Common algae commercially grown to make fish food holds promise as a source for both biodiesel and jet fuel, according to new research by Western Washington University Associate Professor of Chemistry Greg O'Neil and Chris Reddy of Woods Hole Oceanographic Institution, and recently published in the journal “Energy & Fuels.”
The researchers exploited an unusual and untapped class of chemical compounds in the algae to synthesize two different fuel products, in parallel, from a single algae.
"It's novel," said O'Neil, the study's lead author. "It's far from a cost-competitive product at this stage, but it's an interesting new strategy for making renewable fuel from algae."
Two current Western students, undergraduate Garrett Gilbert of Olympia and graduate student John Williams II of Battle Ground, assisted O’Neil in his research and were named in the study. O’Neil completed his research both at Western and at Woods Hole on Cape Cod. The project was supported by O’Neil’s $430,000 Faculty Early Career Development Award from the National Science Foundation.
Algae contain fatty acids that can be converted into fatty acid methyl esters, or FAMEs –the basic building blocks of biodiesel. For their study, O'Neil, Reddy, and their colleagues targeted a specific algal species called Isochrysis for two reasons: because growers have already demonstrated they can produce it in large batches to make fish food, and because it is among only a handful of algal species around the globe that produce fats called alkenones. These compounds are composed of long chains with 37 to 39 carbon atoms, which the researchers believed held potential as a fuel source.
Biofuel prospectors may have dismissed Isochrysis because its oil is a dark, sludgy solid at room temperature, rather than a clear liquid that looks like cooking oil. The sludge is a result of the alkenones in Isochrysis – precisely what makes it a unique source of two distinct fuels.
Alkenones are well known to oceanographers because they have a unique ability to change their structure in response to water temperature, providing oceanographers with a biomarker to extrapolate past sea-surface temperatures. But biofuel prospectors were largely unaware of alkenones.
"The alkenones themselves, with long chains of 37 to 39 carbons, are much too big to be used for jet fuel," says O'Neil. But using a chemical reaction called olefin metathesis, the researchers were able to break the long chains into pieces with only 8 to 13 carbons.
"Those are small enough to use for jet fuel," O'Neil said.\
The scientists believe that by producing two fuels – biodiesel and jet fuel – from a single algae, their findings hold some promise for future commercialization. They stress that this is a first step with many steps to come, but they are encouraged by the initial result.
"It's scientifically fascinating and really cool," Reddy says. "This algae has got much greater potential, but we are in the nascent stages."
Among their next steps is to try to produce larger quantities of the fuels from Isochrysis, but they are also exploring additional co-products from the algae. The team believes there are many other potential products that could be made from alkenones.
"Petroleum products are everywhere – we need a lot of different raw materials if we hope to replace them," said O'Neil. "Alkenones have a lot of potential for different purposes, so it's exciting."
For more information on his alkenone research, contact Greg O’Neil at (360) 778-6283 or gregory.o’email@example.com.