VOC Emissions from Biofuel Crops Martin Graus NOAA Chemical Sciences Division CIRES, University of Colorado, Boulder, Colorado Introduction Plant cuvette laboratory Leaf cuvette field Flux experiment corn field Photo: diffusibility.com Photo: scienceprogress.org
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VOC Emissions from Biofuel Crops
Martin Graus NOAA Chemical Sciences Division
CIRES, University of Colorado, Boulder, Colorado
Introduction Plant cuvette laboratory Leaf cuvette field Flux experiment corn field
Co-Workers: Carsten Warneke (PI) NOAA CSD; CIRES University of Colorado, Boulder Allyson Eller EBIO & CIRES University of Colorado, Boulder Ray Fall BioChem & CIRES University of Colorado, Boulder Joost de Gouw NOAA CSD; CIRES University of Colorado, Boulder Bin Yuan College of Environ Sci and Eng, Peking University Yaling Qian Colorado State University, Fort Collins Philip Westra Colorado State University, Fort Collins
Introduction Plant cuvette laboratory Leaf cuvette field Flux experiment corn field
VOC Emissions from Biofuel Crops
1.! What are the dominant VOCs from biofuel crops:
2.! What are the likely oxidation products
3.! What is the total aerosol and ozone forming potential
4.! What biofuel plant species and/or cultivars have the lowest VOC/SVOC
emissions
Phase 1: laboratory and greenhouse measurements
Phase 2: small scale leaf cuvette study in the field
Phase 3: flux measurements in the field: larger scale
Focus on the air quality impacts of the large scale growth of biofuel crops
Introduction Plant cuvette laboratory Leaf cuvette field Flux experiment corn field
Volatile organic compounds (VOCs) are precursors for ozone and aerosols
corn, poplars, switchgrass, and miscanthus
!! Corn is the dominant biofuel crop in the US.
!! In 2010 35.7 million ha corn were planted in the US. (size of Germany; in 2011 over 37 million ha ! Japan)
!! In 2010 12.4 billion gal fuel EtOH were produced in the US. (compare 137.9 billion gal total gasoline supplied in the US)
!! At typical yields of 2.60 gal/bu this requires 38% of the total US corn production in 2010.
Introduction Plant cuvette laboratory Leaf cuvette field Flux experiment corn field
Motivation: Corn & Switchgrass
1)! USDA NASS report on Acreage (June 30, 2011) 2)! DOE EIA Monthly Energy Review January 2011
!! Very few peer-reviewed corn VOC emission studies published.
!! Emission inventories (including corn) tend to focus on isoprene, terpenes and ‘other VOCs’.
!! Discrepancies in corn emission rates (Lamb et al., 1987, Winer et al., 1989, Lamb et al., 1993, Das et al., 2003)
!! Previously there were no data on VOC emissions from switchgrass.
Introduction Plant cuvette laboratory Leaf cuvette field Flux experiment corn field
Photo: diffusibility.com
Motivation: Corn & Switchgrass
Photo: scienceprogress.org
Energy Independence and Security Act (2007) requires
!! increase of biofuels added to gasoline form 4.7 billion gal in 2007 to 36 billion gal in 2022
!! 21 billion gal must be produced from non-starch feedstock in 2022.
Introduction Plant cuvette laboratory Leaf cuvette field Flux experiment corn field
!! Cellulosic biofuel production is more energy efficient than ethanol production from corn (Hammerschlag, 2006).
!! Switchgrass is a promising feedstock candidate for cellulosic ethanol (Schmer et al. 2008).
Motivation: Corn & Switchgrass
Plant cuvette: •! All Teflon •! Large flow of clean air •! Lights automated •! CO2 controlled Species measured: •! switchgrass •! miscanthus •! bamboo •! Corn •! Poplar (future) Instruments: •! PTR-MS for VOCs •! GC-PTR-MS •! GC-MS •! LiCor for CO2
Phase 1: Plant Cuvette Studies
Introduction Plant cuvette laboratory Leaf cuvette field Flux experiment corn field
Switchgrass results published by Eller et al, Atmos. Environ. (2011) Miscanthus and bamboo results: Crespo et al, in preparation
Switchgrass Blackwell undisturbed: •! Small daytime emissions of
methanol, acetaldehyde and acetone
•! Very small isoprene and monoterpene emissions
•! Almost no emissions of wound compounds
Plant Cuvette studies of Undisturbed Switchgrass
Introduction Plant cuvette laboratory Leaf cuvette field Flux experiment corn field
0.20
0.15
0.10
0.05
0.00
1.251.100.95
0.010
0.008
0.006
0.004
0.002
VO
C e
mis
sio
n r
ate
nm
ol m
-2 s
-1
mass 69 Isoprene
mass 137 Sum of monoterpenes
1:00 AM 9:00 AM 5:00 PM 1:00 AM 9:00 AM 5:00 PM 1:00 AM
0.04
0.03
0.02
0.01
0.00
mass 81 + mass 99 hexenal wound compound
mass 83 + mass 101 hexenol wound compound
mass 143 wound compound
mass 33 Methanol
mass 45 Acetaldehyde
mass 59 Acetone
(+Propanol)
Switchgrass Alamo cutting/harvest and drying: •! Large emissions after cutting of
wound compounds •! Continued emissions during
drying •! Strong decrease of emissions
after one day of drying
Plant Cuvette studies of Switchgrass Harvesting
Introduction Plant cuvette laboratory Leaf cuvette field Flux experiment corn field
0.5
0.4
0.3
0.2
0.1
0.0
0.03
0.02
0.01
0.00
VO
C e
mis
sio
n r
ate
nm
ol m
-2 s
-1
mass 69 Isoprene
mass 137 Sum of Monoterpenes
biomass cut
1:00 AM 9:00 AM 5:00 PM 1:00 AM 9:00 AM 5:00 PM 1:00 AM 9:00 AM
0.15
0.10
0.05
0.00
mass 81 + mass 99 hexenal wound compound
mass 83 + mass 101 hexenol wound compound
mass 143 wound compound
biomass cut
biomass cut mass 33 Methanol
mass 45 Acetaldehyde
mass 59 Acetone (+ Propanol)
Growing and harvesting: yield of 12,000 kg ha-1 yr-1 12-hour day April-November growing season •! 3 kg C ha-1 methanol •! 1 kg C ha-1 acetaldehyde •! 1 kg C ha-1 acetone •! 0.5 kg C ha-1 isoprene + 1-penten-3-ol •! 0.9 kg C ha-1 monoterpenes •! 0.1 kg C ha-1 hexenol •! 0.2 kg C ha-1 hexenal
Switchgrass VOC emission estimates from Plant Cuvette studies
Introduction Plant cuvette laboratory Leaf cuvette field Flux experiment corn field
Switchgrass VOC emission estimates from Plant Cuvette studies
Introduction Plant cuvette laboratory Leaf cuvette field Flux experiment corn field
"! Switchgrass emissions small compared to other potential biofuel crops
•! Comparison with literature data
•! Large variations in emission ratios
•! Corn is weak MT emitter and does not emit isoprene; ‘other VOCs’
may have some significance (Lamb et al., 1993)
Eller et al 2011
Phase 2: Leaf Cuvette studies of Switchgrass and Corn
Introduction Plant cuvette laboratory Leaf cuvette field Flux experiment corn field
Leaf cuvette: •! LiCor6400 coupled to
PTR-MS for VOCs
Instruments: •! PTR-MS for VOCs •! LiCor for CO2
a), H2Ob)
Species measured: •! Various switchgrass •! Sweet and field corn
Partner: •! Horticultural Farm
CSU Ft. Collins
Syn Air
CO2
a)! Assimilation: Net uptake of CO2 b)! Stomatal conductance: how open are pores of the leaf
Leaf Cuvette Compared to Whole Plant Cuvette
Introduction Plant cuvette laboratory Leaf cuvette field Flux experiment corn field
Leaf cuvette (field study): •! In-field well Developed Leaves •! Leaf Level Flux Rates •! Full Control over Environ. Factors
•! High Dilution (Poor VOC Flux LOD) •! Very Fast Dynamic Enclosure
Plant cuvette (lab study): •! Potted Plants; Greenhouse Grown •! Whole Plant Flux Rates •! Limited Control over Environ. Factors •! Good Flux LOD
•! Response Time: Tens of Minutes
Syn Air
CO2
Leaf Cuvette Compared to Whole Plant Cuvette
Introduction Plant cuvette laboratory Leaf cuvette field Flux experiment corn field
Leaf cuvette (field study): •! Positive selection fro well developed top-of-the-canopy leaves
Plant cuvette (lab study): •! Integration over the whole plant and scaled to total leaf area
•! Data indicates that care must be taken for the upscaling of leaf level emission rates •! Methanol is strongest VOC emission from switchgrass
Drivers for Methanol Emission from Switchgrass
Introduction Plant cuvette laboratory Leaf cuvette field Flux experiment corn field
•! About 1/3 of MeOH flux variability can be explained by stomatal conductance. •! Different switchgrass varieties show different MeOH emission rates. •! Factors such as weather history and water availability play a role.
Introduction Plant cuvette laboratory Leaf cuvette field Flux experiment corn field
Comparison of emission rates: •! Corn has significantly higher VOC emissions than switchgrass
Submission to Atmospheric Enivronment special issue on Agriculture and Air Quality will
show this data.
Leaf Plant Cuvette studies: Field Corn vs. Sweet Corn
Introduction Plant cuvette laboratory Leaf cuvette field Flux experiment corn field
Comparison of emission rates: •! Field and sweet corn show similar VOC emission rates and patterns
Submission to Atmospheric Enivronment special issue on Agriculture and Air Quality will
show this data.
Why ecosystem flux measurement: •! No up-scaling from leaf/plant level to ecosystem necessary •! No disturbance of the plants by enclosures •! Ambient environmental factors •! Looking into both emission and uptake of VOC
Why corn field: •! Corn is still the most important biofuel crop •! Little information on VOC emissions in literature from corn or switchgrass •! Leaf cuvette studies showed much larger emissions from corn than from switchgrass
Phase 3: Ecosystem Flux Measurements
Introduction Plant cuvette laboratory Leaf cuvette field Flux experiment corn field
Sonic t ower:3-D sonic (RM Young)fCO2; fH2O (Licor 7500)Net radiat ion (REBS Q*7.1)
Mean dat a t ower:T; RH; WS; WD; PrsGround T & heat f lux
MABEL:CO2; H2O; phot olysisO3; NO; NO2(x2) ; CO
VOC:Acid CIMSPTR-MSTACOH
Sample manifold:1 / 2" PFA; ~15 m50-70 lpm; ~1 sec.
How to measure ecosystem flux: Eddy covariance technique
Cartridges samples sesquiterpene and semivolatiles Leaf level fluxes Peter Harley
Introduction Plant cuvette laboratory Leaf cuvette field Flux experiment corn field
"! July: Strongest biomass increase "! August: Corn ears development
Thanks to: Emissions of Biogenic Aerosol and Ozone Precursors by Biofuel
Crops USDA 2009-35112-05217
Plant cuvette measurements: "! Switchgrass is a low VOC emitters compared to other biofuel crops
Leaf cuvette measurements: "! Corn is stronger VOC emitter than switchgrass Field flux experiment: "! Field experiment (BioCORN 2011) or fluxes from corn field July-August 2011 "! Several research groups involved