This article is part of our Rising Star Portfolio series.

Forget about alt-fuel innovator Solazyme's (Nasdaq: SZYM) 46% drop in stock price since I first purchased it for my Rising Star portfolio. I'm more worried that a potential profit center for the company could also leave certain investors concerned.

My Rising Star portfolio embraces socially responsible companies. Solazyme's an exciting renewable energy play, and its algae-derived biofuels could change the world for the better by reducing reliance on fossil fuels. But the company's increasing financial relationship with the U.S. military might throw a little dirt on Solazyme's squeaky-clean image.

The Pentagon has launched increasing efforts to make the U.S. military green in more ways than its camouflage. Bloomberg recently reported that the U.S. Navy now aims to use alternative fuels for half its requirements by 2020. That could add up to approximately 8 million barrels of biofuel a year.

The U.S. military shelled out a staggering $13 billion on petroleum alone last year, leaving Uncle Sam plenty of good reasons to search for lower-priced alternatives. Solazyme and other young biofuel companies like Amyris (Nasdaq: AMRS), Gevo (Nasdaq: GEVO), and Kior (Nasdaq: KIOR) must be eager to tap this potential market. Solazyme's existing biofuel test relationship with the U.S. Navy suggests that it's already ahead of the game.

Still, if the military ends up driving the lion's share of Solazyme's commercial business, socially responsible investors may feel less proud to own a piece of the company. What if even more of the company's future revenue comes from sources that make ethically minded investors uncomfortable? I know I'd never put defense contractors like Lockheed Martin (NYSE: LMT) or Northrop Grumman (NYSE: NOC) on my socially responsible watch list. Many people consider war to be a necessary evil, but while I respect our troops, I have major ethical problems with the idea of profiting from conflict, even indirectly.

However, socially responsible investing isn't always black and white, and I've found several counterpoints worth weighing against my reservations. If Solazyme successfully reduces our country's reliance on oil from conflict-ridden, oppressive regimes, support from the military now could pay a "peace dividend" down the road. We can also thank military-funded initiatives for many technologies that have made the world a better place, including recent improvements in prosthetic limbs. Also, bear in mind that many military operations aren't directly related to combat. You can even argue that soldiers' decision to sacrifice their own comfort to defend their country and their principles represents its own form of social responsibility.

I believe Solazyme's biofuel efforts represent the greater good, and I still think it's socially responsible for the most part. A greener military that uses fewer fossil fuels would be a win for a cleaner environment. But personally, I'd rather see Solazyme's advancements used for more peaceful pursuits. What do you think? Chime in with your thoughts in the comments box below.

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