Imagine an offshore oil rig surrounded by large fields of red seaweed floating just below the surface. About six times each year, the rig is partially converted to a seaweed processing facility—the seaweed is harvested, liquefied and processed into ethanol, oil or natural gas, and then transported to the shore for distribution. Or perhaps some oil rigs are retired from fossil fuel service completely and retrofitted for servicing seaweed and other renewable, sustainable energy sources instead. Fantasy, or reality? At the present time, neither option is possible, but the founders of India-based Sea6 Energy envision that within the next decade, symbiotic relationships between seaweed farms and offshore oil rigs are entirely feasible, and they want to be the first to do it.
Forming a Plan
In 2010, a small group of alumni from the Indian Institute of Technology Madras created Sea6 Energy with the specific goal of creating a solution to meet growing fuel demand in India by utilizing algae to produce biofuels in the most sustainable fashion possible.
Seaweed was not the first choice, however. Before the group zeroed in on seaweed, and red seaweed specifically, they explored the option of using microalgae as a feedstock. That approach was discounted after they determined that large scale production of microalgae-to-biofuels in a sustainable fashion would require the input of more energy than it would produce. Wastewater-based energy generation could be a viable area for microalgae, but because it’s a niche market for development, that option lacked the potential to provide the massive amounts of fuel required to displace a portion of India’s fuel demand.
The researchers concluded that algae just wasn’t the answer for their problem. They found this especially disappointing because India doesn’t have a land base comparable to the U.S. and Brazil available for ethanol production, and they believed aquatic-based biofuel production would be the fix. After exhausting the microalgae options, the group nearly called off the operation. “Then, one afternoon over a cup of coffee, we said, ‘Hey, nature has already solved this problem. It’s called seaweed,’” says Shrikumar Suryanarayan, chairman of Sea6 Energy. “They sit in the sea, they grab nutrients from the water that are passing by, they grow to be large, so harvesting is not a problem. The only thing we discovered is that, as much as we wanted to, we couldn’t find a seaweed that was doing what microalgae do—produce oil.”
Seaweed does, however, produce carbohydrates, similar to land plants. The galactose polymer produced in seaweed is a six-carbon sugar (hence the company name Sea6, for marine six-carbon sugars) and therefore offered the potential for biofuel conversion. The researchers set out to explore cultivation processes and the biochemistry that would convert it to fuel. They determined that not only would it be possible to use seaweed for ethanol but the process could be carried out in such a way that food versus fuel debates and fresh water usage concerns would be nonissues. “That’s what made us all so excited about this whole project,” Suryanarayan says.
Technical, Logistical Aspects
Once seaweed became the feedstock of choice, Sea6 officials narrowed down the selection even further to focus on red seaweed, which grows very well in tropical waters and has been cultivated and processed for use as a food additive for many years. Other companies, such as Bio Architecture Lab Inc., are focusing their operations on seaweed types that flourish in temperate climates, but Sea6 opted for a tropical strain because it better suits India’s climate, and because the growth area can be extended to encompass a huge area. Suryanarayan estimates that red seaweed could be grown anywhere plus or minus 20 degrees from the equator with the right cultivation technology.
While red seaweed has been farmed for many years, the technology used to cultivate the plant has restricted its growth potential to areas of calm, shallow waters, of which there are few. Therefore, Sea6 Energy set out to develop new technology that would enable the seaweed to be cultivated in rougher, deeper waters, enabling large-scale farms to provide feedstock for substantial biofuel production. The team developed proprietary structures that could be used to establish seaweed farms on the ocean surface “over the horizon” in deep, rough waters, such as the waters surrounding oil rigs, and also nearer to the shore. The cultivation technology developed by Sea6 Energy is also expected to improve the productivity of seaweed farmers by making it possible for them to harvest much more product in the same amount of time and by opening up the opportunity to establish farms in areas that would otherwise be inaccessible. According to Sea6 Energy CEO Sayash Kumar, improving the cultivation process means that India’s current seaweed farming labor force of about 1,000 people could be greatly expanded. “What we are envisioning is that if we can take the seaweed and make biofuel out of it, we could create potential employment in all the coastal communities of India,” he says. “That’s close to one million people.”
Developing technology to establish adequate supplies of feedstock is an all-important step, but how do you break it down and convert it to ethanol? Further, how do you accomplish this in a seawater environment so as not to require unnecessary use of fresh water?
Converting the seaweed’s galactose polymers to galactose for future fermentation would require specialized enzymes. And that is precisely why the company approached global enzyme engineering firm Novozymes for assistance. Novozymes is one of the world’s largest suppliers of enzymes for ethanol production and has taken an active role in the development of second-generation ethanol production. According to GS Krishnan, regional president-India, Novozymes South Asia, the company viewed the collaboration with Sea6 Energy as an opportunity to contribute technical expertise and further the international effort to scale second-generation production. In February, Novozymes announced a one-year exploratory research agreement with Sea6 Energy to develop the conversion process. “We see great synergies among our companies and through our collective efforts and technical know-how, we are hopeful of developing a viable technology to make biofuels from seaweed,” Krishnan says.
Seaweed offers many attractive qualities as a feedstock, including its potential for high yields. Suryanarayan says that while 50 tons per hectare is a typical yield for land plants, red seaweed has been proven to produce twice that amount. Also, seaweed has no lignin, which has been the bane of researchers worldwide who have dedicated years to breaking it down in order to access the fermentable sugars in land-based plants. But that doesn’t mean that converting seaweed to fermentable sugars is easier, unfortunately. Instead of lignin, seaweed offers researchers another challenge—carrageenan, which is also the substance extracted from seaweed for food additive applications. “Compared to land-based carbohydrate polymers, which mostly consist of glucose and xylose, the carrageenan is a highly sulfated galactose polymer which might/might not cause difficulties in processing,” Krishnan says. Bakers yeast offers one possible solution, he says, but the conversion time is slow.
Sea6 Energy’s noble decision to embrace the salt water environment presents another set of challenges, because the enzymes must be able to convert the seaweed to sugar in salt water. It’s a difficult task, but as Suryanarayan points out, “Seaweed is already full of sea water, so what’s the point of washing it off?”
While Sea6 Energy continues to develop its cultivation technology, Novozymes will also tackle the economics of scaling up the technology developed between the two companies. Specifically, Krishnan says his company will focus on developing a low-cost hydrolysis method that can simultaneously extract sugars from seaweed and free them from the polymers for fermentation. A flexible bioprocessing method has a clear advantage over other methods, he says, because it will allow for each step of the conversion process to be individually optimized. “The process conditions will be highly flexible, taking advantage of the optimal conditions for the degradation of the carrageenan to galactose, optimizing pH, temperature and enzyme performance,” he says. The fermentation step could possibly be conducted separately as well, which would allow the producer to optimize fermentation conditions. “This provides much more freedom to optimize and develop the next generation of enzymes as the process matures,” he says.
Farms of the Future
While biofuel production tends to require substantial amounts of feedstock, because seaweed is high-yielding, Sea6 Energy and Novozymes expect that only a nominal portion of the sea will be used to sustain seaweed farms. “It’s not like we’re going to have to cover up the entire sea,” Suryanarayan says. In early trials, Sea6 Energy has produced 250 liters (about 66 gallons) of ethanol per ton of seaweed. Considering that red seaweed has been proven to yield 100 tons per hectare and can be harvested up to six times each year, the company believes it will most definitely be possible to grow and harvest the amount of feedstock necessary to produce ethanol at a commercial scale. Additionally, Suryanarayan says Novozymes wasted no time in performing a life-cycle analysis for large-scale seaweed farming operations and, while there is still work to be done to quantify the data, the initial results are promising. He likens the potential for large, offshore seaweed farms to a desert oasis—creating a haven for wildlife, for example, where there wasn’t one before. Once they are ready to expand the farming operations, the build-out could be achieved quite rapidly. Kumar suggests that seaweed farming operations could multiply by 1,000-fold in just one year.
The research partnership between Novozymes and Sea6 Energy will expire early next year, but both parties are optimistic that tremendous progress can be made during the next several months and that the agreement may be extended past one year. Krishnan stresses that the research and development is still in the early stages and says a pilot plant will not be built until the conversion process is fully developed. Sea6 Energy hopes that by the end of the first year, Novozymes will have guided the way toward enzymes that can be used for the final product, or identified versions that will lead to that. Sea6 Energy tentatively expects to establish a demonstration-scale facility in three to four years. “At the moment, we are sufficiently encouraged by the results we see [and] feel that we are on the right track,” Kumar says. “Probably we will extend the partnership at the end of the year, but that final decision remains to be seen. On the ground, it’s as good as it gets so far.”
Author: Kris Bevill
Associate Editor, Ethanol Producer Magazine