cahen, erice 7-2014 (j. gressel) the challenges for biofuels maybe; likely a high %, for a while...
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Cahen, Erice 7-2014 (J. Gressel)
The Challenges for Biofuels
Maybe; likely a high %, for a while
Maybe by using algae, waste or marginal land ?
Lower than just fossil fuel;more sustainable
1- Food vs.Fuel dilemma
2- Can we produce the amounts needed?
3- Environmental impact
4- EROI
Try to be honest
Jonathan GresselAvi Levy & Biofuel consortiumDept. of Plant Sciences
Cahen, Erice 7-2014 (J. Gressel)
Outline•Zero Generation Biofuels
•First Generation BiofuelsThe problems – food vs. fuel
•Second Generation Biofuels- Lignocellulosics for ethanol- Oils for biodiesel
•Future
Cahen, Erice 7-2014 (J. Gressel)
Plant photosynthesisis < (<<) 1% efficient
Gust, Kramer, Moore, Moore & Vermaas, MRS Bulletin, 2008
Photosynthetic MICRO-organismscan do better, ~ 4%
The source of all biomass
Cahen, Erice 7-2014 (J. Gressel)
Traditional biofuels
India
Africa
InefficientPollutingEnvironmentally negativeCan we do better?
Cahen, Erice 7-2014 (J. Gressel)
OATS was traditional biofuel in temperate climate areas
Cultivated on ca. 20% of land
Cahen, Erice 7-2014 (J. Gressel)
Outline•Zero Generation Biofuels
•First Generation Biofuelsand the problem – food vs. fuel
•Second Generation Biofuels- Lignocellulosics for ethanol- Oils for biodiesel
•Future
Cahen, Erice 7-2014 (J. Gressel)
Monthly production and net imports of fuel ethanol in the U.S. 1993-2012. Data from EIA
Cahen, Erice 7-2014 (J. Gressel)
What are world implications?
Biofuels: Good News/Bad News to developing world
Bad news: no more cheap/free grain for food security in time of famine
Good news: No more “dumping” subsidized grain, sold below production costs
Developing world farmers can now competeand easily triple yields
Cahen, Erice 7-2014 (J. Gressel)
Biofuels: Good News/Bad News to developed world farmers
Good news to grain farmers - prices stable
Bad news to dairy/beef/chicken/hog farmers
- grain prices high…
Bad news to consumers – do not lower fuel prices, higher food costs
Cahen, Erice 7-2014 (J. Gressel)
Ethical question Europe (Japan) must ask:Is it right to support eliminating rainforests and jungles elsewhere, for Europe (Japan) to import soy/palm oil for biodiesel so that Europe (Japan) can preserve “Landscapes”?
Ethical question all must ask:Is it ethical to drive a big car on biofuel, considering effect on agriculture ?
Cahen, Erice 7-2014 (J. Gressel)
All depends on how we do the calculationsMost calculations do not include: - accounting of byproducts - recent advances - appropriate “systems boundaries”
Dale does calculations, based on ability to replace petroleum or on greenhouse gases produced per km driven;Pimentel & Patzek strongly disagree(you can do the math yourself, using the student ppt* on it)* See Total Energy Analysis of ethanol production from corn
on http://wws.weizmann.ac.il/AERI/presentations
Cahen, Erice 7-2014 (J. Gressel)
Teosinte-the progenitor
Corn ca. 1492
Hybridcorn
Domestication of corn
Cahen, Erice 7-2014 (J. Gressel)David McKay SEWTHA
Comparing Potential Biofuel Crops
Power Density [W / m2 ] (cf. to Si solar panel in Kalahari desert ~ 25 Wc / m2 )
Cahen, Erice 7-2014 (J. Gressel)
J. Goldemberg, SP
Brazil: 50% of sugar cane crop > 40% of non-diesel fuel
13.6 million (2011)
Cahen, Erice 7-2014 (J. Gressel)
Outline•Zero Generation Biofuels
•First Generation BiofuelsThe problems – food vs. fuel
•Second Generation Biofuels use agricultural wastes lignocellulosics
- Lignocellulosics for ethanol- Oils for biodiesel- Grasses
but… such crops were not domesticated for biofuels!•Future (3d generation)
Cahen, Erice 7-2014 (J. Gressel)© Materials Research Society 2012
Fig25_05
HOW ARE PLANTS BUILT?
HOW ARE PLANTS BUILT?
Cahen, Erice 7-2014 (J. Gressel)
The plant cell wall is built ofCellulose, hemicellulose and lignin—the most abundant polymers on the planet—sources of
sugars for fermentation
The plant cell wall is built ofCellulose, hemicellulose and lignin—the most abundant polymers on the planet—sources of
sugars for fermentation
Cahen, Erice 7-2014 (J. Gressel)
Switchgrass does not defy the law of conservation of matter; it grows best with …
water nitrogen fertilizer
Data of Lee et al. and Muir et al, collated in Gressel,“Genetic Glass Ceilings, Hopkins, 2007
Cahen, Erice 7-2014 (J. Gressel)
The non-degraded switchgrass residue is burnt energy for process
Contains 5-10% ash, > 60% of ash (=silica)On burning releases 50% more non-precipitable silica than coal*
Same with sugarcane bagasse/other grasses
Rice has highest silica content of grassesHow dangerous is burning rice straw?
*Blevins, L.G., and Cauley, T.H. (2005) Fine particulate formation during switchgrass/coal co-firing. Journal of Engineering for Gas Turbines and Power-Transactions of the ASME 127, 457-463
Cahen, Erice 7-2014 (J. Gressel)
Silicon not a required element for plantssmall amounts may be usefulbut not the high amounts in many
grasses,including sugarcane
Silicon transporters being discovered in plants use antisense RNA or RNA-interference to lower their levels?
Cahen, Erice 7-2014 (J. Gressel)
Process:Heat + acid pre-treatment (delignification)Enzymatically digest cellulose to sugarsFerment sugars to ethanol
But half of cellulose is unavailable 208 kg ethanol/tonne
straw
Claim: with present technology - Canadian wheat straw could provide ethanol for almost all Canadian automobiles; maybe, but …
Cahen, Erice 7-2014 (J. Gressel)
Lignin
Less lignin should higher grain yieldDespite common suggestions / myth:no direct correlation between lignin and strength
Cahen, Erice 7-2014 (J. Gressel)
Solution:Modify crop for:- less ligninor- modified ligninor - more cellulose
Should reduce the acid/heat requirement,add to yield
Cahen, Erice 7-2014 (J. Gressel)
Wheat straw as feedstock for biofuelWheat straw as feedstock for biofuel
• Abundant ~ 0.7 GTonne/year• Cheap• Does not compete with food• 1 GT could provide 10s % USA fuel/yr?
Cahen, Erice 7-2014 (J. Gressel)
Why not use 2 GTonne of free waste biomass ?
With switchgrass and miscanthus, land must be bought, dedicated to cultivation, watered, fertilized and harvested.Straw is available “free” - a by-product of grain production
Cahen, Erice 7-2014 (J. Gressel)
Straw has –ve economic/environmental value
- harbors pathogens if not burnt- requires fungicides on next crop - releases CO2 when burnt - binds nutrients while biodegrading
requires more fertilizer - pollution
-Despite being ~ 70% carbohydrate, straw has relatively low value - as animal feed (less than half
digested) or - as bioethanol source.
Cahen, Erice 7-2014 (J. Gressel)
Is using straw waste sustainable?
Soil scientists used to say “no!” because need organic matter in soil(but straw used to be burnt in Europe)
Most now agree – OK, if 20% left in field
Cahen, Erice 7-2014 (J. Gressel)
Outline•Zero Generation Biofuels•First Generation Biofuels
The problems – food vs. fuel•Second Generation Biofuels use agricultural wastes lignocellulosics
- Lignocellulosics for ethanol- Oils for biodiesel- Grasses
•Future (3d generation)Cultivate & use biofuel-dedicated crops- perennial lignocellulosics- perennial oilseeds- ALGAE
but ….. first learn from what we are doing now
Cahen, Erice 7-2014 (J. Gressel)
Oilseed rape is favored for temperate climes
Is it nice to the environment?Worldwide, oilseed rape emits ca. 9000 Tonnes
Before the ban Europe consumed 18,000 T CH3Br
Is “natural” CH3Br OK, but synthetic bad?Is it OK to double the area for biofuel?
*Gan, J., et al. (1998) Production of methyl bromide by terrestrial higher plants. Geophysical Research Letters 25, 3595-3598
Cahen, Erice 7-2014 (J. Gressel)
Palm oil poor biodiesel (by transesterification*)
congeals at low temperatures
Must catalytically crack it - or mix
Needs shorter chain length- antisense elongases
Needs more mono un-saturation- engineer desaturases
Such engineering in non-cholesterogenic “palmolive” oil
*
Cahen, Erice 7-2014 (J. Gressel)
Only by bringing genes fromelsewhere can we breach theglass ceilings
Cahen, Erice 7-2014 (J. Gressel)
LIPIDSfatty acid chains
Cutins - polymers of short fatty acids; these are unique to plants
Triglycerides - three fatty acid chains bound to a single molecule of glycerol
Waxes - polymers of long fatty acids
Triglycerides
Cahen, Erice 7-2014 (J. Gressel)
30% oil - seeds get US$140/ton (optimistic)- fruits hand-harvested- fruits dried in the shade- seeds removed by hand
Is Jatropha real or gimmick (keep the poor poor)?
Cahen, Erice 7-2014 (J. Gressel)
Some more info on Jatropha curcascommon plant names: Black vomit nut, Purge nut, etc.common oil names: hell oil, oleum infernale, etc.
Toxins: Curcin (a toxalbumin) - similar to ricinPhorbol esters - diterpenoids (alkaloids)
skin tumor promotersNo antidote known
See: http://www.inchem.org/documents/pims/plant/jcurc.htmJatropha poisoning resembling organophosphate intoxication Clin. Tox. 44 337,2006
Imagine releasing a transgenic crop with such components….
So, what to do with toxic byproducts?
Cahen, Erice 7-2014 (J. Gressel)
Websites: “curcin is heat-degradable”Reference:“degradable by prolonged autoclaving”
Curcin ~ Ricinpotent toxin
(slow death marked by vomiting &diarrhea)
Cahen, Erice 7-2014 (J. Gressel)
Castor has similar problems as JatrophaSeeds contain 0.2 to 3% ricin
1 mg/kg toxicfill car with 50 liters (13 gallons diesel)enough ricin by-product to kill 3 peopleat lowest content, 45 at highest
Ricin protein “easy” to eliminate transgenically!
Cahen, Erice 7-2014 (J. Gressel)
Oklahoma bill against castor production & transportation proposed. Why?
Castor beans contain 50% or more oil for producing biofuels.
They also contain high levels of ricin.
Edible crop producers became concerned about ricin residues in fields, equipment, storage bins, and transportion.
Jatropha banned in Western Australiaas “toxic to man and livestock”
Approach should be to ban the toxins – and stimulate DOMESTICATION
Cahen, Erice 7-2014 (J. Gressel)
- Short term – biofuels from food crops
- Medium term – biofuels from cellulosic wastes & algae
-Long term - … algae ??
and, very likely, successful biofuel feedstocks will be transgenic