It works as a roof, or window that grows its own shading. The Urban Algae Canopy is a bio-electric glass structure, in which water flows through and microalgae grows. When the sun shines, the single celled algae photosynthesize and multiply to create shade.
The real upside to this, though, is that one tent produces as much oxygen as 40,000 square meters of woodland, AND 330 pounds of biomass every day.
Biomass is, essentially, plant or animal material that is broken down. It can be used for fuel, in the case of biofuel, or biodiesal; though burning it does release carbon dioxide it is considered a highly sustainable form of fuel since it can be grown.
Image credit: http://www.ecologicstudio.com/v2/index.php