Turning Garbage into Treasure: MIT Students Develop New Use for Waste Vegetable Oil in Brazil


Angela Hojnacki

Angela Hojnacki (Photo credit: Tony Pulsone; other photos courtesy of Angela Hojnacki)

You’re a wastepicker in Brazil, and the government just passed new regulations for disposing of vegetable oil, one of the items you regularly pick up on your fuel-guzzling trips around Sao Paulo. What should you do?

That was the question posed to MIT student group Biodiesel@MIT, whose goal is to increase awareness of waste-to-energy possibilities using waste vegetable oil (WVO). Out of the wastepickers’ problem arose a new group dedicated to finding the answer: Green Grease Project (GGP).

“The obvious solution was to use it as fuel,” says MechE undergrad Angela Hojnacki, president of Biodiesel@MIT and project coordinator of Green Grease Project. “But there are two different ways you can use WVO in a diesel engine. We chose to convert the engine using recycled materials to make it less expensive and more applicable to the wastepicker community in Sao Paulo.”

GGP was able to bring down the conversion cost a whopping $700, from $1,200 to $500. According to Hojnacki, by converting the engines and running on their own WVO, wastepickers, who earn their income by picking up recyclables from around the city and selling them to recycling companies, can decrease their operational costs by 20%.

BiodieselOnce the engine is converted to run on waste vegetable oil, the next step is to filter the oil. The wastepickers put the oil out in the sun to heat it up, isolating the highest-quality oil on top by allowing all the particulates to drop to the bottom. This process is repeated several times, and must be put on hold every time the sun goes down.

Once again, Green Grease Project is on the case, led by Hojnacki. The team is currently working on creating one large container with exchangeable filters and solar collectors to heat the oil up more quickly. This new process would speed things up to about one day, a vast improvement from the approximate two weeks it currently takes.meche logo