When they hear “biofuel,” people tend to assume you’re talking about corn. That makes sense, given that corn is anticipated to provide 80 percent of this year’s ethanol production—much more, say, than algae—until we consider a few numbers.
By all accounts, microalgae* is less land-intensive than corn production, and although it can pull double duty, providing high-quality feed for fish farms, it doesn’t compete with food crops. Furthermore, even by the largely pro-corn Renewable Fuel Association’s (RFA) water-consumption standards, corn ethanol is a thirsty fuel: Drinking 2.8 gallons of water for every gallon of fuel refined, corn is often outclassed in efficiency by algae-based fuels.
Algae biofuel frontrunner Algenol, for example, converts plentiful saltwater into biofuel with yields nearly 17 times higher than those of corn, while producing 1.4 gallons of fresh water per every gallon of fuel produced. But simple consumption comparisons between corn and aquatic fuels are often apples-to-oranges affairs at best. Much like the RFA’s figure, which ignores that growing an ethanol-gallon’s worth of corn costs 1,145 gallons of water, these simplistic metrics often miss something fundamental: Corn biofuel production consumes land, fertilizers, and water, whereas algae biofuel production can filter water, recycle runoff, and improve emissions.
John Decicco, a research professor at the University of Michigan Energy Institute, has debunked this misleading appraisal of corn perhaps better than anyone else. He notes that the change in emissions in choosing corn ethanol over gas was “insignificant at best,” and sometimes up to 70 percent worse. This deficiency is largely thanks to the chemical breakdown of agricultural fertilizers trapped in soil, and the energy-intensive filtering of those that become runoff.
And therein lies a fundamental difference between corn and aquatic biofuel platforms. Looking only at the former, you’d walk away with the impression that biofuel must consume extravagant resources for, at best, a mediocre improvement over gas. When you look at the latter you see how industrial pollution, CO2, and runoff-laden wastewater can be recycled into fuel and new fertilizer.
But if aquatic fuels are really such a comparatively comprehensive solution, why are we still so obsessed with corn biofuels?
The old argument would be that aquatic fuels aren’t yet commercially ready, that costs and yields simply aren’t there yet. But that story no longer holds up. Simply put, when faced with a growing list of algae-based platforms boasting well-tested estimate yields up to 2.8 times that of corn, and 32 to 70 percent fewer emissions than gas, corn looks increasingly weak.
And microalgae is far from the only aquatic flora against which corn seems like a one-trick pony.
Macroalgae, or kelp, is a marine biofuel source promising some benefits that outstrip even its single-celled cousin. Unlike terrestrial corn monocultures, kelp—cultivated or otherwise—grows into aquatic forests. In essence, the kelp farms that would fuel a marine biofuel industry would also form the foundation of a functioning ecosystem—one that filters pollution and sequesters 6.7 tons of carbon per acre.
On the freshwater front, prolific floating plants are also gaining credibility as a candidate for wastewater-to-biofuel refineries looking to cater to small communities. The frontrunner of this movement, duckweed, has the ability to rapidly trap water-borne nutrients and double its growth in as little as two days. As of this year, duckweed will see its most notable commercial venture yet: a refinery in Georgia, with an estimated per-acre yield double that of corn.
Aquatic farms and ecosystems are simply more productive than terrestrial monocultures. So once again, perhaps it’s worth asking why we still associate biofuel with its most old-fashioned manifestation.
Biofuel remains a stepping stone to better solutions—and aquatic biofuel remains more promising than corn.
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