In the struggle to slow down the runaway freight train of humanity’s devastating impact on Earth, scientists are increasingly looking at the role of our oceans.
Collaborating with industry, scientists from the University of Southern California have discovered a ‘kelp elevator’ device that produces enough seaweed, which could provide high-quality biofuels. products to help us eliminate fossil fuels.
Many land-based biofuels capable of powering cars, planes, ships and trucks are currently sourced from all-productive farm crops such as corn, soybeans, and turnips. There are a number of problems with these options, including using little space to provide food, pouring a lot of water, pollution from pesticides and fertilizers, and encroaching on rare biodiversity habitats.
Not only does reliance on large marine algae such as seaweed avoid these problems, but seaweed biology is also better suited for use as a biofuel.
Large kelp (Macrocystis pyrifera) grow at an impressive rate of up to 35 cm (14 inches) per day, in ideal conditions. They are constantly forming new fronds, allowing the ripe fronds, which reach 30 meters (98 feet) in length and would just wither and die, to be harvested without any effect. cause kelp growth.
Because kelp is a protist, rather than a plant, it lacks a strong plant lignin in its molecular content that makes it difficult to convert ground crops into fuel. In addition, growing kelp also traps carbon dioxide, which in turn raises pH levels and oxygen supply in nearby areas – helping to reducing the local effects of ocean acidification.
But there are still questions about whether we can farm enough seaweed to produce fuel in the future in an environmentally friendly way. Now, researchers may have found a way to produce kelp efficiently – by increasing and decreasing the depth of kelp in the water.
“We found that kelp with a deep depth of kelp grew much faster than a kelp control group, producing four times the production of biofuels,” said University of Southern California environmental scientist Diane Young Kim .
Cycling the kelp depth over a day, the team found that they were taking nutrients from the required depth of water closer to the surface at night, adding fuel to the growth. moreover, while still having ample access to sunlight in deeper depths during the day.
The team found that there were large changes in kelp exposed to greater depths that made them better equipped to handle the greater pressure. Their pneumatocysts – the air-filled structures that help kelp ferrules float closer to the sun – became thicker and fuller with water.
The researchers built a kelp elevator off the coast of California out of fiberglass and stainless steel, with flat beams that could “plant” young kelp. The entire structure was cycled through the water column using an automatic, solar-powered winch.
“The good news is that the farm system can be harvested from off-the-shelf products without new technology,” explained one of the team, Marine BioEnergy chief engineer Brian Wilcox. “Once implemented, deep cycle farms could lead to a new way of producing affordable, carbon-neutral fuels all year round. “
This approach could open up the cultivation of large areas of nutrient-poor oceans where kelp would not normally grow, which would also allow us to protect vital carbon sinks from naturally occurring kelp forests. while still making use of the brown algae.
The team urged further research in this area on what remains to be worked out before we can see if this idea sounds as good as it sounds, taking into account the costs and energy requirements of the project. involved in growing, transporting, and converting kelp biofuels to smelting fuels.
But other scientists, such as Woods Hole Institute of Marine Science biologist Scott Lindell, are also working on breeding harder and larger kelp species that would be even more suitable for use as biofuels.
“In a warmer and drier world of the future,” Lindell said in 2019, “it will be difficult to find a better resource for biofuels than farm seaweed that does not require arable land, without clean water, and without fossil fuel fertilizers. compared to today’s land crops. “
This research was published in Renewable and Sustainable Energy Reviews.