A common algae food for fish holds promise as a source of both biodiesel and jet fuel is likely to revolutionize the fuel for transportation in the future, if vested interests do not prevail on the results of two researchers, one of them an Indian origin American.
In a new study published in the journal Energy & Fuels, Greg O’Neil of Western Washington University and Chris Reddy of Woods Hole Oceanographic Institution, tapped a new class of chemical compounds in the algae to synthesize two different fuel products from a single algae.
Algae contain fatty acids which can be converted into fatty acid methyl esters, or FAMEs, the molecules in biodiesel. In this case, researchers targeted a specific algal species called Isochrysis as it can grown abundantly 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. Its oil is a dark, sludgy solid at room temperature, rather than a clear liquid that looks like cooking oil. In fact, the sludge is a result of the alkenones in Isochrysis prompting it to be a unique source of two distinct fuels.
Alkenones 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.
“They didn’t know that Isochrysis makes these unusual compounds because they’re not oceanographers,” says Reddy, WHOI’s marine chemist.
Reddy and O’Neil began first by making biodiesel from the FAMEs in Isochrysis and then they proceeded to separate the FAMEs and alkenones to get a free-flowing fuel. Though they have to add additional steps to the overall biodiesel process, they succeeded to get a supply of a superior quality biodiesel, as well as “an alkenone-rich” secondary product.
“It’s novel,” says 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.”
“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 the researchers used a chemical reaction called olefin metathesis (which earned its developers the Nobel Prize in 2005). The process cleaved carbon-carbon double bonds in the alkenones, breaking the long chains into pieces with only 8 to 13 carbons. “Those are small enough to use for jet fuel,” O’Neil says.
The scientists believe that by producing two fuels from a single algae, their research will revolutionize future commercialization of algae farming. Reddy says, “This algae has got much greater potential, but we are in the nascent stages.”
Now that they are able to extract both biodiesel and jet fuel from the algae, their next focus will be on producing larger quantities of the fuels from Isochrysis, but they are also exploring additional co-products from the algae.
Upbeat with the findings, 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,” says O’Neil. “Alkenones have a lot of potential for different purposes, so it’s exciting.”
This research was funded by the National Science Foundation, the Massachusetts Clean Energy Center, and Woods Hole Oceanographic Institution.