Mercury Emissions from Coal Combustion in China

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Apr 7, 2008 - Nonferrous metals smelting (zinc, copper, gold, and lead). See these two papers for description of the results presented here: Streets et al.
Mercury Emissions from Coal Combustion in China

David G. Streets Argonne National Laboratory Jiming Hao, Shuxiao Wang, Ye Wu Tsinghua University, Beijing

International Conference of the UNEP Global Partnership on Atmospheric Mercury Transport and Fate Research Rome, Italy, April 7-11, 2008

Argonne and Tsinghua collaboration

David G. Streets Argonne National Laboratory USA

Jiming Hao, Shuxiao Wang, Ye Wu Tsinghua University China

Project Sponsors: o

o

o

Melissa Chan, Mark Freeman, Tom Feeley DOE National Energy Technology Laboratory, USA

Thank you!

Conrad Chin, Marianne Bailey, Carl Mazza, Carey Jang US Environmental Protection Agency, USA

National Key Basic Research and Development Program of China 2

This presentation focuses on coal combustion, but there are many other significant sources of Hg in China:  Other combustion sources 

Fuel oil (gasoline, diesel, kerosene, and residual oil)  Biofuels  Grassland/Savanna/Forest fires  Agricultural residue/Household waste burning  Coal mines spontaneous burning  Non-combustion sources (feedstock emissions only)  Mercury mining  Battery/Fluorescent lamp production  Cement production  Iron and steel production  Caustic soda production  Nonferrous metals smelting (zinc, copper, gold, and lead)

See these two papers for description of the results presented here: Streets et al., Atmos. Environ., 39, 7789-7806, 2005 Wu et al., Environ. Sci. Technol., 40, 5312-5318, 2006 3

Coal combustion comprises about 37% of total anthropogenic Hg emissions in China; the next talk discusses the other sources 800

Others 700

Non-ferrous Metal Smelting

600

500

400

300

200

100

20 03

20 02

20 01

20 00

19 99

19 98

19 97

19 96

0

19 95

Total Hg Emissions in China (Mg yr-1)

Coal Combustion

4

Coal is used everywhere in China, often in unfamiliar ways

5

Trends in raw coal consumption in China, 1995-2005

2.65 billion tons 2,500,000

2,000,000

Industrial use (feedstock) (17.8%) For briquettes (4.2%) For coal washing (7.1%) Other uses (combustion) (2.0%)

1,500,000 Residential use (-0.1%)

1,000,000

500,000

Coking (0.9%) Industrial use (combustion) (4.1%) Power plants (8.9%)

-

19 95 19 96 19 97 19 98 19 99 20 00 20 01 20 02 20 03 20 04 20 05

Total Raw Coal Consumption (1000 tons)

3,000,000

6

1,500,000 For briquettes

1.48 billion tons

Coking (8.2%)

1,200,000

Cleaned coal (coking) (8.5%) Cleaned coal (combustion) (4.8%)

900,000

Raw coal (coking) (0.9%) Raw coal (combustion) (4.1%)

600,000

300,000

05

20

04

20

03

20

02

20

01

20

00

20

99

19

98

19

97

19

96

19

95

-

19

Total Coal Consumption for Industrial Use (1000 tons)

Trends in industrial coal consumption in China, 1995-2005

7

Calculation procedure for mercury emissions from coal combustion in China Fractions released during combustion, reduced by control devices, and finally emitted (by species)

Spreadsheet is 107 x 32 (Fuel/Tech combinations x Provinces)

China Energy Statistics

Tech Splits

Hg in fuel

FREL

FRED

FSp

Fuel Use by Sector

Fuel Use by Sector, Technology

Total Hg

Hg released

Hg emitted

Hg(Sp) emitted

Hg to bottom ash

Hg to fly ash

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A n B hu ei i j Fu ing G G jia ua a n ng ns G do u ua ng G ng ui x z i H hou ai H e i H nan lo e ng b jia ei H ng en H an u H be u i Ji na an n Ji gs an u gx i L N iao Jili ei n n M in o g N ng in ol Q gx in ia S gh S ha ai ha an nd xi S on h g S an ic x X hua i in n j Y ian u Zh nn g ej an ia ng

Mercury content of coal as mined (g Mg -1)

Mercury content of raw coal, as mined (g Mg-1) 0.6

0.5

National average, ~0.19 g Mg -1 National Average

0.4

0.3

0.2

0.1

0

9

Inter-province model of coal transportation flows

10

Examples of shares of boiler types with PM control devices for coal-fired power plants, by province, 1999 PC/scrubber

Stoker/scrubber

Stoker/cyclone

100%

80%

60%

40%

20%

nh u

Be i iji ng Fu jia n G G ans ua u ng do G ng ua ng G xi ui zh ou H He b ei e lo ng i jia ng H en an H ub ei H un a Ji n an gs u Ji an gx i

0%

A

Share of boiler types with PM control devices

PC/ESP

11

100.0% 80.0% ESP

60.0%

Scrubber Cyclone

40.0%

Power sector: now mostly ESPs

20.0% 0.0% 1995

1996

1997

Industrial sector: A mixture of wet PM scrubbers, cyclones, and no control

1998 Penetration of PM Control Device Installation

Penetration of PM Control Device Installation

Time development of the penetration of PM control devices

1999 2000

2001

2002

2003

60.0%

40.0%

20.0%

Scrubber Cyclone None

0.0% 1995

1996

1997

1998

1999

2000

2001

2002

2003

12

Mercury removal efficiencies of control technologies have been estimated, but there is no province, combustor, or time variation yet; many values are based on western experience Removal Efficiency (%) Case

Fuel/Combustor Type

PM Control

Provinces of China Anhui

31

Hard coal/PC

filter or ESP

33

Hard coal/PC

34

Beijing

Fujian

Gansu

Guangdong

30.6

30.6

30.6

30.6

30.6

scrubber

6.5

6.5

6.5

6.5

6.5

Hard coal/PC

cyclone

0.1

0.1

0.1

0.1

0.1

32

Hard coal/stoker

filter or ESP

30.6

30.6

30.6

30.6

30.6

35

Hard coal/stoker

scrubber

6.5

6.5

6.5

6.5

6.5

36

Hard coal/stoker

cyclone

0.1

0.1

0.1

0.1

0.1

85

Hard coal/cyclone

scrubber

6.5

6.5

6.5

6.5

6.5

86

Hard coal/cyclone

cyclone

0.1

0.1

0.1

0.1

0.1

37

Cleaned coal/PC

filter or ESP

30.6

30.6

30.6

30.6

30.6

39

Cleaned coal/PC

scrubber

6.5

6.5

6.5

6.5

6.5

40

Cleaned coal/PC

cyclone

0.1

0.1

0.1

0.1

0.1

38

Cleaned coal/stoker

filter or ESP

30.6

30.6

30.6

30.6

30.6

41

Cleaned coal/stoker

scrubber

6.5

6.5

6.5

6.5

6.5

42

Cleaned coal/stoker

cyclone

0.1

0.1

0.1

0.1

0.1

13

Trends in mercury emissions from coal combustion, 1995-2005 350

334 Mg 5.1% AGR

Industrial use (combustion) (4.9%)

300

Residential use (1.3%) Other uses (combustion) (2.0%)

250

200

150

100

50

05 20

04 20

03 20

02 20

01 20

00 20

99 19

98 19

97 19

96 19

95

0

19

Total Mercury Emissions from Coal Combustion (Mg)

Power plants (7.0%)

14

Uncertainty in Hg emissions from coal combustion, as 95% confidence intervals Mercury emissions (Mg) with uncertainty (95% confidence intervals)

500

400

300

200

100

19 95 19 96 19 97 19 98 19 99 20 00 20 01 20 02 20 03 20 04 20 05

0

We estimate that the uncertainty in emission estimates for coal combustion has remained stable over this period at ~ ±35% 15

1200

Best Estimates 1000 800 600 400 200 0

19 95 19 96 19 97 19 98 19 99 20 00 20 01 20 02 20 03

Total Hg emissions with uncertainty (95%confidence interval)

Uncertainty in total Hg emission estimates

In general, the uncertainty level has diminished over time (±78% down to ±44%). This is primarily attributed to decreased emissions from those Hg sources that have the largest uncertainty in both activity levels and emission factors, such as artisanal gold smelting, mercury mining, and battery/fluorescent lamp production. 16

Stochastic simulations are being developed to address uncertainties in Hg emission estimates when large sample sizes are available (e.g., Hg-in-coal)

17

A n B hu ei i j Fu in g G G jia ua a n n g ns G do u u n G an g g ui x z i H ho ai u H ei H nan lo e ng be ji i H an g en H an u H be Ji una i an n Ji gs an u gx Li Ji i N ao li n ei n M in o g N ng in ol Q gx i i Shngh a Sh a ai a an Sh nd xi an ong g Sh ha Si an i ch xi u Ti an Xi an n jin Yu jian Zh n n g e a N j ia n at ng io na l

Speciation Breakdown (%)

Speciation of Hg emitted from coal combustion (1999), by province 100%

80%

60%

40%

Hg0 Hg2+ Hg(p)

20%

0%

National average estimated to be: 64% Hg2+, 19% Hg(p), and 17% Hg0 18

Gridded Hg emissions from coal combustion in 1999 at 30 min resolution (Mg yr-1 per grid cell)

Total Hg (coal combustion sources) 0 - 0.0025 0.0025 - 0.1 0.1 - 0.4 0.4 - 1 1 - 10 10 - 32.5

19

Expected penetration of FGD on coal-fired power plants in China by 2010 and 2020, showing percentages by province 2010: 58% nationwide

2020: 67% nationwide

We assume the Hg removal efficiency of future plants to be: 74% (ESP+FGD)

20

Anticipated growth in electricity generation and coal use in China in 2010 and 2020 Coal

1,800

Electricity 3500

1,600 3000 1,400 2500

1,200 1,000

2000

800

1500

600 1000 400 500

200

20 20

10 20

03 20

02 20

01 20

00 20

99 19

98 19

97 19

19

96

0 95

-

Electricity Generation (billion kWh)

4000

19

Coal Consumption (million tons)

2,000

1) Nationwide, coal-based electricity is projected to increase at an annual rate of 7.5% in 2003-2010, and 3.8% in 2010-2020. 2) As a result, coal use reaches 1.29 billion tons in 2010 and 1.77 billion tons in 2020. 21

250

Planned FGD + SCR, ACI 200

150

Planned FGD

100

50

20 20

20 10

0

19 95 19 96 19 97 19 98 19 99 20 00 20 01 20 02 20 03

Hg Emissions from Power Plants, tons

The benefits of FGD in 2010, and of FGD and other controls (like SCR and a little ACI) by 2020, on mercury emissions from coalfired power plants: Emissions can potentially be stabilized

22

Research question: Can we reconcile emission estimates with measurements of the Hg flux leaving Asia?

Guizhou sites [Feng et al., JGR, 110, D14306, 2005, etc.]

Aircraft measurements and modeling during ACE-Asia campaign [Pan et al., JGR, 111, D07109, 2006; Friedli et al., JGR, 109, D19S25, 2004]

Okinawa site [Jaffe et al., Atmos. Environ., 39, 3029, 2005]

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Future plans  Refine estimates of anthropogenic Hg emissions in China,  

 

including the important contributions from zinc smelters. Incorporate stack test measurements that are now becoming available. Estimate future Hg emissions under alternative scenarios of growth and the penetration of new production and emission control technologies. Incorporate uncertainty explicitly into our calculations through stochastic modeling. Support the Hg atmospheric modeling community and work to reconcile flux measurements with model and emissions estimates, factoring in new information on natural sources and re-emission.

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