From the Sea to the Pump: Is Kelp a Viable Biofuel?

by Bruce Dorminey (RenewableEnergyWorld.com) Brown kelp macroalgae — the strange, foul-smelling seaweed so often found washed up on the Pacific Northwest’s volcanic sand beaches — could ultimately offer an almost unlimited global supply of commercial-quality ethanol or biomethane.
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Although in the U.S. the idea of macroalgae for energy production is often either confused with microalgae cultivation or dismissed by environmentalists who mistakenly believe "farmed" macroalgae will somehow deplete existing wild seaweed populations, Europe seems to be casting a less jaundiced eye toward cultivated kelp's renewable possibilities.
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While more than 70 percent of earth’s surface is dominated by oceans, they currently only produce a paltry two percent of the globe’s food, feed and biomaterials. In fact, the world only averages a million dry metric tons of seaweed biomass annually, mostly from seaweed crops off the coasts of Asia. However, with cultivation improvements by some estimates annual global seaweed production could be ramped up to 3.5 billion dry metric tons. But at this point, Bakken is simply interested in seeing his own project to fruition.
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Meanwhile, although research groups in the U.K, The Netherlands, and Ireland are actively pursuing their own seaweed-based bioenergy projects, private start-ups solely devoted to the idea are hardly plentiful.
Another one of the few such companies is The Bio Architecture Lab (BAL), a five-year old, privately held company headquartered in Berkeley, California, that has spent much of its time pursuing macroalgae production off the coast of Chile. The company garnered headlines early last year when its work on extracting sugars from seaweed feedstock were highlighted in a scientific article that made the cover of Science magazine.
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While Bakken also remains optimistic about the “potential to unlock” seaweed’s bioenergy prowess, he readily admits that his company’s prime focus at the moment is scaling up macroalgae production to commercially acceptable levels. In Europe, that means offshore production of the brown kelp from the top of Norway to southern Portugal.
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SES has a patent on its seaweed carrier, a “large sail-shaped structure” on which to cultivate large numbers of closely spaced macroalgae plants in the ocean itself. With a seaweed breeding facility in Norway, SES is currently conducting cultivation tests off the coasts of Norway, Denmark and Portugal.
As Bakken explains, with conventional seaweed cultivation, the plants are ready for harvest six to seven months after its spores (attached to ropes) are put out to grow at sea. These spores, in turn, typically spawn three- to four-meter long plants that normally grow from the surface down to depths of a few meters. And unlike terrestrial crops, which are sensitive to the vagaries of the weather, seaweed is generally unperturbed by normal wind, waves and current.
Even so, seaweed still needs waters rich in dissolved nutrients like nitrogen, phosphorus and carbon dioxide that are typically found near coastal areas and in deep ocean water. As a result, macroalgae cultivation for biofuel is going to depend greatly upon geographic location and the development of mariculture facilities says Brandon Yoza, a microbiologist with the Hawaii Natural Energy Institute.
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Because the kelp plant is potentially exposed to sunlight filtering beneath the water’s surface, Bakken also notes that seaweed’s photosynthetic efficiency is higher than that for sugar cane.
But despite seaweed’s high marks for the efficient photosynthetic use of incoming solar insolation, Yoza says terrestrial biofuel crops like sugar cane or corn still have significantly higher yields per area. Thus, he notes that profitability from macroalgae is going to depend on a very efficient development process.
Because seaweed is mostly made up of water and salt, Cooney thinks harvesting it efficiently enough to make it viable as a bioenergy alternative will be a major challenge. READ MORE