Thursday, February 06, 2014

Solar Coal to Reduce Air Pollution in China

Greetings from the Australian National University in Canberra,where Professor David Y.H. Pui, from the University of Minnesota, in speaking on "PM2.5 in China: Sources, Effects, Mitigation, and Its Impact on Energy Industry". Professor . Pui related how the US Embassy in Beijing published air pollution readings, including 2.5 μm particles, much to the annoyance of the Chinese government. But readings for this are now published for major Chinese cities. A previous standard was PM10, that is 10 μm particles, based on what would be small enough to enter the lung. Much smaller particles, including engineered nano-particles, can enter all the way to the Alveoli. Also particles around 2.5 μm from combustion can remain suspended in the air for weeks.Particle density can be measured in real time by applying an electrical charge, or more simply by using a filter and air pump.The major sources of emissions in China are coal combustion and vehicle engines. As well as primary particles from combustion, there are particles created by the reaction of gas exposed to sunlight (photochemical smog).

Professor Pui pointed out that since the introduction of standards in the USA, air pollution and also death rates have dropped. Northern Chinese cites have pollution levels ten to hone hundred times the US standard.

Filters can be used to remove particles from coal combustion at power stations and vehicle engines. Baghouse filters can be sued in power plants to collect dust. Modern filters have a PTFE membrane on a fabric (like Gortext jacket). Diesel vehicle engines can use a ceramic filter which is cleaned by high temperatures periodically.

Professor Pui pointed out that the cabin air filter in a modern can can remove most of the air particles within three minutes, with air recirculating.

China will implement a standard for PM2.5 three time the US standard in 2016. It would take northern Chinese cities 20 years to meet the standards, without new measure, such as conversion of coal power stations to natural gas. But the higher cost of natural gas will limit this. Gasification of coal could be used as a lower cost alternative.  Concentrated solar power could be used for gasification of coal to produce synthetic gas could be a longer term solution.

I suggest it would be interesting to see if solar powered gasification of coal would be an option for Australia. This could provide a political solution for Australian governments which need to reduce carbon emissions,while not being seen to be cutting jobs in the coal mining industry. This could be particularly useful for Victoria, which has large reserves of low quality wet brown coal. This process could also be applied to garbage and biomass. See: "Biomass Gasification using Solar Thermal Energy" (Munzinger and Lovegrove, ANU, 2013).
PM2.5 (Particulate Matter less than 2.5 μm) was established by the U.S. Environmental Protection Agency in 1997 as the standard method for sampling fine particles, because of concern over the health effects of fine particles in the ambient environment. The Particle Technology Laboratory (PTL) has developed many instruments and samplers to perform atmospheric measurements, which helped to establish the PM2.5 standard. The effects of PM2.5 pollutants on the atmospheric visibility and human health will be addressed. PM2.5 sources in China have been identified to come from pollutants from coal burning (approx. 40%) and from vehicle emissions (approx. 25%). The strategy for pollution control must be based on reducing the pollutants from these two primary sources. Filtration is one of the principal means to control PM2.5 pollutants. Baghouse filters are used to reduce emissions from coal-fired power plants and Diesel and Gasoline Particulate Filters (DPF and GPF) are used to reduce vehicle emissions. The PM2.5 impact, both short-term and long-term, to the energy industry will also be addressed. An integrative approach, from collaboration among academia, government, and industries, can effectively manage and mitigate the PM2.5 pollutants in China.
David Y. H. Pui, a Distinguished McKnight University Professor, is the L.M. Fingerson/TSI Inc Chair in Mechanical Engineering and the Director of the Particle Technology Laboratory and of the Center for Filtration Research, University of Minnesota. He has a broad range of research experience in aerosol science and technology and has over 230 journal papers and 22 patents. He has developed/co-developed several widely used commercial aerosol instruments. Dr. Pui is a fellow of the American Society of Mechanical Engineers (ASME), and has received many awards, including the Max Planck Research Award (1993), the Humboldt Research Award for Senior U.S. Scientists (2000), the Fuchs Memorial Award (2010)--the highest disciplinary award conferred jointly by the American, German and Japanese Aerosol Associations, and the Einstein Professorship Award (2013) by the Chinese Academy of Sciences (CAS). He was a past President of the American Association for Aerosol Research (AAAR) and of the International Aerosol Research Assembly (IARA) consisting of 16 international aerosol associations.

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