Supertrees, these green lungs cleaning up urban air

Ecological innovations came out with the idea of plant-covered walls growing in our cities, cleaning the polluted air. The CityTree, a wall covered with moss, breathes as much as a little forest. In Singapour, visitors of the Gardens by the Bay can see gigantic supertrees covered with fern. In Peru, a cubic supertree fights against the urban pollution in the capital.

The CityTree, a tiny forest in our cities

Despite its name, the CityTree doesn’t look like a tree. It is a green wall made of 1 600 pots of moss and little perennial plants adapted to our climate. According to the Berlin start-up Green City Solution which designed it, it would be as good for the environment as a forest.


The CityTree filters the air, absorbs the urban pollutants bad for your health by using the tiniest space possible. tiny movable structure (3 x 4 x 0.60 meters) is designed for the urban architecture. Costing 25 000€, the CityTree presents itself to be an alternative to tree’s plantation in cities, which is not easy because of the lack of space.

Thanks to the optimum contact surface with the ambient air due to the moss leaves, one CityTree can absorb 250g of fine particles and nitrogen dioxide per day, which equals to 240 tons equivalent carbon per year. It is as much as 275 real trees!

It does the same work as an air cleaner, transforming dangerous particles which are nutrients for the plants into organic matter, or biomass, and producing dioxygen. This tree could compensate the pollution produced by 417 cars each year. It’s a way to fight against greenhouse gas and to decrease the climate’s changing.

The CityTree is not only an ecological innovation but also an esthetical and technological one. Their creators covet to improve air’s quality and habitant’s life’s quality. It brings greenness and freshness in cities, providing favourable conditions to physical wealth and mental wellness. It filters up to 30% of dangerous particles in a 50 meters range around it, including 15% of nitrogen dioxide.

It also absorbs the heat and disperses it: cleaned air get refreshed down to 17°C in a 5 meters range. Thanks to the benches to the foot of the CityTree, bystanders can chill out and take a deep breath of fresh air. The CityTree could allow reducing energetic consumption through the reduction of air-conditioning.

Perfectly trendy, this green wall is connected! It has a WiFi access, a charging point for electrical bicycles, Bluetooth and NFC terminals or even QR codes. It has screens for commercials or information.

It has a ton of WiFi captors, checking on air’s quality, humidity, temperature and water’s quality. Gathered data will be used to estimate the structure’s efficiency, especially concerning its cleaning up potential. Captors will also take care of the durability of the green wall, programming the plant’s and moss’ watering in case of drought and maintaining good conditions for their growth.

The CityTree is self-sufficient. It produces its own energy through solar panels, powering the captors and the watering pump. Actually the water. As it happens, comes from a rainwater recovery tank able to contain 1 000 litres.

Associating comfort and ecology, this urban tree already seduced some cities which see in it a way to compensate the lack of green space and to reduce air’s pollution.tenths of CityTrees line up in the streets of Berlin ; 3 CityTrees arise in Paris on the Place de la Nation ; another is on the Mont des Arts in Brussels. Altogether, twenty CityTrees got erected all around the world.

Tested in all these cities, These CityTree still have to prove their efficiency. Their creators plan to implant in highly polluted third-world countries like India and to incorporate them in buildings.

The futuristic super-trees of Singapore

For lack of the hanging gardens of Babylon, we can still admire the vertical gardens of Singapore: 18 supertrees arise along Singapore’s bay since 2015. These 25 to 50 meters high giants, covered of plants, are a surrealistic vision, making the greatest pleasure of tourists and Singaporeans. Footbridges connect the impressive structures, giving a breathtaking view on the park below.

The city-state, model of sustainable development, wants to prove that urban expansion and respect of environment are not incompatible. supertrees of Singapore, ecological installations erected in the 250 hectares of greenery in the Gardens by the bay, make the city breath.

Each trunk, made of steel and concrete, is covered with 150 000 plants of different sorts. We can find more than 600 species from all around the world, including tropical flowers and ferns.


© Mike Enerio on Unsplash

Eleven of these super-trees have solar panels. They provide electricity for the night show, the lighting and the watering of the greenhouses called the Cloud Forest and the Flower Dome. They have a rainwater recovery tank and constitute air ducts for the greenhouses.

Each of these greenhouses shaped like flowers – where 220 000 plants blossom – house a tiny artificial ecosystem imitating biomes. As the name let us know, we find a tropical climate in the “cloud forest”. Here we can admire an exotic flora (ferns, orchids, etc. ) and a 35 meters high waterfall. For its part, the “flower dome” recreates a Mediterranean climate. Here grow among others some 500 years old olive trees.

The greenhouses of the Gardens by the Bay park are self-sufficient. The biomass gets used as a renewable energy for the building’s temperature’s regulation, keeping the microclimate healthy for the plants.

The supertrees of Singapore is set in a vast urban project attempting to develop the city-state while still making greener. It needed 400 million euros of investments, aiming to make Singapore a garden-city and prime destination to ecotourism.

The government shared his desire to promote sustainable development and biodiversity through this project, letting tourists discover species from all around the world.

A cubic « giant lung » in Peru

The inhabitants of the Peruvian capital city have been enjoying a supertree erected right in the centre of the city for a couple of years now. The whole world discovered it during the world summit about climate, a very broadcasted event occurring in Lima in the year 2014.

This supertree, or “giant lung” is a 5 meters high for 3,5 meters long and 2,5 meters large costing $100 000. It sucks the air up through gratings under the structure, at the same high as the car’s mufflers.

Its creator, Jorge Gutierrez, wants to makes the environment healthier for his fellow citizens and to fight against climate change. Peru capital city already suffers from a chronic air pollution, and it could get worse because of the augment of the number of cars. According to him, his “giant lung” could replace 1 200 real trees!

The cube cleans up 200 000 m3 of air every day. It filters greenhouse effect gas (nitrogen dioxide and carbon dioxide), bacterias, dust and other pollutants like sulphur dioxide, potassium nitrate, asbestos in the brake pads, rubber dust produced by the friction of the tyres on the road…

A chimney transfers the purified air from the cube to a little cubicle which looks like a phone booth where people come to breath pure and fresh air.

This machine is still a prototype and is not autonomous: it works with electricity. It only requires 2,8 kW per hour, which is the same as an industrial vacuum cleaner. It also consumes 60 litres of water a day.

According to its creator, the installation also cleans up the water but doesn’t make it drinkable. The water coming out of the cube still contains some toxic particles like potassium nitrate, but still can be used to water plants.

Its creator hopes that he can install 400 of these in the streets of Lima and of other cities around the world soon. He also plans to make his cube even greener by making it work with solar energy, and to adapt it to be used in hospitals, schools, near mining exploitations and in and private individuals.

The trees of the future?

The enthusiasm for these revolutionary trees responds to an overwhelming problem: atmospheric pollution is a plague of our century. According to the WHO (World Health Organization), this invisible killer potentially causes 7 million premature deaths every year. This could get worse since, in 2050, 2/3 of the human population will live in cities. It is now vital to adopt strategies of sustainable development to make our cities greener, for our health as well as for the environment.

CityTrees, Singapurian supertrees or giant lungs like in Peru, cities only have to choose their favourite supertrees. These futuristic ecological solutions announce a greener, healthier future, improving life’s quality for an always expanding urban population.


© Eric Parks on Unsplash

These revolutionary trees, however, are only dealing with the consequences of the atmospheric pollution, not its source. We have to keep the efforts put in the energy transition and the transformation of the urban life, by using greener means of transport.

Finally, these artificial supertrees will never replace real trees in terms of aesthetics and contribution to the biodiversity. It is still a commendable initiative, caring for the environment and the issues due to global warming. It deserves our interest.