Environment: ENEA tests 'CityTree', the 'smog-eating' panel for cities

It's called 'CityTree' and it's the innovative mobile plant infrastructure that improves air quality in the city, thanks to its ability to significantly reduce the concentrations of fine dust.

Designed as an urban furnishing solution green for streets and squares but also for schools, shopping centres, companies and airports, the technological device was tested within the European project 'CityTree Scaler', which saw the participation of ENEA, Cnr – Institute of Atmospheric and Climate Sciences (ISAC) and Proambiente Consortium, in collaboration with the German start-up Green City Solutions which produced the panel. The results were published in the online journal open source Atmosphere.

CityTree vegetable filter

CityTree can act as a real plant filter with a potential effect equal to 275 trees in the city: it consists of a self-supporting panel 3 meters long, 4 meters high and 60 centimeters deep covered with a variety of moss capable of absorbing up to 240 tons I say₂ the year. It is an urban furniture solution designed for those neighborhoods or areas hot-spot without parks, gardens and vegetated areas where air pollution is particularly high. "Its effectiveness is localized in the area near the panel, which corresponds to an area of ​​approximately 200 square meters", underlines Felicita Russo, ENEA researcher at the Atmospheric Pollution Laboratory.

CityTree uses a fully automated irrigation system, equipped with a rainwater harvesting system and temperature and humidity detectors that guarantee maximum crop efficiency and lower water consumption.

Efficacy test

To evaluate the effectiveness of this infrastructure, researchers from the Cnr and the Proambiente Consortium conducted measurement campaigns in three different meteorological conditions in Modena, which is located in one of the most polluted areas in Italy, the Po Valley. “Starting from these results, we have reproduced, with modeling tools and thanks to the ENEA CRESCO6 supercomputer, the concentrations of pollutants observed in the field and studied the effective reductions of PM10 and nitrogen oxides (NO_x) obtained thanks to CityTree, together with the extension of the area involved in the felling. In filtering mode, the device guarantees a reduction of up to 15% of PM10”, underlines Maria Gabriella Villani, ENEA researcher at the Atmospheric Pollution Laboratory.

But the results were very encouraging for other types of particulate such as PM2.5 (up to -20%), PM1 (up to -13%), ultrafine particles (-38%) and black carbon (-17 %), always in the area surrounding the filter panel.

Installations in London and Berlin

Currently, this solution green has found a certain diffusion in cities such as London and Berlin, where they have been installed in both environments indoor (airports, shopping centers and inside industrial production warehouses) both outside and at the entrance to schools, in city centers and in the squares at the headquarters of important companies. In these contexts, the purpose of the installations is to obtain areas of 'fresh and clean air', also providing a place for a break, a meeting and information point, internet access and an electric recharging station.

“But it is possible to think of installing the CityTree also in place of the normal canopies at bus stops or in canyon urban areas, places where the city streets are lined with buildings on both sides which create poorly ventilated and, consequently, highly polluted environments. A very localized reduction in the concentration of pollutants during peak hours could be of interest in limiting the population's exposure to smog”, underlines Villani.

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