We saw previously that algae can find their way into our homes, whether in buildings (façades, paint), cosmetics or everyday objects thanks to bioplastics. These innovations offer simple, eco-friendly solutions to today’s environmental challenges.
Today, we invite you to step outside and discover how algae are used outdoors!
Read also: Understanding algae
MICROALGAE IN AND ON OUR ROADS
One unexpected use of algae is in making road surfaces. By artificially reproducing the natural conditions in which oil forms, using microalgae residues, it is possible to obtain a material similar to bitumen. The chemical characteristics of the resulting product are different from those of petroleum-based bitumen, but its physical characteristics are identical (strength and flexibility). So far, laboratory tests have been conclusive and confirm that this bio-asphalt performs well.
It is a low-pollution process that captures CO2 from the atmosphere and offers an eco-friendly, viable answer to sustainability challenges. However, this serious alternative to oil still needs further development before it can be used on a larger scale.
In addition, thanks to their high lipid content, around twenty species of algae can produce biofuel, spirulina for example. Some contain more than 50% of their dry weight in lipids, which can be recovered through a few simple chemical reactions. By mixing this algae oil with alcohol under specific chemical conditions, it is possible to obtain algae fuel. Environmentally friendly, it has a negative carbon footprint. At present, the high cost of this synthesis (€10/l) is holding back large-scale production of these liquid biofuels, but research is under way to reduce costs and develop the technology as quickly as possible. Algae are nevertheless already powering some vehicles indirectly, in the form of biogas. In Chiclana de la Frontera (southern Spain), algae are added to the town’s wastewater to absorb the CO2 from the waste and release O2. The oxygen allows bacteria to grow that break down the organic matter in the water. The clean water is then separated from the microalgae and residual matter. The microalgae are sent to a tank where their decomposition produces methane, a gas that can be used as fuel.
Read also: Algae and their many uses
MICROALGAE IN THE URBAN LANDSCAPE
Microalgae are now also part of the scenery in the centre of Paris, in carbon sinks. Since July 2017, a new kind of Morris column has stood at the Alésia crossroads. Polluted air (exhaust fumes, heavy metals, etc.) enters the column, which is filled with microalgae. Thanks to photosynthesis, the air, stripped of its CO2, comes out clean and loaded with O2, free of heavy metals. When algae growth no longer allows optimal photosynthesis, the system is drained and refilled. The recovered biomass is sent to a wastewater treatment plant and turned into biomethane, which is used for district heating.
And since a Morris column of just 1 m3 can filter as much air as 100 trees, large-scale air purification looks fairly easy to achieve.
Read also: Microalgae make space travel possible
IN THE LIGHT OF MICROALGAE
Some microalgae, known as dinoflagellates, are capable of bioluminescence when disturbed. These organisms, with their astonishing properties, are what make some lagoons light up at night in response to mechanical stimuli. This ability, currently used on a small scale in glow-in-the-dark toys, could eventually be one of the keys to tackling light pollution. Developers in this field aim to offer an alternative to today’s energy-hungry lighting, providing ambient lighting for building façades, shop windows and street furniture, as the light these organisms emit is soft and non-polluting.
All these uses require large quantities of algae, grown at sea or in bioreactors from marine or freshwater strains. Algae crops are renewable, sustainable and eco-friendly but expensive to produce. Research is needed to reduce these costs so that this raw material, which appears to be a viable solution for limiting the depletion of natural resources, can be used more widely.
Read also: Algae in a vegan diet
