Renewable does not mean green. That is the claim of Jesse Ausubel of the Rockefeller University in New York. Writing in Inderscience's International Journal of Nuclear Governance, Economy and Ecology, Ausubel explains that building enough wind farms, damming enough rivers, and growing enough biomass to meet global energy demands will wreck the environment.
Futurepundit points out that renewables do not have to be that bad for land usage I agree that renewables should be a fairly big part of the solution. Up to 30-50%. We just have to not be stupid and build willy-nilly without thinking about mitigating the downsides. Nuclear energy should also be a big part of the mix. What we need to eliminate is coal power and then oil usage.