How realistic is alternative energy? And when?

A resource from the Department of Energy hydrogen and fuel cell program.

"DOE Announces $1 Million to Evaluate Technology Pathways for Cost-Competitive Hydrogen Fuel. Selected projects will evaluate the most promising technology paths toward achieving $2 to $4 per gallon gasoline equivalent of hydrogen fuel or less by 2020."

Another resource, founded at the Massachusetts Institute of Technology, Union of Concerned Scientists. From this page:

"Renewable energy resources like wind and solar power...could reliably provide up to 40 percent of U.S. electricity needs within the next 20 years."

From this page:

"Germany already generates about 20 percent of its power from renewable energy and hydroelectric power, and has far fewer resources than the United States. Denmark gets 30 percent of its power from renewable sources—and accomplished it while growing its economy by 80 percent.* If we pursue smart energy solutions here in America, clean energy could reliably provide up to 40 percent of U.S. electricity needs by 2030."

From this page:

"We can cut projected U.S. oil consumption in half within the next 20 years.
Clean vehicle and fuel technologies provide the foundation for the practical, realistic Half the Oil savings plan, which would dramatically reduce oil use by boosting vehicle fuel efficiency, increasing the use of clean biofuels, and creating the next generation of advanced vehicles that no longer rely exclusively on oil.The technology is already here."

See the clean vehicle timeline on this page. Hydrogen fuel cell vehicles will be released in 2015.

* This is in large part due to Rifkin's work with the European Parliament, which has adopted his third industrial revolution.