If they are able to get to the point they want, they can issue carbon "credits" to companies, the credits being representative of how much co2 they are allowed to produce. The credits could be traded... and there's the rub. It creates a completely artificial commodities market where government 100% controls supply of said commodity. Consider all that and then consider that we also exhale co2, and try not to be a little terrified of the future implications if they end up being successful in this. Nuclear is efficient. They don't want more efficiency, they want more control.