Jan 16, 2018
An experimental tower over 100 meters (328 feet) high in northern China – dubbed the world’s biggest air purifier by its operators – has brought a noticeable improvement in air quality, according to the scientist leading the project, as authorities seek ways to tackle the nation’s chronic smog problem.
The tower has been built in Xian in Shaanxi province and is undergoing testing by researchers at the Institute of Earth Environment at the Chinese Academy of Sciences.
The head of the research, Cao Junji, said improvements in air quality had been observed over an area of 10 square kilometres (3.86 square miles) in the city over the past few months and the tower has managed to produce more than 10 million cubic metres (353 million cubic feet) of clean air a day since its launch. Cao added that on severely polluted days the tower was able to reduce smog close to moderate levels.
The system works through greenhouses covering about half the size of a soccer field around the base of the tower.
Polluted air is sucked into the glasshouses and heated up by solar energy. The hot air then rises through the tower and passes through multiple layers of cleaning filters.
“The tower has no peer in terms of size … the results are quite encouraging,” said Cao.
Xian can experience heavy pollution in winter, with much of the city’s heating relying on coal.
The tower’s operators say, however, that the system still works in the cold months as coatings on the greenhouses enable the glass to absorb solar radiation at a much higher efficiency.
Cao’s team set up more than a dozen pollution monitoring stations in the area to test the tower’s impact.
The average reduction in PM2.5 – the fine particles in smog deemed most harmful to health – fell 15 percent during heavy pollution.
Cao said the results were preliminary because the experiment is still ongoing. The team plans to release more detailed data in March with a full scientific assessment of the facility’s overall performance.
The Xian smog tower project was launched by the academy in 2015 and construction was completed last year at a development zone in the Chang’ a district. The purpose of the project was to find an effective, low-cost method to artificially remove pollutants from the atmosphere. The cost of the project was not disclosed.
Source: south china morning post