LEWISTON – Bates College, which last fall contracted to buy all of its electricity from renewable sources, has taken another step toward environmental sustainability with an arrangement to heat some student residences with cleaner-burning biofuel.

In late March, Bates started heating 12 residential houses on Frye Street with so-called B5, a blend of petroleum heating oil with 5 percent biofuel made from soy or canola oil.

Biofuel is a cleaner alternative to pure heating oil, as well as diesel vehicle fuel, and pure biofuel is a renewable, domestically produced resource.

Bates has joined a handful of other Maine institutions heating with biofuel, including Colby College, the University of Southern Maine, Maine Aububon, L.L. Bean and state government, which uses it to heat the governor’s mansion, among other buildings.

The biofuel is costing the college roughly the same as straight No. 2 heating oil.

In addition to the arrangement with American Alternative Energy, a group of students and faculty is exploring the idea of Bates someday making its own biofuel from cooking oil discarded by the college’s dining services.

With Bates on the verge of building a new dining facility, the group is investigating the prospect of including a biofuel conversion system in the new building. Instead of going into the waste stream, they reason, cooking fats could be made into fuel for heating some college buildings and running its diesel vehicles.