green wall outdoors are not a new idea. Indoor plants have long been used to absorb carbon dioxide and produce oxygen, and there’s even evidence that they can lower stress levels in humans who work near them. In some buildings, they’re used primarily as an aesthetic design feature, but there are also practical applications. For example, NASA is currently investigating the potential of green walls on spacecraft – both the International Space Station and future long-term lunar and Martian missions.
The process of building an artificial green wall
The process of building an artificial green wall is relatively simple. First, a grid of hollow tubes is attached to the walls and ceiling. Then, nutrient-rich water is pumped through the tubes and sprayed onto the roof, where it slowly trickles down to the wall. The nutrients in the water feed algae, which grow on the top sheet of plastic and capture CO2. As they do so, they convert light into energy, which makes them grow more quickly. This raises their surface area, which increases their efficiency at removing CO2.
What happens next depends on what you want out of your artificial green wall. If you want food, you can harvest the algae. In Japan, engineers are working on a technique for growing edible seaweed in green walls; eventually, it could replace fish farms and potentially even ocean fishing as a source of protein. If you don’t care about food but do care about CO2 removal, you can simply leave the algae to keep growing until they reach the bottom of your wall, a process that should take about six months, and then replace them with new ones. Or if you just want to look at pretty walls made of plants, you can just let them grow until they cover almost your entire wall surface.