Shifting the world to 100 percent clean, renewable energy as early as 2030 -- here are the numbers

Most of the technology needed to shift the world from fossil fuel to clean, renewable energy already exists. Implementing that technology requires overcoming obstacles in planning and politics, but doing so could result in a 30 percent decrease in global power demand, say Stanford civil and environmental engineering Professor Mark Z. Jacobson and University of California-Davis researcher Mark Delucchi.

To make clear the extent of those hurdles – and how they could be overcome – they have written an article that is the cover story in the November issue of Scientific American. In it, they present new research mapping out and evaluating a quantitative plan for powering the entire world on wind, water and solar energy, including an assessment of the materials needed and costs. And it will ultimately be cheaper than sticking with fossil fuel or going nuclear, they say.