Kelp ‘elevator’ could open up biofuel production in the ocean

A new method for growing kelp in the open ocean could allow the algae to be used for large-scale biofuel production

Spotted: Biofuels, usually made from corn, soy or other food crops, are a popular alternative fuel source. Now, researchers at USC’s Wrigley Institute for Environmental Studies have developed an aquaculture technique that could allow kelp to be used as a low-carbon biofuel. The technique involves using an “elevator” to increase the yield of kelp “crops”.

One issue with using crops such as corn as a biofuel is that growing the crops uses land and resources that could be used to produce food. Moreover, the use of pesticides and fertilisers also produces pollution. Unlike these land-based crops, kelp does not compete for freshwater, land or fertilisers and does not threaten important habitats when it is brought into cultivation. However, kelp also does not grow as quickly as land-based crops.

To solve this problem, the researchers developed a device called a “kelp elevator” which raises and lowers the floating algae to optimise its growth. To thrive, kelp needs to grow in “sun-soaked waters” no deeper than about 60 feet deep. In open oceans, the shallower, sunlit layer lacks the nutrients available in deeper water. Juvenile kelp is attached to the elevator, and the structure is raised and lowered in the water column, giving kelp access to both the nutrient-rich deeper waters and the sunlit upper waters.

The study results suggested that the kelp was both able to absorb enough nitrogen when lowered into deep water at night and to withstand the greater underwater pressure. “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 Marine BioEnergy, which designed and built the experimental system. “Once implemented, depth-cycling farms could lead to a new way to produce affordable, carbon-neutral fuel year-round.”

While biogas is a promising alternative to petroleum-based fuels, it is not the only use for seaweed. At Springwise, we have covered a number of seaweed-based innovations, including its use in a phosphate-free cleaner, in a bioplastic and even as a meat-free burger.

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