With a massive oil slick now marring the once pristine U.S. Gulf coast, it seems like a good time for America to rethink its reliance on crude oil to fuel economy. At least that was the message coming from President Obama in his recent speech on the ongoing environmental crisis.

With an energy bill now waiting in the wings that seeks to wean America off its oil addiction through a controversial cap and trade scheme, there will be some winners if the legislation is successful in prompting a fundamental restructuring of America's energy landscape.

But for investors looking to cash in on any green energy opportunities that might emerge, a brief re-visiting of recent investment history in the so-called green energy space might be in order.

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Green-Tech Investment: Still Not Ready For Prime Time
Over the past ten years, a whole slew of companies have come into the investment scene capitalizing on investor interest in such emerging industries as bio-fuels, solar power, wind and fuel cells. However, the investment record for these industries has been more red than green.

For many over-exuberant investors, the road to ruin has been signposted with green-tech names. These would include companies like Pacific Ethanol (Nasdaq:PEIX), whose unit that operates production plants fell into Chapter 11 bankruptcy last year, Evergreen Solar (Nasdaq:ESLR) who continues to report increasing losses in the face of slumping prices for its products, FuelCell Energy (Nasdaq:FCEL) a maker of backup power plants using fuel cells that has yet to make inroads beyond its small niche market, and Energy Conversion Devices (Nasdaq:ENER) an outfit that appears to have been so over-focused on pure research, that its stunned its shareholders recently with a massive $358 million non-cash impairment charge.

Taxpayers and The Men In The White Coats: Not A Good Combination
So, what went wrong? First, much of the market opportunity for these companies was solely a product of government mandates, whether ethanol/gasoline blend levels in the U.S. to high, and eventually unsustainable, solar subsidies in countries like Germany and Spain. The market for their products was, and for the most part remains, funded by taxpayers, a situation that clearly not sustainable in these days of sovereign financial woes.

The massive write-down recently recorded by ENER indicates that by the time a decision was taken to pull the plug on a particular project may have occurred after massive amounts of money had already been sunk into it.

The Bottom Line
Until alternative energy is fully supported by free market forces, the only ones to profit from it will be the politicians and the scientists. And that day will only come when conventional energy prices are significantly higher than they are today. (Learn more about green investing, see: Clean Or Green Technology Investing.)

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