If the world economy expands to meet the aspirations of countries around the globe, energy demand is likely to increase even if strenuous efforts are made to increase the efficiency of energy use. Given adequate support, renewable energy technologies can meet much of the growing demand at prices lower than those usually forecast for conventional energy. By the middle of the 21st century, renewable sources of energy could account for three-fifths of the world's electricity market and two-fifths of the market for fuels used directly.

Moreover, making a transition to a renewables intensive energy economy would provide environmental and other benefits not measured in standard economic accounts. For example, by 2050 global carbon dioxide (CO,) emissions would be reduced to 75% of their 1985 levels provided that energy efficiency and renewables are both pursued aggressively .And because renewable energy is expected to be competitive with conventional energy, such benefits could be achieved at no additional cost.