Researchers from Utah State University have developed a model that simulates algae growth and their lipid productivity at various global locations using photobioreactors, which are closed outdoor installations that create an artificial environment for algae.
The microscopic algae produce significant amounts of lipids mainly in the form of triacylglycerol which can be utilized to generate biofuels.
To assess the biofuel-generating potential of algae at various global locations, the researchers grew Nannochloropsis oculata — microscopic algae found in freshwater and marine systems — in photobioreactors exposed to a constant temperature and ambient light. They simulated the algae growth and lipid content at 4,388 global locations by tweaking the variables hourly according to location-specific metrological data.
“We have found that the algae yielded maximum annual average lipid between 24 and 27 cubic metres per hectare per year for Egypt, Saudi Arabia, Ethiopia, Australia, Brazil, Colombia and India,” says lead researcher Jason Quinn from the Utah State University. “The major advantage of growing microalgae is that it does not require quality land like traditional terrestrial crops,” adds Quinn.
Terrestrial crops such as soybeans, on the other hand, required 27 times more agricultural land to give the same output. When it comes to biofuel-generating potential in terms of volumes, algae also surpass soybeans and corn.
Besides Egypt and Saudi Arabia, countries like Kuwait, Qatar and the United Arab Emirates can use this knowledge to utilize non-arable land and supplement 30% of their yearly consumption of transportation fuel by microalgae-based biofuel, suggests the study, which was published in the Proceedings of the National Academy of Sciences1.
In theory, the prospect of algae-based biofuel for the Middle East is appealing. “With year-around sun and mild winters, most of the Middle East countries have access to seawater with plenty of non-arable land for algae cultivation,” says Kourash Salehi-Ashtiani from the New York University Abu Dhabi.
But despite its promise in facilitating pilot studies and providing a uniform way of testing algae strains across different locations, the use of photobioreactor models has its limitations, closer to a modeling experiment, says Salehi-Ashtiani.
It cannot for instance address how an algal strain will deal with contamination and invasion of grazers when grown in fields, outside the protective cover of the photobioreactor.
Evan Stephens from the Institute of Molecular Bioscience at University of Queensland, Australia says, “This model has done a good job of modelling light and temperature in different geographical regions, but the utilization of advanced, closed photobioreactor systems is not currently economical for low-value commodities like fuel.”
For this model to be really useful, it must include data on the economic costs and available resources, and these could change the results entirely, adds Stephens.
Moody, J. W. et al. Global evaluation of biofuel potential from microalgae. Proc. Natl Acad. Sci. USA. (2014) doi:10.1073/pnas.1321652111