Currently America is powered by a wide range of both renewable and nonrenewable resources, making loads of pollution annually. I'm not a tree hugger, but getting all of America running on just renewable resources would drastically change how much we pollute, and how comfortable towns and cities are. It would also prevent certain weather, like smog and acid rain, which make cities look and feel dirty.
So, getting America running on renewable energy sources would make the environment more pleasant, cities prettier and cleaner, and happier people. Not to mention disputes over oil would pretty much go away.