China opens the world’s largest air purifier in a battle against smog
Air pollution is a big problem in many big cities. By 2050 it’s estimated that 6.6 million people will die each year due to air pollution. In China, a country with numerous cities with populations well over the 15 million people mark, air pollution has compounded itself to a point where its a deadly problem killing around 1.8 million people per year as of 2015.
To help solve this problem, China has built the world’s biggest air purifier in Xian, Shaanxi province. At over 100m tall, the experimental tower has already managed to improve air quality in the region. Lead scientist on the project, Cao Junji, claims the city has seen an improvement in air quality over an area of 10 square kilometres over the past few months, with the tower producing 10 million cubic metres of clean air a day since its opening.
The tower is still undergoing testing by researchers at the Institute of Earth Environments at the Chinese Academy of Sciences to track its effectiveness. Cao’s research team set up over a dozen pollution monitoring stations around the tower’s effective area to track just how much of an impact it’s having on the city’s air quality.
According to their research, there was a 15% reduction in the fine PM2.5 particles found in smog during heavy pollution. These particles are believed to be the worst offenders when it comes to health problems caused by air pollution. However, these results are still deemed preliminary as the team plans to continue assessing the facility’s overall performance, releasing more detailed data around March.
An artists impression of the finished tower in Xian.
This isn’t the first smog-cleaning tower built in China, another seven-metre tower was constructed in Beijing last year and produces around eight cubic metres of clean air per second. However, this purifier was powered by electricity which, in China, is predominantly produced from coal-fired power plants. Not particularly handy for trying to clean the air.
This new tower, however, runs on very little power thanks to its efficient air scrubbing method. Xian’s tower works by sucking polluted air into its glasshouse structure and heating it up via solar energy. The hot air then rises through the tower, being scrubbed by multiple layers of cleaning filters. While some power is used to suck air in initially, the rest is simple physics.
“It barely requires any power input throughout daylight hours,” Cao explains. “The idea has worked very well in the test run.”
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Cao says that this experimental tower in Xian is a scaled-down version of a much bigger smog tower the team hopes to build in many other cities in China. A full-sized tower would stretch 500m into the sky, with a diameter of 200m. The attached greenhouses used for heating the air would cover an area of 30 square kilometres and Cao hopes this would be powerful enough to clean the air for a small city.
In the UK we’re also trying to cut down on air pollution, but we haven’t yet started any projects of quite the same scale for scrubbing the air of our cities. As outlined in the UK’s Clean Growth Strategy, the plan is to cut down on air pollution by adopting electric vehicles and moving to renewables. It’s a less immediate way to clean up air quality, but China’s method seems more like kicking a can down the road, than solving the heart of the problem.