Friends and critics of the program packed the auditorium to hear the debate. The system will require companies to buy permits or allowances to exceed their "cap" on greenhouse gas emissions.  Companies with lower emissions can sell or "trade" their allowances. Industries will initially receive 90-percent of the allowances for free to help them prepare.  Air Resources Board Chair Mary Nichols says the measure will encourage innovation. 

"We've crafted a program here that will be good for the California economy, it'll help us rebound economically and I think it will prove to be something that will be attractive as an idea that will be picked up by others as well."

The audience included many oil refinery workers who expressed their concerns that the program's additional costs will make the industry less competitive and result in lost jobs.