Simulating sunlight to boost algae power

Home Technologist Online Simulating sunlight to boost algae power

A public-private partnership in Germany has developed a novel LED-based technology to optimise the growth and productivity of algae, which could help meet the world’s demand for energy in the form of biofuel.

A laboratory bench with a series of LED-based bioreactors that grow algae.

Because food crops are also used for energy production, millions of people are threatened by starvation. However, algae could provide an alternative: they thrive in harsh conditions and need only sunlight to grow.

A major challenge, though, is to exactly reproduce sunlight in the laboratory. But thanks to their development of new technology in collaboration with a LED manufacturer, researchers at the Technische Universität München (TUM) are now able to simulate all kinds of light situations.

The untapped potential of algae

Scientists estimate that there are more than 50,000 species of algae and cyanobacteria. Of these, 5000 are known. So far, only ten have been exploited with commercial success. Yet, since algae are so undemanding and thrive even in salt water basins set up on barren fields, they could help solve the problems posed by the use of food crops for energy production.

“Algae grow much faster than soy beans or corn. They require neither fertile ground nor pesticides and have a ten-fold higher yield per hectare and year,” says Thomas Brück, Director of the Department of Industrial Biocatalysis at TUM.

Upon closer investigation of specific types of algae, the scientists discovered a variety of promising products. Many algae produce intermediate chemicals and synthesise protein mass and fats. While protein mass could be used as livestock feed, the fats could be converted into fuels.

Identifying the right algae and the right light conditions

Close-up of a bioreactor containing a green slurry of algae

Green gems: Algae – tiny single-celled creatures – could become green alternatives to conventional biofuel crops. They could even become routine additions to your dinner plate. (Photo: Andreas Heddergott/TUM.)

But even within a single species, the ability to produce specific products varies widely. “In our investigations we keep seeing huge differences in productivity,” says Thomas Brück. “So, we have to identify not only the right species, but must also cultivate the candidates with the highest productivity.”

In collaboration with the Berlin-based company FUTURELED GmbH, the researchers have developed a unique combination of light and climate simulation to optimise algae cultivation. The system uses spectrum-tuned LEDs to simulate the natural spectrum of sunlight.

“Nobody can really predict whether algae from the tropics will be as productive under German light conditions as in their native environment,” says Thomas Brück.

“Just as nobody knows whether candidates that work here will be equally successful in the light conditions of the Sahara. But now we can test all of these things in our laboratory.”

How LEDs make a difference

The highly efficient LEDs provide light with wavelengths between 400 and 800 nanometres and a radiation intensity of 1000 watts per square metre, with an intensity distribution that very closely models natural sunlight. The various LED types can be controlled individually, allowing the researchers to program specific spectra.

This kind of facility would not have been possible using either incandescent or fluorescent lamps. Incandescent lamps generate too much heat and fluorescent lamps cannot produce the full spectrum of sunlight in the required intensity. Triggering specific, targeted wavelengths is impossible in both of these variants.

The spectral bandwidths of the LEDs can be specifically tuned to the molecular switches that control the growth of algae. If these portions of the spectrum are not properly reproduced, the results can be distorted significantly.

The German State of Bavaria and the Airbus Group are funding the project with €12 million.

Adapted from article by Andreas Battenberg, TUM Research News

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