Students in Professor Drennen's Environmental Economics class (Econ 212) now have the “right” to emit one ton of sulfur dioxide. More to the point, it means that it will keep anyone else from emitting that ton. For the second year in a row, students in this class raised the funds and successfully bid on the permit through an annual auction for emission permits at the Chicago Board of Trade. The students paid $200 for their permit. The lowest successful bid this year was $160. Drennen notes that the students were willing to spend as much as $260 for the permit.