Nanotech firms are revolutionizing the fields of electronics, materials science and medicine. Now they are fast becoming an ally in the cleantech revolution, where their innovations often enjoy a healthy overlap with the eco-ambitions of other organizations or their own.

And that hasn't escaped the attention of some venture capitalists. Forbes reports:

...By comparison, worldwide investment in nanotechnology in 2005 only reached $9.6 billion. And yet, as the latest branch to spring from the nanotech value chain, clean-tech represents an emerging beneficiary of and opportunity for nanotechnology. From my standpoint, the parallels between nanotech and clean-tech have converged to the point where it's often difficult to distinguish between them.

Consider Nanosphere company Harris & Harris Group, a venture capital firm focused expressly on "tiny tech" investments. Of the 31 nanotech companies in Harris & Harris' portfolio, 10 can also be classified as clean-tech businesses. All of them leverage nanotech to improve the generation or sustainability of energy.

The movement is far from US-centric, however. In fact, some foreign government-backed firms are pulling ahead and posing a challenge for US startups.

Potential clean-tech investors also need to be aware that foreign governments are funding their domestic clean-tech initiatives at a much faster pace than the U.S., with the Asia/Pacific region representing 38% of the pie, followed by Europe and, in third place, the U.S. That means that in addition to competing with large domestic incumbents, U.S. start-ups must also contend with foreign competitors backed by government programs. Notable examples are solar energy in Germany, fuel cells in South Korea and high-performance batteries in Japan.

Interesting times.