An algae green wall
For professionals.
“Green walls” filled with algae suspension are photobioreactors – they are one of the newest bioengineering solutions that can be used as part of the adaptation of cities to climate change.
Microscopic algae, microalgae are used, which utilize light and carbon dioxide as a source of energy for their operation – as a result of photosynthesis they produce oxygen and organic compounds. Importantly, we can use low quality water for their breeding, e.g. municipal sewage, which is treated by them and can therefore be reused for other purposes. For the correct course of growth of algae, they need optimum access to light and a specific temperature – ideally between 16-27 degrees Celsius. Another important element will be to guarantee suspension the possibility of continuous movement so that even every single alga has adequate exposure to light. These organisms grow very quickly and can double their weight in one day.
Examples of use
The BIQ building, located in Hamburg, was built in 2013. 120 panels – photobiorectors (flat cubicles with dimensions of 2500 mm x 700 mm x 90 mm) were placed on the façade of a rather small multi-family building. In addition to the energy supply, this façade also shadows the building, preventing its walls from heating up (the higher the intensity of the sun, the greater the weight of the algae, which means that the façades of the building are less heated). This suspension, together with the heat energy produced by the façade, is then transported to the heat exchanger where water, algae and heat energy are separated, which can then be used for the current functioning of the building. The algae movement in the photobioreactor is ensured by the compressed air drawn into each photobioreactor (in the form of a large gas bubble) in the relevant time sequences. The water moves from the bottom upwards. This façade removes up to 6 tons of CO2 per year from the air delivered by the system described above. The mature biomass – up to 80% – is converted into methane in the biogas plant, which is then used to generate electricity for the building but also for its heating.
The algae suspension may have different colors depending on the species of these microorganisms used to make it, some of them may have fluorescent capabilities.
References:
https://www.sciencedirect.com/science/article/pii/S2095263519300962
https://www.arup.com/projects/solar-leaf
https://pdf.sciencedirectassets.com/277910
https://www.researchgate.net/publication/317632092_Exploring_the_Feasibility_of_Algae_Building_Technology_in_NSW