Investigation of primary and secondary aerosols Investigation of primary and secondary aerosols from wood combustion with a high resolution from wood combustion with a high resolution

time of flight aerosol mass spectrometertime of flight aerosol mass spectrometer

Maarten Heringa Maarten Heringa

Laboratory of Atmospheric ChemistryPaul Scherrer Institut, Switzerland

Gothenburg 23-06-2008

Why are we interested in wood burning?Why are we interested in wood burning?

Biomass has the potential to become the world’s largest and most sustainable renewable energy source. (2004 Survey of Energy Resources World Energy Council)

Three billion people use small-scale wood fueled appliances that are both inefficient and highly polluting. (2007 Survey of Energy Resources World Energy Council)

Examples of wood burningExamples of wood burning

Wood burning in Roveredo SwitzerlandWood burning in Roveredo Switzerland

Wood is used as fuel for 75% of the domestic heating installationsin Roveredo Switzerland1

1(Alfarra et al., 2007 Environ. Sci. Technol)

Incomplete combustionC,H,O + O2 + → CO2 + H2O + CO + CxHyOz

N2 + impurities NOx + salts + minerals + BC

Complete combustionC,H,O + O2 + → CO2 + H2ON2 + impurities NOx + salts + minerals

Wood combustionWood combustion

Cellulose, hemicellulose and lignin are the main constituents of wood

Wood combustion markersWood combustion markers

Levoglucosan has been reported as major constituentof fine particulate emissions2 and its prominent fragmentat m/z 60 has been used as marker ion3

2(Reid et al., 2005 Atmos. Chem. Phys) 3(Alfarra et al., 2007 Environ. Sci. Technol)

Fragment m/z 60 is not unique for levoglucosan!

ObjectivesObjectives

• Characterization of primary emissions– Log wood burners– Automatic pellet burners– Wood burning markers m/z 60, 73 and 137

• Investigation of the stability of wood burning markers m/z 60, 73 and 137

• Investigation of the SOA formation potential of wood burning emissions in the PSI smog chamber

HR-ToF-AMS

Particle Inlet (1 atm)

QuadrupoleMass Spectrometer

AerodynamicLens (2 Torr)

Chopper (150 Hz)

Turbo Pump (~1E-3 Torr)

TOF Region

AERODYNAMIC SIZING CHAMBER

Turbo Pump (~1E-5 Torr)

Turbo Pump (~1E-8 Torr)

Flow ~ 2.2 cm3/sec

Detector

Q-AMSQ-AMS

TOF SpectrometerFlow

~ 1.3 cm3/sec

(Jayne et al., 2000; De Carlo et al., 2006)

Thermal Vaporization

(600°C)and

Electron Ionization

(70 eV)

eˉ

Critical orifice (130 µm)

Critical orifice (100 µm)

DETECTION CHAMBER

Primary emissionsPrimary emissions

Pellet burner80% (7.2 kW), 1.46 kg/h

Log wood burner0.5kg softwood + 2 x 2.7kg beech

Clean air generator

Heated Diluter(150°C)

Scheme of the setupScheme of the setup

TOF-AMS

Excess airExcess air

Diluter

MAAP

CO, CO2 ,O2 analyzer

FMPS

CVS

Dilution ratio~150x

Dilution ratio calculationsDilution ratio calculations

Pellet burnerPellet burner

140

120

100

80

60

40

20

0

Mas

s C

once

ntra

tion

(mg

m-3

)

15:1522.10.2007

15:30 15:45 16:00

Date and Time

Org NO3 SO4 Chl PAH

12

8

4

0

Mas

s C

once

ntra

tion

(mg

m-3

)

15:3022.10.2007

15:40 15:50

Date and Time

10x

Start automatic burnerStart automatic burner

40

30

20

10

0

Nitr

ate

Equ

ival

ent M

ass

Con

cent

ratio

n (µ

g m

-3)

14012010080604020m/z

60

73 137

10

8

6

4

2

0

Nitr

ate

Equ

ival

ent M

ass

Con

cent

ratio

n (µ

g m

-3)

14012010080604020m/z

Species

AirWaterAmmoniumNitrateSulphateChloridePAHOrganics

Start peak

Wood burning markersm/z 60, 73, 137

10

8

6

4

2

0

Nitr

ate

Equ

ival

ent M

ass

Con

cent

ratio

n (µ

g m

-3)

14012010080604020m/z

Species

AirWaterAmmoniumNitrateSulphateChloridePAHOrganics

Stable burning automatic burnerStable burning automatic burner

40

30

20

10

0

Nitr

ate

Equ

ival

ent M

ass

Con

cent

ratio

n (µ

g m

-3)

14012010080604020m/z

60

73 137

Stable burning

Wood burning markersm/z 60, 73, 137

m/z 44 is the base peak(like in OOA)

(Lanz et al., 2008 Environ. Sci. Technol.)

Reproducibility of a log wood burnerReproducibility of a log wood burner

2.7kg of beech cut to a standard size and weight

(Weimer et al., 2008 Geophysical Research)

400

300

200

100

0

Mas

s C

once

ntra

tion

(mg

m-3

)

14:0024.10.2007

15:00 16:00 17:00

Date and Time

Organics Ammonium Nitrate Sulphate Chloride PAH

Log wood burnerLog wood burner

1st load

2nd load

Start

Flaming

First load of beechFirst load of beech

60

40

20

0

Nitr

ate

Equ

ival

ent M

ass

Con

cent

ratio

n (µ

g m

-3)

14012010080604020m/z

Species

AirWaterAmmoniumNitrateSulphateChloridePAHOrganics60

13773

End of the fireEnd of the fire

8

6

4

2

0

Nitr

ate

Equ

ival

ent M

ass

Con

cent

ratio

n (µ

g m

-3)

14012010080604020m/z

Species

AirWaterAmmoniumNitrateSulphateChloridePAHOrganics

60 137

73

Clean air generator

Heated Diluter

Excess air

Heated line (150°C)

1:8

~4 L/min

Smog chamber setupSmog chamber setup

Aethalometer

CO,CO2,NOx,O3

TOF-AMSCPC + SMPS

CO2

Smog chamber experimentSmog chamber experiment

• Humidification of the chamber• Background measurements• Start the burner• Filling the chamber• Measurement primary emissions• Lights on

Organics and black carbonOrganics and black carbon

120

100

80

60

40

20

0

µg/m

3

543210-1Time after lights on (h)

2.0

1.5

1.0

0.5

0.0

Org/B

C

Org BC Org/BC

Wood burning markersWood burning markers

120

100

80

60

40

20

0

Org

µg/

m3

543210Time after lights on (h)

3.0

2.5

2.0

1.5

1.0

0.5

0.0

Percentage m

/z 60

3.0

2.5

2.0

1.5

1.0

0.5

0.0

M/z

60

µg/m

3 org ratio_60_org org60

0.16

0.14

0.12

0.10

0.08

0.06

0.04

0.02

0.00

Org

44/o

rg

543210Time after lights on (h)

org44_to_org start org44_to_org flaming

100

80

60

40

20

0

60.460.260.059.859.6m/z

2.0

1.5

1.0

0.5

0.0

Nitr

ate

equi

vale

nt m

ass

(µg

m-3

)

OxidationOxidation

50

40

30

20

10

0

60.460.260.059.859.6m/z

1.0

0.8

0.6

0.4

0.2

0.0

Nitr

ate

equi

vale

nt m

ass

(µg

m-3

)

100

80

60

40

20

0

44.444.244.043.843.6m/z

2.0

1.5

1.0

0.5

0.0

Nitr

ate

equi

vale

nt m

ass

(µg

m-3

) CO2+

C2H4O+

500

400

300

200

100

0

44.444.244.043.843.6m/z

10

8

6

4

2

0

Nitr

ate

equi

vale

nt m

ass

(µg

m-3

)

ConclusionsConclusions

Automatic pellet burners produce high concentrations of organics during the ignition

During stable burning the spectrum of the organics is dominated by m/z 44 which is the dominant signal of OOA

Log wood burners show large variations in concentration between runs and during a burning cycle

The wood burning marker at m/z 60 is mainly formed during the start consist of one molecular formula is stable for > 5 hours

Oxidation of the gas phase emissions of the tested log wood burner increased the organic aerosol mass with a factor of ~ 2-3

Take homeTake home

Burning automatic pellet burners emit less organics during stable burning than log wood burners. Nevertheless, high concentrations of organics are emitted during the ignition.

Log wood burners show large variations in emissions between runs and during a single burning cycle. The spectral changes during the burning cycle makes it more difficult to identify a representative source profile.

A particle filter can reduce the primary aerosol emissions. However, due to SOA formation, only a reduction of 25-40% can be established (for a particle filter with 80% efficiency)

Thanks to…Thanks to…

Thank you for your attention

Roberto Chirico, Peter DeCarlo, Agnes Richard, Torsten Tritscher, Marco Steiger, Rami Alfarra,

Andre Prévôt & Urs Baltensperger

Michael Sattler & Christian Gaegauf

Nickolas Meyer & Heinz Burtcher