greenhouse gas emissions from food and biofuel production: contribution of soil n2o emissions -...
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Greenhouse gas emissions from food and biofuel production: Contribution of soil N2O emissionsLouise Barton1, Wahidul Biswas2, Klaus Butterbach-Bahl3, Ralf
Kiese3, Daniel Carter4 and Daniel Murphy1
1University of Western Australia
2Curtin University of Technology
3Department of Agriculture & Food Western Australia
4Institute for Meteorology & Climate Research, Germany.
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CARBON FOOTPRINTING:Gaining the “Competitive Advantage”
GREENHOUSE GASES & AGRICULTURAL PRODUCTION
CO2-EQU
(100 years)
SOURCES
CO2 X 1 Transportation, manufacturing inputs, electricity
CH4 X 25 Transportation,
manufacturing inputs
N2O X 298 N fertiliser production, land emissions
Source: Forster et al. 2007. Changes in Atmospheric Constituents and in Radiative Forcing. In: Climate Change 2007: The Physical Science Basis. Contribution of Working Group I to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change, Cambridge University Press.
NO2- NO N2O N2
N2O NO3-
NH3 NH2OH NO2
- NO N2O N2
Nitrification
Nitrifier Denitrification
Denitrification
N2O FROM SOILS
• Default emission factorfert = 1.0%
• Emission factorfert:
(N2O-Nfertilised soil – N2O-N non-fertilised soil ) * 100
Nitrogen applied
• Required to use default value in the absence
of published, country specific values
CALCULATING SOIL N2O EMISSIONS:National Inventories & LCA
• > 200 studies
• Temperate climates
• Ammonium nitrate, CAN, organic N
• Sandy loam to clay soils
• Few studies in semi-arid regionsSources: Bouwman et al. 2002. Global Biogeochemical Cycles 16:1058; Galbally et al. 2005. Environmental Sciences 2: 133–142; Stehfest & Bouwman 2006. Nutr Cycle Agroecosystems 74: 207–28; Galbally 2009. Journal of Environmental Quality 37: 599–607.
DEFAULT N2O EMISSION FACTORFERT
Calculate GHG emissions from the production of wheat and biodiesel in south-western Australia by:
• Measuring in situ soil N2O emissions continuously
from wheat/canola production for 3 years; and
• Incorporating these ‘local’ soil N2O emission data
into a life cycle assessment (LCA) of GHG
emissions.
OUR AIMS
REFINING N2O EMISSIONS
CUNDERDIN, WA
• Semi-arid environment
• 156 km east of Perth, WA
• Rainfall: 368 mm yr-1
• Air Temperature:
– Mean min:11.4 °C – Mean max temp: 25.1 °C
• Crops grown in winter, soil ‘fallow’ during summer
50 cm x 50 cm x variable height (15–95cm)
Jun-05 Dec-05 Jun-06 Dec-06 Jun-07 Dec-07 Jun-08
N2O
flu
x (g
N2O
-N h
a-1 d
ay-1
)
-2
0
2
4
6
8
10
12 No N Plus N Fertiliser
DAILY N2O EMISSIONS: 3 Years
Wheat Wheat CanolaSource: Barton et al. 2010. GCBB 2: 1‒15 ; Barton et. al. 2008. GCB 14: 177-192.
N applied Total loss Emission factor
(kg N ha-1 yr-1) (%)
Canola 2007/08 75 0.13 0.06
Wheat 2006/07 75 0.13 0.02
Wheat 2005/06 100 0.11 0.02
AUSTRainfed crops 0.11–1.2 0.3
GLOBALLY Crops 0.11–17 1.00
In Australia’s <550 mm rainfall regions: N2O EFFert will change from to 0.3% to 0.08%
ANNUAL N2O EMISSIONS
LIFE CYCLE ASSESSMENT: Wheat Production
LCA METHODOLOGY: Wheat Production
• Goal
Estimate total GHG emitted during the production and transport of rain-fed wheat grown in in south-western Australia
• Function Unit
Delivery of 1 tonne of wheat to port
• Life Cycle Inventory (LCI)
Calculated using Simapro 7, with libraries developed by RMIT, or using local information
Source: Biswas et. al. 2008. Water and Environment Journal 22: 206-216
WHEAT PRODUCTION GHG EMISSIONS: International N2O default value (1.0%)
Production of urea and superphosphate
24%
Production of herbicide
6%
N2O emissions from paddock
36%
Farm machinery production
6%
CO2 emission from urea hydrolysis (from paddock)
19%
Transportation of inputs and wheat
9%
487 kg of CO2 equ- per tonne
Source: Biswas et. al. 2008. Water and Environment Journal 22: 206-216
WHEAT PRODUCTION GHG EMISSIONS: ‘Local’ N2O value
304 kg of CO2 equ- per tonne
12%
operation
27%
Prduction of
Production of urea and superphosphate
35%
Production of herbicide
9%
N2O emissions from paddock
9%
Farm machinery production
8%
CO2 emission from urea hydrolysis (from paddock)
27%
Transportation of inputs and wheat
12%
9%
8%
paddock
2
35%
Source: Biswas et. al. 2008. Water and Environment Journal 22: 206-216
LIFE CYCLE ASSESSMENT: Biodiesel Production &
Combustion
• Goal
Estimate GHG emitted from production and combustion of biodiesel (canola oil) produced from grain grown in south-western Australia
• Function Unit
Production and combustion of one GJ of canola based biodiesel
• Life Cycle Inventory (LCI)
Calculated using Simapro 7, with libraries developed by RMIT, or using local information
LCA METHODOLOGY: Biodiesel Production & Combustion
GHG EMISSIONS FROM BIODIESEL PRODUCTION & COMBUSTION : International N2O default value (1.0%)
63 kg CO2 equ-/GJ
Source: Biswas et. al. 2011. Environmental Science & Technology (accepted).
Paddock N2O emissions
49%
Urea hydrolysis15%
Farm machinery operation
3%
Canola seed to oil2%
Fertiliser production
17%
Herbicide & Pesticide production
10%
Transportation3%
Canola oil to biodiesel 1%
GHG EMISSIONS FROM BIODIESEL PRODUCTION & COMBUSTION : ‘Local’ N2O value
37 kg CO2 equ-/GJ
35%
Paddock N2O emissions
13%
Urea hydrolysis25%
Farm machinery operation
6%
Canola seedto oil 4%
Canola oil to biodiesel 2%
Fertiliser production
29%
Pesticide production
1%
Herbicide production
16%
Transportation4%
Source: Biswas et. al. 2011. Environmental Science & Technology (accepted).
CONCLUSIONS
• IPCC emission factor (Effert) overestimates soil N2O emissions from Australian rain-fed, cropping systems
• ‘Life Cycle Assessment’ of GHG from food and biofuel production is sensitive to soil N2O emissions, and analysts need to consider the implications of utilising international default values.
• Obtaining soil N2O estimates is costly and time-consuming, and requires a national coordination
ACKNOWLEGMENTS• Research funded by the Department of Climate
Change, Grains & Research Development Corporation (GRDC), Department of Agriculture & Food Western Australia
• Presenting author currently funded by GRDC and the Australian Government’s Climate Change Research Program
GHG Emissions: Biodiesel vs. Diesel
Mineral Diesel Sources: Beer et al. 2007. Report Number KS54C/1/F2.29, CSIRO; Grant et al. 2008. Report KN29A/WA/F2.5, DAFWA.
kg C
O2
-e/G
J
37 37
16
54
70
11
67
78
Production Combustion Total
BD100 BD20 Diesel