So if we don't have time to wait around for tens of millions of years, how about speeding things up? It turns out that some of the hundreds of thousands of different types of algae contain up to 75 percent oil. From 1978 to 1996, the Department of Energy (DOE) funded a program with the National Renewable Energy Laboratory (NREL) called the "Aquatic Species Program." The program's initial focus was to sequester carbon dioxide emissions from coal-fired power plants, but when researchers discovered that some algae had high oil content the emphasis shifted to growing algae to produce biodiesel. Because of their extremely fast growth rates and high oil content, NREL suggested that 7.5 billion gallons of diesel fuel could be produced from roughly a half-million acres of algae grown in desert land covered with algae ponds. More recent research has suggested that around 15,000 gallons of oil can be obtained annually from an acre of land cultivated with algae, compared with about 20 gallons of oil if that acre were planted with corn that was then processed into biodiesel fuel. If that's true, we would need about 9.5 million acres-an area roughly the size of Maryland-to grow enough algae to replace our current oil consumption.

Great! Let's do it! Except, even though we've had more than a dozen years of continued research since the end of the NREL program, making oil from algae isn't quite ready for prime time yet. Finding the right strains of algae, learning how to grow them and stress them so that they produce the maximum amount of oil, and learning how to extract that oil has taken significant research, but is fairly well understood in the laboratory. The problem comes in scaling things up. Questions like how deep to make the ponds (light only penetrates about six inches in an algae-filled pond), how many different strains of algae, how to avoid contamination from bacteria or other invasive species, and how to keep your oil-producing algae from escaping and invading the local environment are all details that need to be worked out.

"None of this makes any sense until we get to the farm level," says Clayton McNeff, Chief Science Officer for Ever Cat Fuels, a Minnesota company that's building a prototype processing plant to harvest oil from algae. "It's the scale-up," he adds. "A lot more research needs to go into the area-we need more funding. We need to get out of the laboratory, do some bigger ponds with the ideas we currently have and see if they work on a larger scale." McNeff indicates that they will be doing this in the next few years, but there is a lot of work that still needs to be accomplished. "It depends how much resources are put into it. If we have the willpower, I think it can be done in the next ten years." Growing the algae, developing the commercial systems, and figuring out the best methods of extraction all need to be worked out.

Clearly, you won't be filling your TDI's tank with pond scum biodiesel anytime soon. As with so many promising alternative fuels, this one isn't ready quite yet despite what you might have read or heard. Replacing the 390 million gallons of gasoline we use in the U.S. every day with something made from pond scum seems the very edge of credibility. You know what they say about things that sound to good to be true...

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