MIT helps Brazilian waste pickers to use leftover cooking oil as vehicle fuel

There are estimated half-million garbage pickers in Brazil, known as catadores, who turn waste into profit by sorting out recyclable items and selling their findings to recycling companies. With help from some MIT students, the catadores have a less-expensive and environmentally friendly option to transport those goods by using recycled cooking oil for their fuel.

In summer 2010, members of MIT’s biodiesel team, along with a Media Lab student and one Brazilian MIT student, traveled to Sao Paulo, Brazil, to begin work on the project, called Green Grease. They worked with Rede CataSampa, one of the many catadores cooperatives, to convert two of its large trucks to run directly on filtered vegetable oil.

The team, led by Libby McDonald, a Green Hub Global Program Associate at the Community Innovators Lab in the Department of Urban Studies and Planning, decided to convert the vehicles to use filtered oil instead converting the waste oil to biodiesel. Although conversion allows more flexibility since biodiesel can be used in any diesel vehicle, without any modifications, the biodiesel conversion process requires relatively complex machinery and expensive, toxic chemicals.

By contrast, the oil-filtration process and vehicle conversions are simple and can make use of many recycled parts that the catadores were able to find or improvise, explains junior Angela Hojnacki, president of the Biodiesel@MIT team and a member of the Green Grease team bringing the technology to Brazil. Additional advantage is the warm temperature in Brazil which allows the waste oil to flow properly, without extra heaters that would be needed in colder climates.

The use of filtered vegetable oil could decrease the presence of a pollutant that, if dumped into rivers as it tends to happen now, can kill fish and disrupt ecosystems. In order to counter that, Brazil has begun implementation of environmental regulations which restrict the disposal of waste oil and require the installation of grease traps in residential buildings’ plumbing systems. Aside better environmental practice, it can drastically reduce, or eventually even eliminate, the fuel costs for the catadores to operate their trucks.

Converting the trucks involved installing a separate, parallel fuel tank and fuel delivery system, along with a set of valves that can be adjusted so the vehicle can operate on either standard diesel fuel or filtered oil, depending on what is available. As part of the process, the local catadores found materials such as an old metal street sign that was converted to use as a gasket for the added fuel tank.

Now that the truck drivers in one cooperative have been trained in how to carry out the vehicle conversions and set up filtration systems, they can convert it into a small business – converting other vehicles and providing the oil. On a follow-up visit this year, with the help of the catadores they trained in Sao Paulo, the team plans to expand the project to additional eight cities (Diadema, Garulhos, Sao Jose do Campos, Rio Claro, Campinas, Palmital, Barueri, and Osasco).