How to pick the best microalgae

The fuel of the future may be produced by microalgae – but which microalgae?

We know these microorganisms use sunlight and water to generate oils, some of which have potential as sustainable biofuels. It’s a simple and efficient process that needs little space and few resources.

Not all microalgae are equal, however, so the really good biofuel makers need to be pinpointed.

In a new paper, published in Journal of Renewable and Sustainable Energy, Argentinian researchers describe their system to assess the potential of certain microalgae species – and identify three good candidates.

Led by Lucas Martín from National University of the South, the team designed a tool to compare how much oil was produced by each of nine species, taking into account economic, biological and environmental factors.

The promising species they identified are Halamphora coffeaeformis, Navicula cincta and Navicula gregaria. All live in water and scored high on the test, meaning that they produced plenty of oil, were cheap and easy to grow and didn’t require special environments to grow in.

They also have the ability to clump together as a biofilm in water, which makes them much easier to harvest. Harvesting usually accounts for up to 30% of the production cost, so this is useful economically.  

This test also revealed that the microalgae currently being studied as biofuel makers aren’t necessarily the best for the job.

“This tool provides a useful criterion for selecting suitable microalgal species for commercial biodiesel production,” says Martín. “The most surprising thing was the low score obtained by species that are widely studied for the production of biodiesel such as Chlorella vulgaris.”

Previously, experiments to test microalgae were time-consuming and costly, because they required huge amounts of algae and very specialised equipment. This standardised tool allows large-scale identification to quickly sort through the hundreds of thousands of known algae species.

“Our work makes it possible to perform an analysis of the microalgae based on laboratory-scale data, without the need to go through a pilot-scale experiment,” says Martín.

This also provides ways of identifying other uses of microalgae without relying on costly experiments, where other uses are often found by complete accident. This allows a more deliberate approach to fully investigating the potential uses of these remarkable microalgae.

“We think this procedure could be applied to any other bioproducts that are being produced for microalgae, in addition to biodiesel,” says Martín.