According to a new study by Stanford researcher Mark Jacobson and Mark Delucchi, of the University of California-Davis, by 2030 all new energy generation could come from wind, water and solar, and by 2050, all pre-existing energy production could be converted to renewables, using only technology that is already available and at a similar cost to using fossil fuels.

Their plan calls for using wind, water and solar energy to generate power, with wind and solar power contributing 90 percent of the needed energy. Geothermal and hydroelectric sources would each contribute about 4 percent with the remaining 2 percent from wave and tidal power.

Road vehicles, ships and trains would be powered by electricity and hydrogen fuel cells. Aircraft would run on liquid hydrogen. Homes would be cooled and warmed with electric heaters and water would be preheated by the sun.

Commercial processes would be powered by electricity and hydrogen. In all cases, the hydrogen would be produced from electricity.

Jacobson and Delucchi calculated the number of wind turbines, solar plants, rooftop photovoltaic cells, geothermal, hydroelectric, tidal and wave-energy installations needed to implement their plan. They found that to power the world for all purposes from wind, water and solar resources, the footprint needed is about 0.4% of the world’s land (mostly for solar) and the spacing between installations (mostly wind turbines) is another 0.6% percent of the world’s land. The land between wind turbines could be used for other purposes, such as farming, or could be eliminated if the wind turbines were offshore.

The researchers also calculated the amount of materials needed for their plan and found that even rare earth metals and platinum are available in sufficient amounts.

The need for "base load" power would be eliminated by having having long distance transmission lines connecting wind and solar plants at different locations.

They estimated that their plan would save between 2.5 to 3 million lives each year compared to the present fossil fuel based system, mainly from reduced air pollution, and that, when costs such as the the medical costs resulting from air pollution are taken into account, the total cost of the planned system is similar to the present system.

Mark Jacobson said. "We really need to just decide collectively that this is the direction we want to head as a society."