The US would require roughly the same amount of windmills per capita as Denmark. (There's a chance that the average Dane uses less energy than the average American, but I can't be bothered to look that up...)
The cost per capita in the US would be about the same as in Denmark. Probably less, due to economy of scale.
The cost per capita in the US would be about the same as in Denmark. Probably less, due to economy of scale.