A Primer: Can Algae Replace Gas?

The clean-energy promise of one of the planet's simplest organisms

Can algae, that banal scourge of the swimming pool, fuel an energy-independent America? The hype is certainly there. News reports have been flowing quick and steady about the potential of algal biofuels. Just yesterday, Treehugger proclaimed them the #1 green technology in the offing.But you'd be excused for still being baffled. No one is answering the most basic questions: What is algae technology, and why is it so promising? Why isn't it already available? What are the challenges that remain to be solved?What Are Algae?Algae are some of the planet's simplest organisms. Comprised of just a single cell, or sometimes a few cells, they're slightly more complex than bacteria but far less complex than most plants.But like plants, algae are loaded with chloroplasts, which lets them create energy using just carbon dioxide, water, and sunlight. Algae use this energy to reproduce or to store it for leaner times. Some algae in

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particular store energy as lipids (aka, oils). These lipids, in turn, can be readily refined into basically any hydrocarbon you like, from biodiesel to jet fuel-and the whole process is carbon-neutral. That's the miracle of algae.Plants can also be used to create lipids-these are the biofuel crops such as camelina being developed by companies like Targeted Growth-but they still waste a good deal of their energy on things like stems and seeds. Algae, by contrast, are simpler, with fewer outputs, and thus far more efficient. Their per-acre yields are so high that we could conceivably produce all the oil we need with a space that, at maximum, is just 1/7 the area we now use to grow corn.Unlike many other biofuels, algae doesn't displace food crops. That's significant because one fundamental dilemma with biofuels is that they'll crush our economy with rising food costs, by competing with edible crops for arable land.The ChallengesBut algae aren't great multitaskers. "Algae usually just reproduce or make oil," says Tom Todaro, CEO of Sustainable Oils. "They don't usually do both. Under favorable conditions they'd rather multiply than store their energy."So there's a dilemma: You want your algae to multiply so you have a lot of it, but if they're spending energy multiplying they won't make any oil. That's why companies such as Sustainable Oils are trying to engineer algae that balance the two imperatives, multiplying rapidly in the first few days of life, and making oil thereafter.Volume is another problem: No one has ever produced as much algae as we'd need to actually start replacing gasoline at a meaningful scale. Sustainable Oils is just breaking ground on a 50,000-gallon test facility in Colorado, but industrial levels would require plants that accommodate 100 million gallons of algae.

It's not as simple as just building bigger algae ponds. No one knows exactly how to cultivate that much algae-from how to feed them all carbon dioxide, to how they'll behave and interact at such great quantity. Just getting them sunlight is a problem. Algae usually sits in a thin layer atop water, soaking up sunlight; Building huge, shallow ponds is way too expensive, so we'll need to find ways to get sunlight deeper into vats. (And remember, if we use lots of electriciy in the process the whole projecct is moot).Again, biology is being marshaled to solve these problems; some have explored creating algae with physical properties that allow sunlight to soak deeper into a pool (so algae to grow at greater depths). Others pursuing engineering solutions have created bioreactors, which churn algae during cultivation, or grow them in tubes. But bioreactors, while promising, are expensive. "You have to understand that oil is the world's most efficient market in the world," says Mark Tegen, CEO of Inventure, whose company refines algae into fuel compounds. "You have to wring every cost out to make it competitive, and biology is where you get your bang for the buck."Then comes a third problem: To release the algae's oils they have to be dried out. Companies like Inventure already do this, but again, industrial scales may require new technologies. Centrifuging isn't practical, but algae are being bred that naturally excrete their oil, while the chemical and mechanical processes for separating the oils artificially are still being refined.

The ProspectsDespite these problems, there's good reason for optimism. After all, money has been flowing into the sector, and it's not just crazy bubble money-some of the savviest investors in the world are making big bets because the advances have come so quickly. "My bet is that we'll see something in 5-10 years," says Tegen. "The scene is like tech in 1996. We're living in dog years and there's mayhem. But in just the last two years alone, the advancements have been shocking."Photo from flickr by Steve Jurvetson