3. How much will it cost?

The projected economic cost of the regulation is becoming a matter of fierce debate between industry groups and the administration.

The U.S. Chamber of Commerce this week said the rule could cost $50 billion per year through 2030, a figure that Republican lawmakers have seized on. The rule is projected to cost billions because many high-carbon energy sources like coal are cheaper than low-carbon alternatives.

The Obama administration dismissed the Chamber’s report and noted that the details of the rule were not yet public.

EPA has labeled the rule “economically significant,” which means it will be required to conduct a full analysis of the costs and benefits. Opponents of the rule will be ready to pounce when the results are released.