Coal to gas conversion is not an accomplice to the worsening haze in Beijing

On the morning of January 3rd, according to the Beijing Environmental Protection Bureau, the annual average concentration of PM2.5 in Beijing decreased by 9.9% in 2016, to 73 micrograms per cubic meter. However, the gray sky outside the window and the buzzing air purifier indoors constantly remind people that the New Year's haze in the Beijing Tianjin Hebei region is still ongoing. According to the latest consultation results from the China Environmental Monitoring Center, heavy haze in the Beijing Tianjin Hebei region will be maintained before January 7th, and some areas may reach severe pollution.

Under the continuous ravages of haze, various sounds about haze are also disturbing people's thoughts. Recently, a post online that some people believe that the 'coal to gas' conversion is the main source of 'abundant water vapor' in Beijing and is an 'accomplice' in exacerbating haze and air pollution has attracted public attention. In addition, there is a voice that believes natural gas cannot be considered a clean energy source, as its combustion process produces a large amount of nitrogen oxides. Some people even believe that after coal to gas conversion in thermal power plants, nitrogen oxide emissions not only do not decrease, but also increase, thereby worsening the haze pollution situation. So, has the 'coal to gas' policy exacerbated Beijing's haze pollution as mentioned above? The reporter sought confirmation from relevant experts regarding this matter.

Researcher Wang Zifa from the Institute of Atmospheric Physics, Chinese Academy of Sciences, stated that based on the current natural gas consumption in China, the amount of gaseous water produced by burning natural gas is about 300 million tons per year. If all of it were to be converted into liquid water (although it is impossible to do so), the thickness of liquid water would be less than 0.1 millimeters per year in the densely populated eastern region of the country (estimated area of about 3.6 million square kilometers), accounting for only a few h

Feng Yinchang, director of the Key Laboratory of Air Particle Pollution Prevention and Control in National Environmental Protection Cities and member of the overall expert group of the National Clean Air Research Program, said in response to the above question that whether 'coal to gas' will lead to an increase in nitrogen oxides mainly depends on factors such as the combustion method and quality of coal before gas conversion, and the combustion technology adopted after gas conversion. If low nitrogen combustion technology is adopted, the emissions of nitrogen oxides will be reduced. In fact, whether it is coal, gas, or oil, they all emit nitrogen oxides.

Feng Yinchang said that the treatment of denitrification in China started later than desulfurization, and in recent years, the concentration of nitrogen oxides in the atmospheric environment has not decreased as significantly as sulfur dioxide. The increase in nitrogen oxide concentration may cause secondary pollution, but this is controllable. The causes and mechanisms of pollution are very complex. It is unscientific to say that particulate matter pollution is still severe just because the concentration of nitrogen oxides has not significantly decreased.

At present, many places in China are implementing coal to gas conversion in adjusting their energy structure to prevent and control haze pollution. In the view of Fengyin Factory, optimizing and adjusting the energy structure is an important direction for preventing and controlling air pollution, and coal to gas conversion is one of the important ways to adjust the energy structure.

Feng Yinchang stated that China's air pollutants mainly include sulfur dioxide, particulate matter, heavy metals, and nitrogen oxides. After the implementation of the 'coal to gas' policy, the full combustion of natural gas has basically achieved zero emissions of harmful substances and zero pollution, as well as reduced emissions of sulfur dioxide, particulate matter, and heavy metals, which has a significant effect on improving the regional environment. At the same time, the thermal efficiency of gas heating furnaces can reach about 10 times that of coal-fired heating furnaces. Using gas heating furnaces not only saves fuel and raw materials, but also improves the yield of finished products.

Academician He Kebin of Tsinghua University stated in an interview with reporters that since the implementation of the 'Ten Measures for the Air' in 2013, various regions have taken strong measures to control atmospheric PM2.5 pollution, including coordinating regional environmental resources, optimizing industrial and energy structures, and so on. As a result, the concentration of atmospheric PM2.5 in the Beijing Tianjin Hebei region has been decreasing year by year. Last spring and summer, many people had a significantly higher frequency of 'basking in the blue sky' on their social media than in previous years. However, after the onset of winter, heavy pollution weather occurred frequently, and the public felt a stronger contrast. This also indicates that the next step is to continue to strengthen the prevention and control of winter pollution in the Beijing Tianjin Hebei region, especially in the areas of clean coal for civilian use, the elimination and treatment of small coal-fired boilers and 'scattered and disorderly' enterprises, in order to reduce the intensity of pollutant emissions during the winter heating period in the Beijing Tianjin Hebei region.