“I do feel better,” expresses a manager at a restaurant near the world’s largest air purifier or smog tower, in reference to the improvement in air quality she noticed even if she was unaware of the tower’s purpose.
“I can’t help looking at the tower each time I pass. It’s very tall, very eye-catching, but it’s also very quiet. I can’t hear any wind going in or out. The air quality did improve. I have no doubt about that,” affirms an environmental science student at Shaanxi Normal University.
To find a low-cost solution to the country’s chronic smog problem, researchers built the 100-meter high air purifier in Xian of Shaanxi province that will artificially eliminate air pollutants. Its huge size makes it capable to filter more than 10 million cubic meters of air daily and noticeably improve the quality of air within its 10-kilometer radius.
Data analysis shows a 15 percent drop in particulate concentration at 12 test sites. “The tower has no peer in terms of size … the results are quite encouraging,” Cao Junji, the project leader, tells the South China Morning Post.
The smog tower takes advantage of solar heat to warm the air and create an upward flow towards the tower’s filter, and the filtered, cleaner air exits at the top of the tower. In this way, the facility requires minimum electricity, unlike the 7-meter tall air purifier of Beijing, which is fueled by coal-fired power plants.
“It barely requires any power input throughout daylight hours. The idea has worked very well in the test run,” Cao adds, referring to the Xian air purifier. During winter, the tower is still capable of using solar heat through its special coating on the glass, which increases the absorption of solar energy.
While the results are still preliminary, the research group is planning to build a five times taller smog tower with a diameter of 200 meters in some cities, as mentioned in the patent application they filed four years ago. This size of smog tower can cleanse the air of a small city.