Ensiling as a method to preserve energy crops and to enhance the energy yields Seija Jaakkola (UH) Ensiling

Transcription

1 Ensiling as a method to preserve energy crops and to enhance the energy yields Seija Jaakkola (UH) Ensiling Fred Stoddard (UH) Energy crops, cultivations Maritta Kymäläinen (HAMK) Biogas Pekka Maijala, Liisa Viikari (UH) - Biotechnology

2 Raw materials Water soluble Maize Zea mays, cv Ronaldino tn / ha /a Requires strong weeding, frost sensitive 120 kg N /ha DM = 17% Cellulose Arabino xylans Lignin 14-20% 24% 17% 14% Water soluble Hemp Cannabis sativa, cv Uso 14 tn / ha /a No weeding required 60 kg N /ha DM = 33% or 63% after two days pre-wilting Cellulose Arabino xylans Lignin 6% 37% 12% 17%

3 Methods ensiling and alkaline preservation Ensiling: Anaerobic conditions+ bacteria + carbohydrates acid formation Mainly lactic- and acetic acids formed Additives enhance ensiling in different ways Lactic acid bacteria Molasses, other sugars Enzymes Acids, mainly formic acid A.I.V silage for feed Preservation with alkaline additives, mainly urea 4 M 8 M

4 Ensiling and alkaline preservation

5 Water soluble carbohydrates formed acids 30 % Water soluble carbohydrates Formed acids % of dry matter 25 % 20 % 15 % 10 % 5 % 0 % no additives Maize acid no additives acid Hemp no additives alkali

6 Carbohydrates 80 % 70 % 60 % 50 % 40 % 30 % 20 % 10 % 0 % Glc Xyl Ara Man Gal Fru -18% -14% een-roads-engineers-investigate.html Fresh Untreated Maize Acid ensiled untreated acid ensiled Hemp dry alkali preserved

7 Lignin and pectin % of dry matter 18 % 16 % 14 % 12 % 10 % 8 % 6 % 4 % 2 % 0 % Lignin Gal-A Fresh Untreated Maize Acid ensiled untreated acid ensiled Hemp dry alkali preserved

8 Stuctural changes in hemp - SEM Hemp : Fibre Stem Hemp ensiled with formic acid: Fiber Stem

9 Methane vs. ethanol Hydrolytic bacteria Acidogenic bacteria Acetogenic bacteria Methanogenic bacteria Fatty acids, Propionic acid, Alcohols Acetic acid, H 2 Biomass Polysaccharides, Proteins, Fats Sugars, Amino acids, fatty acids CH 4 + CO 2 H 2 / CO 2 Hydrolysis Acidogenesis Acetonegesis Methanogenesis Enzymes, thermal pretreatment may be needed Yeast Biomass Polysaccharides, Proteins, Fats Sugars (monosaccharides) Ethanol Hydrolysis

10 Total carbohydrates, % of dry matter 35 % 30 % 25 % 20 % 15 % 10 % 5 % 0 % Hydrolyzability of and ensiled crops No additives Glc Xyl Ara Man Gal Fru FA No additives Celluclast+ Novozyme 188 Volume 5ml 2% DM conc. 50 C Total yields proved to be 5-10% higher in 10x larger hydrolysis volume FA Urea Maize Hemp 2008 Hemp

11 Methane yields from the and ensiled hemp dm3 CH4 / kg VS Oxalic acid Formic acid DM 33% no additives FA 4M FA 8M no additives 4M no additives 8M FA Urea DM 63% Maize Hemp 2008 Hemp 2009

12 Energy carriers to gasoline liter ethanol = 0,66 liter gasoline 1 m 3 methane =1,13 liter gasoline Potential methane Theoretical ethanol Equivalent gasolineliter / ha Ethanol without pretreatment 0 No additives Maize FA No additives FA Urea Hemp

13 Conclusions Effects to ETHANOL Storing with additives increased the yield of sugars in enzymatic hydrolysis Water soluble sugars well preserved Some cellulose hydrolysed during ensiling Storing altered the structure of the substrate? Suffered from acid formation when no additives were supplied. Effects to METHANE Storing with or without additives increased methane yield Formed acids were utilized, as well as the preserved water soluble sugars Prolonged storing seemed to decrease methane yields

14 Acknowledgements The Graduate School for Biomass Refining (Bioregs) KWS Seeds, Einbeck, Germany for the kind donation of maize seeds. Funding for the field trials was provided by the Academy of Finland's Sustainable Energy programme SusEn under the grant "Carbonsequestering species mixtures for sustainable energy cropping", in the consortium "Bioenergy, electricity and emission trading markets (BEET). Laura Huikko and Mervi Salonen for technical help

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