Marine Corps Base 29 Palms - GE awarded grant for green electricity grid model.
The Air Force
recently dedicated the largest solar array in North America at Nevada's Nellis Air Force Base.
That same day, a C-17 transport plane made the Air Force's first cross-country flight using a blend of synthetic fuel.
Massive wind turbines can be seen at the U.S. Naval Base at Guantanamo Bay, Cuba.
Army leaders are smitten with hybrid vehicles, fuel cells and other emerging technologies, to help troops on the battlefield and to curb fuel consumption.

FACT: The Defense Department is the largest energy consumer in the United States, with an energy bill of nearly $14 billion last year, up from $11 billion the year before. The military services and other components of DoD go through the equivalent of 340,000 barrels of oil a day, or 1.5 percent of total U.S. energy consumption.

QUESTION: Why would we indirectly provide aid and comfort to the enemy by purchasing his oil?

Northwestern article on domestic and abroad "greening" of military

And it's not exclusively energy-related. Note the following exerpt from the Medill School paper at Northwestern. This is clearly a "hearts and minds" approach via bettering the local environment:
"Even bigger changes have happened in Fallujah, where the Corps recently built the city’s first sewage treatment facility, Smith said. Before the plant was installed, residents poured human waste into the Euphrates River, but now the plant is improving both the environment and quality of life for those in Fallujah, according to Smith. “In my mind, such a treatment facility has, and likely will, have far greater impact on the future health and well-being for the citizens than the solar lights might."

Check this from Nature.com's blog:

"The Pentagon, says AFP, is already trying to reach a target of obtaining 25% of its electricity from renewables by 2025. There are strong reasons to go green beyond climate change too: a 1% decrease in fuel consumption would mean 6,400 fewer soldiers in fuel convoys at risk of insurgent attacks. “When you don’t use as much fuel, not only does it not cost you as much, but it also saves lives and injuries of those people who would have to deliver fuel through hostile territory,” says Keith Eastin, assistant army secretary for Installations and the Environment. AFP also notes that Obama’s stimulus package earmarked $300 million for Defense Department research on renewable energy. Some of the research from this may eventually lead to clean-tech in the non-military sector. “Just by nature of the fact that we are big, we can be a test bed for a whole lot of things that normally wouldn't seem to make a lot of powerful economic sense,” says Eastin.

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Boston Globe article on green military as a matter of national security.