Chinese city uses gigantic chimney to combat air pollution

In Xian, one of China's most polluted cities, a giant 60 meter chimney located among high-rise buildings is actually an outdoor air-purifying system that filters out noxious particles and emits clean air into the atmosphere.

The system, currently being tested as a solution to China's growing city air pollution crisis, is solar powered. The Chinese scientists who designed the prototype claim that the system could cut the level of air pollution in urban areas in China and elsewhere.

Xian

Since the 1990's Xian has participated in the economic revival of inland China in the northwest region. It has emerged as an important industrial, cultural and educational center for the northwest region. It has facilities for research and development, national security and the space exploration program.

In 2015 the city had a population of 8,705,600 but the metro area had 12.9 million.

Results of the XIan project so far are promising

The technology used in the project has excited Chinese researchers who are looking for solutions to the challenge of heavy pollution in Chinese cities. Early results are yet to be published but Cao Junji, a chemist at the Chinese Academy of Sciences' Key Laboratory of Aerosol Chemistry and Physics in Xian said those results look promising.

An American atmospheric scientist Donald Wuebbles at the University of Illinois said: “This is certainly a very interesting idea. I am not aware of anyone else doing a project like this one.”

Proposal made for another tower 300 meters tall

The prototype was built with $2 million funding from the provincial government.

The project was visited by Bai Chunli the president of the Chinese Academy of Sciences last month. He said that Chinese leaders are eager to find new innovative solutions to the widespread pollution in Chinese cities as it is a widespread public health problem. A 2015 study found that pollution contributed to 1.1 million premature deaths in China just in that one year.

Cao submitted a proposal for another 300-metre high tower in Xian and also is negotiating proposals with cities in Guangzhou, Hebei and Henan.

The stack effect of the chimney

The system looks and works as follows:"The concrete chimney sits atop a large open structure with a glass roof. Solar radiation hitting the glass heats the air, causing it to rise towards the base of the tower. The air then passes through a wall of industrial filters before billowing out the chimney. The system is inspired by renewable-energy power plants that generate electricity from solar heat."

Renaud de Richter, a chemical engineer at the Ecole Nationale Superieure de Chimie de Montpelier who himself has worked on solar energy towers said that the prototype was both well-designed and well-made. Richter said that Cao's success could convince investors to support other applications that are based on the flow of solar-powered air through chimneys. The technology is known as solar updraft.

Tests of the system

Cao first tested the air filters of the system during two weeks in January when pollution was at its peak. He placed monitors at the tower and ten monitoring stations over a 10 square kilometre area. They measure particulate matter under 2.5 micrometer (PM2.5) in diameter, a type of pollution in many Chinese cities.

Cao found that the tower was expelling between 5 and 8 million cubic meters of filtered air each day. The surrounding air showed a decrease of 19.5 percent of PM2.5 concentrations when compared with monitors in other parts of the city.

More larger chimneys are needed

Since the impact was just local Cao is proposing arrays of about half a dozen larger chimneys that would be distributed in different areas of cities. He also designed a much larger 500 meter high tower. Only multiple systems will have a significant effect and reduce air pollution Cao claims.

Critics of the system

Neil Donahue, of Carnegie Mellon University in Pittsburgh Pennsylvania agrees that pulling large volumes of air through high efficiency particulate filters would clean the air. However, he is concerned about the benefits as compared to the costs: "I would like to see an assessment of the power and resource use for the filtration." He claims that turning the power used into clean electricity or not emitting the pollution in the first place could also attain the goal of reducing pollution.

Wuebbles of the University of Illinois also worried that the filters take out only particulate matter and not precursors to it such as sulfur dioxide gas and nitrogen oxides. Both are also dangerous to human health. Wuebbles said the sky may look cleaner but the air quality could still be quite bad.

In reply, Cao noted that the system did already remove nitrogen oxides. Cao also said concerns about costs were exaggerated with the costs of running the pilot project about $30,000 a year.

Previously published in Digital Journal

China to reduce growth rate and combat pollution

The Premier of China Li Kequiang told the delegates at the opening of the National People's Congress that he would make the smoggy skies in many cities blue again and pledged to work more quickly to address pollution problems.

	1 of 2
China burns a great deal of coal to produce both heat and electricity contributing to the pollution problem in many cities. Public discontent over the lack of progress in tackling China's pollution problems has resulted in the issue becoming a priority for leadership of the Communist Party. Fortunately, the 10 day event attended by 3,000 members of the parliament got under way under blue skies as heavy gusts from the north blew away the grey smog that covered Beijing just the day before.

The situation has grown so bad that protests have broken out as residents have opposed the building of chemical plants and garbage incinerators as the population becomes more aware of the dangers of the continuing pollution. Premier Li said that the people were hoping for faster progress in improving air quality and promised. "We will make our skies blue again".

Li said the government would work to upgrade coal-fired power plants to achieve ultra-low emissions but would also prioritize integration of renewable energy sources into the energy grid. However, China is also lowering growth targets as it tries to become more reliant on a consumer driven economy rather than depending on exports. China is planning to cut steel production to reduce surplus production. The target for growth was around 6.5 percent or higher if possible according to the report by Li. This would be a bit lower than last year's rate of 6.7 per but still among the world's strongest growth.

Li pointed out that growing debt levels could pose a threat to future growth rates. Li also noted: "Both the de-globalisation trend and protectionism are growing. There are many uncertainties about the direction of the major economies' policies and their spillover effects, and the factors that could cause instability and uncertainty are visibly increasing." Song Lifang an economist at the Renmin University of Peking said that Trump's tough policies could hurt China but would have a limited effect, saying: "With China's domestic economy still in the phase of transformation, the tasks for China's economic growth are arduous but with great potential."

The Li report calls for 11 million new jobs, one million more than last year's target. Reform advocates complain that state companies still control many industries and benefit from monopolies and low cost bank loans making it difficult for entrepreneurs to compete. China promised foreign companies would get equal treatment to their Chinese counterparts after complaints by the US and European groups that the Chinese were trying to squeeze foreign companies out of some markets. However, the rhetoric contrasts with that of Donald Trump who promises to put America first. Although China is increasing its military spending by about 7 percent this is still considerable lower than the US which will increase spending by $54 billion or 10 percent.

China hopes to cut steel production by 50 million tonnes and coal output by more than 150 million tons this year. In a report the National Development and Reform Commission (NDRC) said it would shut or stop construction of coal-fired power plants with a combined capacity of more than 50 million kilowatts. The reduction is a continuation of moves to reduce the share coal plays in energy production and help cut pollution in a number of cities particularly in the north. The cut backs will also help meet climate-change goals while streamlining unwieldy and over-supplied smoke-stack industries such as steel.Premier Li said:"Officials who do a poor job in enforcing the law, knowingly allow environmental violations, or respond inadequately to worsening air quality will be held accountable." In its report, the NDRC said it would cut energy consumption per capita by 3.4 percent and curb carbon intensity by 4 percent this year. In 2016 China far exceeded its goal of eliminating 250 million tons of coal output and 45 million tonnes of steel capacity.

China plans to slow growth tackle inequality and pollution

The Chinese Premier Wen Jiabao has set a target of less than 8 per cent growth for China. Compared to many advanced western countries struggling to rise out of a recession this is quite high growth but lower than in earlier years.

The Premier will give his report on March 5 to the National People's Congress in Beijing. The report is more or less like the U.S. State of the Union Address. The median estimate for economic growth was 7.5 per cent compared with an 8 per cent rate maintained from 2005 to 2011.

China is attempting to move its economy from one driven mostly by exports and investment. The goal is to encourage domestic consumption and make sure that more Chinese share in the benefits of economic growth.

As well as devoting more resources to tackling inequality China wants to address pollution as well. China is now the world's largest energy consumer as well as the world's biggest emitter of carbon dioxide.

The older leadership is preparing to hand the reins of the Communist Party to a younger generation and wants to tackle issues such as home costs, land seizures, and growing inequality. Even the premier complains that the Chinese growth model is unstable, unbalanced, uncoördinated and unsustainable. This is a remarkable bit of self-criticism. Only foreign investors seem most anxious for there to be continuous high growth as it increases their profits!

Even the Communist Party mouthpiece the People's Daily joined in the chorus of criticism. After a high-speed crash that killed forty last July the daily called for economic development that is not stained with blood.

Compared to the Maoist period inequality has risen dramatically in China. In the last 25 years it has gone from .3 to .5. At a level of .4 many analysts predict social unrest. For much more see the full article.

‘