â–² From 1960 to 2015, changes caused by aerosol emissions, solar energy capacity factors and air pollution control policies
Controlling air pollution will not only improve environmental quality, but also bring huge economic value.
Recently, Bart Sweerts and colleagues of Professor Martin Wild's research group at the School of Atmospheric and Climate Sciences, Federal Institute of Technology, Zurich, Switzerland, analyzed the ground solar radiation observation data of 119 observation stations in China from 1960 to 2015 and found that due to air pollution, China ’s The solar energy potential decreased by an average of 11% to 15% between 1960 and 2015. If the ground solar radiation returns to the level of the 1960s, China's solar power generation capacity will increase by 12% to 13%. Related research results were recently published in the journal Nature-Energy.
"This discovery clearly shows how air pollution will hinder the development of solar energy, and also provides a sufficient reason for the return of air quality to the good level of the 1960s." Bart Sweerts, the first author of the paper, told the China Science Journal .
Solar radiation is associated with air pollution
"The original intention of our research is to tell everyone that controlling air pollution can not only improve air quality, but also produce huge economic value." Yang Su, one of the authors of the paper and a senior engineer of the National Meteorological Information Center of China Meteorological Administration, told China Science News.
He told reporters that this research was the result of the work he and Sweerts completed during a visit to the Wild Research Group of the Federal Institute of Technology in Zurich. As for the relationship between air pollution and solar radiation, he began to pay attention during his Ph.D.
Sweerts told the China Science News that China's installed solar capacity ranks first in the world, and there is a trend of continued development in the future. In addition, China's rooftop distributed solar power plants have also developed rapidly in recent years. Accompanied by this, air pollution is very serious in areas with high population density in China. Various factors made the study of the relationship between air pollution and solar energy one of the main topics, which also attracted his attention.
Over the past 20 years, the scale of global solar photovoltaic power generation has continued to expand. From 2000 to 2017, the installed solar capacity worldwide increased from 4 GW to 385 GW, continuously exceeding people's expectations. China ’s investment in solar photovoltaics is also huge, with installed capacity growing from 1 GW in 2010 to 130 GW at the end of 2017. As of 2017, China has accounted for more than half of the new global installed capacity, and exceeded the original goal of achieving 110 GW by 2020, and is moving towards the target of 400 GW of installed capacity by 2030. The Chinese government hopes that this will enable it to implement its commitments under the Paris Agreement at an early date and make it a reality that 20% of its electricity comes from renewable sources.
The reason why this study determined that air pollution has a direct impact on solar energy production stems from a result of Yang Su and colleagues.
Yang Su told the China Science News that solar radiation has been considered constant for a long time. However, more and more evidence shows that solar radiation has changed significantly in the past 60 years.
Yang Suo and his partners analyzed the characteristics of surface solar radiation (SSR) changes and the impact of clouds on SSR at different periods based on long-term observation data such as total solar radiation and cloudiness at 119 ground observation stations in China. The results show that China's SSR experienced a declining and then rising process from 1958 to 2016. Among them, SSR decreased significantly from 1958 to 2005 ("dark"), and began to rise from 2005 to 2016 ("brightened"). And this is closely related to China's proactive measures to reduce air pollution, especially to eliminate the impact of coal as the main source of air on the air.
Economic value of air pollution control
Sweerts and others found that the reduction of solar radiation has seriously affected solar energy production in the past 60 years. Moreover, this influence is also increasing with the development of China's solar photovoltaic industry. If the two stages of 1961 to 1965 (base value) and 2011 to 2015 (dark period) are used as reference standards, then by 2030, China ’s solar power output will reach a maximum of 422 GW, and the minimum will be 300 GW, of which the proportion of distributed solar photovoltaics will also drop from 45% to 20%, the gap is not small.
Their research shows that due to air pollution, China's "photoelectric potential" fell by an average of 11% to 15% between 1960 and 2015. If the solar light intensity returns to the level of the 1960s, China's solar power generation will increase by 12% to 13% by 2030, that is, new power generation of 51 billion to 74 billion kWh. "And this 'electricity dividend' will make China's public utilities sector gain an additional US $ 4.7 billion to US $ 6.7 billion," Sweerts said.
He took China's solar photovoltaic power generation in 2016 as an example. If according to the installed capacity of the year, when the solar light intensity returns to the level of the 1960s, a "power dividend" of 14 billion kWh will be added, which is the economic value of 1.9 billion US dollars. Correspondingly, with the reference value as a reference, the solar capacity factor in the most severely affected areas has dropped by 20% to 28%.
Based on such research, what issues should China's solar energy industry pay attention to? In this regard, Sweerts said that China has now entered the correct development track, that is, while vigorously developing the solar photovoltaic industry, effective measures are taken to control air pollution. "Although it is very difficult to make predictions about the future, given that China has achieved great success in both of these areas, we look forward to such developments in the future and the expected gains," Sweerts said.
Next research goal
In the course of conducting this research, Sweerts and Yang Su found that Tibet and Qinghai, two places with small population density and few industrial enterprises in China, also experienced a decline in solar capacity factors. Therefore, next, they may continue to study the relationship between solar radiation "darkness" and low wind speed, because this factor will also affect the stability of solar production and overall production capacity.
In addition, "the next research object may be India." Sweerts told reporters. In his view, India and China have many similarities in terms of the solar development stage and air pollution status.
Regarding the research results of Sweerts and Yang Su, Zhang Hua, a researcher of the Chinese Academy of Meteorological Sciences, believes that the main value lies in the ability to transform the scientific results of the current research on the surface solar radiation change trend into the availability of solar energy in China. "This is part of the use of green energy in China, and is also a matter of great concern to the Chinese government and related companies." Zhang Hua said.
However, she also pointed out that the premise of the current conclusion of the study is to attribute the change trend of surface solar radiation in China since the 1960s to anthropogenic (coal-fired) aerosol emissions, but in fact there are still many uncertainties for this reason , For example, whether changes in the cloud have a big impact on it.
"Even so, the paper still provides a very valuable reference for China's solar energy utilization." Zhang Hua said. (â– Reporter Ji Hongmei)
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