High-tech CityTree cleans as much pollution as 275 trees

High-tech CityTree cleans as much pollution as 275 trees

The CityTree is a new technology that cleans the air, while occupying just 1% of the space that would be needed using the 275 real trees it replaces.

Cities are expanding, but the majority of them are also exceeding health limits for air pollution. Innovations that are small in size but can help clean the air could become the pillars of smart cities.

One German company is proposing an intriguing solution: a piece of urban furniture that combines the power of biology and the ease of automated Internet Of Things (IoT) technology to create what’s called a CityTree.

The CityTree is not a tree per se, but actually a densely packed moss culture, vertically housed in an unit that blends in with its urban surroundings. In an area of 3.5 square metres (37.6 square feet), the CityTree does the equivalent job of 275 trees of filtering the air of fine dust, nitrogen oxides and carbon dioxide (up to 240 metric tons per year).

A combination of mosses and plants to absorb particulates – potentially by up to 30%. Built-in watering and Internet of Things (IoT) monitoring create a self-sustaining outdoor feature that can be used as a bench. Solar panels are used to power the “Tree” and rainwater is collected and pumped into the soil to keep the moss fresh.

Moss was chosen because of its biological properties, says Zhengliang Wu, co-founder of Green City Solutions: “Moss cultures have a much larger leaf surface area than any other plant. That means we can capture more pollutants.”

CityTree in Paris

CityTree in Paris


European cities such as Berlin, Paris, Amsterdam and Oslo all have CityTrees in place, while the Crown Estate and Northumbrian Water are both trialling systems in the UK.

Not only does the CityTree help improve air quality within a radius of 50 metres (164 feet), it can also serve as an analog billboard, displaying lettering, images or digital data via a QR code, iBeacon or NFC (near-field communications).

The installation powers itself through its solar panels, and rainwater is collected and automatically redistributed using a built-in irrigation system. Sensors can be added so that data can be collected on the CityTree’s performance.

Cities can invest in CityTrees at USD $25,000 each, and the company has installed about 20 of these units in Oslo, Paris, Brussels and Hong Kong, with plans to expand to India and Italy. While it might not be as pleasing as a real, live tree, on a practical level, it’s an innovative idea that takes up less space, while combining the power of nature and solar energy with the interconnectivity of new technologies to clean up the air.

For more information,

Or visit Green City Solutions.

Photos courtesy of CityTree


May 18, 2018