The Seaweed Solution

PACIFIC GROVE, CA – “If you find yourself getting tangled in the kelp,” the commentator said over the loudspeaker, “just relax. The kelp floats, and you’ll come free.”

I looked around at my fellow triathletes, poised on the beach by Lovers Point Park awaiting the start of our 1500-meter swim. I didn’t know about them, but the hours I’d spent training in the Stanford pool hadn’t included a kelp hazard. There wasn’t much time to worry, though: The horn blared and we plunged into Monterey Bay.

A dozen yards from shore, I found myself in the thick of the kelp bed, alternately taking a few open-water strokes and pulling myself over the slippery brown strands. This late in the season, the giant marine algae are at their peak, stretching from holdfasts anchored to the sea floor up to the bay’s surface, where their buoyant photosynthetic fronds turn sunlight into biomass.

Kelp is one of the fastest-growing organisms around: The species that hosts playful sea otters and vibrant garibaldi fish along the California coast can put on a half-meter of length in a single day. A kelp strand can reach 80 meters in length – about the same yardage that Tyler Gaffney rushed for last Saturday against Arizona State – creating a veritable underwater forest along many cold-water coastlines.

So it’s no surprise that it’s caught the eye of biofuel prospectors around the globe. As marine species that rely on buoyancy to support their physical structure, kelp and other brown algae are light on the tough-to-digest structural compounds like lignin and cellulose, which plague those trying to efficiently convert plant biomass into ethanol. However, they do come with their own unique package of sugars that need to be converted into machine-burnable fuel. But recent advances in biotechnology – which combine the genes of marine herbivores with the fast metabolism of the bacterial lab rat E. coli – are boosting ethanol production efficiency into the range of commercial viability.

Of course, the kelp must still be grown in – and harvested from – the sea. Because there’s currently a relatively small human demand for kelp products, there’s little economic conflict over resource use. (By contrast, the “food vs. fuel” competing uses of corn have caused much head-shaking over the United States corn-based ethanol industry.)

But, there’s also little precedent for producing the amount of kelp biomass that would be needed to make the industry a real competitor in the energy sector.

In Chile, Scotland, and Norway, various firms are experimenting with ways to grow and harvest kelp. Essentially, they must develop extensive trellis systems that can survive tempestuous seas while the juvenile kelp embedded in their frames put on metric tonnes of biomass. They also need to find ideal locations for these kelp farms: Goldilocks-esque situations with nutrient-rich currents to fuel kelp growth, shallow enough for firm anchorage and easy retrieval, yet out of the way of shipping lanes and fishing grounds.

With high hopes of finding and developing these sites, the British government has already written kelp biofuels into its 2050 plan for greenhouse gas emissions reduction. And researchers on the technology front seem optimistic. Still, it’s difficult to know at this stage just how large a corner of the energy market kelp biofuels can capture. And the downstream environmental impacts remain to be seen. Any large-scale installation is sure to affect the surrounding environment, particularly when it involves the growth of nutrient- and light-thirsty seaweed. While on the one hand, artificial kelp beds may serve as stand-in habitat for juvenile fish and other marine creatures, on the other hand, they may also strip the water column of nutrients critical to ecosystems further down-current.

Of course, that’s the same concern environmentalists voice over every new project: We can’t predict the details, but it’s easy to imagine a slough of bad outcomes. Weighing these risks against those associated with climate change – and with some rather nasty fossil fuel extraction techniques like fracking and deep-sea drilling – is a touchy business, but it does seem like kelp biofuel is a technology worth pursuing.

At any rate, I thought, as I floundered through a particularly dense mat of the stuff and dreamt of climbing out of the water and onto my bicycle, here’s at least one kelp forest that could use a trim.

Holly welcomes questions, comments, and pointers on a kelp-dodging forward crawl via email at

About Holly Moeller

Holly is a Ph.D. student in Ecology and Evolution, with interests that range from marine microbes to trees and mushrooms to the future of human life on this swiftly tilting planet. She's been writing "Seeing Green" since 2007, and still hasn't run out of environmental issues to cover, so to stay sane she goes for long runs, communes with redwood trees and does yoga (badly).