Boeing, UAE partners make progress with oilseed halophytes as feedstock for renewable jet fuel; desert plants fed by seawater
Boeing and research partners in the United Arab Emirates have made breakthroughs in sustainable aviation biofuel development, finding that desert plants fed by seawater (the oilseed-producing halophyte Salicornia bigelovii) can produce biofuel more efficiently than other well-known feedstocks. (Earlier post.) The Sustainable Bioenergy Research Consortium (SBRC), affiliated with the Masdar Institute of Science and Technology in Abu Dhabi, will test these findings in a project that could support biofuel crop production in arid countries, such as the UAE.
S. bigelovii is a leafless, C3, succulent annual salt marsh plant that produces an oilseed on seawater irrigation in coastal desert environments; the oil from the seeds is suitable for biofuel production. Yields on seawater are similar to conventional oilseeds under ideal conditions. SBRC research also found that the entire shrublike plant (i.e., its lignocellulosic biomass as well as the the oil) can be turned into biofuel effectively.
As reported in 2012 by Masdar researchers, while halophytes such as Salicornia bigelovii have the potential to produce biofuel feedstocks such as oils from its seeds and sugars from its biomass, the high salinity of the plant have challenged the existing methods for production of cellulosic biofuels.
Laboratory experiments at Masdar Institute on removing the salt from the plant has led to some interesting findings. The liquid fraction obtained after pretreatment contains 2.6 times more ash than the solid fraction. Preliminary extractives analysis demonstrates that most of the salt can be removed by controlling two factors; firstly time of the initial washing and secondly, salinity of the water being used. The effect of temperature has also been studied during these experiments. By repetitive washing (in Soxhlet apparatus), the ash in the solid fraction is reduced to 6% as compared to the feed which ranges between 16-37 %. Results achieved using strong acid hydrolysis and high performance liquid chromatography analysis confirm 22% glucan, 18% xylan, 16% arabinan, and 13% lignin in the extractives-free biomass. These numbers indicate that S. bigelovii could be a very suitable feedstock for bioenergy processes such as gasification, BIO-SPK, or bio-energy fermentation.—Chaturvedi et al. (2012)
The Masdar researchers have now published a new paper (Cybulska et al., 2014) in which they report that composition of the washed S. bigelovii biomass was comparable to traditional lignocellulosic biomasses with relatively high glucan and xylan content (26 and 22 g/100 gDM, respectively) but with lower lignin content (7 g/100 gDM).
They subjected the washed feedstock to hydrothermal pretreatment, producing highly digestible (up to 92% glucan-to-glucose conversion) and fermentable (up to 100% glucose-to-ethanol conversion) fiber fractions. Liquid fractions obtained in the pretreatment did not show inhibition towards Saccharomyces cerevisiae.
No significant differences among the enzymatic convertibility and microbial fermentability of the fibers as well as low xylose recoveries suggest that lower severity pretreatment conditions could be exploited for S. bigelovii.—Chaturvedi et al. (2014)
|The ISEAS concept. Click to enlarge.|
In the coming year, SBRC scientists will create a test ecosystem (Integrated Saltwater Energy and Agricultural Systems, ISEAS) to support the development and commercialization of biofuel sources for aviation and co-products by planting two crops of halophytes in Abu Dhabi’s sandy soil.
Waste seawater from a fish and shrimp farm will nourish the halophytes that clean the water as they grow. The water will next flow into a field of mangroves before returning to the ocean. Both crops would be converted into aviation biofuel using SBRC research findings.
Plants called halophytes show even more promise than we expected as a source of renewable fuel for jets and other vehicles. The UAE has become a leader in researching desert land and seawater to grow sustainable biofuel feedstocks, which has potential applications in other parts of the world. This project can have a global impact, since 97 percent of the earth’s water is ocean and 20 percent of the earth’s land is desert.—Dr. Alejandro Rios, Director of the SBRC
Funded by Boeing, Etihad Airways and Honeywell UOP, the SRBC is dedicated to the development and commercialization of sustainable aviation biofuel, which emits 50 to 80 percent less carbon through its lifecycle compared to fossil fuel.
SBRC’s research success, announced at the World Future Energy Summit, continues the momentum for a sustainable aviation biofuel industry in Abu Dhabi. On 18 January, Etihad Airways conducted a demonstration flight with a 777-300ER (Extended Range) powered in part with biofuel refined in the UAE. On 19 January, Boeing, Etihad Airways, Masdar Institute and others launched BIOjet Abu Dhabi: Flight Path to Sustainability, an initiative to advance biofuel research, feedstock production and refining capability. (Earlier post.)
Iwona Cybulska, Tanmay Chaturvedi, Grzegorz P. Brudecki, Zsófia Kádár, Anne S. Meyer, Robert M. Baldwin, Mette Hedegaard Thomsen (2014) “Chemical characterization and hydrothermal pretreatment of Salicornia bigelovii straw for enhanced enzymatic hydrolysis and bioethanol potential,” Bioresource Technology, Volume 153, Pages 165-172 doi: 10.1016/j.biortech.2013.11.071
Iwona Cybulska, Tanmay Chaturvedi and Mette H. Thomsen (2013) “Characterization of Salicornia bigelovii to evaluate halophyte potential for second generation biofuel production” (35th SBFC)
Edward P. Glenn, Tekie Anday, Rahul Chaturvedi, Rafael Martinez-Garcia, Susanna Pearlstein, Deserie Soliz, Stephen G. Nelson, Richard S. Felger (2013) “Three halophytes for saline-water agriculture: An oilseed, a forage and a grain crop,” Environmental and Experimental Botany, Volume 92, Pages 110-121, doi: 10.1016/j.envexpbot.2012.05.002
T. Chaturvedi, I. Cybulska, R. M. Baldwin, M.H. Thomsen (2012) “Second generation bioenergy production from Salicornia bigelovii—a halophyte that shows great promise as an energy crop in UAE”