Seminar

We propose two grand ideas to apply large-scale solar systems to mitigate PM2.5 pollution and yellow dust storm in East Asia. The first idea employs a solar-assisted large-scale cleaning system (SALSCS) to mitigate PM2.5 pollution in urban air (Cao, Pui and Lipinski, Aerosol and Air Quality Research, in press, 2015). The system combines a solar updraft tower with a filter bank to remove PM2.5 pollutants. Numerical calculations show that an updraft tower with a radius of 2.5 km and a chimney height of 500 m is capable of drawing 2.5 x 105 m3/s urban air into the green house. A filter bank located at a distance of 166 m from the axis of the chimney removes the PM2.5 pollutants from the urban air and thus clean air is emitted from the chimney outlet. By locating several SALSCS around the edge of a large city, e.g., Beijing, it can effectively mitigate PM2.5 in large urban areas.

The second idea involves erecting a long chain of windbreak walls equipped with solar panels in the proximity of yellow dust storm origins (Pui et al., Particuology 13: 146-150, 2014). The solar panels are mounted on rotating shafts of 100 m wide extending from the side of a pole of 100 m high. We propose to link 1,000 such poles to make a wind breaking fence 100 m in height and 100 km in length. On sunny days the shafts can rotate to achieve the maximum solar intensity on the solar panels. The generated electricity will be sufficient to power a down-wind town with 2.4 million households. When there is a warning of a dust storm, the panels rotate so that the back-side consisting of stainless steel plates faces the dust storm. They will serve in a similar function as tree rows serving as wind-breakers but many times taller than the trees. The fence will remove airborne dust by impaction and also interrupt the wind flow pattern, which will help to mitigate the dust storm.  The energy generated would help the down-wind town to prosper, which can trigger further socio-economic changes and adoption of integrated and sustainable land management practice, which will further minimize the dust storm formation possibility in the future.