisting the flow of electricity. Then they will tweak or replace that part.
