Consequences of agro-biofuel production for greenhouse gas emissions

Transcription

1 Consequences of agro-biofuel production for greenhouse gas emissions NJF seminar, 10 September 2009 Dr. Mette S. Carter Dr. Henrik Haugaard-Nielsen Dr. Anders Johansen Prof. Per Ambus

2 Carbon cycling in biofuel production CO 2 Residue = fertilizer N 2 O + CH 4 C 2 H 5 OH CH 4 Bio-ethanol production Bio-gas production Organic carbon in maize biomass Maize field 2 Risø DTU, Technical University of Denmark

3 CH 4 flux the day after residue application 150 kg plant available N ha -1 1 CH 4 flux (μg CH 4 -C m -2 h -1 ) gras-clover 3 Risø DTU, Technical University of Denmark

4 CH 4 flux the day after residue application 150 kg plant available N ha -1 1 CH 4 flux (μg CH 4 -C m -2 h -1 ) gras-clover 4 Risø DTU, Technical University of Denmark

5 Cumulative N 2 O flux during the first 2 months after application (in CO 2 -equivalents) 500 Cumulative N 2 O flux (g CO 2 m -2 ) grass-clover 5 Risø DTU, Technical University of Denmark

6 Cumulative N 2 O flux during the first 2 months after application (in CO 2 -equivalents) 500 Cumulative N 2 O flux (g CO 2 m -2 ) grass-clover 6 Risø DTU, Technical University of Denmark

7 Maize yield 2008 (kg dry matter m -2 ) Maize yield (kg dry matter m -2 ) grass-clover Organic material 7 Risø DTU, Technical University of Denmark

8 Conversion of maize biomass to biofuels g CO 2 44 g CO 2 per g maize dry matter 35 g C 2 H 5 OH 12 g VS 6 liter CH 4 Bio-ethanol production Bio-gas production g maize dry matter Maize field 8 Risø DTU, Technical University of Denmark

9 N 2 O emission versus avoided fossil CO 2 for maize biofuels CO 2 balance (g CO 2 m -2 ) N2O N 2 O Avoided CO2 fossil Avoided minus fossil N2O CO CO 2 minus 2 N 2 O 0 +grass-clover 9 Risø DTU, Technical University of Denmark

10 N 2 O emission versus avoided fossil CO 2 for maize biofuels CO 2 balance (g CO 2 m -2 ) N2O N 2 O Avoided minus fossil N2O CO 2 minus N 2 O 0 +grass-clover 10 Risø DTU, Technical University of Denmark

11 N 2 O emission versus avoided fossil CO 2 for winter rye biofuels CO 2 balance (g CO 2 m -2 ) N2O N 2 O flux in CO2- equ Avoided CO2 fossil CO 2 minusn2o N 2 O maize 11 Risø DTU, Technical University of Denmark

12 Major findings Anaerobic digestion of slurry and plant material may act to reduce N 2 O emissions related to fertilization but only if the fermentation process is completed No greenhouse gas advantage of fertilizing the maize crop because the extra crop yield was offset by increased field emissions of N 2 O Winter rye biofuels have a slightly lower net CO 2 gain as compared to maize biofuels, but winter rye still is a potential energy crop 12 Risø DTU, Technical University of Denmark

13 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 Jens Ejbye Schmidt 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 13 Risø DTU, Technical University of Denmark