Scientists at Stanford and the University of California at Davis recently reported in Scientific American¹ on their analysis of the technologies needed to shift the world from fossil fuels to clean, renewable energy in the next two decades. Their plan calls for shifting all of the world’s energy needs to wind, water, and solar power — the so-called WWS combination.

There are certainly some compelling arguments for making the change. For example, a gasoline-powered car wastes 80 percent of its energy. So, only 20 percent of the energy in our gasoline is used to actually move the car. The rest floats away as heat. Meanwhile, electric cars lose only 20 percent of their energy as heat.

Based on a U.S. Energy Information Administration forecast updated May 19, 2009, the researchers assumed that if using mostly fossil fuels, the world would need 16.9 million megawatts of energy capacity in 2030. That’s up 35 percent from the 12.5 million megawatts needed today. This “base case” assumes that about 7.4 percent of our energy needs will be supplied by WWS.

They also calculated that by using wind, water, and solar power to generate electricity, we’d need only two-thirds of the base case forecast, or 11.5 million megawatts, in 2030. Most of this saving would come from the improved efficiency of electric vehicles over cars with internal combustion engines.

There are two potential benefits of using a WWS system to provide energy in the developed world:

It would help to stabilize the geopolitical situation because it would relieve the United States, the EU, and Japan from their dependence on foreign oil, which enriches the leaders of countries such as Iran and Venezuela that oppose the U.S.

It would also make a positive impact on the environment because wind turbines, hydroelectric systems, and solar cells give off no pollution at the point where they produce the energy.

Last year, one of the scientists, who works at Stanford, published a quantitative study in the journal Energy and Environmental...