Note: The US government has already spent (and is still spending) an absolutely enormous amount of money on "clean" energy

United States Department of Energy - Wikipedia, the free encyclopedia

Employees 16,000 federal (2009)
93,094 contract (2008)
Annual budget $24.1 billion (2009)
...
The Department of Energy was formed after the oil crisis on August 4, 1977 in order to end the United States dependence on foreign oil by President Jimmy Carter's signing of legislation...

Flashback: Congress Approves Clean Energy Provisions of Stimulus; Consistent With Apollo Economic Recovery Act

The investment package approved by the House includes $34 billion to improve energy efficiency over the next two years, $17.7 billion to modernize and expand the transit systems, including the construction of high-speed rail networks and new light rail systems. The House voted to spend $7.9 billion to scale up renewable energy development, $10.9 billion to modernize and expand the electric grid, and $29.14 billion on roads and bridges, much of which state transportation department directors say will be spent on fixing infrastructure rather than building new highways. The measure includes $500 million for green-collar job training. Other details of the $110 billion in clean energy investments in the bill, which are consistent with the comprehensive measures proposed in The New Apollo Program and the Apollo Economic Recovery Act, are below...
    * $1.6 billion to DOE for research in the basic energy sciences.
    * $400 million is for the Advanced Research Project Agency – Energy (ARPA-E).
    * $2.5 billion to DOE for energy efficiency and renewable energy research and development.

Total: $4.5 billion

If not now for climate change, when? - War Room - Salon.com

Meanwhile, we’ll continue to go about our business as usual, soothing any occasional discomfort with our reliance on fossil fuels by reassuring ourselves that technology will swoop in and save the day -- that with some modicum of research funding, we’ll discover a miraculous new energy source that will power our lavish lifestyles indefinitely while reducing carbon emissions, creating thousands of new jobs, and making children around the world hold hands and sing.

At this point, though, we’re not even going to allocate any funding towards such research.