Perennial grasses as lignocellulosic feedstock for II generation bioethanol production in Mediterranean environment

Transcription

1 Perennial grasses as lignocellulosic feedstock for II generation bioethanol production in Mediterranean environment Danilo Scordia, Giorgio Testa, Salvatore L. Cosentino Dept. of Agriculture and Food Science - DISPA, University of Catania, Italy Summer School July 2014, Hotel Costa da Caparica, Lisbon, Portugal

2 Leglislation on renewable energies Directive 2009/28/CE (RED), goals within 2020: 20% increase of renewable energies 10% increase biofuels in the transport sector 20% decrease greenhouse gas emission (GHG) However, for biomass: Sustainability criteria Food vs fuel competition Land Use Change (dluc and iluc)

3 Environmental stratification of Europe

4 Mediterranean Climate areas in the world The 65% of the annual precipitation between November and April Annual rainfall range between 275 and 900 mm The number of hours of the Temperatures below 0 C does not overpass 262 hours in a year (< 3% yearly total) (Aschmann, 1973)

5 Ecological benefit of perennial crops Several studies have demonstrated the higher sustainability of perennials over annual crops Lower soil disturbance decreases the risk of soil erosion; Increase the carbon stocks in the soil; Longer growing cycle, higher potential yield; Lower nutrient request due to nutrients recycling; Lower demand of herbicide or pesticides; Higher NUE, WUE and RUE; Habitat creation.

6 Perennial grasses studied Arundo donax L. Originating from Asia, native in Mediterranean environment; C3 photosynthetic pathway; Vegetative propagation; Thermal requirement: 7-35 C and medium-low water demand; Growing season: spring-summer. Miscanthus x giganteus Greef et Deuter Hybrid between Miscanthus sinensis x Miscanthus sacchariflorus; C4 photosynthetic pathway; Vegetative propagation; Thermal requirement: C and medium-high water demand; Growing season: spring-summer. Saccharum spontaneum spp. aegyptiacum (Willd.) Hackel Originating from North-Africa, endemic in Sicily (south Italy) C4 photosynthetic pathway; Vegetative propagation; Thermal requirement:?-35 C and low-medium water demand; Growing season: spring-summer

7 Lignocellulosic cell wall (Rubin, 2008)

8 Diagram flow of II generation bioethanol Lignocellulosic biomass Filtration Washing solid Cellulase enzymes Solid Solid Saccharification Size reduction Size reduction SSF/SSCF Steam, Chemicals Pretreatment Liquid C5-C6 sugars Yeasts Fermentation Distillation Detoxification hydrolisate Bioethanol Lignin residue Inhibitory composunds, Chemicals By-products

9 Material and methods (field) Trial carried out at «Azienda Didattico-Sperimentale», University of Catania (10 m a.s.l., N, E) 3 species: Arundo donax, Miscanthus x giganteus, Saccharum spontaneum spp. aegyptiacum; Rhizome transplant: 28 February 2002 (Miscanthus e Saccharum), 27 July 2002 (Arundo) Plot: 16 m 2 (4 x 4 m 2 ) Rhizome density: 4 m -2 Experimental design: randomized blocks, three replications Fertilization: 80 kg N ha -1 and 100 kg P 2 O 5 ha -1 at transplant, only N al II year; Irrigation: 300 mm at I and 150 mm at II year during summertime Harvest: every year in winter time (results shown 2008/2009 and 2009/2010, seventh and eighth growing season)

10 Measurements Main meteorological Minimun, mean and maximum daily temperatures, daily precipitation Bio-morphologic traits Stem height, node number, basal diameter, stem density Yield traits Fresh and dry weight of one stem, fresh and dry aboveground biomass yield (Mg ha -1 ) Raw material composition: HPAEC-PAD (Davis, 1998) Theoretical ethanol yield [% C6 x (180/162)]*0.51 [% C5 x (150/132)]*0.51

11 Meteorological trend

12 Morpho-biometric Year 2008/ /2010 Parameter/species Arundo Miscanthus Saccharum Arundo Miscanthus Saccharum Stem height (cm) 317.2a 136.1c 242.5b 384.8a 132.8c 294.1b Node number (n.) 45.0a 11.0c 13.3b 49.0a 11.4c 16.3b Basal diameter (mm) 1.5a 0.8c 1.1b 1.9a 0.6c 1.3b Stem density (n. m -2 ) 31.2c 161.2a 59.1b 50.0c 140.8a 79.9b Weight one stem (g) 77.8a 13.4c 31.2b 89.4a 10.8c 42.6b Moisture content (%) 33.4b 11.6c 39.1a 38.2b 12.3c 43.5a Within each experimental year (2009 and 2010), different letters in the same row indicate significance (p 0.05). Percentage values were previously arcsin % transformed.

13 Aboveground biomass DM yield (Mg ha -1 )

14 Raw material (% s.s.) Composition Arundo (% w/w) Miscanthus (% w/w) Saccharum (% w/w) Glucan 34.60c 40.99a 36.81b Xylan 20.41b 19.98c 21.53a Galactan 0.66a 0.57a 0.72a Arabinan 1.81b 1.74b 2.16a Mannan 0.12a 0.09a 0.16a Rhamnan 0.06b 0.02c 0.14a Total polysaccharides 57.66c 63.39a 61.52b K. Lignin 20.44b 22.40a 20.03b Whole Ash 7.20a 4.80c 5.40b AL Ash 1.67a 0.84c 1.21b Within each experimental year (2009 and 2010), different letters in the same row indicate significance (p 0.05). Percentage values were previously arcsin % transformed.

15 Theoretical Ethanol Yield (kg Mg -1 )

16 TEY (Kg DM Mg -1 ) Feedstock Composition (% w/w) Glucan Xylan Arabinan Mannan Galactan Lignin Ash TEY (kg DM Mg -1 ) Corn stover a NR Wheat straw b NR Rice straw c Sugarcane bagasse d NR NR Corn cobs e NR NR 13.9 NR Eucalyptus f NR NR Poplar g Willow h Swithgrass j NR Kenaf k NR Hemp hurds l Flax straw m NR NR NR A.donax n M. x giganteus n S. spontaneum n a,h Sassner et al., 2008; b Linde et al., 2008; c Wi et al., 2013; d Rudolf et al., 2008; e Lee et al., 2011 ; f Romaní et al., 2010; g Wyman et al., 2009; j Xu et al., 2010; k Berti et al., 2013; k Berta et al., 2010; j Buranov and Mazza, 2008 n Present study; NR (not reported).

17 TEY (Mg ha -1 ) Agricultural residues Woody Fiber Herbaceous perennial grasses

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19 Bioconversion perennial grasses Bioconversion at USDA-FPL, Madison, WI, USA Pretreatment: steam explosion o Condition: oxalic acid [2 8% w/w], temperature ( C), reaction time (10-40 min) SSF: cellulase enzymes (1000 CMC/g e 160 pnpg/g cellulosa), nutrient g L -1 (5 YE, 5 Urea, 0.5 MgSO 4 7H 2 O, 1 KH 2 PO 4 ), 2 g L -1 yeast (Scheffersomyces stipitis CBS 6054); o Condition: ph 6.0, 30 C, 150 rpm, 96 h Hemicellulose hydrolysate fermentation: nutrient g L -1 (5 urea, 0.5 MgSO 4 7H 2 0, 1 KH 2 PO 4 ), 2 g L -1 Scheffersomyces stipitis CBS 6054 o Condition: ph 6.0, 30 C, 150 rpm, 96 h

20 Analytic determination Raw material: HPAEC-PAD (Davis, 1998) Sugar and ethanol: Gilson HPLC and RID (Hitachi High Technologies Corporation model L-2490, Japan), using a column HPX- 87H (Bio-rad Laboratories Inc., Hercules, CA) Inhibitory compounds: HPLC (HP, 1090 Series II, Hewlett- Packard, Now Agilent Technologies, Palo Alto, CA) using a column Phenomenex C18(2) Total phenols: estimated colorimetrically by the Folin-Ciocalteu method (Scalbert et al., 1989)

21 C5 Fermentation to ethanol Arundo Miscanthus Bioconversion efficiency Arundo: 64%; Miscanthus: 75%; Saccharum: 69%. Saccharum

22 SSF C6 to ethanol a) Arundo, b) Miscanthus, c) Saccharum a b c Bioconversion efficiency Arundo: 51%; Miscanthus: 73%; Saccharum: 53%.

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28 Mass balance Yield (Mg DM ha -1 ) A. donax: 33.8 M. giganteus: 18.4 S. spontaneum: 25.6 C5 biocon. Eff (% TY) A. donax: 64.0 M. giganteus : 75.0 S. spontaneum: 69.0 C6 biocon. Eff (% TY) A. donax: 51.0 M. giganteus : 73.0 S. spontaneum: 53.0 Ethanol Yield (kl ha -1 ) A. donax: 7.9 M. giganteus : 6.2 S. spontaneum: 6.9

29 Conclusions Biomass production is attractive when sustainable, therefore when a biomass crop is grown with the highest output level and the lowest input supply and consequently with a positive energy balance (ratio and net gain); Arundo and Saccharum, endemic in south Mediterranean, show interesting productive traits, while the lower yield in Miscanthus might be related to the higher water demand for this crop in semi-arid environments; From a hectare of Arundo, Miscanthus and Saccharum it is possible to obtain higher TEY (Mg ha -1 ) of agricultural residues, woody and fiber crops; However, further research is needed to improve the efficiencies of bioconversion of both C5 and C6 sugars to ethanol.

30 Thanks for your attention Danilo Scordia