Water spray geoengineering to clean air pollution
for mitigating severe haze in China’s cities
Shaocai Yu, Professor, Ph.D...
Current Researches in my group:
1. US EPA WRF-CMAQ model and OBSto study
and forecast air pollution-haze in China
2. Water...
1。, WRF-CMAQ空气质量模式研究中国东部区域大气污染
和雾霾演变规律及其动态预警预报
Meteorological Model
WRF modeling System:
Δx=12 km, 4km
34 layers
Land-Surf...
1. Model domain for studying and forecasting air pollution
On 1/7/2014, published
in《Environ Chem
Lett》
The Springer had a Press Release for this paper in
English, Chinese and German,
More than 600 world medias, newspapers, an...
Background(Air pollution and haze formation)
v Main emission sources in China:
v Industrial: point sources, coal-combustion is mainly
responsible for air pollution i...
Backgound (How USA controls air pollution)
vLos Angeles Photochemic. Smog Event (Aug-Sep., 1955)
vHourly O3con. >500 ppb...
v1948 Pittsburgh Donora smog event :
vkilled 20 people and sickened 7,000
vPittsburgh: capital of the iron and steel in...
Background (air pollution in USA)
vAir pollution and haze in Utah’s valley, Salt Lake City
vMost serious air pollution c...
背景 (英国London治理大气污染现状)
vLondon Great Smog event(1952)
vCauses:Coal combustion
vControl method:
vClean air law for Londo...
Background (air pollution control in China)
vControl strategy:
vSeptember 2013,State Council issued <<Action Plan for th...
v 2014-03-26 PM2.5 conc. ,
v Beijing had yellow warning for heavy haze (03-24)
03-26 AQI in Beijing: 400
Provincial Coal...
v Surface weather map (http://www.nmc.gov.cn/publish/observations/weatherchart-h000.htm)
Beijing: Low pressure system,poo...
vThe air Pollution Control during Beijing Olympic Games
vThe city suspended 50% vehicles, Shut down steel Corporation
an...
Background (air pollution control in China)
vEmergency plan for heavy air pollution days
vBeijing: week haze from 2/20-2...
Background (air pollution control in China)
vRemoval of pollution in the air (Yu et al. 2000; 2001)
vWet deposition:
vF...
Background (air pollution control in China)
v Recent very good air quality in China
Precipitation in China on
5/13 14:00-...
Water spray geoengineering to clean air pollution for cities
v Inspiration :
v Wet dep. is the most
effective method to ...
v Rivers and lakes accounted for 8% areas in
Hangzhou. Qian Tang River passes through the city.
Water spray geoengineerin...
v PM2.5 concentrations (CPM2.5) with precipitation scavenging
time can be calculated as follows (Seinfeld and Pandis, 200...
PM2.5 conc. as a
function of
scavenging time for
different scavenging
coefficients
PM2.5concentration
Scavenging time (hr)...
Scavenging time
needed (h) to
decrease PM2.5
conc. from three
original PM2.5
conc. to 35
µgm-3
PM2.5 (µg m-3)
µ(hr-1) 100 ...
v Precipitation scavenging coefficient µ(hr-1) (Pruppacher
and Klett, 1997):
da: aerosol particle diameter
Dr: raindrops ...
v Precipitation rate,
particle and drop
sizes determine
scavenging
coefficient
Scavengingcoefficient(hr-1)
Par$cle	
  dia...
Water spray geoengineering to clean air pollution and haze(Yu, 2014)
Charged drops increase scavenging coefficients
A. K. ...
Air assisted electrostatic spray gun
Ø Droplet diameter with charges: 100-300 µm,
Price: 50,000RMB
Ø Shot range: 20 -100...
Conceptual pictures of the water spray
geoengineering
v For cities water
sprinklers are installed
on the roof of building...
Water cost estimates:
Ø  Beijing City area: 16,801km2,
Ø  a sprinkler for every 250 m,
Ø  total 268816 sprinklers
Ø  A...
The arguments in favor of this engineering approach:
(1)Precipitation scavenging processes are natural processes。
(2) Spee...
For possible potential problems:
(1)If too much water is sprayed into the atmosphere at one time
and one place, this will ...
Definitely, there are still significant challenges in
designing a specific delivery system that is capable of
delivering w...
South China Morning Post (HongKong):
"We will do some tests in Zhejiang University campus
first and then Hangzhou city if ...
Ø  It will take ten years or longer to realize the effective
management of the haze through direct control of
air polluta...
Water spray geoengineering to clean air pollution for mitigating severe haze in china’s cities. Keynote from Prof. Shaocai Yu
Water spray geoengineering to clean air pollution for mitigating severe haze in china’s cities. Keynote from Prof. Shaocai Yu
Upcoming SlideShare
Loading in …5
×

Water spray geoengineering to clean air pollution for mitigating severe haze in china’s cities. Keynote from Prof. Shaocai Yu

623 views

Published on

CLEEN's MMEA program organised an international seminar on cleaner air - Outdoor and indoor air quality together with Zhejiang University and assistant organizer Insigma group.
This is one of the keynote presentations in the seminar.
More info in www.mmea.fi

The cleantech field is expanding rapidly and Finnish companies are committed to working for a better environment in the fields of energy efficiency, air quality and monitoring. The world-class Cleantech know-how from Finland and the cooperation with Chinese partners and the results were highlighted in the MMEA seminar. Some of the leading Finnish cleantech companies together with Finnish and Chinese research institutions were present at the event. The seminars focused on cooperation between Finland and China concerning indoor and outdoor air quality and solutions to make them better.

Published in: Environment
0 Comments
0 Likes
Statistics
Notes
  • Be the first to comment

  • Be the first to like this

No Downloads
Views
Total views
623
On SlideShare
0
From Embeds
0
Number of Embeds
74
Actions
Shares
0
Downloads
8
Comments
0
Likes
0
Embeds 0
No embeds

No notes for slide

Water spray geoengineering to clean air pollution for mitigating severe haze in china’s cities. Keynote from Prof. Shaocai Yu

  1. 1. Water spray geoengineering to clean air pollution for mitigating severe haze in China’s cities Shaocai Yu, Professor, Ph.D. Research Center for Air Pollution and Health, College of Environmental and Resource Sciences, Zhejiang University, China. 浙江大学环境与资源学院
  2. 2. Current Researches in my group: 1. US EPA WRF-CMAQ model and OBSto study and forecast air pollution-haze in China 2. Water spray geoengineering to clean air pollution 3.Air pollution and environmental health
  3. 3. 1。, WRF-CMAQ空气质量模式研究中国东部区域大气污染 和雾霾演变规律及其动态预警预报 Meteorological Model WRF modeling System: Δx=12 km, 4km 34 layers Land-Surface: PX LSM PBL: ACM2 Cloud Physics: Morrison Cumulus: Kain-Fritsch, not for 4km Shortwave: RRTMg, or CAM Longwave: RRTMg, or CAM Coupler 双向耦合器 Chemical Transport Model CMAQ Modeling System: Photochemistry: CB05 59 organic and inorganic species, 156 chemical reactions Aerosol module: AE6 3 lognormal modes, organic and inorganic Emission: SMOKE In-line emission for biogenic species AQPREP Prepares virtual CMAQ compatible input met. files CMAQ-mixactivate: cloud drop, ice number conc. Direct forcing: Aerosol size, composition, conc. WRF模式 CMAQ模式 US EPA Two-way coupled WRF-CMAQ modeling System (Interaction and feedback) (Yu et al., 2014)
  4. 4. 1. Model domain for studying and forecasting air pollution
  5. 5. On 1/7/2014, published in《Environ Chem Lett》
  6. 6. The Springer had a Press Release for this paper in English, Chinese and German, More than 600 world medias, newspapers, and TVs have widely reported the results Such as sciencedaily, natureworldnews, pbs, IBtimes, CNN, Wall Street Journal, usa.chinadaily, Hongkong Herald, SouthChina Morning Post, and Chinese Academy of Science, eastday, sina, Shanghai people's Broadcasting Station etc
  7. 7. Background(Air pollution and haze formation)
  8. 8. v Main emission sources in China: v Industrial: point sources, coal-combustion is mainly responsible for air pollution in China v Personal activities: traffic, heating, cooking, v Biogenic emissions: area sources v As a city, emissions: ü Local sources: controllable ü Long-range Transport:uncontrollable Background (emission sources in China) Air pollution is not easy to manage because of this nature
  9. 9. Backgound (How USA controls air pollution) vLos Angeles Photochemic. Smog Event (Aug-Sep., 1955) vHourly O3con. >500 ppb vMain reason: car emissions vControlling car emissions improves air quality significantly Haze problem is still big right now (2011)
  10. 10. v1948 Pittsburgh Donora smog event : vkilled 20 people and sickened 7,000 vPittsburgh: capital of the iron and steel industry vEmissions in Donora : U.S. Steel industry (Zinc) Significantly improve air quality method now: Shut down the polluting enterprises, enterprise transformation, especially high-tech industry. Backgound (How USA controls air pollution)
  11. 11. Background (air pollution in USA) vAir pollution and haze in Utah’s valley, Salt Lake City vMost serious air pollution city in USA。 vJanuary 25, 2014: Largest Air Pollution Rally in US History in Utah's Capitol Hill vSources: Copper industrial and car emissions vPM2.5>150 µg/m-3 Air pollution is serious because the industrial emissions are still there!!!
  12. 12. 背景 (英国London治理大气污染现状) vLondon Great Smog event(1952) vCauses:Coal combustion vControl method: vClean air law for London. vShutting down all power plants and industrial facilities in London. The massive transformation of traditional stoves, reducing coal use, central heating, improvement of city public traffic system. In both USA an UK, Shutting down polluting industrials is main reasons for the significant improvement of air pollutions
  13. 13. Background (air pollution control in China) vControl strategy: vSeptember 2013,State Council issued <<Action Plan for the Prevention and Control of Air Pollution>> vThis plan aims to reduce air pollution by over 10% from 2012 to 2017 vTechnology: Direct emission reduction and regional joint prevention and control vIn Beijing:four methods: Reducing coal use and emissions, controlling dust and car vHowever, from 2013 to now, all these measures have not achieved significant results (Xinhua)!!
  14. 14. v 2014-03-26 PM2.5 conc. , v Beijing had yellow warning for heavy haze (03-24) 03-26 AQI in Beijing: 400 Provincial Coal Consumption
  15. 15. v Surface weather map (http://www.nmc.gov.cn/publish/observations/weatherchart-h000.htm) Beijing: Low pressure system,poor dispersion conditions L L L March25 L Cold Front 0:00 6:00 12:00 18:00
  16. 16. vThe air Pollution Control during Beijing Olympic Games vThe city suspended 50% vehicles, Shut down steel Corporation and other 21 key polluting enterprises vSO2, NOx, NMVOC emissions reduced by85%, 46%, 57% vSix provinces: air pollution joint prevention and control n “APEC Blue” in Beijing (2014 Fall) n widely credited to temporarily shutting down hundreds of factories in cities in Beijing and surrounding six provinces Air quality improvement mainly due to shutting down polluting factories and stop driving, instead of direct emission reduction by technology!! Background (air pollution control in China)
  17. 17. Background (air pollution control in China) vEmergency plan for heavy air pollution days vBeijing: week haze from 2/20-27 (2014)(PM2.5>200 µg/m3) v《Beijing's Heavy Air Pollution Emergency Plan》: vShut down 58 enterprises; reduce 30% production in 41 factories etc vAll emergency plans are used, no obvious effect vFinally on the 27, haze disappeared because of wind and rain vWhy? vAir pollutants are already in the atmosphere, all emergency can only reduce emissions, but there is no effective way to remove pollutants in the atmosphere !! Haze was removed by Nature (wind and rain), no other way (Xinhua)
  18. 18. Background (air pollution control in China) vRemoval of pollution in the air (Yu et al. 2000; 2001) vWet deposition: vFalling rain droplets or snow particles scavenge aerosols vBrownian diffusion, interception, impaction and turbulent diffusion vEffective way to remove particles and trace gases vDry deposition vAerosols and other acidic substances directly deposit to the surface vWind speed, atmospheric stability, chemical and surface characteristics These are scientific basis for removing haze by rain and wind, Wet dep. is more efficient for removing air pollutants
  19. 19. Background (air pollution control in China) v Recent very good air quality in China Precipitation in China on 5/13 14:00-5/14 14:00 PM2.5 in China on 5/14 14:00 Rain causes good air!!!
  20. 20. Water spray geoengineering to clean air pollution for cities v Inspiration : v Wet dep. is the most effective method to clean haze v spray water into the atmosphere like watering a garden v Shanghai with a big river has heavy haze Shanghai can use water spray geoengineering to curb its haze and air pollution 1/23/2013
  21. 21. v Rivers and lakes accounted for 8% areas in Hangzhou. Qian Tang River passes through the city. Water spray geoengineering to clean air pollution for cities Hangzhou can use water spray geoengineering to curb its haze and air pollution
  22. 22. v PM2.5 concentrations (CPM2.5) with precipitation scavenging time can be calculated as follows (Seinfeld and Pandis, 2006): CPM2.5=C0,PM2.5e-µt C0,PM2.5:initial PM2.5 concentration µ:precipitation scavenging coefficient(hr-1) t:scavenging time(hr) Water spray geoengineering to clean air pollution and haze(Yu, 2014)
  23. 23. PM2.5 conc. as a function of scavenging time for different scavenging coefficients PM2.5concentration Scavenging time (hr) scavenging coefficient µ(hr-1) Water spray geoengineering to clean air pollution and haze(Yu, 2014)
  24. 24. Scavenging time needed (h) to decrease PM2.5 conc. from three original PM2.5 conc. to 35 µgm-3 PM2.5 (µg m-3) µ(hr-1) 100 200 1000 0.01 105.0 174.3 335.2 0.05 21.0 34.9 67.0 0.1 10.5 17.4 33.5 0.5 2.1 3.5 6.7 1 1.0 1.7 3.4 1.5 0.7 1.2 2.2 2 0.5 0.9 1.7 2.5 0.4 0.7 1.3 3 0.3 0.6 1.1 Water spray geoengineering to clean air pollution and haze(Yu, 2014)
  25. 25. v Precipitation scavenging coefficient µ(hr-1) (Pruppacher and Klett, 1997): da: aerosol particle diameter Dr: raindrops diameter E(Dr, da) is collection efficiency, P is precipitation rate (rainfall intensity). Water spray geoengineering to clean air pollution and haze(Yu, 2014)
  26. 26. v Precipitation rate, particle and drop sizes determine scavenging coefficient Scavengingcoefficient(hr-1) Par$cle  diameter(um) Droplet  size Automatic sprinkler system need to be specially designed to spray droplet size and rain strength Water spray geoengineering to clean air pollution and haze(Yu, 2014)
  27. 27. Water spray geoengineering to clean air pollution and haze(Yu, 2014) Charged drops increase scavenging coefficients A. K. BARLOW and J. LATHAM,A laboratory study of the scavenging of sub-micron aerosol by charged raindrops, Quart. J . R. Met. SOC. (1983), 109, pp. 763-770 Ø Charged drops increase E by two orders Ø PM2.5 particles have positive charges Collection coefficient Charge Charge-free drop Charged drop
  28. 28. Air assisted electrostatic spray gun Ø Droplet diameter with charges: 100-300 µm, Price: 50,000RMB Ø Shot range: 20 -100 meters
  29. 29. Conceptual pictures of the water spray geoengineering v For cities water sprinklers are installed on the roof of buildings (and tower) v For the open place, build towers v This can apply to industrial areas。 Water spray geoengineering to clean air pollution and haze(Yu, 2014)
  30. 30. Water cost estimates: Ø  Beijing City area: 16,801km2, Ø  a sprinkler for every 250 m, Ø  total 268816 sprinklers Ø  A sprinkler sprays 7.6 Tons/day。Price: 1ton/4yuan Ø  Electricity for bring 1 ton water to 50 m high: 0.095yuan。 Ø  1 spray point fee: 31.1yuan/day Ø  Fee for 268816 spray points: 8,366,214yuan Ø  Assume that 300 days is needed, fee: 2.51billion yuans/year Ø  If the water can be collected with 50% efficiency, fee Ø  1.26billion yuan/year Water spray geoengineering to clean air pollution and haze(Yu, 2014)
  31. 31. The arguments in favor of this engineering approach: (1)Precipitation scavenging processes are natural processes。 (2) Speed of action: precipitation scavenging management can work quickly because the precipitation scavenging can remove air pollution within half hour 。 (3)Technological feasibility: all technologies and material required are pre-existing: high building, high tower, water, automatic sprinkler head to spray water etc. (4)Low cost issue: the low-tech nature of this engineering approach has led us to believe that it will have low cost (5) Efficacy: (6) Some tipping points:remove other gaseous pollutants such as SO2 and Nox, reduce possible O3 and secondary PM formation and clean the streets of the megacities。 Water spray geoengineering to clean air pollution and haze(Yu, 2014)
  32. 32. For possible potential problems: (1)If too much water is sprayed into the atmosphere at one time and one place, this will cause flood as we can expect. (2)If water droplets do not reach ground but evaporate completely during the falling, this will increase the relative humidity in the atmosphere in the megacities. (3) If water is sprayed into the atmosphere in the cold days such as winter time, this will produce snow and cause slipping grounds because of freezing rain. Water spray geoengineering to clean air pollution and haze(Yu, 2014)
  33. 33. Definitely, there are still significant challenges in designing a specific delivery system that is capable of delivering water in the right manner, right place and right time to encourage most effective precipitation scavenging for air pollution and how to set up the sprinkler systems for a city to mitigate the regional haze with low cost Research Question for water spray geoengineering Water spray geoengineering to clean air pollution and haze(Yu, 2014)
  34. 34. South China Morning Post (HongKong): "We will do some tests in Zhejiang University campus first and then Hangzhou city if everything goes well," he says. "If we are successful, our work can be followed by the other cities in China and around the world." Prospects: Water spray geoengineering to clean air pollution and haze(Yu, 2014)
  35. 35. Ø  It will take ten years or longer to realize the effective management of the haze through direct control of air pollutant emissions as governments say, Ø  Under the condition with no big change in the energy structure and current emission situation in China, I think the water spray geoengineering may be effective emergency scheme for mitigating serious haze pollution in China. Prospects Water spray geoengineering to clean air pollution and haze(Yu, 2014)

×