Making biofuels from seaweed is one of the latest ideas for creating sustainable fuels that don't compete with food crops. Two different teams, one US-led and one in India, are working on solutions.
By growing on the surface of the ocean and using nutrients that derive from saltwater, seaweed as a feedstock is highly scalable yet avoids several problems associated with crops on land: competing with food crops for fresh water and arable land, and requiring fertilizer. Seaweed, a form of algae, is already cultivated around the world as a cheap form of food. It reproduces easily and is high in carbohydrates. However, because its chemistry differs from that of land plants, it requires a different type of process for converting them to sugars that can then be used for producing ethanol.
One of the latest ideas for creating sustainable fuels that don't compete with food crops is making feedstocks from seaweed, such as this red seaweed (Plocamium sp.). (Source: Wikimedia Commons/Derek Keats)
In Chennai, India, Sea6 Energy is working on a process that not only converts red seaweed (Plocamium sp.) to liquid fuel, but uses sea water for the process steps instead of the large quantities of fresh water used in converting agricultural crops to biofuels. That fresh water requirement is a major problem in drought-plagued areas of the world such as India, and is becoming a potential problem in traditionally more well-watered areas like the temperate zone US. The company's fermentation process reportedly uses regular yeast to digest the seaweed's carbohydrates without requiring the use of genetically engineered bacteria, more common in many seaweed-to-fuel conversion attempts.
Red seaweed is among the most productive seaweed species, and already used for other purposes, such as in the production of cosmetics. Sea6 Energy is focusing on improving seaweed cultivation methods, which have remained labor intensive, to scale up production and boost yields even higher. The company's engineers have developed proprietary structures that could extend seaweed farming beyond the shallow waters where it currently takes place, to more extreme environments in rougher seas.
In the US, the research team, led by BioArchitecture Labs, is investigating the combination of engineered bacteria with brown seaweed. In a paper published in Science, the team describes its process for converting the sugars in seaweed into ethanol by genetically engineering a bacteria that can digest them. The team's researchers say their process "enables bioethanol production directly from macroalgae via a consolidated process, achieving a titer of 4.7 percent volume/volume and a yield of 0.281 weight ethanol/weight dry macroalgae (equivalent to ~80 percent of the maximum theoretical yield from the sugar composition in macroalgae)."
A commentary in the same issue of Science points out that seaweed would have to be grown on more than 11,000 square kilometers (2.718 million acres) to produce enough ethanol to replace only 1 percent of the current US gasoline consumption. For comparison, a total of about 80 million acres of corn are currently grown in the US. As we've pointed out in blogs and several comment discussions on Design News posts, it's unlikely that any one sustainable and alternative fuel and energy source will single-handedly replace petroleum-based sources. Instead, it will likely take a mix, since they're not all created equal.
I hear you, William. The "best technological choice", of course, can look different depending on which lens we are looking through. The economics that drive manufacturing are the reasons behind looking first for a drop-in replacement, not looking first for the "best" technology from some other standpoint, such as least harm to the environment, easiest to produce, easiest/simplest to distribute, or some other factor.
Isn't it unfortunate when the best choice is passed by because of expediency or external influence, with logic and insight being ignored. WE might be better off if some of that corn ethanol were provided as a beverage, to discourage folks from driving. That would indeed reduce automotive emissions pollution. (I am not seriously suggesting this as an alternative, but as another point of view).
Before the corn lobby ever heard of alternative fuels, we had a focus on ethanol because researchers were looking for what appeared to be the fastest, more-likely to-be-a-drop-in replacement for gasoline. By the time it became apparent that ethanol might not be the best way to go--whether made from corn, kudzu, seaweed or sugar cane trash--an entire industry had been created, and momentum had become established, no doubt helped by the corn lobby.
One question: Why convert anything into ethyl alcohol when there are a whole lot of better alternatives? By better I mean more energy per unit of weight, and also less corrosive. We have so much ethanol because the corn farmers lobbied for it, NOT because it was a good choice. We should all remember that fact. How about something more like bio-diesel fuel? Just rearrange those carbon-hydrogen bonds and we are there. No, it is not easy and some things that do work may not be practical. That is a challenge.
Jack, the US research team is focused on conversion technology, whereas the Indian team intends to also intensively farm seaweed. Seaweed cultivation methods already exist: the Indian team wants to improve them, as we state in the article.
Ann, can you tell if the idea is to harvest naturally occuring seaweed or is it to create "sea farms" at some location in the ocean? If it's the latter, I can imagine that we will be running into the same problems with do with land base development. There will be years of environment impact studies before they could even start one that would produce a usuable level of anything.
@naperlou - we've already seen that situation here in the Midwest where the rates keep going up due to reduced usage. The worst part about that is the electric company then sticks a note in your bill saying, in essence, "your rates are going up, if you think you pay too much, here's are some things you can do to decrease your usage...". So then they can raise rates again. At the end of the day you are in a worse situation than you were when you started. You are having to deal with crummy light bulbs, less comfortable air, decreased capabilities, but still paying the same (or more) than you were before all this started.
Greg, thanks for your input. We report on both new technologies that are already ready to go, and on stuff like this that is just out of the lab and taking a different approach from what's already been done. I agree with you on experimentation--that's the essence of science and invention, and inherent in the creative process.
I agree that the potential for this technique appears limited right now and will probably not make a significant dent in the energy demands of the world. However, I applaud the idea of thinking outside the box and trying this new approach. Sometimes experimentation with different ideas can lead to another totally new idea (which would not have otherwise been thought of).
On the other hand, were there any unintended effects with this process? (i.e. will growing too much of this type of seaweed in one location disturb the ecosystem and cause some unanticipated environmental damage?). It would be good to study what other effects this process would have on the ecosystem too.
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