Achten biofuel carbon debts
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This document summarizes a study on the implications of biodiesel-induced land use changes for CO2 emissions. The study examined 12 case studies across tropical regions. The main findings were: 1) Converting high-carbon stock lands like peatlands or rainforests to biofuel production can result in "carbon debts" that may take decades or centuries to repay through CO2 savings from biofuel use. 2) The time needed to offset the carbon debt depends on the type of land converted and the yield of the biofuel crop. Oil palm generally had shorter repayment times than Jatropha or oil palm on peatlands. 3) Land use changes from biofuel production can neg
![09/06/2011
Material and Method
3 feedstocks
6 countries
12 cases
Achten and Verchot (submitted)
Material and Method
Land use change
Carbon debt (CD) [kg C ha-1]
Loss of biomass carbon
Loss of soil carbon
Allocation to biodiesel (A) [%]
CO2 emission reduction rate (CO2RR) [kg C ha-1 yr-1]
Repayment time (RT) [yr]
CD * A
RT =
CO2 RR
Fargione et al. (2008) Science
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![09/06/2011
Resulting repayment times
Oil palm
Peatland forest: Indonesia/Malaysia
423-918 years
Fargione et al. (2008) Science; Gibbs et al. (2008) Environ.
Res. Lett. [accounted for 50 years of soil emissions]
169 years
Wicke et al. (2008) Biomass & Bioenergy [accounted for 25
years of soil emissions]
Tropical rainforest: Indonesia/Malaysia
30-86 years
Wicke et al. (2008) Biomass & Bioenergy; Fargione et al.
(2008) Science
Fargione et al. (2008) Science
Resulting repayment times
Jatropha
Cases Ghana Ycatan, Michocan, Chiapas Zambia
Mexico Mexico Mexico
Carbon debt 239.8 + 184.5 + 140.0 + 18.3 + 24.7 +
(dLUC + iLUC 25%) 11.0 0 112.3 197.9 24.5
(Mg CO2 ha-1)
Repayment rate 1.89 – 1.89 – 0.79 – 0.79 – -0.32 –
(Mg CO2 ha-1 yr-1 ) 2.99 2.99 1.89 1.89 0.79
Repayment time 90 + 4 = 76 + 0 = 105 + 84 = 14 + 148 = 95 + 94 =
(yr)
94 76 189 162 188
Woodland Woodland Forest Forest Woodland
Industrial scale Smallholder systems
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Achten biofuel carbon debts
- 1. 09/06/2011 Implications of biodiesel- induced land-use changes for CO2 emissions Case studies in tropical America, Africa and Southeast Asia. Achten W.M.J. & Verchot L. Introduction Are biofuel environmentally sustanable? Life cycle assessments (LCA) Reduction in CO2-eq Oil palm: 38-79.5% Jatropha: 49 to 72% Soybean: 57 to 74% 1
- 2. 09/06/2011 Introduction Are biofuel environmentally sustanable? Life cycle assessments (LCA) LCAs often do not include land use change Carbon debt & Repayment time GHG emissions Biodiesel Carbon debt (CO2eq per ha) LCA Land use change: Biodiesel land • clearing system reduces GHG Fossil CO emissions compared to fossil 2 • soil emissions diesel Repayment time (yr) Time 2
- 3. 09/06/2011 Material and Method 3 feedstocks 6 countries 12 cases Achten and Verchot (submitted) Material and Method Land use change Carbon debt (CD) [kg C ha-1] Loss of biomass carbon Loss of soil carbon Allocation to biodiesel (A) [%] CO2 emission reduction rate (CO2RR) [kg C ha-1 yr-1] Repayment time (RT) [yr] CD * A RT = CO2 RR Fargione et al. (2008) Science 3
- 4. 09/06/2011 M&M: Land use change Direct land use change (dLUC) Observed: Household surveys, remote sensing Estimated: stakeholder interviews Indirect land use change (iLUC) Observed: Household surveys Estimated: Scenario’s (based on Fritsche et al. 2010) 25% of ‘used’ land in dLUC 50% of ‘used’ land in dLUC 75% of ‘used’ land in dLUC Achten and Verchot (submitted) 4
- 5. 09/06/2011 M&M: Carbon debt Aboveground biomass carbon loss from former land use: Measured (1 case) Literature review (region specific) Belowground biomass carbon loss from former land use Root/Shoot ratios: literature Soil carbon loss IPCC tier 1 Carbon debt Achten and Verchot (submitted) 5
- 6. 09/06/2011 M&M: Allocation Expressed in % Extracted from literature review Achten et al. (2007) BioFPR M&M: CO2 emission reduction rate Based on comparative life cycle assessments Literature review Resulting repayment times Oil palm Cases Malaysia Manokwari West Boven Indonesia Kalimantan, Digoel, Indonesia Indonesia Carbon debt 698.8 + 253.6 + 1578.9 + 669.5 + 5.3 (dLUC + iLUC 25%) 0.0 24.8 109.8 (Mg CO2 ha-1) Repayment rate 7.69 6.90 6.90 6.90 (Mg CO2 ha-1 yr-1 ) Repayment time 76 + 0 = 32+ 2 = 199 + 7 = 84 + 1 = (yr) 76 34 206 85 Secondary PEAT Forest 6
- 7. 09/06/2011 Resulting repayment times Oil palm Peatland forest: Indonesia/Malaysia 423-918 years Fargione et al. (2008) Science; Gibbs et al. (2008) Environ. Res. Lett. [accounted for 50 years of soil emissions] 169 years Wicke et al. (2008) Biomass & Bioenergy [accounted for 25 years of soil emissions] Tropical rainforest: Indonesia/Malaysia 30-86 years Wicke et al. (2008) Biomass & Bioenergy; Fargione et al. (2008) Science Fargione et al. (2008) Science Resulting repayment times Jatropha Cases Ghana Ycatan, Michocan, Chiapas Zambia Mexico Mexico Mexico Carbon debt 239.8 + 184.5 + 140.0 + 18.3 + 24.7 + (dLUC + iLUC 25%) 11.0 0 112.3 197.9 24.5 (Mg CO2 ha-1) Repayment rate 1.89 – 1.89 – 0.79 – 0.79 – -0.32 – (Mg CO2 ha-1 yr-1 ) 2.99 2.99 1.89 1.89 0.79 Repayment time 90 + 4 = 76 + 0 = 105 + 84 = 14 + 148 = 95 + 94 = (yr) 94 76 189 162 188 Woodland Woodland Forest Forest Woodland Industrial scale Smallholder systems 7
- 8. 09/06/2011 Resulting repayment times Soybean Cases Sorriso, Brazil Guarantã do Santarém, Norte & Alta Brazil Floresta, Brazil Carbon debt 134.5 + 0.0 23.5 + 33.6 55.3 + 159.1 (dLUC + iLUC 25%) (Mg CO2 ha-1) Repayment rate 0.87 0.87 0.87 (Mg CO2 ha-1 yr-1 ) Repayment time (yr) 41 + 0 = 7 + 10 = 16 + 47 = 41 17 64 Amazon Cerrado Region Region Resulting repayment times Soybean Lapola et al. (2008) PNAS 8
- 9. 09/06/2011 Discussion In our cases Soybean < oil palm < Jatropha < oil palm on peat Final result mainly depends on Carbon debt caused (direct and indirect) Performance of biofuel crop Very site specific Land use deplaced Potential crop yield Discussion Caution Land use change/dynamics are difficult to assess (uncertain) Carbon content of land use types is based on literature 9
- 10. 09/06/2011 Conclusion Land use changes can negate the greenhouse gas balance of biofuels and postpone net greenhouse gas emission benefits for long periods Site specific Type of land use changed Performance of biofuel Biofuel climate mitigation potential In areas with low carbon content Areas not used in production systems Areas where biofuel feedstock is sufficient performing Thank you for your kind attention Questions? 10