While you are correct on paper, that doesn't make it so in the real world. We have to look no further than the FCC as an example of this, albeit on a smaller scale. Back in the mid 90s, Congress gave the FCC authority levy any 'fee' it saw fit and use the funds for purposes it deemed worthy to promote communication services and accessibility. This one small law then allowed the FCC to tack on whatever fee they wanted, whenever they wanted (thus all the 'telecom' fees you see on any communication services such as infrastructure fees, connectivity fees, 911 service fees, etc). None of these needed specific Congressional approval because they weren't 'taxes'. The FCC has added and changed these at will. They also have spent the money at will, all using that first Congressional authorization as cover, not needing any new bills for each change.
It takes no stretch of the imagination to see how the EPA could use a tactic like this on a much grander scale.
Yes they can charge “fees” and penalties but not on the scale that congress can and will. The taxes under a Cap and Trade plan would not only go to the general treasury, but into the global economy as a pay-off. Then there is the huge amount of money that will flow into the alternative energy sector to try to show that they are viable entities. Nope the EPA cannot do near the economic damage that Congress can.