Energy

"Kelp elevator" for biofuel production boosts growth by four times

"Kelp elevator" for biofuel pr...
A researcher tends to kelp being grown on an experimental system called the "kelp elevator"
A researcher tends to kelp being grown on an experimental system called the "kelp elevator"
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A diagram depicting the team's "kelp elevator"
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A diagram depicting the team's "kelp elevator"
A researcher tends to kelp being grown on an experimental system called the "kelp elevator"
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A researcher tends to kelp being grown on an experimental system called the "kelp elevator"

So far as feedstocks for the production of biofuels go, kelp is a highly promising one on many fronts, and a new technology promises to boost its credentials even further. Scientists at the University of Southern California (USC) have demonstrated how raising and lowering it in the ocean environment with a "kelp elevator" can significantly boost biomass yield, by maximizing its exposure to both sunlight and nutrients.

One of the key reasons kelp is seen as potentially greener source of biofuel is because unlike other feedstocks, such as corn, sugarcane or canola, it doesn't require any land to grow. This is good news for both the preservation of vital natural habitats that might otherwise be cleared away and farmers who can instead use their precious space for agriculture purposes. Further to that, it doesn't require freshwater, pesticides or fertilizer, instead growing naturally within the marine environment.

So much so, kelp is one of nature's fastest-growing plants, but raising it in controlled aquaculture settings raises a few challenges. The plant needs to be fixed to a substrate within sun-drenched waters to really thrive, but these parts of the ocean don't offer the same abundance of nutrients found in deeper waters. So the USC team came up with an idea to get the best of both worlds, called the kelp elevator.

A diagram depicting the team's "kelp elevator"
A diagram depicting the team's "kelp elevator"

The elevator consists of fiberglass tubes, stainless steel cables and horizontal beams, which are used to subject the kelp to depth cycling as the entire structure is raised and lowered. This was put to the test off the coast of California where over the course of 100 days, scientists raised the kelp species Macrocystis pyrifera to the sunny surface during the daytime and lowered to it depths of around 260 ft (80 m) at night, so it could soak up vital nutrients like nitrate and phosphate. Raising the kelp in this way saw it grow much faster, producing four times the biomass of regular kelp.

“The good news is the farm system can be assembled from off-the-shelf products without new technology,” said Brian Wilcox, co-founder and chief engineer of company Marine BioEnergy, which came up with the elevator. “Once implemented, depth-cycling farms could lead to a new way to produce affordable, carbon-neutral fuel year-round.”

Marine BioEnergy is now working on adapting its kelp elevator for use in open-ocean kelp farms. The research was published in the journal Renewable and Sustainable Energy Reviews, while the video below offers an overview of the research.

Could seaweed fuel airplanes and automobiles?

Source: University of Southern California

6 comments
Robt
On a large scale, the question would be what other organisms and sea life need currently rely on the nutrients that the kelp will be inhaling?
Chris Coles
Rather, why not include fish that feed on the Kelp to create a system for food and kelp production?
piperTom
So they lower the kelp into the dark to get nutrients... Have they thought of raising the nutrient rich water from the depths? Seems a lot less trouble to move water within the sea than to lower, then raise, the whole garden.
Trylon
Agreed with piperTom. Artificial upwelling would seem to be much easier. Even better, nutrient-rich water is found as deep as 1000m or more, which also happens to be the same depth OTEC systems use for cold water intakes. So they could kill two birds with one stone, bringing up cold water both for nutrients and energy conversion.
Fritz
HELIOFLOAT GmbH would provide XL offshore solar power - algae grow on substrate and fishfarm
Min size 1km²
ljaques
Upwelling would upset two different microclimates for miles around, while dipping merely benefits the kelp farm without screwing everything up. I thought man was growing a conscience, but I guess not. The THOU SHALT NOT MESS WITH MOTHER NATURE law still applies.