Delhi’s New Smog Tower
- August 24, 2021
- Posted by: admin1
- Category: DPN Topics
Delhi’s New Smog Tower
Subject – Environment
Context – Delhi Chief Minister Arvind Kejriwal inaugurated on Monday the country’s first ‘smog tower’, an experimental set up worth Rs 20 crore to purify air in a 1-km radius around the structure.
- The structure is 24 m high, about as much as an 8-storey building — an 18-metre concrete tower, topped by a 6-metre-high canopy. At its base are 40 fans, 10 on each side.
- Each fan can discharge 25 cubic metres per second of air, adding up to 1,000 cubic metres per second for the tower as a whole. Inside the tower in two layers are 5,000 filters. The filters and fans have been imported from the United States.
Smog tower: How it works
- The tower uses a ‘downdraft air cleaning system’ developed by the University of Minnesota, said Anwar Ali Khan, senior environmental engineer, Delhi Pollution Control Committee, who was in charge of the project.
- IIT-Bombay has collaborated with the American university to replicate the technology, which has been implemented by the commercial arm of Tata Projects Limited.
- Polluted air is sucked in at a height of 24 m, and filtered air is released at the bottom of the tower, at a height of about 10 m from the ground. When the fans at the bottom of the tower operate, the negative pressure created sucks in air from the top. The ‘macro’ layer in the filter traps particles of 10 microns and larger, while the ‘micro’ layer filters smaller particles of around 0.3 microns.
- The downdraft method is different from the system used in China, where a 60-metre smog tower in Xian city uses an ‘updraft’ system — air is sucked in from near the ground, and is propelled upwards by heating and convection. Filtered air is released at the top of the tower.
Supreme Court order
In 2019, the Supreme Court directed the Central Pollution Control Board (CPCB) and the Delhi government to come up with a plan to install smog towers to combat air pollution.
No evidence so far
This is the first experiment with a large-scale outdoor air-purification system in India. Small smog towers have been raised in Netherlands and South Korea; larger ones have been set up in China.
Experts said there isn’t enough evidence that smog towers work.