The United States needs billions of tons of biomass every year for biofuel. Corn, soybeans and other land crops are most common but come with indirect negative environmental impacts, along with the economic and moral consequences of choosing between food or fuel.
With three quarters of the planet covered in water, kelp might be part of the solution. That theory is being tested off the coast of Catalina Island.
"I think we just made a major breakthrough. I think kelp as a biofuel source has been investigated for a while but how to grow it on a scale that is commercially relevant has been the missing piece," said Diane Y. Kim, associated director of special projects at the USC Wrigley Institute for Environmental Studies.
Beginning in 2019, Marine Bioenergy, Inc. and USC researchers began testing a concept: to farm kelp in the open ocean.
Kelp is one of nature's fastest-growing plants and it is considered perfect for making bioethanol, but it naturally grows in water bathed in sunlight, up to about 60 feet.
In the open ocean, water near the surface is nutrient-poor, but loaded with nutrients in deeper waters. Trying to take advantage of both was the inspiration for what's being called a "kelp elevator."
"We can protect the kelp, we can protect all the hardware and since we have to go down to the nutrients every night anyway, this is easy to do," said Brian Wilcox, co-founder of Marine Bioenergy, Inc.
A test buoy and a winch were placed off the coast of Catalina Island. USC biologists attached kelp to an underwater boom, that for 104 days surfaced the kelp during the day to absorb sunlight and at night, dragged the kelp over 260 feet deep into nutrient-rich waters.
In a study in February of 2019, researchers found that only did the kelp survive the lower depths, but once it returned to the surface, it grew four times faster than kelp grown naturally.
"Some people were sure it would work, some people were sure it wouldn't work. I was more on the fence where I just had no idea what would happen, so when we started to get the first pictures of the kelp growing on there, it was just... 'yeah, this is amazing, it's really growing!'," said research associate Ignacio Navarrete.
A plan is in development to build a pilot-scale ocean farm, which would be dept-cycled using solar-powered drone submarines and then harvested four times a year, without requiring land, fresh water, artificial fertilizers or pesticides.
That means millions of tons of biomass to replace liquid fossil fuel could be created at competitive prices.
"Our farms are going to be really close to the coast , but to the degree that all the nutrients flood all over the ocean, we help absorb some of those nutrients. That's beneficial because sometimes it's just too many artificial nutrients dumped into the ocean through runoff from agriculture and so on," said Cindy Wilcox, co-founder of Marine Bioenergy, Inc.