If you want an example of this actually getting somewhere here is one: So TVA was doing this too with landfill gas and solar, but more people bought into it than expected so they had to build a 29MW wind farm in order to keep up. So theres an example of a utility building a wind farm in order to meet their requirements, if more people want to pay the extra money then I'm sure they will build even more (so would any utility if they amount they charge extra is enough to make the wind pwoer economical). In fact in some areas wind power is already economical with the absurdly expensive power (read California), so if they charge you extra there they are just screwing you since its cheaper for them anyways.