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Biofuel crops Ovvero: come aumentare (per ora) il prezzo del cibo.

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Presentazione sul tema: "Biofuel crops Ovvero: come aumentare (per ora) il prezzo del cibo."— Transcript della presentazione:

1 Biofuel crops Ovvero: come aumentare (per ora) il prezzo del cibo

2 Qualche numero * Consumo combustibili liquidi: benzine (12,7 Mt), gasolio autotrazione (25,4 Mt) olio combustibile (8,3 Mt) la domanda complessiva di gasoli (30,6 Mt) (prodotti petroliferi totali, pari a 84,7 Mtep) * Consumo di energia totale in Italia nel 2006 pari a 195,6 Mtep * Nel 2006 l'Italia ha importato 87 milioni di tonnellate di greggio * Consumo di gas naturale: 69,7 Mtep Consumo italiano circa 709 M barili /anno 1 barile sono 159 litri, 1 TEP sono 7.5 barili Consumo italiano petrolio: 94,3 M TEP

3 Un poco di storia Il biofuel storicamente più usato: il legno Comporta una serie di vantaggi (rinnovabile, spesso accessibile facilmente, a basso costo) e di svantaggi (combustione spesso poco efficace con rilascio di polveri sottili, poco pratico,...) …traditional biofuels are not new, have not always been good for health or for the environment and have competed with food production. Will the next generations be better?

4 Biofuels Ethanol (sugar fermentation) Butanol (fermentation) Diesel (vegetable oil trans-esterification) Methane/H2 (waste fermentation) Microbial Fuel Cells

5 saccharification Corn Cooking α-amylase, gluco-amylase Sugar soln. Ethanol + CO 2 Distillation Ethanol A bushel of corn (56 lbs.) used in ethanol manufacture yields the following products and co-products: 17.6 lbs Ethanol, 17 lbs. Dry distillers grains, 18.4 lbs. Carbon dioxide Yield: 2.8 gal/bu @ 56 lbs/bu = 100 gal/ton (Theoretical 3.1 gal/bu) Yield: 2.8 gal/bu @ 154 bu/ac = 430 gal/ac; Yield: 4824 l/ha Yield 12.7 l/25.4 kg 500l/t Fermentation 1 ac = 0.4 ha; 1 gal = 4.54 l; 1 lb = 0.45 kg; 1 bu = 36.3 l

6 12.0 billion gal/year by end of 2006 One new dry grind ethanol plant every 30 days Over 100 dry mill plants in operation or under construction Ethanol Production in the U.S. Renewable Fuels Standard, RFS = amount of ethanol to be blended

7 Energy consuming Where biotech can help? α-Amylase Breaks starch into dextrins or short chains in Liquefaction. Reduces viscosity for pumping. Bacillus licheniformis Glucoamylase Releases sugars from dextrins or starch chains in Saccharification. Aspergillus niger, Trichoderma reesei Pullulanase Breaks branched amylopectin starch molecules into straight chains. Protease Breaks starch-protein matrix for yeast nutrition. Trichoderma reesei Phytase Converts phytic acid to Pi. Improves Liquefaction, Fermentation and animal nutrition of DDGS

8 Corn wet vs. dry milling Products: Ethanol Corn Syrup Corn Gluten Meal Corn Oil CO 2

9 Prodotti ad alto valore Co-Products: DDGS (Distillers dried grain Fiber Steep Water (acqua di macerazione?) Corn Gluten Feed Senza questi co-prodotti la produzione di Etanolo NON sarebbe economicamente conveniente

10 Fermentazione butanolica: Glucosio 2 Acetil CoA butanolo Microorganisms capable of producing n-butanol by fermentation are Clostridium acetobutylicum, C. beijerinckii, and C. tetanomorphum. Clostridium acetobutylicumC. beijerinckiiC. tetanomorphum

11 Butanol plant - Commercial Solvents Corp. Terra Haute, Indiana Commercial Solvents Corporation was established at the end of World War I and earned distinction as the pioneer producer of acetone and butanol by fermentation processes developed and patented by Dr. Chaim Weizmann

12 Caratteristiche carburanti Il butanolo contiene più energia a parità di peso e non corrode

13 Butanol as a transportation fuel Butanol (4-carbons) is more like petrol (4-12 carbons) Higher energy density than ethanol (88% vs. 66%) Less corrosive and less water soluble than ethanol 85% Butanol/gasoline blends used in unmodified engines Can use same pipelines as petrol Easier to integrate into existing transportation infrastructure The n-butanol biosynthetic pathway. The enzymes in green are from Clostridium beijerinckii. Enzymes in black are from other organisms: AtoB, Escherichia coli; Erg10, S. cerevisiae; PhaA, Ralstonia eutropha; PhaB, Ralstonia eutropha; Ccr, Streptomyces collinus. Each enzyme candidate was evaluated in the pathway for n- butanol production (except thl, which is native to Clostridia).

14 Partendo dal metabolismo centrale (glicolisi, ciclo di krebs e sintesi di aminoacidi) è possibile sintetizzare diversi composti utilizzabili come carburanti o comunque precursori per lindustria chimica

15 Higher alcohols through synthetic non-fermentative pathways Atsumi et al (2008) Non- fermentative pathways for synthesis of branched- chain higher alcohols as biofuels. Nature 451:86-89

16 Biodiesel Estrazione di olio da colture oleaginose (colza, girasole, soia, palma da olio, ricino...) Trasesterificazione per ottenere lestere (metilico in genere) dellacido grasso Separazione degli esteri metilici dal glicerolo Gli esteri sono utilizzati come carburanti Il glicerolo è sottoprodotto ad alto valore aggiunto

17 Trasesterification Sostituzione della funzione alcolica del glicerolo con la funzione di un alcool primario a catena corta (il più usato è il Metanolo) La reazione può avvenire per catalisi acida, basica o con diversi altri modi (sonicazione, lipasi, controlled substrate feeding...) FAME Transesterification typically takes place in batch and takes one or more hours to reach high levels of conversion. It is a typical two-phase reaction due to the immiscibility of oil and alcohol, therefore, the rate of transesterification is primarily controlled by the rate of mass transfer between the methanol and oil phases.

18 Nuovi reattori e processi per aumentare le rese e diminuire i tempi (costi)

19 Economy (settimanale) 09/04/2008


21 The second generation biodieselSpecial oilseeds Ricinus communis (castor bean) Pongamia pinnata Calophyllum inophyllum Jatropha curcas (black vomit nut) Jatropha curcas is the most highly promoted oilseed crop: * can grow in the desert without water and fertilizer, but without commercial yield * fuel properties of Jatropha biodiesel are comparable to commercial diesel None of the websites promoting its use mention its common name: black vomit nut, purge nut, physic nut, nor the names of its oil: hell oil, oil infernale. The fruits contain irritants and the seeds contain alkaloids as well as curcin, a toxalbumin similar in structure and effect to ricin. The seed oil is irritant/cancer potentiator/synergist and contains curcusones, diterpenoids of the tiglian (phorbol) type with levels between 0.03 and 3.4% of phorbol esters

22 Raccolta e estrazione Raccolta a mano quando i frutti sono ancora verdi. I semi vengono spremuti con sistemi artigianali per estrarre lolio: Price for farmers: $0.14/kg seed Biodiesel_From_Jathropa.htm

23 Problem: what do you do with the protein residue after crushing? The amino acid content of Jatropha meal is exceptional, except for low lysine. If the seed cake were rendered non-toxic and could be used as animal feed, the profitability of cultivating Jatropha, which was more expensive than diesel in India in 2005, would be dramatically increased. Unesterified farmgate price of oil would be near $0.50/l, close to the retail USA pump price for processed diesel. Price of soybeans, where most of the value is in the meal, is $0.37/kg. Ingesting 4 seeds can be toxic to a child, with symptoms resembling organophosphate insecticide intoxication, yet with no known antidote for the lethal mixture. Oh, did I mention that Japtropha has no need for pesticides and deters pests from entering the field? Yeah, jatropha is naturally disease- and pest-resistant. And the matter that is left over after the seeds have been pressed for oil is naturally high in nitrogen, phosphorus and potassium, which are the big three nutrients used to fertilize other crops.

24 Domesticazione accelerata Dwarf the stalks for easier harvesting as well as to increase the harvest index (seed yield divided by biomass). Suppress branching, rendering the plants to have single or less branched stalks can facilitate mechanical harvesting. Anti-shattering genes. The fruits are picked green, because if they were allowed to dry on the crop, the fruits would open, and drop the seeds to the ground. Supress curcin expression. This toxalbumin has been purified, sequenced and the gene cloned. Suppress phorbol ester production. la pianta diventerebbe più sensibile a insetti e malattie…

25 Ricino Ricin, a toxalbumin is the major toxic protein of the seeds (0.2–3% ricin). The estimated oral lethal dose of ricin to man is 1 mg/kg. Two to four seeds may cause severe poisoning in an adult, and eight are generally fatal. The amount of ricin in the residue from manufacturing 50 l of biodiesel has sufficient ricin to kill about two average size people at the lowest ricin levels, and 30 at the highest levels. Imperative to suppress Ricin production by transgenesis

26 researchers, led by Federico García Maroto, have genetically altered the castor-oil plant so as to use it as a factory to produce bio lubricants.

27 Lignocellulosic materials for biofuels Biofuels production from lignocellulosic biomass needs to overcome the cell-wall plant fibers recalcitrance to enzymatic hydrolysis. Bioethanol from straw achieve only a 20% efficiency of conversion due to hinderance by lignin. Pre-treatment needed to expose the crystalline cellulose core to hydrolisis by cellulase (acid, alkali, ammonia, steam explosion…) Wheat straw & corn stover are by-products with negative value Cellulose 30-50% plant matter, produces C6 sugars (glucose) Hemicellulose 20-30% plant matter, produces C5 sugars (xylose) Lignin 15-30% biomass, glue holds plant together, no conversion

28 Energy consuming Where biotech can help?

29 Reduced lignin content can increase yields of fermentable sugars after pretreatment of plant biomass with hot acid and can also reduce or eliminate the need for this step. es. Energypoplar: progetto per aumentare la resa nel pioppo

30 Genetically engineering plants to produce cellulases and hemicellulases, and to reduce the need for pretreatment processes through lignin modification, are promising paths to solving this problem, together with other strategies, such as increasing plant polysaccharide content and overall biomass. * cultivating perennial grasses as crops such as switchgrass (Panicum virgatum) to produce biofuel is nonsense * yields can vary more than fourfold from less than two to more than nine tonnes per hectare ad es. nel pioppo si ottiene un aumento di resa di EtOH del 50% in seguito alla riduzione di pochi % di lignina Alternative più sensate: canne come Arundo donax e Miscantus con una produttività maggiore e che richiedono poco fertilizzante

31 2 nd problem: carbohydrate recovery I pentosi sono il principale componente delle emicellulose, ma il lievito comune non riesce a fermentarli. Altri organismi riescono a metabolizzarli e quindi si possono usare i loro geni.

32 Pentose metabolism Introduce the following genes (enzymes) from Pichia stipitis: – D-xylose reductase (XYL1) – xylitol dehydrogenase (XYL2) – D-xylulokinase (XYL3) Growth of this engineered yeast strain is very slow because… …Reductive step and oxidative step both require co-factors: – NADPH and NAD+ – producing NADP+ and NADH respectively Excess accumulation of NADH under oxygen limitation

33 Terzo problema: la lignina Le zone più lignificate (xilema) sono le parti più difficili da biodegradare anche da parte dei microorganismi del terreno. Il reticolo del sistema vascolare rimane intatto mentre tutta la parte del mesofillo è stata distrutta dopo pochi mesi di permanenza nel residuo umido del sottobosco. La lignina è un polimero molto complesso difficile da degradare

34 Third generation technologies: algae and cyanobacteria for biofuel production Organism survival: contaminated and taken over by indigenous local organisms Growth and lipid content: Most algae either grow or alternatively they produce lipid (fat) bodies, but not both simultaneously. Carbon dioxide enrichment Light penetration Forme di domesticazione che indeboliscono la capacità di competere: occorre fornire un vantaggio o fare colture pure

35 Quattro conti sulle superfici Attenzione che se applichiamo questi conti allItalia... Cropping area needed to replace 15% of transport fuels in the USA Di quanta terra avremmo bisogno per produrre biocarburanti come * Ethanolo e butanolo da zuccheri e amidi * diesel da oleaginose

36 * Resa media per ettaro: Mais: 10 t, * La superficie agricola utile (SAU) in Italia è di circa 13 milioni di ettari Quanta energia spendiamo per produrre un litro di biodiesel o bioetanolo? (quanto carburante si consuma per produrne un litro?) Indice EROEI (rapporto tra energia ottenuta (ricavata) e energia spesa (investita)) Nel 2006 la produzione di etanolo da canna da zucchero in Brasile è quasi di 6 mila litri per ettaro coltivato 34 milioni di veicoli italiani consumano circa mille litri ciascuno di carburante all'anno equivalente a 5.7 milioni di ettari di suolo brasiliano coltivato a canna da zucchero. Siccome la canna da zucchero non cresce in Italia, potremmo forse usare mais o barbabietola….

37 La media degli agricoltori statunitensi consuma 82 litri di carburante per ettaro di terreno per la produzione di un raccolto (senza contare l'energia per fare il concime, gli antiparassitari, i diserbanti, per fabbricare i trattori, ecc.) Il bioetanolo da cellulosa è molto più costoso di quello ottenuto dalla canna da zucchero e solo importanti progressi scientifici possono renderlo conveniente. Il costo non è dovuto alla materia prima (cellulosa) ma alla sua trasformazione in bioetanolo. I processi industriali attuali fanno costare il bioetanolo da cellulosa tre volte quello ottenuto da canna da zucchero. In Italia, produzioni medie di biodiesel da colza e girasole pari a 966 litri per ettaro (850 Kg/ha). In USA di 1029 litri per ettaro.

38 EROEI Energy Return On Energy Investment Per il biodiesel è un valore pari a circa 3, un impianto eolico (20- 30); per lestrazione e raffinazione del petrolio (10-100). Per il bioetanolo il valore del EROEI è intorno a 7-8 nel caso migliore. Per bioetanolo da barbabietola o da mais è vicino a 1. Se non addirittura meno, il chè significa che abbiamo bisogno di combustibili fossili per produrlo oltre che di sussidi economici (es. riduzione della tassa sul carburante) IN SOLDONI: la produzione di biodiesel da soia e girasole, sia quella dell'etanolo da mais, legno ed erba, consumano allo stato attuale tanta o più energia di quanta se ne possa ricavare, non tenendo conto né delle tasse, né dei danni ambientali.

39 First generation (conventional) biofuels Biofuel typeSpecific nameBiomass feedstockProduction process BioethanolConventional bioeth.Sugar beets, grainsHydrolysis & fermentation Vegetable oilPure plant oil (PPO)Oil crops (e.g. rape seed)Cold pressing/extraction Biodieselfatty acid methyl/ethyl ester Oil crops (e.g. rape seed)Cold pressing/extraction & transesterification BiodieselBiodiesel from waste FAME/FAEE Waste/cooking/fryingoil Transesterification BiogasUpgraded biogas(Wet) biomassDigestion Bio-ETBEethyl tertiary butyl ether bioethanolChemical synthesis Biofuels in the European Union A VISION FOR 2030 AND BEYOND Final draft report of the Biofuels Research Advisory Council

40 Second generation biofuels Biofuel typeSpecific nameBiomass feedstockProduction process BioethanolCellulosic bioethanolLignocellulosic materialAdvanced hydrolysis & fermentation Synthetic biofuels Biomass-to-liquids (BTL) Fischer-Tropsch (FT) diesel Synthetic (bio)diesel Biomethanol Heavier (mixed) alcohols Biodimethylether (Bio-DME) Lignocellulosic materialGasification & synthesis Biodiesel hybrid 1 st -2 nd gener. NExBTLVegetable oils and animal fatHydrogenation (refining) BiogasSNG (Synthetic Natural Gas) Lignocellulosic materialGasification & synthesis BiohydrogenUpgraded biogasLignocellulosic materialGasification & synthesis or Biological process

41 Bibliografia * Gressel (2008) Transgenics are imperative for Biofuel crops. Plant Science, 174:246-263. * Chisti Y. (2008) Biodiesel from microalgae beats bioethanol. Trends Biotechnol. 2008 Jan 21; * Schmer MR, Vogel KP, Mitchell RB, Perrin RK. (2008) Net energy of cellulosic ethanol from switchgrass. Proc Natl Acad Sci U S A. 105:464-9. * Searchinger et al., (2008) Use of U.S. Croplands for Biofuels Increases Greenhouse Gases Through Emissions from Land Use Change. Science (Feb. 2008)

42 Butanol Steen et al (2008) Metabolic engineering of Saccharomyces cerevisiae for the production of n-butanol. Microb Cell Fact. 7: 36. Atsumi et al (2008) Non-fermentative pathways for synthesis of branched-chain higher alcohols as biofuels. Nature 451:86-89. Keasling & Chou (2008) Metabolic engineering delivers next- generation biofuels. Nature Biotechnology 26:298 – 299.

43 Lignocellulosic Mielenz JR. (2001) Ethanol production from biomass: technology and commercialization status. Curr. Op. Microbiol. 4:324-329. Himmel, M.E. et al., (2007) Science, 315, 804-807. Hal A, Joel M, Elke N, et al. (2006) Engineering yeast transcription machinery for improved ethanol tolerance and production. Science 314:1565-1568. Mariam B. Sticklen (2008) Plant genetic engineering for biofuel production: towards affordable cellulosic ethanol. Nature Reviews Genetics 9:433-443 | doi:10.1038/nrg2336. Lionetti et al., (2010) Engineering the cell wall by reducing de-methyl- esterified homogalacturonan improves saccharification of plant tissues for bioconversion. PNAS 107:616-621 Edward M. Rubin (2008) Genomics of cellulosic biofuels Nature 454:841-845. (EROEI ethanol)

44 Hydrogen Rühle T, Hemschemeier A, Melis A, Happe T. (2008) A novel screening protocol for the isolation of hydrogen producing Chlamydomonas reinhardtii strains. BMC Plant Biol. 8:107. Melis A, Seibert M, Ghirardi ML. (2007) Hydrogen fuel production by transgenic microalgae. Adv Exp Med Biol. 2007;616:110-21. Review. Alper & Stephanopoulos (2009) Engineering for biofuels: exploiting innate microbial capacity or importing biosynthetic potential? Nature Reviews Microbiology 7, 715-723 Generali

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