Carbon-eating bio curtains – the answer to city pollution?

Buildings in space-starved cities could soon become shrouded in curtains of pollution-eating algae as the inventors of the carbon capture technology seek to commercialise a product.

The ‘urban curtain’ photobioreactor is an opaque bioplastic membrane covered with pillows of algae that capture and store CO₂ from the atmosphere and release oxygen.

The system was developed by PhotoSynthetica, a company set up by London-based architect EcoLogicStudio in partnership with researchers at Bartlett University College London (UCL) and the University of Innsbruck. It is intended as an efficient and slimline alternative to planting trees and shrubs in cities with limited space.

The latest trial installations, on buildings in Dublin and Helsinki, used innovative bioplastic membranes instead of ETFE and were able to remove one kilo of CO₂ per day, which is equivalent to 20 large trees.

Efforts are under way to refine the system, explore the potential to harvest the algae biomass created as the raw material used to produce the bioplastic and find a manufacturer to bring a product/s to market in 2020.   

Claudia Pasquero, director of the Urban Morphogenesis Lab at the Bartlett UCL and co-director of EcoLogicStudio, says: ‘UCL is experimenting with producing a 100% bio-based plastic that will allow us to push for innovation in the manufacturing system. We will be looking for manufacturers that can integrate these materials and produce a bio-based foil.’

The algae curtain is custom designed for the building and its context to optimise algae growth. A series of modules use daylight to feed living micro-algal cultures. Unfiltered air introduced at the bottom of the curtain creates bubbles that rise through the watery medium, coming into contact with voracious microbes.

CO₂ molecules and air pollutants are captured and stored by the algae and grow into biomass. The culimination of the process is when freshly photosynthesised oxygen is released at the top of the curtain and into the urban microclimate. The algae is luminescent, making it possible to create attractive night-time displays.

EcoLogicStudio is testing the use of large-scale, high resolution 3D printing to make solid photo-bioreactor components which could be integrated into a permanent structural facade.

A prototype bio-sculpture of the system, created for display at the Centre Pompidou in Paris and currently being exhibited in Vienna, has a thick porous skin impregnated with algae as a form of biogel and is designed to increase air pollution filtering.

The plan is to offer both soft curtain and hard facade options based on the requirements and context, says Marco Poletto, co-director of EcoLogicStudio: ‘The 3D printed solution was developed to address the air quality issue and the thick permeable membrane essentially functions as a large filter. The algae curtain relies on a certain amount of equipment and machinery, but if you want to maximise the production of biomass it is currently the most productive and efficient system. It is really the question of the context and the building typology.’