As unrest begins spreading in the Middle East, it may be time to start considering the alternatives we have for foreign oil beyond screaming "drill, baby, drill." True renewable energy sources like wind and solar have a long way to go before cost or capacity is ready to meet massive scale demands. But alternative fuels may be attractive to meet some of the incremental demand without changing everything about our energy consumption.

Here are a few interesting and somewhat bizarre technologies I'm keeping a close eye on as they move closer to hitting the pavement.

What's that smell coming from your tailpipe?
Last year, ExxonMobil (NYSE: XOM) announced an investment in an algae-based technology for making biofuels. The project may be a drop in the bucket for ExxonMobil, but this is a big development for partner Synthetic Genomics and for competitors that are hoping biofuels become more mainstream.

One such competitor, Rentech (AMEX: RTK) may be on the right path, designing equipment for turning everything but the kitchen sink into fuel. It can make municipal waste, pet coke, and even urban woody green waste (grass clippings, dead trees, etc.) into fuel ready-made for your car. If Rentech has anything to do with it, you'll be driving your car with recycled sticks instead of fossil fuels pulled out of the ground. If all goes well, this fuel will be available in California sometime in 2012.

Syntroleum (Nasdaq: SYNM) is turning natural gas, fats, oils and greases into synthetic fuels, including jet fuel. Anything is possible if McDonald's waste could someday power a cross-country commercial flight.

Alternative fuels aren't yet the cash cow that traditional fuel sources are, so until infrastructure is built, this is a pretty speculative investment. Rentech did report a 55.4% jump in first-quarter revenue to $42.1 million last week, but it still hasn't swung into profitability. And a lower net loss of $5.5 million, from a $15.5 million loss last year, was mostly because of fertilizer products instead of the fuel the company is pushing.

And distribution may be an issue once capacity is scaled up. Clean Energy Fuels (Nasdaq: CLNE) is focused on building a natural gas infrastructure for fueling stations around the country, bringing the somewhat-alternative fuel source to the masses. As biofuel usage grows, this would seem like a natural partner in the expansion of alternatives to traditional gasoline.

The demand for Rentech and Syntroleum's technology should continue to improve as the appetite for alternative fuels increases. Speculating on these fuel sources isn't for the faint of heart, but continued growth and high oil prices put these companies in a sweet spot if you're looking for an alternative to natural gas and oil investments.

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Fool contributor Travis Hoium does not have a position in any company mentioned. You can follow Travis on Twitter at @FlushDrawFool, check out his personal stock holdings or follow his CAPS picks at TMFFlushDraw.

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