As the increase of carbon emissions are reaching a breaking point, an innovative use of micro-algae has emerged. Flat plane photo-bioreactors made from bio-plastic sheets and acrylic pipes have been installed on the facades of buildings as an attempt to curb this increase. Deemed as “Urban Curtains” they are designed to extract greenhouse gas-filled air from inside buildings to feed growing microalgae, which efficiently release oxygen through photosynthesis. The large surface area photo bioreactors house the growing algae and are designed with curves to optimize the area and to maximize sunlight distribution as the systems feed polluted air from the bottom and release breathable oxygen from the top. Examples of these innovative designs have been proven to successfully produce algal biomass that extracts the amount of carbon dioxide equivalent to 20 trees daily. Although this solution is unlikely to be scalable enough to address overall global emissions, these carbon extracting building frontage solutions are among the most viable options at perpetual carbon neutrality.