We have seen previously that algae can be used in our homes in construction (facades, paint), cosmetics , and everyday objects thanks to bioplastics. These innovations represent simple and ecological solutions to current environmental constraints.
Today, we invite you to step outside the building to discover the uses of algae outdoors!
MICRO ALGAE IN AND ON OUR ROADS
An unexpected use of algae is the manufacture of road surfaces . Indeed, by artificially mimicking the natural conditions of oil formation on microalgae residues, it is possible to obtain a material similar to bitumen. The chemical characteristics of the resulting product are different from that derived from oil, but the physical characteristics are identical (strength and flexibility). For the moment, laboratory tests are conclusive, and ensure the good performance of this bio-asphalt.
It is a low-polluting production that captures atmospheric CO2 and represents an ecological and viable response to sustainable development issues . This serious alternative to oil, however, still requires development in order to be usable on a larger scale.
On the other hand, thanks to their high lipid concentration, around twenty species of algae can produce biofuel . In fact, some contain more than 50% of their dry weight in lipids that can be recovered through a few simple chemical reactions. By mixing this algae oil with alcohol and thanks to specific chemical conditions, it is possible to obtain algofuel. Environmentally friendly , it has a negative carbon footprint . Currently, the high price (10€/l) of this synthesis is a barrier to the large-scale production of these liquid biofuels, but research is underway to limit these costs and develop the technology as quickly as possible. However, algae already allow some vehicles to run indirectly, in the form of biogas. In Chiclana de la Frontera (southern Spain), algae are added to the city's wastewater to absorb CO2 from the waste and release O2 . Oxygen allows the growth of bacteria that degrade the organic matter in these waters. The clean water is separated from the microalgae and residual matter. The microalgae are then sent to a tank where their degradation creates methane, a gas that can be used as fuel .
MICRO ALGAE IN THE URBAN LANDSCAPE
Microalgae are now also part of the decor in central Paris in carbon sinks . Indeed, since July 2017, a new type of Morris column has appeared at the Alésia crossroads. Polluted air (exhaust gases, heavy metals, etc.) enters the column filled with microalgae. Thanks to photosynthesis, the air, stripped of its CO2, comes out clean, loaded with O2 and freed from its heavy metals. Then, when the growth of the algae no longer allows for optimal photosynthesis, the system is drained and refilled. The recovered biomass is transported to a treatment plant and transformed into biomethane, used for district heating.
And since a Morris column of only 1m3 can filter as much air as 100 trees, this suggests that large-scale decontamination would be relatively easy to implement.
IN THE LIGHT OF MICRO ALGAE
Some microalgae, dinoflagellates, are capable of bioluminescence when agitated. It is the presence of these organisms with astonishing properties that allows certain lagoons to light up at night in the event of mechanical stimuli. This ability, currently used on a small scale in luminescent toys, could ultimately be one of the keys to the fight against light pollution . Indeed, the ambition of developers in this field is to offer an alternative to current energy-intensive lighting, allowing ambient lighting of building facades, shop windows or even street furniture, the light emitted by these organisms being soft and non-polluting.
All these uses require large quantities of algae produced in the open sea or in bioreactors from marine or freshwater strains. Algae cultures are renewable, sustainable, ecological but expensive to produce. Research must be conducted to limit these costs to allow a greater use of this raw material which seems to be a viable solution to limit the depletion of natural resources .
