I suspect the economics and the facts behind this are much more complex than the story makes it appear, and the writier was unsuccessful in either understanding or communicating the information with which he actually had to work.
It is a rather obvious outcome of a carbon-credit trading system that all the carbon credits will be used, since a credit trading system only makes sense where the emitters are up against some natural or legally-imposed limit. Therefore, the system will keep them at that limit, and will not reduce emissions at all.
This would mean the wind turbines were still a net positive (if there was to be a carbon limit imposed at all) since their output would've added a significant net plus to the power grid, enabling carbon credits that would've had to be used for power production to go to goods production, a net plus.
Now, of course, all this means no net reduction is carbon emissions at all, and a significant-but-not-stunning increase in energy production, so of course there is no net downward effect on CO2 levels.
The stupid is therefore not the wind turbines, which are actually of some positive utility, but in the whole bullshit carbon credit trading system.