Rooftop gardens, green roofs, and other urban green spaces have been extremely beneficial for reducing stormwater runoff, for carbon sequestration, for creating a source of local food, and more. Recently, a new type of elevated garden created by Cloud Collective has hit the streets of Geneva, Switzerland: an algae farm. The farm is located on a highway overpass, which provides the ideal conditions for algae growth: sunlight, and CO2 from car emissions. The algae are grown in a bioreactor system on the wall of the overpass, made up of a closed, transparent tube system filled with algae, filters, pumps, and solar panels (thecloudcollective.org).
The algae is harvested as the tubes drain and filter the green gooey algae mix within. What are the Swiss going to do with all that algae? Algae can be used in food supplements, to make products like cosmetics and fertilizers, be used to make biofuel, or turned into green electricity as biomass (thecloudcollective.org). They act like all other plants, generating energy from photosynthesis using sunlight and CO2, and producing oxygen. In fact, algae are even more productive than plants. They are “more efficient at utilizing sunlight than terrestrial plants, consume harmful pollutants, and have minimal resource requirements and do not compete with food or agriculture for precious resources” (Sudhakar and Premalatha 2011). Additionally they have much higher growth rates. The current algae farm is only up temporarily as an experiment in a local festival, but similar experiments are being built elsewhere on buildings and bridges, and the farm designers believe the gardens could be extremely beneficial and practical for cities everywhere.
My thoughts after reading about this experiment and Switzerland left me with the following thoughts. With a big more trial and error, I think algae farms such as this could be an extremely efficient way to cut down our CO2 emissions. The apparatus doesn’t seem to take up too much space, or be too costly to operate (although I couldn’t find any numbers on pricing, so this is just my best guess based on the components of the contraption). Also, they look cool and remind me of my childhood dream of getting slimed on Slime Time Live.
I was interested to learn more about algae production to combat CO2, so I did some more research and learned that this was not the only experiment of it’s kind. For example, In 2009, Dow Chemical and Algenol Biofuels built a plant that used algae to convert CO2 into biodiesel or an ingredient in plastics (Wald, 2009). The goals for the products would be to reduce or replace the use of natural gas, reduce CO2, and provide oxygen. I am interested to see how algal cultivation will continue to create opportunities to reduce carbon dioxide, as well as create advances in medical science and other exciting and evolving fields.
Images of Geneva algae tubes
Wald, L. Matthews. 2009. Algae Farm Aims to Turn Carbon Dioxide into Fuel. The New York Times.