Historically, kelp was harvested and burned to create potash for gunpowder. But now the world is looking to kelp to sustain life — not take it away

Energy-producing biomass crops typically include soybeans and corn, but the largest subgroup of seaweed also could prove to be a rich resource. New studies show that giant kelp has potential as the latest in biofuels.

Giant kelp forests are abundant along North America’s West Coast as well as southern oceans near South America, South Africa, Australia and New Zealand and are home to a large number of marine animals and birds.

The billowy algae resemble land forests, like trees towering over the ocean floor, and they typically grow in environments with ample sunshine at the ocean surface and rich in nutrients.

Giant kelp, Macrocystis pyrifera, is also one of the largest species of marine algae in the world. It grows quickly; has blades that grow along its entire stem; and can add more than 30 centimeters of leafage daily, sometimes reaching nearly 53 meters. These advantages make giant kelp a clear biofuel winner.

| BUT WHY KELP?

It’s simple: Kelp grows in the oceans. Currently, 8 percent of agricultural land goes to producing crops for biofuels. These land crops also require water and can be carbon intensive due to farming and fertilization.

Kelp, on the other hand, takes up no land space, eliminates competition for fresh water and requires no harmful fertilization processes.

Additionally, its low cellulose content and lack of lignins— natural compounds found in plants that give them strength and structure — make it easier to process.

Fuel from sugar

Sugar batteries aren’t new. This form of biobattery generates an electric current by oxidizing glucose. Read more›››

The output of the artificial photosynthesis would be oxygen and a higher chemical (such as sugar), while the input of the sugar fuel cell is oxygen and sugar. The combination would close the loop: The sugar biobattery releases CO2 and water, which in turn feed the artificial photosynthesis unit.

Creating an integrated power-generation device using artificial photosynthesis presents several challenges, including performance optimization, device design, reaction dynamics and intermediate formation, says KU’s Ahsan Ul Haq Qurashi. “A multidisciplinary approach is crucial to tackle these challenges, integrating advanced materials and prototype engineering to create an efficient and effective system.”‹‹‹ Read less

In a 2021 paper in Bioengineered, a group of researchers from India and Saudi Arabia foresaw a huge potential for macroalgae as a sustainable biofuel source. The team also identified problems, however, such as seasonal changes in kelp’s biochemical values and unpredictability in harvesting enough kelp for the process.

Harvesting coastal macroalgae would also affect the vast array of marine life protected by kelp forests. We would effectively be assisting life above water but harming it below. Removing these coastal forests, then, is not an option. So, let’s try growing kelp on farms in the open ocean.

This, however, is tricky business.

The trifecta for growing kelp is sunlight, something to anchor to and nutrients which are available near coastlines but not in the surface waters of the open ocean. But how do we give a kelp farm all three in deep, open ocean?

Build an underwater, drone-guided elevator, of course.

The idea of growing kelp in the open ocean isn’t new, but the method of growing it is. Howard A. Wilcox of the United States Navy first proposed the idea in the 1970s, but it was abandoned along with the entire concept of biofuels when oil prices fell after the decade’s energy crisis ended.

Now Wilcox’s son Brian, co-founder of American company Marine BioEnergy, is picking up where his father left off.

Marine BioEnergy developed a method to grow giant kelp in open ocean waters and partnered with a team of researchers at University of Southern California Dornsife’s Wrigley Institute for Environmental Studies to test it.

| GOING UP

The test was carried out by an anchored buoy system that acts as a kelp elevator, but the real-deal commercial ocean kelp farms would involve a drone submarine attached to the farm, towing it to make sure the kelp gets what it needs, when it needs it.

CAPTION: Kelp depth cycling

The method, known as depth-cycling, aims to let the kelp access surface sunlight in the daytime hours and nutrients of cooler, turbulent, deep waters at night when the “elevator” drops below the thermocline — the layer separating the warmer and cooler waters — to 274 feet.

The depth can vary depending on location.

A major concern that usually accompanies any marine exploration or experimentation is the effect on the environment.

These farms, however, are moving to access the nutrients, not surfacing the nutrient to feed the farms.

This means no adverse side effects like algae blooms.

They would also dive to avoid ships and threatening weather and are designed to protect marine life.

Acquired nutrients would be returned to the thermocline via a tube from harvesting ships.

The researchers in the test case found that the depth-cycled kelp grew 5 percent daily while the control group grew 3.5 percent.

Also of note: Even though kelp as a fuel source will ultimately release carbon into the atmosphere, that carbon is only what it had already absorbed from the ocean, completing the carbon cycle and achieving carbon neutrality.

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“Looking forward, we expect that carbon-neutral energy for all applications will be met with a combination of kelp/biomass fuels, wind, solar, hydroelectric and other technologies, depending on local conditions,” says Cindy Wilcox, president and co-founder of Marine BioEnergy.

| CAN KELP POWER THE WORLD?

Electric options for long-haul vehicles are limited. Batteries only last so long. They are also heavy, which means decreased load capacity. Liquid fuel, then, is still in high demand. “With 0.5 percent of the oceans under cultivation, we can supply feedstocks for all long-haul vehicles worldwide,” Wilcox tells KUST Review.

IMAGE: Abjad Design

FEEDING THE UAE

Kelp isn’t just a promising source of biomass for energy. It’s also long been a source of human food in some cultures. Read more›››

Now, a group of researchers from the University of Southern Denmark thinks the kelp that grows in the United Arab Emirates’ coastal waters could help the desert nation improve its food security.

The researchers in 2022 found the seaweed Ulva intestinalis has a rich concentration of such essential minerals as potassium, magnesium, iron and zinc that makes it a promising novel food source comparable to date palm fruit, one of the UAE’s primary locally grown foods.

The seaweed, the study notes, could help make additives to improve the nutritional value of such local staples as rice and bread.‹‹‹ Read less

But it’s not just for vehicles. Giant kelp can also be digested into methane to power the spinning generators of the electric grid on days of low wind and low sun, she says.

Open-ocean kelp farms have the potential to utilize massive open ocean areas to supply an energy feedstock sufficient for the projected peak world population, according to Marine BioEnergy.

There’s still a way to go before the world can count on the “kelp elevator” for sustainable fuel, however. As a group of Irish researchers noted in a 2020 paper in the journal Energies, the technology for creating economically feasible biofuels from macroalgae is still on the ground floor.