Researchers have devised a new system that can transform brown seaweed into biofuel. They believe the development opens the door to a new possible source of energy that could help replace fossil fuels.
They are using bacteria genetically engineered to break down a sugar in seaweed called alginate that until now was inaccessible.
The results are being published in the journal Science.
The researchers then generated ethanol, and they say the method has the potential to produce other biofuels too, Live Science reports.
Yasuo Yoshikuni, a study researcher and chief science officer and co-founder at Bio Architecture Lab in California, explained that the new system could be used to make various products, such as a source (also called a feedstock) for other biofuels, which could include butanol or chemicals used in biodiesel.
|Fuel from Seaweed. ( Image: Bio Architecture Lab)|
"It opens up a vast new potential for biofuel feedstocks," said Tom Richard, director of the Institutes of Energy and the Environment at Pennsylvania State University.
Still, scientists must find out if it is economically feasible to use seaweed to produce biofuel and whether it is environmentally attractive.
Seaweed is a better alternative than corn or sugar cane because seaweed is not a popular food crop and does not compete with farming. This time they used kombu.
"This is one of the great debates about biofuel: Is there sufficient agricultural land to produce the food we require in society and also produce significant amounts of biofuels", Richard said.
Although high in sugars and thus useful to make biofuels, seaweed appeared to have limited because alginate until now could not be broken down efficiently enough to produce biofuel on an industrial scale.
As marine microbes can already break down alginate, transport the products and metabolize them, Yoshikuni's team first investigated the details of this process. They then engineered a more industry-friendly microbe, E. coli, to do something similar and yield ethanol.
The last of the steps could be replaced to produce other biofuels or even chemicals such as plastics and polymer building blocks.
This system also exploits other sugars in the seaweed, mannitol and glucan, since the E. coli can break down mannitol and commericially available enzymes can easily break glucan down into glucose.
This system could be used in any brown seaweed.
Dan Trunfio, BAL's CEO, said harvesting seaweed along 3 per cent of the world's coastlines, where kelp already grows, could produce 60 billion gal of ethanol.
Richard and Somerville, however, acknowledged that producing ethanol this way may require more work to become cost-effective on an industrial scale.
BAL, which is now testing farming methods at four pilot seaweed farms off Chile, is working on commercializing the process to make ethanol and renewable chemicals, Trunfio said.
But the environmental question remains.
Seaweed needs nutrients such as nitrogen and phosphorus – which are lacking in the oceans, and fertilizing the ocean is harmful because it creates dead zones with low oxygen content. But he noted that since BAL's seaweed farms are located near salmon farms, the seaweed can use salmon waste as fertilizer.