NREL released a report last week (June 2012) showing that we could power 80% of the US with already commercially available clean, renewable energy technology by 2050. Now, before getting into the key findings from the report, I think it's useful to put this into a bit of perspective and historical context.
Even more ambitious than the above, Mark Jacobson and Mark Delucchi wrote in 2009 about how the whole world could be 100% powered by renewable energy by 2030. These guys aren’t wackos, either. Mark Z. Jacobson is a professor of civil and environmental engineering at Stanford University and director of Stanford’s Atmosphere/Energy Program, and Mark A. Delucchi is a research scientist at the Institute of Transportation Studies at the University of California, Davis. I have seen no indication that they were technically wrong.
Another very reputable body, the U.S. National Oceanic and Atmospheric Administration (NOAA), noted this year that research it has conducted has found that clean, renewable energy could cheaply supply 48 states of the continental U.S. with 70% of its electricity demand by 2030 (and that’s without including hydroelectric).
Renewable electricity generation from technologies that are commercially available today, in combination with a more flexible electric system, is more than adequate to supply 80% of total U.S. electricity generation in 2050 while meeting electricity demand on an hourly basis in every region of the country.
Notably, many technologies that we expect will soon be commercially viable weren’t even included in the identified renewable energy potential, because the study focused on commercially available technologies. This includes floating offshore wind turbines, enhanced geothermal, wave energy, tidal energy, ocean thermal energy conversion, and more. Add all of that in and I’m sure 100% renewable energy is more than viable.