Lux Research, a leading consultancy on nanotechnology and other emerging technologies, today released the key findings (opens .pdf file) from its recent "Cleantech Report." Nothing in the news release will come as a much of a surprise to regular readers of The Motley Fool, but it does serve as a useful reminder that investors need to exercise caution when contemplating investing in the space.

For starters, it is important to remember that for every First Solar (NASDAQ:FSLR), up 133% since its IPO in November, there is also a Canadian Solar (NASDAQ:CSIQ), which is down 32% from its opening price that same month.

The same is true in other areas. Broadly speaking, there is great interest in everything from ethanol production and solar arrays to electricity generated by tidal power. And given that venture capital in clean tech has ballooned from $623 million in 2005 to $1.5 billion this past year, it is likely that the number of clean tech companies to test the public markets will continue to increase this year. Yet as both VeraSun (NYSE:VSE) and, more recently, Ocean Power Technologies (NASDAQ:OPTT) remind us, being involved in the production of alternative energy is not enough -- both companies have taken it on the chin since their IPOs.

A safer, albeit less exciting, way to play the clean tech angle is to invest in some of the blue chips, which, as the report notes, have invested almost $22 billion in clean tech R&D in 2006. Included in this list are companies such as IBM (NYSE:IBM) and General Electric (NYSE:GE).

Over the past few months, I have documented Big Blue's "Big Green Innovations" campaign, as well as GE's foray into the sector, and how I believe they offer a more attractive way to play the sector. The Lux report states that there are now 930 energy start-ups operating worldwide. It is simply not realistic to expect that more than a fraction will succeed over time. On the other hand, it is not unrealistic to think that the big ones will use their size and strength to keep getting bigger.

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Fool contributor Jack Uldrich owns stock in both IBM and GE. The Fool has a strict disclosure policy.