Green technology innovators have faced an uphill battle getting funding for start-ups that might develop alternative energy products. But all that is changing, thanks to deep-pocket investors like Google and even the Pentagon.

One start-up, called Nanosolar, in Palo Alto, Calif., has received more than $100 million in funding and was started using seed money from the founders of Google. Nanosolar has invented a solar panel technology that can be cheaply mass produced. The company claims that its solar panels will be able to generate power almost as cheaply as conventional sources of electricity. The massive funding behind this company, which comes from venture capital firms and government grants, is part of a clear trend toward growing investment in green technologies.

Innovation in green technologies is coming from another surprising source -- the Pentagon. The agency that brought us the Internet and GPS is now working on radical advancements in solar, wind, hybrid and other green technologies.

When the U.S. military rolled into Baghdad, it was followed by a dangerous, slow and expensive convoy of fuel tankers and trucks full of batteries. All those military gadgets and gas-guzzling Humvees turned out to be a major limitation in large-scale battle. As a result, the Pentagon is working on green technologies, such as hybrid vehicles.

There are military advantages to green technologies as well. Hybrid Humvee replacements can switch to "stealth mode," which is not only electric, but silent. Solar and wind generators don't have the "heat signatures" enemies can use to target the heat produced by diesel generators that typically power Army outposts. As with other military technology developments, these green innovations are likely to end up in consumer products as well.