Mar 17 2016
A group of scientists are working to generate electricity from an unusual source: damaged tomatoes, which are not fit to be sold at grocery stores. The pilot project involves a biological-based fuel cell, which utilizes waste tomatoes discarded during harvests in Florida.
Image Credit: Alison Hancock/Shutterstock.com
The work was presented at the American Chemical Society’s (ACS) 251st National Meeting & Exposition.
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. The process also helps purify the tomato-contaminated solid waste and associated waste water.
Namita Shrestha, Graduate Student, South Dakota School of Mines & Technology
Shrestha is a graduate student in the laboratory of Venkataramana Gadhamshetty, Ph.D., P.E., at the South Dakota School of Mines & Technology. They are working 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.
Tomatoes are an important crop in Florida, says Gadhamshetty. He emphasizes that the project is vital to the state, as about 396,000 tons of tomato waste is generated in Florida every year. However, the state lacks a proper treatment process.
Gadhamshetty started work on this topic as a professor at Florida Gulf Coast University.
The project began a few years ago when Alex visited my lab in Fort Myers, Florida, and said he was interested in researching a local problem, especially local tomatoes grown in our state and the large waste treatment issue. 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.
Venkataramana Gadhamshetty, Ph.D., P.E., South Dakota School of Mines & Technology
The group made a microbial electrochemical cell to exploit the tomato waste and generating electric current.
Microbial electrochemical cells use bacteria to break down and oxidize organic material in defective tomatoes.
Namita Shrestha, Graduate Student, South Dakota School of Mines & Technology
The oxidation process is started by the bacteria when they react with tomato waste. The reaction releases electrons, which are captured in the fuel cell, becoming a source of electric energy. The researchers also found that the natural lycopene pigment present in the tomatoes is an ideal mediator to improve the generation of electrical charges in damaged fruits.
A few of their results were not very instinctive.
Typical biotechnological applications require, or at least perform better, when using pure chemicals, compared to wastes. 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.
Venkataramana Gadhamshetty, Ph.D., P.E., South Dakota School of Mines & Technology
Currently, the power output generated by their device is quite low: 10 mg of tomato waste yields just 0.3 W of electricity. However, the researchers feel that more research and an expected scale up could boost the electrical energy output.
Shrestha's theoretical calculations suggest that there is sufficient tomato waste generated in Florida annually, and by employing an optimized biological fuel cell, this waste can satisfy Disney World's electricity needs for three months.
Our research question at this time is to investigate the fundamental electron transfer mechanisms and the interaction between the solid tomato waste and microbes.
Venkataramana Gadhamshetty, Ph.D., P.E., South Dakota School of Mines & Technology
The team plans to enhance the fuel cell by investigating which of its parts – electricity-producing bacteria, electrode, wiring, and biological film – is resisting the electricity flow, to replace or tweak that particular part.