Public pressure and private investment dollars are combining to bring clean energy technologies -- defined as energy sources that are low in carbon emissions -- from the fringes of the energy industry to its center, said Cambridge Energy Research Associates, or CERA, in a new report.
"We are seeing a major shift in public opinion," said Daniel Yergin, CERA's chairman. "This is providing a vital impetus that is moving clean technology across the great divide of cost, proven results, scale and maturity that has separated it from markets served by mainstream technologies."
Among renewable sources, wind power is poised to make the greatest gains, followed by solar power and biofuels, CERA said. But nuclear and hydroelectric generation will attract almost half of the $7 trillion, CERA said.
In the United States, renewable energy sources currently account for about 6.5 percent of total energy consumed, according to the Energy Department. Nuclear power makes up only an additional 8 percent of overall consumption, which is dominated by fossil fuels such as petroleum, coal and natural gas.
But worldwide, there is a "bubbling" of clean energy clusters, CERA said, including Brazil, where biofuel technologies are growing; Germany, where a solar energy process called photovoltaic technology is growing; and Spain, which has become a center of wind energy development.
The biggest driver behind clean energy may be increased oil and natural gas prices, which are making expensive clean technologies economically viable. But government policies that subsidize clean energy, put a price on carbon emissions or mandate reductions in pollutants or the use of renewable energy are also key drivers, CERA said.
The research firm identified a number of new clean energy technologies that show promise. They include geothermal plants, which would generate energy by tapping heat from deep in the earth, ocean generation plants, which would use wave or tidal power to generate electricity, and concentrating solar power, where the sun's rays are focused to create steam-powered electricity.