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Going Green: The Practical Payoffs Of Microbial Fuel Cells

University of Texas at Arlington PhD student Ben Johnston
University of Texas at Arlington PhD student Ben Johnston

Today we continue in the spirit of Earth Day with the first in a series of stories, “Going Green: The Practical Payoffs." We’re taking you to the UT Arlington campus where a biomedical engineering student has come up with a way to get a special kind of bacteria to eat food waste. The process creates energy in an environmentally-friendly, money-saving way. KERA’s BJ Austin says the young inventor hopes to take his microbial fuel cell from the lab to the workplace.

Institutional kitchens like hospitals and nursing homes throw away a lot of food each day as trays are cleaned and dishes are washed. It typically goes to the dumpster and into the landfill. Food processors also have a lot of that high nutrient waste. They have to pay to have the waste hauled away, or recycled by another company. Workers at Alternate Feed, across from Schepps Dairy in Dallas, process 24 thousand gallons of left-over dairy products a day.

What if companies could get rid of that high nutrient waste-stream and create energy at the same time -- energy that could run machinery in the plant or the kitchen?

University of Texas at Arlington PhD student Ben Johnston says his modified microbial fuel cell could do that.

Johnston: The hydrogen would come out and they’d run all their machinery in the food production plant on the hydrogen they’d be producing.

Link: Greenovation Winners

Johnston’s microbial fuel cell recently won the Texas Greenovation contest, sponsored by the Texas Manufacturing Assistance Center at UTA. His invention netted him cash and assistance from the Small Business Development Center for Enterprise Excellence. Tom Pryor runs the Center.

Pryor: And our role is to commercialize this idea. This has the potential of creating energy from food waste, very innovative.

Ben Johnston says he first became intrigued with a special kind of electrically active bacteria during his undergraduate studies as a biology major at Hamilton College.

Johnston: Geobacteraceae is the most famous family. There’s Shewanella oneidensis.

They’re called geobacters. They live on metals and eat things like radioactive material and petroleum products. But Johnston says the bacteria also love sugar, and that’s where his food-waste-to-energy microbial fuel cell comes in.

Johnston: Simple sugar, somewhat broken down nutrients. And they’ll break that down further. If you switch the end product, where it’s not just water and you add a little bit of voltage to the whole system, you can have hydrogen as your final product.

Each fuel cell will have two sections, about two feet tall joined by a semi-permeable membrane. On one side, you’ve got the bacteria cleaning the waste water by eating the residual food nutrients. The bacteria release electrons and hydrogen ions. The membrane allows the hydrogen ions to pass through to the second chamber. The electrons are transported through a small circuit. And when the two meet, they make hydrogen gas.

Johnston: You could power like a forklift, or something like that. There are some currently available small motors that run on hydrogen fuel stacks.

Johnston sees hydrogen as an emerging fuel source. His innovations include the membrane and its placement between the two chambers, and the use of solar panels to boost voltage and increase the flow rate in and out of the two cells. Johnston envisions using an array of the small fuel cells to process a continuous flow of waste.

Dana McLaughlin is the Sustainability Counselor for UTA’s Small Business Development Center.

McLaughlin: There is a real pull for environmental products and sustainability. We know that the technology works. I think getting the working prototype businesses can actually see it in action, I think that is his biggest hurdle.

Johnston, 26,  says doctoral studies take most of his time right now.

Johnston: The summer will be the ramping up phase, getting a few prototypes built.

The goal is to find a buyer, a company willing to be the first one to make Johnston’s microbial fuel cell a part of the daily workplace.

So here’s the downside: Johnston says working with the special bacteria is a little like standing next to a very pungent yogurt. 

Former KERA reporter BJ Austin spent more than 25 years in broadcast journalism, anchoring and reporting in Atlanta, New York, New Orleans and Dallas. Along the way, she covered Atlanta City Hall, the Georgia Legislature and the corruption trials of Louisiana Gov. Edwin Edwards.