Greenhouse gas emissions from cultivation of energy crops may affect the sustainability of biofuels Risø International Energy Conference 11 May 2011
Mette S. Carter Henrik Haugaard-Nielsen Stefan Heiske Sune T. Thomsen Morten Jensen Jens Ejbye Schmidt Anders Johansen Per Ambus
Archived at http://orgprints.org/18331
Combinations of biomasses and biofuels Biomass
Biofuel technology
Rye straw
Bioethanol
Vetch straw
Biogas
Rye-vetch intercrop
Combined bioethanol and biogas
Grass-clover
Maize 2
Risø DTU, Technical University of Denmark
www.bioconcens.elr.dk
Carbon cycling in biofuel production CO2
N 2O
C2H5OH
Bioethanol production Maize field Organic carbon in maize biomass 3
Risø DTU, Technical University of Denmark
www.bioconcens.elr.dk
Contribution of soil N2O emissions to total GHG emissions during biofuel production
Tuomisto and Helenius, 2008 4
Risø DTU, Technical University of Denmark
www.bioconcens.elr.dk
Contribution of soil N2O emissions to total GHG emissions during biofuel production
32 % Smeets et al., 2009 N2O = 10-80 %
Tuomisto and Helenius, 2008 5
Risø DTU, Technical University of Denmark
www.bioconcens.elr.dk
Cumulative N2 O emission (mg N m-2 )
Cumulative N2O emission, unfertilized crops 1200
2007/2008
1000
2008/2009
800 600 400 200 0 Rye
Vetch
Rye-vetch Grass-clover
Maize
Crop
6
Risø DTU, Technical University of Denmark
www.bioconcens.elr.dk
Biomass yield (g DW m- 2 yr-1)
Harvested biomass of unfertilized crops
(2 yr)
1400 1200 1000 800 600 400 200 0 Rye
Vetch
Rye-vetch
Grass-clover
Maize
Crop
7
Risø DTU, Technical University of Denmark
www.bioconcens.elr.dk
Biomass yield (g DW m- 2 yr-1)
Harvested biomass of unfertilized crops
(2 yr)
1400 1200 1000 800 600 400 200 0 Rye straw
Vetch straw
Rye-vetch straw
Grass-clover
Maize
Crop
8
Risø DTU, Technical University of Denmark
www.bioconcens.elr.dk
Bioethanol yield (g eth g -1 DW)
Bioethanol yields C2H5OH
0.30 0.25 0.20 0.15 0.10 0.05 0.00
Rye straw, Vetch straw, Rye-vetch Grass-clover Maize whole HTT HTT straw, HTT crop HTT = HydroThermal preTreatment 9
Risø DTU, Technical University of Denmark
www.bioconcens.elr.dk
N2O emissions related to avoided fossil CO2 Bioethanol
CO2-equivalents (tons CO2 ha-1)
C2H5OH
10 8 Avoided fossil Avoided fossil CO2 CO2
6 4 2 0 -2 Rye straw Vetch straw Rye-vetch Grass-clover straw Biomass
10
Risø DTU, Technical University of Denmark
Maize
www.bioconcens.elr.dk
N2O emissions related to avoided fossil CO2 Bioethanol
CO2-equivalents (tons CO2 ha-1)
C2H5OH
10 N2O N2O
8
Avoided fossil Avoided CO2 minus fossil CO2N2O minus N2O
6 4 2 0 -2 Rye straw Vetch straw Rye-vetch Grass-clover straw Biomass
11
Risø DTU, Technical University of Denmark
Maize
www.bioconcens.elr.dk
N2O emissions related to avoided fossil CO2 Biogas
CO2-equivalents (tons CO2 ha-1)
CH4
10 N2O N2O
8
Avoided fossil Avoided CO2 minus fossil CO2N2O minus N2O
6 4 2 0 -2 Rye straw Vetch straw Rye-vetch Grass-clover straw Biomass
12
Risø DTU, Technical University of Denmark
Maize
www.bioconcens.elr.dk
Biogas residues are used as fertilizer CO2
Residue = fertilizer
N 2O
CH4
Biogas production Maize field Organic carbon in maize biomass 13
Risø DTU, Technical University of Denmark
www.bioconcens.elr.dk
Biomass yield (g DW m-2 yr-1)
Biogas produced on fertilized maize
150 kg N ha-1
1600 1200 800 400 0 Control 14
Slurry
Risø DTU, Technical University of Denmark
Treatment
Digested slurry+maize www.bioconcens.elr.dk
CO2-equivalents (tons CO2 ha-1)
Biogas produced on fertilized maize
15
150 kg N ha-1
12 10 N2O N2O
8 6
Avoided Avoidedfosil fossilminus CO2 CO2 minus N2O N2O
4 2 0 Control
Slurry
Risø DTU, Technical University of Denmark
Treatment
Digested slurry+maize www.bioconcens.elr.dk
Conclusions Biomass Rye straw
Bioethanol
Vetch straw
Biogas
Rye-vetch intercrop
Combined bioethanol and biogas
Grass-clover
Maize 16
Biofuel technology
Risø DTU, Technical University of Denmark
No advantage to fertilize maize crop - extra crop yield offset by increased N2O www.bioconcens.elr.dk emissions
Thanks to all the people who contributed… Mette Hedegaard Christel Barker Nina Wiese Thomsen Liselotte Meltofte Anja Nielsen Marianne Munck Kristian Albert Poul Sørensen
Anne Belinda Thomsen Mette Hedegaard Thomsen Piotr Oleskowicz-Popiel Henrik Bangsø Nielsen Steffen Blume Ingelis Larsen Erik Steen Jensen Hanne Østergård
BioConcens: Biomass and bioenergy production in organic agriculture – consequences for soil fertility, environment, spread of animal parasites and socio-economy www.bioconcens.elr.dk
17
Risø DTU, Technical University of Denmark
www.bioconcens.elr.dk
Accounting methodology • We assume that bioethanol and biogas replace petrol • Avoided fossil CO2 is obtained by calculating how much petrol the produced bioethanol and/or biogas corresponds to based on energy (LHV)
MJethanol MJbiogas
MJpetrol
Avoided fossil CO2
• Not accounted for: Fuel consumption by farm machinery and during biofuel production • N2O emissions from rye, vetch and rye-vetch are allocated between straw and grain according to energy content 18
Risø DTU, Technical University of Denmark
N2O
www.bioconcens.elr.dk
Carbon cycling in biofuel production CO2
N 2O
C2H5OH
CH4
Bioethanol production
Biogas production Maize field Organic carbon in maize biomass
19
Risø DTU, Technical University of Denmark
www.bioconcens.elr.dk
N2O emissions related to avoided fossil CO2 Co-production of bioethanol and biogas
CH4
CO2-equivalents (tons CO2 ha-1)
C2H5OH
10 N2O N2O
8
Avoided fossil Avoided CO2 minus fossil CO2N2O minus N2O
6 4 2 0 -2 Rye
Vetch
Rye-vetch Grass-clover
Maize
Energy crop 20
Risø DTU, Technical University of Denmark
www.bioconcens.elr.dk
