Washington, Jan 29 (IANS): A common algae commercially grown to make fish food holds promise as a source for both bio-diesel and jet fuel, a study says.

Algae contains fatty acids that can be converted into fatty acid methyl esters, or FAMEs, the molecules in biodiesel.

"It is novel and far from a cost-competitive product at this stage, but it's an interesting new strategy for making renewable fuel from algae," said Greg O'Neil of Western Washington University and lead author.

"The alkenones themselves, with long chains of 37 to 39 carbons, are too big to be used for jet fuel," O'Neil noted.

For the study, O'Neil and colleagues targeted a specific algal species called Isochrysis for two reasons.

First, growers have already shown they can produce it in large batches to make fish food and second that Isochrysis is among only a handful of algal species around the globe that produce fats called alkenones.

Alkenones are known to oceanographers as they have a unique ability to change their structure in response to water temperature.

This provides 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," said Chris Reddy of Woods Hole Oceanographic Institution.

By producing two fuels -- biodiesel and jet fuel -- from a single algae, the findings hold some promise for future commercialisation.

"Petroleum products are everywhere -- we need a lot of different raw materials if we hope to replace them. Alkenones have a lot of potential for different purposes, so it's exciting," O'Neil concluded.

The study appeared in the journal Energy & Fuels.