Turning fermented food into future fuel

Noon update - This is Otago Polytechnic’s April Fools' Day joke for this year. While our Automotive Engineering and Food Design departments have a proud history of creativity and innovation, the world probably isn’t quite ready for cabbage-fueled cars. 😀

Students at Otago Polytechnic are collaborating on an innovative project which could help ease the cost at the petrol pump.

A partnership between Automotive Engineering and Culinary Arts students has produced a small-scale BioHybrid Hydrogen Conversion System (BHCS), using fermented waste vegetables.

The prototype generates low-pressure hydrogen gas in a controlled anaerobic chamber, which is fed into an internal combustion engine to reduce fuel use.

Senior Automotive Engineering lecturer Miles Perhour says hydrogen cars are being developed as a zero-emission alternative.

“Our breakthrough is instead of solely running on hydrogen, it’s a dual fuel system,” he says.

“It’s still primarily petrol, but we’re introducing small amounts of low-pressure hydrogen gas into the intake to support improved combustion efficiency.”

One of the polytechnic’s training vehicles has been retrofitted to run the waste to energy project and comes as fuel prices surge amid global supply concerns.

Early experiments used potatoes, breaking the starch into sugars and running a small-scale fermentation process to produce a hydrogen-rich gas.

But Senior Food Design lecturer Rhea Cycle says a switch to fermented products really revved up the project.

Culinary Arts students Al Gae & Kim Chiwell discuss the blend of fermented veges to feed into the anaerobic chamber

“What we actually found was more efficient was using things like sauerkraut and seaweed - anything with anaerobic fermentation - because it produced higher gas output," says Rhea.

Automotive Engineering student Cam Shafton says they’re continuing to fine-tune the air-fuel mixture, ignition timing, and emissions performance.

The team admit their proof-of-concept still has some limitations, including low efficiency, storage challenges, and high feedstock use.

“The current system requires about 20kg of fermented cabbage per tank,” says Cam.

Staff stress the project remains strictly experimental and lunchroom leftovers are not yet being requisitioned.

The students will host a public demonstration of their fermented fuel-injected vehicle from 10am outside Otago Polytechnic’s Automotive department on Forth Street.

Testing is set to idle down at noon.